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WO2020202474A1 - Tôle d'acier, flan personnalisé, produit moulé pressé à chaud, tuyau en acier et produit moulé trempé creux - Google Patents

Tôle d'acier, flan personnalisé, produit moulé pressé à chaud, tuyau en acier et produit moulé trempé creux Download PDF

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Publication number
WO2020202474A1
WO2020202474A1 PCT/JP2019/014687 JP2019014687W WO2020202474A1 WO 2020202474 A1 WO2020202474 A1 WO 2020202474A1 JP 2019014687 W JP2019014687 W JP 2019014687W WO 2020202474 A1 WO2020202474 A1 WO 2020202474A1
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WO
WIPO (PCT)
Prior art keywords
thickness
intermetallic compound
aluminum
steel sheet
steel plate
Prior art date
Application number
PCT/JP2019/014687
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English (en)
Japanese (ja)
Inventor
雄二郎 巽
富士本　博紀
泰山　正則
康信 宮▲崎▼
優貴 鈴木
Original Assignee
日本製鉄株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 日本製鉄株式会社 filed Critical 日本製鉄株式会社
Priority to PCT/JP2019/014687 priority Critical patent/WO2020202474A1/fr
Priority to JP2019530107A priority patent/JP6601598B1/ja
Publication of WO2020202474A1 publication Critical patent/WO2020202474A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/20—Deep-drawing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/12—Aluminium or alloys based thereon

Definitions

  • the present disclosure relates to steel sheets, tailored blanks, hot press molded products, steel pipes, and hollow hardened molded products.
  • Hot press molding (hereinafter, may be referred to as "hot stamping") is attracting attention as one of the techniques for molding automobile members.
  • hot stamping a steel sheet for hot pressing is heated to a high temperature and pressed in a temperature range equal to or higher than the Ar 3 transformation temperature. Further, in hot stamping, a press-formed steel sheet is rapidly cooled by heat removal from a die, and a transformation is caused at the same time as molding under a press pressure.
  • hot stamping is a technique capable of producing a press-molded product having high strength and excellent shape freezing property.
  • tailored blanks in which the end faces of at least two butt-welded steel sheets are butted and joined by laser welding, plasma welding, etc. are used for pressing. It is applied as a material. Since the tailored blank joins a plurality of butt-welded steel plates according to the purpose, the plate thickness and strength can be freely changed in one component. As a result, by using the tailored blank, it is possible to improve the functionality of the automobile member and reduce the number of parts of the automobile member. Further, by hot stamping using a tailored blank, it is possible to manufacture a high-strength stamped product in which the plate thickness, strength and the like are freely changed.
  • the tailored blank When a tailored blank is used as a press material and an automobile member is molded by hot stamping, the tailored blank is heated to, for example, a temperature range of 800 ° C to 1000 ° C. For this reason, a steel plate plated with aluminum such as Al—Si, which has a high plating boiling point, is often used for the tailored blank for hot stamping.
  • Patent Documents 1 to 5 disclose that in a steel sheet having an aluminum plating layer, an intermetallic compound layer remains and the aluminum plating layer is removed in a region around the steel sheet.
  • Patent Documents 3 and 4 disclose requirements for a welded portion to maintain a required strength in a tailored blank for hot stamping formed by butt laser welding a steel sheet having an aluminum plating layer.
  • Patent Document 5 discloses that in a steel sheet having a plating layer such as aluminum plating, the edge region of the steel sheet is subjected to laser ablation treatment.
  • a steel sheet plated with a metal mainly containing aluminum has an intermetallic compound layer provided on the base steel sheet and an aluminum-plated layer provided on the intermetallic compound layer (for example, Patent Document 1). See ⁇ 5).
  • a tailored blank provided with a steel plate having a large thickness of an intermetallic compound layer is hot stamped to produce a hot press molded product (hereinafter, may be referred to as a “hot stamp molded product”), the welded portion. Cracks or the like may occur in the hot stamped product in areas other than the above. This phenomenon is considered to be due to the large thickness of the hard and brittle intermetallic compound layer.
  • the hot stamped product is preferably manufactured using a tailored blank having a steel plate having a thin intermetallic compound layer.
  • Patent Document 1 and Patent Document 2 disclose that a steel sheet is obtained by removing the aluminum plating layer of the planned welding portion to leave an intermetallic compound layer, and using this steel sheet as a steel sheet for butt welding. Then, a tailored blank is formed in which the end faces of the region of the steel sheet in which the intermetallic compound layer remains are butt-welded, and by using this tailored blank, breakage of the weld metal in the hot stamped product can be avoided. It is disclosed.
  • Patent Document 1 and Patent Document 2 disclose that the hot stamped molded product has corrosion resistance.
  • the corrosion resistance at the welded portion is not yet sufficient after being coated on the hot stamped molded product, and further improvement of the corrosion resistance after coating has been required.
  • An object of the present disclosure is that in a steel sheet for butt welding using a steel sheet having a thin metal-to-metal compound layer, a decrease in tensile strength of a joint is suppressed, and even after coating on a hot press-formed product. It is an object of the present invention to provide a steel sheet for butt welding, which can obtain a tailored blank having excellent corrosion resistance after painting of a welded portion.
  • the present disclosure includes the following aspects.
  • the thickness of the aluminum plating layer per side of the steel sheet other than the edge is a 0 ⁇ m, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0 ⁇ m.
  • the thickness of the aluminum-plated layer per one side of at least a part of the edge of the steel sheet is a 1 ⁇ m, and the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m.
  • Equation (1) b 1 ( ⁇ m)> b 0 ( ⁇ m) Equation (2): 3 ⁇ m ⁇ b 0 ( ⁇ m) ⁇ 10 ⁇ m Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% (However, the thickness a 1 of the aluminum plating layer includes 0) ⁇ 2>
  • the base steel plate is C: 0.02% to 0.58%, Mn: 0.20% to 3.00%, Al: 0.005% to 0.20%, Ti: 0% in terms of mass%.
  • Nb 0% ⁇ 0.20%
  • V 0% ⁇ 1.0%
  • W 0% ⁇ 1.0%
  • Cr 0% ⁇ 1.0%
  • Mo 0% ⁇ 1.0%
  • Cu 0% to 1.0%
  • Ni 0% to 1.0%
  • B 0% to 0.0100%
  • Mg 0% to 0.05%
  • Ca 0% ⁇ 0.05%
  • REM 0% to 0.05%
  • Bi 0% to 0.05%
  • Si 0% to 2.00%
  • P 0% to 0.03%
  • S 0%
  • the steel plate according to ⁇ 1> which has a chemical composition of ⁇ 0.010%, N: 0% to 0.010%, and the balance: Fe and impurities.
  • ⁇ 3> The steel sheet according to ⁇ 1> or ⁇ 2>, wherein the thickness of the aluminum-plated layer at a portion other than the edge portion is 8 ⁇ m to 50 ⁇ m.
  • a tailored blank comprising a weld metal and at least two steel plate portions connected to the weld metal.
  • the at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion.
  • at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate.
  • An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in a portion other than the edge portion in this order.
  • the thickness of the aluminum-plated layer per one surface at least a part of the edge connected to the weld metal is a 1 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m.
  • the thickness of the aluminum plating layer per one side in the portion other than the edge portion connected to the weld metal is a 0 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 0 ) is b 0 ⁇ m.
  • Equation (1) b 1 ( ⁇ m)> b 0 ( ⁇ m) Equation (2): 3 ⁇ m ⁇ b 0 ( ⁇ m) ⁇ 10 ⁇ m Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% (However, the thickness a 1 of the aluminum plating layer includes 0) ⁇ 5> A hot press-formed product comprising a weld metal and at least two steel plate portions connected to the weld metal.
  • the at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion.
  • at least one steel plate portion is an edge portion connected to the weld metal
  • intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate.
  • An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in a portion other than the edge portion in this order.
  • the thickness of the aluminum-plated layer per one side at least a part of the edge connected to the weld metal is a 2 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 2 ) is b 2 ⁇ m.
  • Equation (4) 0.8% ⁇ ⁇ 2 ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) / t 1 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5%
  • Equation (5) 10 ⁇ m ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) (However, the thickness a 2 of the aluminum plating layer includes 0) ⁇ 6>
  • a steel pipe comprising a weld metal and a steel plate portion in which two peripheral edges are formed in an open tubular shape facing each other and the weld metal is connected to the two peripheral edges.
  • the steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
  • the at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate, and the portion other than the edge portion is the said.
  • An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
  • the thickness of the aluminum-plated layer per one surface at least a part of the edge connected to the weld metal is a 1 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m.
  • the thickness of the aluminum plating layer per one side in the portion other than the edge portion connected to the weld metal is a 0 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 0 ) is b 0 ⁇ m.
  • the steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
  • the at least one steel plate portion is an edge portion connected to the weld metal, and intermetallic compound layers containing at least iron and aluminum are provided on both sides of the base steel plate, and the portion other than the edge portion is the said.
  • An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
  • the thickness of the aluminum plating layer per one side at least a part of the edge connected to the weld metal is a 2 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 2 ) is b 2 ⁇ m.
  • Equation (4) 0.8% ⁇ ⁇ 2 ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) / t 1 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5%
  • Equation (5) 10 ⁇ m ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) (However, the thickness a 2 of the aluminum plating layer includes 0)
  • a decrease in tensile strength of the joint is suppressed, and even after coating on a hot press-formed product.
  • a steel sheet for butt welding which can obtain a tailored blank having excellent corrosion resistance after painting of a welded portion.
  • FIG. 1 is an enlarged schematic cross-sectional view showing an example of the periphery of the edge portion of the planned welding portion in the butt welding steel plate of the present disclosure.
  • FIG. 2 is an enlarged schematic cross-sectional view showing another example around the edge portion of the planned welding portion in the butt weld steel sheet of the present disclosure.
  • FIG. 3 is an enlarged schematic perspective view showing another example around the edge portion of the planned welding portion in the butt weld steel sheet of the present disclosure.
  • FIG. 4 is an enlarged cross-sectional photograph showing an example of an untreated edge portion.
  • FIG. 5 is an enlarged cross-sectional photograph showing an example of an edge portion of a planned welding portion in the butt welding steel plate of the present disclosure.
  • FIG. 6 is a schematic view showing an example of a cross section of a welded portion in the tailored blank of the present disclosure.
  • FIG. 7 is an enlarged cross-sectional photograph of the tailored blank formed through the untreated edges of the two butt-welded steel plates in the vicinity of the weld metal.
  • FIG. 8 is an enlarged cross-sectional photograph of the tailored blank formed in the vicinity of the weld metal of the two butt-welded steel sheets of the present disclosure formed through the edge of the planned welding portion.
  • FIG. 9 is a schematic schematic view showing an example of the steel pipe of the present disclosure.
  • FIG. 10 is a schematic schematic view showing another example of the steel pipe of the present disclosure.
  • the steel sheet of the present disclosure indicates a steel sheet that forms a tailored blank by butt welding with another steel sheet, and will be referred to as a butt welding steel sheet below.
  • the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
  • the content of the component (element) may be referred to as "C amount" in the case of the content of C (carbon), for example.
  • the content of other elements may be described in the same manner.
  • the term "process” is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. ..
  • the term “base steel sheet” refers to a steel sheet before aluminum plating, and represents a steel sheet in a state before the intermetallic compound layer and the aluminum plating layer are provided.
  • the term “intermetallic compound layer” refers to an intermetallic compound layer formed between the base steel sheet and the aluminum plating when aluminum plating is applied to both surfaces of the base steel sheet.
  • the term “aluminum plating layer” refers to a region of aluminum plating applied on a base steel sheet excluding an intermetallic compound layer.
  • the term “cross section” of a steel sheet for butt welding refers to a cross section cut in the plate thickness direction. Specifically, in FIG.
  • the plate thickness direction of the butt-welding steel plate is Z
  • the direction in which the planned welding portion extends is X.
  • the direction orthogonal to the direction Z and the direction X is defined as Y.
  • the cross section means a cross section cut by the YZ plane.
  • the X, Y, and Z directions shown in FIG. 1 indicate the same directions as the X, Y, and Z directions shown in FIG.
  • the term "edge" of a steel sheet for butt welding is a region located around the steel sheet for butt welding, which is the maximum, and is the edge of the steel sheet as a steel sheet for butt welding. Represents an area within 5 mm from.
  • the "edge" of the butt-welding steel sheet represents a position where the end face is in contact with the surface of the butt-welding steel sheet facing in the plate thickness direction (that is, the surface of the steel sheet).
  • the term "end face” of a steel sheet for butt welding refers to a surface in which the surface in the plate thickness direction is exposed between the surfaces facing each other on the plate thickness direction side.
  • the terms "a portion other than the edge portion” and "a region other than the edge portion” of the butt-welding steel sheet refer to a region excluding the edge portion of the steel sheet as a butt-welding steel sheet.
  • the "part other than the edge portion” and the “region other than the edge portion” represent the central portion of the butt welding steel plate, and in the minimum case, the opposite width of the butt welding steel plate (that is, from the facing end faces). It occupies the area excluding 5 mm ⁇ 2 from the length to the end face).
  • the term "welded portion” refers to a region including a weld metal and a portion around which the increase in thickness of the intermetallic compound layer is saturated.
  • the butt welding steel sheet of the present disclosure an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order. That is, the butt welding steel sheet of the present disclosure is formed from such an aluminum-plated steel sheet. Further, in the butt welding steel sheet of the present disclosure, the thickness of the aluminum plating layer per one side in the portion other than the edge of the butt welding steel sheet is a 0 ⁇ m, and the thickness of the intermetallic compound layer (IMC 0 ) is b 0.
  • the thickness of the aluminum-plated layer per one side of at least a part of the edge of the butt-welding steel sheet is a 1 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m.
  • Equation (1) b 1 ( ⁇ m)> b 0 ( ⁇ m) Equation (2): 3 ⁇ m ⁇ b 0 ( ⁇ m) ⁇ 10 ⁇ m Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5%
  • the aluminum-plated steel sheet applied as the butt-welding steel sheet of the present disclosure has a base steel sheet and aluminum-plated layers provided on both sides of the base steel sheet. Further, an intermetallic compound layer (IMC 0 ) containing iron and aluminum is provided between the base steel plate and the aluminum plating layer. Further, at least a part of the edge portion of the butt welding steel plate has the intermetallic compound layer (IMC 1 ) provided on both surfaces of the base steel plate.
  • the intermetallic compound layer (IMC 1) thickness is greater than the thickness of the intermetallic compound layer in the region other than the edge (IMC 0) (i.e., to satisfy the above equation (1).).
  • the thickness of the intermetallic compound layer (IMC 0 ) in the region other than the edge of the butt welding steel sheet is 3 ⁇ m to 10 ⁇ m (that is, the above formula (2) is satisfied). Then, the relationship of the above formula (3) is satisfied at the edge portion where the intermetallic compound layer (IMC 1 ) is formed.
  • the plate thickness t 0 of the base steel plate is a value converted to ⁇ m. When there is no aluminum plating layer on the intermetallic compound layer (IMC 1 ), a 1 is 0 (zero) ⁇ m.
  • the shape of the steel plate for butt welding is not particularly limited.
  • a hot stamped product obtained by applying a steel plate plated with aluminum as a steel plate for butt welding and hot stamping a tailored blank obtained by butt welding the end faces of the edges of the steel plate for butt welding is known.
  • Patent Documents 1 to 5 For example, when a steel plate with an excessively thick intermetallic compound layer is used as a steel plate for butt welding to obtain a tailored blank and then a hot stamped product is obtained, the aluminum plating layer and the intermetallic compound are formed in areas other than the welded portion. Cracks and chips may occur in the layer.
  • the intermetallic compound layer is hard and brittle.
  • the too thick intermetallic compound layer existing in the base steel sheet cannot withstand the load during hot stamping, and as a result, cracks and chips occur. If the cracks and chips propagate to the base steel sheet, the corrosion resistance of the base steel sheet is lowered. Therefore, it is preferable that the thickness of the intermetallic compound layer is not too thick in the region other than the welded portion.
  • the thickness of the intermetallic compound layer is not too thin.
  • the interfacial roughness between the intermetallic compound layer and the aluminum plating layer tends to decrease.
  • the aluminum component of the aluminum plating layer melted by butt welding and heating by hot stamping becomes easy to move.
  • the aluminum component of the molten aluminum plating layer moves, the aluminum plating layer hangs down in hot stamping, and the uniformity of the thickness decreases.
  • the thickness of the intermetallic compound layer is not too thin.
  • Patent Document 1 and Patent Document 2 in order to avoid breakage of the weld metal, as described above, butt welding in which the aluminum plating layer of the welded portion to be welded is removed and the intermetal compound layer remains.
  • a tailored blank is disclosed in which a steel plate for butt welding is used and a planned welding portion of the steel plate for butt welding is butt welded. Then, in the hot stamp molded product using this tailored blank, the decrease in welding strength can be suppressed.
  • the butt-welding steel sheets disclosed in Patent Documents 1 and 2 have an aluminum plating (Al—Si metal plating) layer provided on the base steel sheet, and a metal is provided between the base steel sheet and the aluminum plating layer. An inter-compound layer is formed. Since the intermetallic compound layer is relatively fragile, an inhibitor is added to the molten metal bath to limit the growth of the intermetallic compound layer.
  • the aluminum plating layer is as thick as 20 ⁇ m, while the intermetallic compound layer is as thin as 5 ⁇ m.
  • the aluminum plating layer is removed from the planned welded portion of the butt-welded steel sheet by a brush or laser ablation before the tailored blank is manufactured.
  • a thin intermetallic compound layer remains.
  • the corrosion resistance of the welded portion after painting becomes inferior due to the thin thickness of the intermetallic compound layer.
  • the thickness of the intermetallic compound layer is thin, the amount of aluminum mixed in the weld metal is small. Therefore, in the butt welding steel sheets disclosed in Patent Document 1 and Patent Document 2, scale (iron compound) is likely to be generated on the surface of the weld metal by being heated to a high temperature at the time of hot stamping. As a result, when the hot stamp molded product is painted, the adhesiveness of the paint is lowered, and the corrosion resistance after painting at the welded portion is inferior.
  • the butt welding steel sheet of the present disclosure at least an intermetallic compound layer (IMC 1 ) is formed on both sides of the base steel sheet at least a part of the edge portion of the butt welding steel sheet. Then, the thickness of the intermetallic compound layer (IMC 1) is thicker than the thickness of the intermetallic compound layer formed in a region other than the edge (IMC 0). Therefore, due to the thickness of the intermetallic compound layer (IMC 1 ) formed in at least a part of the edge portion, the butt weld steel sheet of the present disclosure is formed even after being coated on a hot stamped product. It is considered that the welded part has excellent corrosion resistance.
  • the steel sheet for butt welding of the present disclosure has a thick intermetallic compound layer (IMC 1 ) formed at least a part of the edge of the steel sheet, aluminum is contained in the weld metal after butt welding. It is mixed moderately. Therefore, the generation of scale is suppressed on the surface of the weld metal, so that the chemical conversion treatment property is improved and the adhesiveness of the paint is improved. As a result, it is considered that the steel sheet for butt welding of the present disclosure is excellent in corrosion resistance after coating of the welded portion even after coating on the hot stamped molded product.
  • IMC 1 intermetallic compound layer
  • the butt-welded steel sheet of the present disclosure is made of aluminum having no aluminum plating layer or a reduced thickness on a thick intermetallic compound layer (IMC 1 ) formed at a planned welding portion at the edge of the steel sheet. There is a plating layer. Therefore, in the butt-welding steel sheet of the present disclosure, when the end faces of the edges having the intermetallic compound layer (IMC 1 ) are butt-welded and welded, a large amount of aluminum is mixed in the weld metal due to the aluminum plating layer. Is suppressed.
  • the thickness of the intermetallic compound layer (IMC 1) is larger than the thickness of the intermetallic compound layer (IMC 0), aluminum-plated layer is formed in a region other than the edge, to melt at butt welding Movement is suppressed. Therefore, the amount of aluminum mixed in the weld metal is suppressed. That is, an appropriate amount of aluminum due to the aluminum plating layer is mixed with the weld metal. As a result, the weld metal suppresses the decrease in hardenability, so that the mechanical strength of the joint can be ensured.
  • the thickness of the intermetallic compound layer (IMC 0 ) is thin, cracks and omissions of the aluminum plating layer and the intermetallic compound layer (IMC 0 ) during hot stamping are suppressed. .. As a result, the deterioration of corrosion resistance in the region other than the edge of the hot stamped product is suppressed.
  • the butt welding steel sheet of the present disclosure has a numerical range of 0.8% to 3.5% in the above-mentioned formula (3).
  • the numerical value of the formula (3) is in this range, aluminum is appropriately mixed in the weld metal. Therefore, the decrease in mechanical strength of the hot stamped molded product is suppressed, and the decrease in corrosion resistance after painting is suppressed.
  • the base steel sheet is a steel sheet before aluminum plating.
  • the base steel sheet may be obtained by a usual method and is not particularly limited.
  • the base steel plate may be either a hot-rolled steel plate or a cold-rolled steel plate.
  • the thickness of the base steel sheet may be set according to the purpose, and is not particularly limited.
  • the thickness of the base steel sheet is such that the total thickness of the steel sheet after the aluminum plating layer is provided is 0.8 mm to 4 mm, and further, the thickness is 1 mm to 3 mm. The thickness can be mentioned.
  • the base steel sheet it means various properties related to mechanical deformation and fracture such as high mechanical strength (for example, tensile strength, yield point, elongation, drawing, hardness, impact value, fatigue strength, etc.). It is preferable to use a steel plate formed so as to have.
  • Examples of the preferable chemical composition of the base steel sheet include the following chemical compositions.
  • C 0.02% to 0.58%, Mn: 0.20% to 3.00%, Al: 0.005% to 0.20%, Ti: 0% to 0.20%, Nb: 0% to 0.20%, V: 0% to 1.0%, W: 0% to 1.0%, Cr: 0% to 1.0%, Mo: 0% to 1.0%, Cu: 0% to 1.0%, Ni: 0% to 1.0%, B: 0% to 0.0100%, Mg: 0% to 0.05%, Ca: 0% to 0.05%, REM: 0% to 0.05%, Bi: 0% to 0.05%, Si: 0% to 2.00%, P: 0.03% or less, S: 0.010% or less, N: 0. It has a chemical composition of 010% or less, and the balance: Fe and impurities.
  • % indicating the content of the component (element) means “mass%”.
  • C (C: 0.02% to 0.58%) C is an important element that enhances the hardenability of the base steel sheet and mainly determines the strength after quenching. Further lowering the three points A, it is an element which promotes lowering the quenching temperature. If the amount of C is less than 0.02%, the effect may not be sufficient. Therefore, the amount of C is preferably 0.02% or more. On the other hand, when the amount of C exceeds 0.58%, the toughness of the hardened portion is significantly deteriorated. Therefore, the amount of C is preferably 0.58% or less. It is preferably 0.45% or less.
  • Mn is a very effective element for enhancing the hardenability of the base steel sheet and stably securing the strength after quenching. If the amount of Mn is less than 0.20%, the effect may not be sufficient. Therefore, the amount of Mn is preferably 0.20% or more. It is preferably 0.80% or more. On the other hand, if the amount of Mn exceeds 3.00%, not only the effect is saturated, but also it may be difficult to secure stable strength after quenching. Therefore, the amount of Mn is preferably 3.00% or less. It is preferably 2.40% or less.
  • Al functions as a deoxidizing element.
  • Al has an effect of reducing oxide-based inclusions that adversely affect the mechanical strength of the base steel sheet. If the amount of Al is less than 0.005%, it may be difficult to obtain the effect of the above action. Therefore, the amount of Al is preferably 0.005% or more. On the other hand, if the amount of Al exceeds 0.20%, the effect of the above action is saturated, which is disadvantageous in terms of cost. Therefore, the amount of Al is preferably 0.20% or less.
  • Ti, Nb, V, and W are elements that promote mutual diffusion of Fe and Al in the aluminum-plated layer and the base steel sheet. Therefore, at least one of Ti, Nb, V, and W may be contained in the base steel sheet. However, if 1) the amount of Ti and Nb exceeds 0.20%, or 2) the amount of V and W exceeds 1.0%, the effect of the above action is saturated, which is disadvantageous in terms of cost. Therefore, the Ti amount and the Nb amount are often 0.20% or less, and the V amount and the W amount are preferably 1.0% or less.
  • the Ti amount and Nb amount are preferably 0.15% or less, and the V amount and W amount are preferably 0.5% or less.
  • the lower limit of the Ti amount and the Nb amount is 0.01% or more, and the lower limit values of the V amount and the W amount are 0.1% or more.
  • Cr, Mo, Cu, Ni, and B are elements that are effective in enhancing the hardenability of the base steel sheet and stably ensuring the strength after quenching. Therefore, one or more of these elements may be contained. However, even if the contents of Cr, Mo, Cu, and Ni are more than 1.0% and the amount of B is more than 0.0100%, the above effect is saturated and it is disadvantageous in terms of cost. Therefore, the content of Cr, Mo, Cu, and Ni is preferably 1.0% or less.
  • the amount of B is preferably 0.0100% or less, preferably 0.0080% or less. In order to obtain the above effect more reliably, it is preferable that the content of Cr, Mo, Cu, and Ni is 0.1% or more, and the content of B is 0.0010% or more.
  • Ca, Mg, and REM have the effect of refining the morphology of inclusions in steel and preventing the occurrence of cracks during hot press forming due to inclusions. Therefore, one or more of these elements may be contained. However, when added in excess, the effect of miniaturizing the morphology of inclusions in steel is saturated, which only increases the cost. Therefore, the Ca amount is preferably 0.05% or less, the Mg amount is 0.05% or less, and the REM amount is 0.05% or less. In order to obtain the effect of the above action more reliably, it is preferable to satisfy any one of Ca amount of 0.0005% or more, Mg amount of 0.0005% or more, and REM amount of 0.0005% or more.
  • REM refers to a total of 17 elements of Sc, Y and lanthanoid, and the content of REM refers to the total content of these elements.
  • lanthanoids they are industrially added in the form of misch metal.
  • Bi is an element that becomes a solidified nucleus in the solidification process of molten steel and has an effect of suppressing segregation (for example, Mn) into the dendrite secondary arm spacing by reducing the dendrite secondary arm spacing. Therefore, Bi may be contained.
  • Mn segregation
  • Bi for a steel sheet that often contains a large amount of Mn, such as a steel sheet for hot pressing, Bi has an effect of suppressing deterioration of toughness due to segregation of Mn. Therefore, it is preferable that such a steel grade contains Bi.
  • Bi even if Bi is contained in an amount of more than 0.05%, the effect of the above action is saturated, resulting in an increase in cost.
  • the amount of Bi is set to 0.05% or less. It is preferably 0.02% or less.
  • the Bi amount is preferably 0.0002% or more. More preferably, it is 0.0005% or more.
  • Si 0% to 2.00%
  • Si is a solid solution strengthening element and can be effectively utilized up to 2.00%.
  • the amount of Si is preferably 2.00% or less.
  • the preferred upper limit is 1.40% or less, more preferably 1.00% or less.
  • the lower limit is not particularly limited, and 0.01% or more is preferable in order to obtain the effect of the above action more reliably.
  • P is an element contained as an impurity. If P is contained in excess, the toughness of the base steel sheet tends to decrease. Therefore, the amount of P is preferably 0.03% or less. It is preferably 0.01% or less. The lower limit of the amount of P does not need to be specified.
  • the amount of P may be 0% or more than 0%. From the viewpoint of cost, it is preferably 0.0002% or more.
  • S is an element contained as an impurity and has an action of forming MnS and embrittlement of the base steel sheet. Therefore, the amount of S is preferably 0.010% or less. A more desirable amount of S is 0.004% or less. The lower limit of the amount of S does not need to be specified.
  • the amount of S may be 0% or more than 0%. From the viewpoint of cost, it is preferably 0.0002% or more.
  • N is an element contained as an impurity that forms inclusions in steel and deteriorates toughness after hot press forming. Therefore, the amount of N is preferably 0.010% or less. It is preferably 0.008% or less, more preferably 0.005% or less. The lower limit of the amount of N does not need to be specified. The amount of N may be 0% or more than 0%. From the viewpoint of cost, it is preferably 0.0002% or more.
  • the rest are Fe and impurities.
  • the impurity refers to a component contained in raw materials such as ore and scrap, or a component mixed in the manufacturing process, which is not intentionally contained in the base steel sheet.
  • the aluminum plating layer is formed on both sides of the base steel plate.
  • the method for forming the aluminum plating layer is not particularly limited.
  • the aluminum plating layer may be formed on both sides of the base steel sheet by a hot dip galvanizing method.
  • the hot-dip galvanizing method is a method in which a base steel sheet is immersed in a molten metal bath containing mainly aluminum, and aluminum plating is applied to both surfaces of the base steel sheet.
  • the aluminum plating layer is a plating layer containing aluminum as a main component, and may contain 50% by mass or more of aluminum. Depending on the purpose, it may contain an element other than aluminum (for example, Si), or may contain impurities that are mixed in during the manufacturing process.
  • the aluminum-plated layer may contain, for example, 5% to 12% of Si (silicon) in mass%, and the balance may have a chemical composition consisting of aluminum and impurities. Further, it may contain 5% to 12% of Si (silicon) and 2% to 4% of Fe (iron) in mass%, and the balance may have a chemical composition consisting of aluminum and impurities.
  • Si is contained in the above range, deterioration of workability and corrosion resistance can be suppressed. Moreover, the thickness of the intermetallic compound layer can be reduced.
  • the thickness of the aluminum-plated layer provided in the region other than the edge of the butt-welding steel sheet is not particularly limited, and for example, the thickness is often in the range of 8 ⁇ m to 50 ⁇ m, and may be in the range of 8 ⁇ m to 35 ⁇ m. It is preferably in the range of 15 ⁇ m to 30 ⁇ m, more preferably.
  • the thickness of the aluminum-plated layer represents the average value of the thickness in the region other than the edge of the butt-welding steel plate.
  • the aluminum plating layer prevents corrosion of the steel plate for butt welding. Further, when the tailored blank is processed by hot press molding, the aluminum-plated layer suppresses the generation of scale (iron compound) due to surface oxidation even when heated to a high temperature. Further, the aluminum plating layer has a higher boiling point and melting point than the plating coating with an organic material or the plating coating with another metal material (for example, a zinc material). Therefore, when molding by hot press molding, the coating does not evaporate, so that the surface protection effect is high.
  • the aluminum plating layer can be alloyed with iron (Fe) in the base steel sheet by heating during hot dip galvanizing and hot press forming. Therefore, the aluminum-plated layer is not always formed of a single layer having a constant component composition, but includes a partially alloyed layer (alloy layer).
  • the intermetallic compound layer is a layer formed at the boundary between the base steel plate and the aluminum plating layer when aluminum plating is provided on the base steel plate. Specifically, the intermetallic compound layer is formed by the reaction of iron (Fe) of the base steel sheet with a metal containing aluminum (Al) in a molten metal bath containing aluminum as a main component.
  • the intermetallic compound layer is mainly formed of a plurality of types of compounds represented by Fe x Al y (x and y represent 1 or more).
  • the aluminum plating layer contains Si (silicon), it is formed of a plurality of kinds of compounds represented by Fe x Al y and Fe x Al y Si z (x, y, z represent 1 or more).
  • the content common to the intermetallic compound layer (IMC 1 ) formed in at least a part of the edge portion and the intermetallic compound layer (IMC 0 ) is simply referred to as an intermetallic compound layer. ..
  • the thickness of the intermetallic compound layer (IMC 0 ) formed in the region other than the edge of the butt welding steel sheet is in the range of 3 ⁇ m to 10 ⁇ m (that is, the above formula (2) is satisfied).
  • the thickness of the intermetallic compound layer (IMC 0 ) is preferably in the range of 4 ⁇ m to 8 ⁇ m.
  • the thickness of the intermetallic compound layer (IMC 1 ) is efficiently improved.
  • the thickness of the intermetallic compound layer (IMC 0 ) is 3 ⁇ m or more, the movement of the aluminum plating layer is less likely to occur.
  • the uniformity of the thickness of the aluminum plating layer is ensured by suppressing the sagging of the aluminum plating layer.
  • an intermetallic compound layer (IMC 1 ) is formed on both sides of the base steel sheet at least a part of the edge portion.
  • the aluminum plating layer may be removed or the aluminum plating layer having a reduced thickness may remain on the intermetallic compound layer (IMC 1 ) formed at the edge portion.
  • the thickness of the intermetallic compound layer (IMC 1) is greater than the thickness of the intermetallic compound layer in the region other than the edge (IMC 0).
  • the intermetallic compound layer (IMC 1 ) is formed at the edge of the planned weld.
  • the intermetallic compound layer (IMC 1 ) provided at least a part of the edge portion is not particularly limited as long as it is provided at the edge portion of the planned welding portion among the edge portions provided in the butt welding steel plate.
  • the intermetallic compound layer (IMC 1 ) may be provided at the edge of the planned welding portion in the following manners. 1) An embodiment in which the entire region is within 5% of the end face of the butt welding steel plate with respect to the length from the opposite end face to the end face, and is provided along the edge of the butt welding steel plate. 2) A part of the area within 5% of the end face of the butt welding steel plate with respect to the length from the opposite end face to the end face, and is provided along the edge of the butt welding steel plate. Aspect.
  • the aspect provided along the entire length of the edge of the butt welding steel plate.
  • the aspect is provided along only the length corresponding to the portion to be butt-welded in the total length of the edge of the butt-welding steel plate.
  • An embodiment provided in a region excluding the edge of the butt-welding steel sheet within a range of 5% or less from the end face of the butt-welding steel sheet with respect to the length from the opposite end face to the end face.
  • the intermetallic compound layer (IMC 1 ) is not formed at the edge portion that is not scheduled to be welded, and the intermetallic compound layer (IMC 0 ) may remain.
  • the edge portion that is not scheduled to be welded has the same structure as the region other than the edge portion.
  • an intermetallic compound layer (IMC 1 ) may be formed on the edge portion that is not scheduled to be welded, if necessary.
  • the edge of the planned weld represents the edge on which butt welding is performed to form a tailored blank.
  • An edge that is not planned to be welded represents an edge that is not planned to be butt welded to form a tailored blank.
  • the thickness of the intermetallic compound layer (IMC 1) is preferably in the range of 5 ⁇ m to 30 ⁇ m, preferably in the range of 8 ⁇ m to 25 ⁇ m, and more preferably in the range of 8 ⁇ m to 18 ⁇ m. ..
  • the thickness of the intermetallic compound layer (IMC 1 ) When the thickness of the intermetallic compound layer (IMC 1 ) is 5 ⁇ m or more, the corrosion resistance of the welded portion after painting becomes more excellent. On the other hand, when the thickness of the intermetallic compound layer (IMC 1 ) is 30 ⁇ m or less, the decrease in strength of the weld metal is likely to be suppressed.
  • the portion where the thickness of the intermetallic compound layer (IMC 1 ) gradually increases from the thickness of the intermetallic compound layer (IMC 0 ) is excluded from the measurement of the thickness of the intermetallic compound layer (IMC 1 ). In other words, the thickness of the intermetallic compound layer (IMC 1) represents the thickness of a portion increase from the thickness of the intermetallic compound layer (IMC 0) is saturated.
  • the thickness of the intermetallic compound layer (IMC 1) is intermetallic compound layer as a (IMC 0) (the thicknesses of / IMC 0 of IMC 1) thickness ratio to the thickness of the thickness ratio exceeds 1.
  • This thickness ratio is preferably 1.2 or more, more preferably 1.5 or more.
  • the upper limit of the thickness ratio is not particularly limited, and examples thereof include 7 or less, and 5 or less.
  • FIG. 1 is an enlarged schematic cross-sectional view showing an example of the periphery of the edge portion of the planned welding portion in the butt welding steel plate of the present disclosure.
  • FIG. 2 is an enlarged schematic cross-sectional view showing another example around the edge portion of the planned welding portion in the butt welding steel plate of the present disclosure.
  • the butt-welding steel sheet 110 has an edge portion 22 of a planned welding portion and a region 26 other than the edge portion.
  • the intermetallic compound layer (IMC 0 ) 16A is provided on the base steel plate 12, and the aluminum plating layer 14A is provided on the intermetallic compound layer (IMC 0 ) 16A.
  • the intermetallic compound layer (IMC 1 ) 16B is provided on the base steel plate 12, and the aluminum plating layer 14B is provided on the intermetallic compound layer (IMC 1 ) 16B. It is provided. The thickness of the aluminum-plated layer 14B is reduced as compared with the aluminum-plated layer 14A provided in the region 26 other than the edge portion. Further, in the butt welding steel plate 120 shown in FIG.
  • the region 26 other than the edge portion is the same as the region 26 other than the edge portion in the butt welding steel plate 110 shown in FIG.
  • the intermetallic compound layer (IMC 1 ) 16B is provided on the base steel plate 12, and the aluminum plating layer 14A is removed.
  • FIG. 4 is an enlarged cross-sectional photograph showing an example of an untreated edge portion.
  • FIG. 5 is an enlarged cross-sectional photograph showing an example of an edge portion of a planned welding portion in the butt welding steel plate of the present disclosure.
  • an intermetallic compound layer (IMC 0 ) 16C is provided on the base steel plate 12, and an aluminum plating layer 14C is provided on the intermetallic compound layer (IMC 0 ) 16C. ing. Since the edge portion shown in FIG.
  • the thickness of the intermetallic compound layer (IMC 0 ) 16C is about the same as the thickness of the intermetallic compound layer in the region other than the edge portion.
  • an intermetallic compound layer (IMC 1 ) 16B is formed on the base steel plate 12. Therefore, as shown in FIG. 5, the thickness of the intermetallic compound layer (IMC 1 ) 16B at the edge portion of the butt-welded steel sheet of the present disclosure is thicker than that of the untreated edge portion shown in FIG. You can see that. That is, from the enlarged cross-sectional photographs shown in FIGS.
  • the thickness of the intermetallic compound layer (IMC 1 ) at the edge of the planned welding portion is the thickness between the metals in the region other than the edge. It can be seen that the thickness is larger than the thickness of the compound layer (IMC 0 ).
  • the butt welding steel sheet of the present disclosure has an intermetallic compound layer (IMC 1 ) having a thickness larger than the thickness of the above-mentioned intermetallic compound layer (IMC 0 ) on both sides of the base steel sheet at least a part of the edge portion. Is formed. At the edge where the intermetallic compound layer (IMC 1 ) is formed, only the intermetallic compound layer (IMC 1 ) may be provided. Further, an aluminum plating layer having a reduced thickness may be provided on the intermetallic compound layer (IMC 1 ) as long as the mechanical strength of the weld metal does not decrease. In particular, the presence of an aluminum-plated layer in addition to the intermetallic compound layer (IMC 1 ) is permitted as long as the following formula (3) is satisfied.
  • the steel sheet for butt welding of the present disclosure has a thickness of a 1 ( ⁇ m) per side of the aluminum plating layer at the edge where the intermetallic compound layer (IMC 1 ) is formed, and one side of the intermetallic compound layer (IMC 1 ).
  • the thickness per area is b 1 ( ⁇ m) and the thickness of the base steel plate is t 0 ( ⁇ m)
  • the plate thickness represents the thickness of the base steel plate measured in a region other than the edge portion.
  • the plate thickness of the formula (3) is converted into ⁇ m and substituted. Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5%
  • the intermetallic compound layer on (IMC 1) 16B if it has an aluminum-plated layer 14B, a 1 indicates the thickness of the aluminum layer 14B ( ⁇ m).
  • b 1 indicates the thickness ( ⁇ m) of the intermetallic compound layer (IMC 1 ) 16B.
  • FIG. 2 when the aluminum plating layer on the intermetallic compound layer (IMC 1 ) 16B is removed (that is, when the aluminum plating layer 14B is not provided), a 1 is 0 (that is, when the aluminum plating layer 14B is not provided). ⁇ m), where b 1 indicates the thickness ( ⁇ m) of the intermetallic compound layer (IMC 1 ) 16B.
  • b 1 is synonymous with the thickness of the above-mentioned intermetallic compound layer (IMC 1 ).
  • a 1 represents the thickness of the portion excluding the portion where the thickness of the aluminum layer in the region other than the edge gradually decreases. That, a 1 represents the thickness of the portion decrease in thickness of the aluminum layer is saturated.
  • a 1 becomes 0 (zero) ( ⁇ m). However, it decreases until the aluminum plating layer disappears, and if the aluminum plating layer exists again (for example, when the aluminum plating layer exists away from the region other than the edge), the aluminum that exists again the thickness of the plating layer and a 1.
  • the value represented by the above formula (3) exceeds 3.5%, the average aluminum concentration in the weld metal (molten solidification region after welding) increases, so that soft parts that are not hardened are generated and become hot. The mechanical strength of stamped products tends to decrease.
  • the value represented by the above formula (3) is less than 0.8%, the corrosion resistance of the welded portion after painting tends to decrease.
  • the value represented by the above formula (3) is preferably in the range of 1.0% to 3.5%, more preferably in the range of 1.6% to 3.3%, and preferably in the range of 2.0% to 3.0%. The range is even more preferred.
  • “per one side” represents the measured value of the thickness on one side.
  • intermetallic compound layer (IMC 1 ) formed at the edge and the aluminum plating layer existing on the intermetallic compound layer (IMC 1 ) are on one side and satisfy the formula (3). Good. It is preferable that both sides satisfy the formula (3). Further, on the intermetallic compound layer (IMC 1), if the aluminum plating layer does not exist, it is substituted into a 1 of the formula (3) 0 (zero).
  • the thickness a 1 ( ⁇ m) per side of the aluminum plating layer and the thickness b 1 ( ⁇ m) per side of the intermetallic compound layer (IMC 1 ) can be measured by measuring the aluminum plating layer and the intermetallic compound layer (IMC 1 ) described later. The procedure may be the same as for IMC 1 ).
  • the intermetallic compound layer (IMC 1 ) formed on at least a part of the edge portion of the butt-welding steel sheet is formed on the edge portion of the planned welding portion of the butt-welding steel sheet.
  • the width of the intermetallic compound layer (IMC 1 ) formed at the edge of the planned welding portion is preferably 0.2 mm to 5.0 mm on average. When used for laser welding, it is preferably 0.6 mm to 1.5 mm. When used for plasma welding, it is preferably 1.0 mm to 4.0 mm.
  • the width of the intermetallic compound layer formed at the edge of the butt welding steel plates (IMC 1) is an average value of values obtained by measuring the width at the position of the five locations of the intermetallic compound layer (IMC 1).
  • the specific measurement method is as follows. First, five measurement samples including a cross section in which the entire width of the intermetallic compound layer (IMC 1 ) formed on the edge of the butt welding steel plate can be observed are collected. That is, the measurement sample is a metal having a length L of an intermetallic compound layer (IMC 1 ) formed in a direction along the edge of the butt-welding steel plate (in the X direction (direction in which the planned welding portion extends) shown in FIG. 1).
  • the intermetallic layer (IMC 1 ) length L) is collected from the vicinity of the central position at 5 locations divided into 5 equal parts.
  • the length L of the intermetallic compound layer (IMC 1 ) formed in the X direction is divided into five equal parts.
  • a measurement sample is collected from a position passing near the central position C along the direction of the arrow F1.
  • the steel sheet for butt welding is cut so that the cross section is exposed, embedded in resin, polished, and the cross section is enlarged with an optical microscope.
  • the distance from the edge of the steel plate for butt welding to the portion where the increase from the thickness of the intermetallic compound layer (IMC 0 ) is saturated is calculated.
  • the same measurement is performed for each sample for measurement collected, and the average value measured at five points is defined as the width of the intermetallic compound layer (IMC 1 ).
  • W shown in FIG. 1 is the width of the intermetallic compound layer (IMC 1 ) formed at the edge portion.
  • this aluminum-plated layer is the intermetallic compound layer (IMC 1 ). It may remain in the entire area above. However, since the aluminum-plated layer causes a decrease in static tensile strength, it is preferable that the residual amount is small.
  • the aluminum-plated layer on the intermetallic compound layer (IMC 1 ) is at the distance from the edge of the butt-welding steel sheet to the portion where the increase from the thickness of the intermetallic compound layer (IMC 0 ) is saturated. On the other hand, it is preferable that it remains at a rate of less than 50%.
  • the ratio of the remaining aluminum plating layer is preferably 30% or less, more preferably 10% or less.
  • the confirmation of the base steel plate, the intermetallic compound layer, and the aluminum plating layer, and the measurement of the thickness of the intermetallic compound layer and the aluminum plating layer are performed by the following methods.
  • the steel sheet for butt welding is cut so as to be exposed in the direction orthogonal to the edge (that is, the Y direction shown in FIG. 1) and embedded in the resin.
  • Polish the cross section of the embedded steel plate for butt welding is line-analyzed from the surface of the steel sheet for butt welding to the base steel sheet by an electron probe microanalyzer (FE-EPMA), and the aluminum concentration and the iron concentration are measured.
  • the aluminum concentration and the iron concentration are preferably average values measured three times.
  • the measurement conditions are an accelerating voltage of 15 kV, a beam diameter of about 100 nm, an irradiation time of 1000 ms per point, and a measurement pitch of 60 nm.
  • the measurement distance may be such that the thickness of the plating layer can be measured, and is, for example, 30 ⁇ m to 80 ⁇ m in the plate thickness direction.
  • the thickness of the base steel sheet is preferably measured with an optical microscope.
  • the region where the aluminum (Al) concentration is less than 2% by mass is determined to be the base steel sheet, and the region where the aluminum concentration is 2% by mass or more is the intermetallic compound layer. Or it is judged to be an aluminum plating layer. Further, among the intermetallic compound layer and the aluminum plating layer, a region having an iron (Fe) concentration of more than 4% by mass is determined to be an intermetallic compound layer, and a region having an iron concentration of 4% by mass or less is determined to be an aluminum plating layer.
  • the thickness of the intermetallic compound layer is the distance from the boundary between the base steel plate and the intermetallic compound layer to the boundary between the intermetallic compound layer and the aluminum plating layer.
  • the thickness of the aluminum plating layer is the distance from the boundary between the intermetallic compound layer and the aluminum plating layer to the surface of the steel sheet on which the aluminum plating layer is formed.
  • the thickness of the aluminum plating layer and the thickness of the intermetallic compound layer are linearly analyzed from the surface of the butt welding steel sheet to the surface of the base steel sheet (the boundary between the base steel sheet and the intermetallic compound layer), and specifically. , Measure as follows.
  • the thickness of the aluminum plating layer and the thickness of the intermetallic compound layer (IMC 0 ) in the region other than the edge portion are in the direction perpendicular to the end face of the planned welding portion of the butt-welding steel sheet (that is, that is, according to the above-mentioned criteria. It is an average value measured near the center position of 5 points divided into 5 equal parts in the Y direction shown in FIG. Specifically, these thicknesses are values obtained as follows. For the thickness of the aluminum plating layer, the thickness from the surface of the steel sheet having the aluminum plating layer to the intermetallic compound layer is determined in the vicinity of the center position of the five equal parts as described above.
  • the average value of the obtained values is taken as the thickness of the aluminum plating layer.
  • the measurement of the thickness of the aluminum-plated layer excludes the cross section of the portion where the thickness is gradually decreasing near the boundary between the region other than the edge portion and the edge portion.
  • the thickness of the intermetallic compound layer (IMC 0 ) is such that the intermetallic compound layer and the base steel plate are formed from the boundary between the intermetallic compound layer and the aluminum plating layer near the center positions of the five equal parts as described above. Find the thickness to the boundary. Then, the average value of the obtained values is taken as the thickness of the intermetallic compound layer.
  • the measurement of the thickness of the intermetallic compound layer (IMC 0 ) excludes the cross section of the portion where the thickness gradually increases near the boundary between the region other than the edge portion and the edge portion.
  • the thickness of the aluminum plating layer is measured from the surface of the steel sheet on which the aluminum plating layer is present to the intermetallic compound layer according to the above-mentioned criteria. However, the thickness was measured within 10% of the total width from the position where the thickness reduction was saturated to the edge of the butt welding steel sheet, and the thickness reduction was saturated. The region excluding the range within 10% from the position toward the edge side of the butt welding steel sheet is divided into three equal parts, and the measurement is performed at the central position divided into three equal parts. Then, the average value of the three measured points is used.
  • the thickness of the intermetallic compound layer (IMC 1 ) is measured from the surface of the steel sheet having the aluminum plating layer to the intermetallic compound layer according to the above-mentioned criteria.
  • the range from the position where the increase in thickness is saturated to the edge of the steel sheet for butt welding is within 10% of the edge of the steel sheet for butt welding, and the increase in thickness is saturated.
  • the region excluding the range within 10% from the position toward the edge side of the butt welding steel sheet is divided into three equal parts, and the measurement is performed at the central position divided into three equal parts. Then, the average value of the three measured points is used.
  • FIG. 1 The thickness of the intermetallic compound layer
  • the thickness of the aluminum plating layer 14B (that is, a 1 ) and the thickness of the intermetallic compound layer (IMC 1 ) (that is, b 1 ) are in the range of Y. It is the average value of the values measured in, and the range of X 1 and X 2 is excluded from the measurement.
  • an intermetallic compound layer (IMC 1 ) on at least a part of the edge portion of a steel sheet for butt welding for example, the following method can be mentioned.
  • At least a part of the edge of the butt-welding steel sheet has a step of applying a treatment by a laser gouging method to the surface of the aluminum-plated layer formed on both sides of the base steel sheet (referred to as forming method A).
  • the forming method A is a method for forming an intermetallic compound layer (IMC 1 ) as follows. First, as a steel plate before forming a tailored blank, a steel plate for butt welding cut to a desired size is prepared. Next, the surface of the aluminum-plated layer formed on both sides of the base steel sheet along the edge of the butt-welding steel sheet on a part of the edge of the butt-welding steel sheet is treated by a laser gouging method. To give. Thereby, it is a method of forming an intermetallic compound layer (IMC 1 ).
  • the surface of the aluminum-plated layer of a butt-welding steel sheet is irradiated with a laser beam to melt the butt-welding steel sheet, and the melted product is produced by the dynamic pressure of an assist gas (air, inert gas, etc.).
  • an assist gas air, inert gas, etc.
  • the assist gas only needs to efficiently disperse the melt product, and the injection nozzle shape and injection direction (upper, lower, front, rear, lateral, oblique, etc.) for injecting the assist gas, and the assist gas are injected.
  • the position to do is not particularly limited.
  • the injection nozzle shape may be appropriately selected according to the purpose.
  • the injection direction and the injection position of the assist gas may be appropriately adjusted according to the purpose.
  • a flat nozzle wider than the target gouging width is used, and injection is performed from the rear in the traveling direction of the laser beam toward the irradiation position of the laser beam.
  • the intermetallic compound layer (IMC 1 ) is formed in the portion where the edge portion of the butt-welding steel sheet is treated by the laser gouging method, which is thicker than the intermetallic compound layer (IMC 0 ).
  • An aluminum plating layer may remain on a part of the edge portion treated by the laser gouging method.
  • the assist gas is preferably injected at a range of 3.0kgf / cm 2 ⁇ 7.0kgf / cm 2.
  • the laser output is preferably in the range of 0.5 kW to 4.0 kW, and the laser scanning speed is preferably in the range of 3.0 m / min to 7.0 m / min.
  • an intermetallic compound layer (IMC 1 ) is formed on at least a part of the edge of the butt-welded steel sheet
  • the order of applying the laser gouging method to the edge of the butt-welded steel sheet is the above-mentioned forming method. It is not limited to A.
  • another preferable method for forming the intermetallic compound layer (IMC 1 ) on at least a part of the edge portion of the butt weld steel sheet for example, the following method can be mentioned.
  • a process of applying a laser gouging method to the surface of an aluminum-plated layer formed on both sides of a base steel sheet and a treatment by a laser gouging method are performed on at least a part of a region other than the edge of the butt welding steel sheet. It may have a step of cutting the steel sheet so that the applied portion is located at the edge of the steel plate for butt welding (referred to as forming method B).
  • the forming method B is, for example, the following method.
  • the aluminum-plated steel sheet is punched to prepare an aluminum-plated steel sheet cut to a desired size.
  • at least a part of the region other than the edge portion is treated by a laser gouging method on the surface of the aluminum-plated layer formed on the base steel sheet.
  • the treatment by the laser gouging method is performed so as to extend in a region other than the edge of the aluminum-plated steel sheet, for example, in one direction.
  • an intermetallic compound layer (IMC 1 ) is formed in the portion treated by the laser gouging method, for example, in a state of being extended in one direction.
  • the width of the portion of the aluminum-plated steel sheet on which the intermetallic compound layer (IMC 1 ) is formed by the laser gouging method is preferably 0.4 mm to 10 mm. ..
  • the portion where the intermetallic compound layer (IMC 1 ) is formed may be cut at a position near the center line of the portion where the intermetallic compound layer (IMC 1 ) is formed so as to have a desired width.
  • a steel plate for butt welding may be obtained by cutting at a position other than the vicinity of the center line in this portion.
  • the width of the portion where the intermetallic compound layer (IMC 1 ) formed by the above forming method A is formed is 20 from half the width of the melt-solidified region (welded metal) after the butt-welding steel plate is butt-welded. It should be% to 40% larger. Further, the width of the portion where the intermetallic compound layer (IMC 1 ) was formed before cutting in the aluminum-plated steel sheet of the butt-welded steel sheet formed as in the above forming method B was obtained by butt-welding the butt-welded steel sheet. It is preferably 20% to 40% larger than the width of the later melt-solidified region (welded metal).
  • the tailored blank of the present disclosure includes a weld metal and at least two steel plates connected to the weld metal. Then, at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion. Of the at least two steel plates, at least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base steel plate at the edge portion connected to the weld metal. In the portion other than the edge portion, an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel plate portion in this order.
  • the thickness of the aluminum plating layer per one side of at least a part of the edge portion connected to the weld metal is a 1 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m
  • the thickness of the aluminum-plated layer per surface in the portion other than the connecting edge is a 0 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 0 ) is b 0 ⁇ m.
  • Equation (1) b 1 ( ⁇ m)> b 0 ( ⁇ m) Equation (2): 3 ⁇ m ⁇ b 0 ( ⁇ m) ⁇ 10 ⁇ m Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% (However, the thickness a 1 of the aluminum plating layer includes 0)
  • the tailored blank of the present disclosure has at least one butt-welded steel sheet of the present disclosure, and at least two of the butt-welded steel sheets of the present disclosure are interposed via an edge having an intermetal compound layer (IMC 1 ). It is a welded steel sheet obtained by butt welding the steel sheets for butt welding. If the tailored blank has at least one butt-welded steel sheet of the present disclosure, the tailored blank is the end face of the edge portion of one butt-welded steel sheet having an intermetallic compound layer (IMC 1 ) and the edge of another steel sheet.
  • IMC 1 intermetal compound layer
  • Tailored blank may be welded in a state of abutting the end surfaces to each other of the edges having the intermetallic compound layer in the two butt welding steel plate (IMC 1), the intermetallic compound layer in the three steel plates (IMC 1 ) May be welded in a state where the end faces of the edges are butted against each other.
  • the tailored blank of the present disclosure includes at least one steel plate for butt welding of the present disclosure, and at least two steel plates for butt welding in which the edges of the two steel plates for butt welding are arranged so as to face each other. It has a weld metal that joins the edges of steel sheets for butt welding.
  • Two or more butt-welding steel sheets for obtaining a tailored blank may be used in combination according to the purpose.
  • steel plates of the same strength class may be used, or steel plates of different strength classes may be used.
  • steel plates having the same thickness may be used, or steel plates having different thicknesses may be used.
  • steel plates having the same thickness of the intermetallic compound layer IMC 1 in the steel plate for butt welding may be used, or steel plates having different thicknesses of the IMC 1 may be used.
  • the welding method for performing butt welding is not particularly limited, and examples thereof include welding methods such as laser welding (laser beam welding), arc welding, and electron beam welding.
  • examples of the arc welding include plasma welding, TIG (Tungsten Inert Gas) welding, MIG (Metal Inert Gas) welding, MAG (Metal Active Gas) welding, and the like, and examples of suitable arc welding include plasma welding. ..
  • the welding conditions may be selected according to the desired conditions such as the thickness of the butt welding steel sheet to be used. Further, welding may be performed while supplying a filler wire, if necessary.
  • the tailored blank is preferably on the end face where the welded joint is adjacent to the portion having the intermetallic compound layer (IMC 1 ). That is, the tailored blank is formed in which the portion where the intermetallic compound layer (IMC 1 ) is formed is in contact with the end faces, and the joint portion is formed by butt welding the end faces to each other.
  • the tailored blank is a tailored blank including at least two butt-welding steel plates and a weld metal, and is for butt-welding in which the edges of at least one butt-welding steel plate of the present disclosure are arranged so as to face each other.
  • a steel plate and a welding metal provided adjacent to at least a part of the edges of at least two butt-welding steel plates that is, a welding metal for joining the edges of at least two steel plates
  • a tailored blank in which at least an intermetallic compound layer (IMC 1 ) is formed on both sides of a base steel plate on at least a part of adjacent steel plates.
  • the intermetallic compound layer (IMC 1 ) is provided on both sides of the two butt-welding steel sheets joined by the weld metal, which are located around the weld metal.
  • FIG. 6 is a schematic view showing an example of a cross section of a welded portion in the tailored blank of the present disclosure.
  • the tailored blank 200 shown in FIG. 6 is formed by butt-welding the end faces of the edges of two butt-welding steel plates 120 of the same type.
  • the tailored blank 200 includes two butt-welding steel plates 120 and a weld metal 30 for joining two butt-welding steel plates 120.
  • the two butt-welded steel sheets 120 are planned to be welded because the intermetallic compound layer (IMC 0 ) 16A and the aluminum plating layer 14A are provided on both sides of the base steel sheet 12 in the region 26 other than the edge portion, respectively.
  • IMC 0 intermetallic compound layer
  • an intermetallic compound layer (IMC 1 ) 16B is provided on both surfaces of the base steel plate 12.
  • the intermetallic compound layer (IMC 1 ) 16B is provided adjacent to the weld metal 30.
  • the tailored blank 200 shown in FIG. 6 is butt-welded through the edges of two butt-welded steel plates 120 of the same type, but the butt-welded steel plate for forming the tailored blank 200 of the present disclosure is formed. Is not limited to the aspect shown in FIG.
  • FIG. 7 is an enlarged cross-sectional photograph of the tailored blank formed through the untreated edges of the two butt-welded steel plates in the vicinity of the weld metal.
  • the arrow E indicates that ferrite is present around the edge of the butt-welding steel plate in the weld metal.
  • the tailored blank shown in FIG. 7 it is considered that the presence of ferrite is observed in the weld metal due to the concentration of aluminum mixed in a large amount from the steel sheet.
  • FIG. 7 is an enlarged cross-sectional photograph of the tailored blank formed through the untreated edges of the two butt-welded steel plates in the vicinity of the weld metal.
  • the arrow E indicates that ferrite is present around the edge of the butt-welding steel plate in the weld metal.
  • FIG. 8 is an enlarged cross-sectional photograph of the tailored blank formed in the vicinity of the weld metal of the two butt-welded steel sheets of the present disclosure formed through the edges.
  • the arrow N indicates that there is no ferrite around the edge of the butt-welded steel plate in the weld metal.
  • the tailored blank shown in FIG. 8 it is considered that the presence of ferrite is not observed because the concentration of aluminum mixed in a large amount in the weld metal is small.
  • the hot press molded product includes a weld metal and at least two steel plate portions connected to the weld metal. Then, at least two steel plate portions have an edge portion connected to the weld metal and a portion other than the edge portion. Of the at least two steel plate portions, at least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base steel plate at the edge portion connected to the weld metal. In the portion other than the edge portion, an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
  • the thickness of the aluminum plating layer per one side at least a part of the edge portion connected to the weld metal is a 2 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 2 ) is b 2 ⁇ m.
  • Equation (4) 0.8% ⁇ ⁇ 2 ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) / t 1 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% Equation (5): 10 ⁇ m ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) (However, the thickness a 2 of the aluminum plating layer includes 0)
  • the thickness b 2 [mu] m of thickness a 2 [mu] m of the aluminum layer, and the intermetallic compound layer (IMC 2), as well as the thickness b 1 [mu] m of thickness a 1 [mu] m of the aluminum layer, and the intermetallic compound layer (IMC 1) Measure by line analysis according to the criteria of. The line analysis is performed on the edge portion connected to the weld metal from the surface portion at the edge portion to the surface of the base steel plate (the boundary between the base steel plate and the intermetallic compound layer).
  • the measurement location is the edge portion corresponding to the laser gouging position in the steel plate portion connected to the weld metal (that is, the intermetallic compound layer (IMC 1 ) in the butt-welded steel plate connected to the weld metal of the present disclosure). Measure the provided edge). Specifically, in the edge portion corresponding to the position where the laser gouging treatment is performed to connect with the weld metal, the range within 10% from the weld metal and the range within 10% of the total width from the weld metal to the portion other than the edge portion, and The region excluding the range within 10% from the boundary between the portion other than the edge portion and the edge portion is divided into three equal parts, and the treatment is performed at the central position divided into three equal parts.
  • the average value of the three measured points is used.
  • the plate thickness t 1 ⁇ m of the base steel sheet it is preferable to select and measure a portion that is less affected by hot press forming.
  • the base steel plate having a thickness of t 1 ⁇ m is preferably measured with an optical microscope.
  • the value represented by the formula (5) is preferably 12 ⁇ m or more in terms of excellent corrosion resistance of the welded portion.
  • the thickness a 2 [mu] m of the aluminum layer may be 0 (zero) [mu] m, may exceed 0 .mu.m.
  • the thickness a 2 ⁇ m of the aluminum plating layer may be 0 ⁇ m, or may exceed 0 ⁇ m.
  • the hot press-formed product of the present disclosure the weld metal, the edge portion connected to the weld metal, and the portion other than the edge portion are arranged in this order from the weld metal toward the steel plate portion. That is, the hot press molded product (hot stamp molded product) of the present disclosure is produced by hot pressing the tailored blank of the present disclosure. That is, the hot stamped product is a hot stamped product including at least two butt-welded steel plates and a weld metal, and the edges of at least one butt-welded steel plate of the present disclosure are arranged so as to face each other.
  • a butt-welded steel plate and a weld metal provided adjacent to at least a part of the edges of at least two butt-welded steel plates that is, a weld metal that joins the edges of at least two butt-welded steel plates.
  • an intermetallic compound layer (IMC 2 ) is formed on at least a part of the edge portion adjacent to the weld metal in the butt welding steel sheet adjacent to the weld metal by quenching.
  • the intermetallic compound layer (IMC 2 ) is provided on both sides of the two butt-welding steel sheets joined by the weld metal, which are located around the weld metal.
  • the hot stamped product can be manufactured as follows. First, the tailored blank is heated to a high temperature to soften the tailored blank. Then, using a mold, the softened tailored blank is molded and cooled by hot stamping and then quenched to obtain a hot stamped product having a desired shape. The hot stamp molded product is hardened by heating and cooling to obtain, for example, a molded product having a high tensile strength of about 1500 MPa or more.
  • thermoforming a heating method for hot stamping it is possible to adopt a heating method such as infrared heating, energization heating, induction heating, etc., in addition to a normal electric furnace and radiant tube furnace.
  • the aluminum-plated layer of the butt-welded steel sheet is changed to an intermetallic compound layer that provides protection against corrosion and oxidation of the butt-welded steel sheet during heating.
  • the aluminum plating layer contains silicon (Si)
  • the aluminum plating layer becomes an intermetallic compound layer, that is, an Al—Fe alloy phase, due to mutual diffusion with Fe when heated. And change to an Al—Fe—Si alloy phase.
  • the melting points of the Al—Fe alloy phase and the Al—Fe—Si alloy phase are high, 1000 ° C. or higher.
  • phase There are a plurality of types of Al—Fe phase and Al—Fe—Si phase, and when heated at a high temperature or for a long time, the phase changes to an alloy phase having a higher Fe concentration. These intermetallic compound layers prevent corrosion and oxidation of butt weld steel sheets.
  • the weld metal is caused by the intermetallic compound layer (IMC 1 ) (or the intermetallic compound layer (IMC 1 ) and the aluminum plating layer) formed on at least a part of the edge of the steel plate for butt welding. Since aluminum is appropriately mixed, it contains an alloy phase (intermetallic compound layer) similar to the above. In particular, by having the above alloy layer on the surface of the weld metal, the generation of scale on the surface of the weld metal is suppressed. As a result, the chemical conversion treatment property is improved on the surface of the weld metal, and the adhesiveness of the paint is improved. As a result, the welded portion is considered to have excellent corrosion resistance after painting.
  • the preferable state of the aluminum plating layer as a hot stamp molded product is a state in which the surface is alloyed (a state in which the surface is an intermetallic compound layer) and the Fe concentration in the alloy phase is not high. If unalloyed Al remains, only this portion is rapidly corroded, the corrosion resistance after coating is deteriorated, and the coating film swelling is extremely likely to occur, which is not preferable. On the other hand, if the Fe concentration in the alloy phase becomes too high, the corrosion resistance of the alloy phase itself deteriorates, the corrosion resistance after coating deteriorates, and the coating film swells easily. That is, the corrosion resistance of the alloy phase depends on the Al concentration in the alloy phase. Therefore, in order to improve the corrosion resistance after painting, the alloying state is controlled by the amount of Al adhered and the heating conditions.
  • the maximum temperature reached during hot stamping is not particularly limited, and is preferably 850 ° C to 1000 ° C, for example. In hot stamping, the maximum temperature reached is usually about 900 ° C. to 950 ° C. because it is necessary to heat in the austenite region.
  • a tailored blank heated to a high temperature is press-molded with a mold cooled by water cooling or the like, and at the same time, it is quenched by cooling with the mold. Further, if necessary, water may be sprayed directly onto the blank material through the gap of the mold to cool the blank material. Then, a hot stamp molded product having a desired shape can be obtained.
  • the metal structure of the base steel sheet becomes at least a part, preferably the whole, austenite single-phase structure. Then, when pressed in a die, austenite is transformed into at least one of martensite and bainite by cooling under the desired cooling conditions. Then, in the obtained hot stamped product, the metal structure of the base steel sheet becomes one of martensite, bainite, or martensite-bainite.
  • an example of the process from the production of the steel plate for butt welding to the production of the hot stamped product is as follows. First, an aluminum-plated layer is formed on both sides of the base steel sheet to obtain an aluminum-plated steel sheet. At this time, an intermetallic compound layer is formed between the base steel plate and the aluminum plating layer. Next, an intermetallic compound layer is grown by laser gouging treatment at at least a part of the edge of the aluminum-plated steel sheet. At this time, all the aluminum plating layers may be changed to intermetallic compound layers, or some aluminum plating layers may not be changed to intermetallic compound layers and may remain as aluminum plating layers.
  • the steel plate having aluminum plating on both sides of the base steel plate is wound into a coil. Next, the steel sheet wound in a coil shape is pulled out and punched to obtain a punched steel sheet.
  • the laser gouging treatment on at least a part of the edge of the aluminum-plated steel sheet may be formed in a state where the aluminum-plated steel sheet is wound into a coil and then the coiled aluminum-plated steel sheet is pulled out. Good.
  • a punching process is performed so that the laser gouging treated region becomes the edge portion of the butt welding steel sheet to obtain a punched steel sheet.
  • the laser gouging treatment on at least a part of the edge portion of the aluminum-plated steel sheet may be performed after the aluminum-plated steel sheet wound in a coil shape is pulled out and punched to form the punched steel sheet.
  • laser gouging treatment may be applied to at least a part of the edge of the punched steel sheet.
  • an intermetallic compound layer (IMC 1 ) is formed in a portion other than the edge of the punched steel sheet, for example, the regions that have been subjected to laser gouging treatment are butted.
  • the laser gouged region of the punched steel sheet may be cut so as to be the edge of the steel sheet for welding.
  • At least one punched steel sheet that has been subjected to laser gouging treatment is prepared at least a part of the edge portion of the butt welding steel sheet.
  • the number of punched steel plates may be two or more, if necessary.
  • end faces having laser gouging-treated edges are butt-welded and butt-welded to obtain a tailored blank.
  • the tailored blank is heated in a heating furnace.
  • the heated tailored blank is pressed, molded and hardened by a pair of upper and lower dies. Then, by removing it from the mold, the desired hot stamp molded product can be obtained.
  • the steel pipe includes a weld metal and a steel plate portion formed in an open tubular shape in which two peripheral edges face each other, and the two peripheral edges are connected to the weld metal.
  • the steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
  • At least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base steel plate at the edge portion connected to the weld metal.
  • an intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the base steel sheet in this order.
  • the thickness of the aluminum plating layer per one side at least a part of the edge connected to the weld metal is a 1 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 1 ) is b 1 ⁇ m
  • the thickness of the aluminum-plated layer per side of the portion other than the edge connected to the weld metal is a 0 ⁇ m
  • the thickness of the intermetallic compound layer (IMC 0 ) is b 0 ⁇ m.
  • Equation (1) b 1 ( ⁇ m)> b 0 ( ⁇ m) Equation (2): 3 ⁇ m ⁇ b 0 ( ⁇ m) ⁇ 10 ⁇ m Equation (3): 0.8% ⁇ ⁇ 2 ⁇ (a 1 ( ⁇ m) + b 1 ( ⁇ m)) / t 0 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% (However, the thickness a 1 of the aluminum plating layer includes 0)
  • the steel pipe includes the steel plate for butt welding of the present disclosure, and the weld metal and the portion having the edge portion provided with the intermetallic compound layer (IMC 1 ) are connected. Then, in the steel pipe of the present disclosure, the weld metal, the edge portion connected to the weld metal, and the portion other than the edge portion are arranged in this order from the weld metal toward the steel plate portion. That is, the steel pipe has at least one weld metal (that is, the weld metal that joins the edges of the open pipes of the steel plate), and is a tubular body made of the butt weld steel plate (or tailored blank) of the present disclosure adjacent to the weld metal. It has an intermetallic compound layer (IMC 1 ) on both sides of the above.
  • IMC 1 intermetallic compound layer
  • Examples of the steel pipe include aspects obtained as follows. 1) the first edge, the first intermetallic compound layer (IMC 1) provided, on the second edge, the second intermetallic compound layer welding steel plate butt provided (IMC 1) 1 Prepare a sheet. This single steel plate for butt welding is formed into a tubular shape to form an open pipe. Then, in the obtained open pipe, the end face of the edge portion provided with the first intermetallic compound layer (IMC 1 ) and the end face of the edge portion provided with the second intermetallic compound layer (IMC 1 ) are butted against each other. It may be a steel pipe obtained by welding with.
  • the end face of the edge portion of the first butt-welded steel plate provided with the second unwelded compound layer (IMC 1 ) and the first unwelded steel sheet may be a steel pipe obtained by welding in a state where the end face of the edge portion of the second butt welding steel plate provided with the intermetal compound layer (IMC 1 ) is butt-welded.
  • the open pipe may be formed by being curved in a direction parallel to the welding line in the tailored blank before forming the open pipe, or may be formed by being curved in a direction of intersection.
  • FIG. 9 is a schematic schematic view showing an example of the steel pipe of the present disclosure.
  • the steel pipe 410 shown in FIG. 9 represents an aspect formed from one steel plate for butt welding.
  • the steel pipe 410 is provided with a first intermetallic compound layer (IMC 1 ) 16D and a second intermetallic compound layer (IMC 1 ) 16E adjacent to the weld metal 30.
  • an intermetallic compound layer (IMC 1 ) is formed on both edges of the steel plate for butt welding, and the aluminum plating layer is removed.
  • a first intermetallic compound layer (IMC 1 ) 16D is formed at the first edge of the butt weld steel sheet, and a second intermetallic compound layer (IMC 1 ) 16E is formed at the second edge.
  • the steel pipe 410 uses one steel plate for butt welding as an open pipe, and has an end face of a first edge portion provided with a first intermetallic compound layer (IMC 1 ) 16D and a second intermetallic compound layer (IMC). 1 ) It is formed by welding in a state where it is abutted against the end face of the second edge portion provided with 16E.
  • FIG. 10 is a schematic schematic view showing another example of the steel pipe of the present disclosure.
  • the steel pipe 420 shown in FIG. 10 represents an aspect formed from a tailored blank having two steel plates, a first steel plate for butt welding and a second steel plate for butt welding.
  • the steel pipe 420 has a second intermetallic compound layer (IMC 1 ) 16H in the first steel plate and a first intermetallic compound layer (IMC 1 ) 16J in the second steel plate adjacent to the weld metal 30.
  • IMC 1 intermetallic compound layer
  • the tailored blank for forming the steel pipe 420 includes an end face on which the first intermetallic compound layer (IMC 1 ) 16F of the first butt-welded steel plate is formed and a first butt-welded steel plate.
  • the steel pipe 420 is curved in a direction perpendicular to the welding line of the tailored blank to form an open pipe, and includes a second intermetallic compound layer (IMC 1 ) 16H in the unwelded first butt-welded steel sheet. It is formed by welding the end face of the edge portion and the end face of the edge portion of the second steel plate for butt welding provided with the first intermetallic compound layer (IMC 1 ) 16J.
  • two or more butt-welding steel plates forming the tailored blank for forming the steel pipe may be used in combination according to the purpose.
  • Examples of the combination of two or more butt-welding steel sheets include the same combination as the steel sheet described in the above-mentioned butt-welding steel sheet for forming a tailored blank.
  • the method of forming into a tubular shape is not particularly limited, and for example, any method such as a UOE method or a bending roll method may be used.
  • the welding after forming into a tubular shape is not particularly limited, and examples thereof include electric stitch welding in which welding is performed by laser welding; plasma welding; electric resistance welding or high frequency induction heating welding.
  • the hollow hardened molded product includes a weld metal and a steel plate portion formed in an open tubular shape in which two peripheral edges face each other and to which the two peripheral edges are connected to the weld metal.
  • the steel plate portion has at least one steel plate portion, and the at least one steel plate portion has an edge portion connected to the weld metal and a portion other than the edge portion.
  • At least one steel plate portion is provided with an intermetallic compound layer containing at least iron and aluminum on both sides of the base metal steel plate at the edge portion connected to the weld metal, and the base material is provided at a portion other than the edge portion.
  • An intermetallic compound layer containing iron and aluminum and an aluminum plating layer are provided on both sides of the steel sheet in this order. Further, the thickness of the aluminum plating layer per one side at least a part of the edge portion connected to the weld metal is a 2 ⁇ m, and the thickness of the intermetallic compound layer (IMC 2 ) is b 2 ⁇ m.
  • IMC 2 intermetallic compound layer
  • Equation (4) 0.8% ⁇ ⁇ 2 ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) / t 1 ( ⁇ m) ⁇ ⁇ 100 ⁇ 3.5% Equation (5): 10 ⁇ m ⁇ (a 2 ( ⁇ m) + b 2 ( ⁇ m)) (However, the thickness a 2 of the aluminum plating layer includes 0)
  • the hollow hardened molded product (hereinafter, may be referred to as “hollow hot stamp molded product”) is a tailored product obtained by butt welding the butt welding steel plate of the present disclosure or the butt welding steel plate of the present disclosure. It is a hollow molded product obtained by quenching a steel pipe formed from a blank.
  • the weld metal, the edge portion connected to the weld metal, and the portion other than the edge portion are arranged in this order from the weld metal toward the steel plate portion. That is, the hollow hot stamped product obtained by hot stamping the steel pipe has at least one weld metal (that is, the weld metal that joins the edges of the steel plate).
  • the hollow hot stamped product has intermetallic compound layers (IMC 2 ) on both sides of the hollow hot stamped product at the edge of the butt-welded steel plate of the present disclosure adjacent to the weld metal by quenching. ..
  • the method of the intermetallic compound layer (IMC 2) are described above That's right.
  • the total thickness is smaller than the total thickness of the thickness b 0 [mu] m of the aluminum layer thickness a 0 [mu] m and the intermetallic compound layer in the portion other than the edge (IMC 0).
  • the hollow hot stamp molded product is obtained, for example, as follows.
  • a steel pipe obtained by using the butt welding steel plate of the present disclosure is formed by a bender.
  • the steel pipe is heated by a heating furnace, energization heating, or high frequency induction heating. Since the temperature for heating the steel pipe needs to be in the austenite region, it may be, for example, 850 ° C to 1000 ° C, or 900 ° C to 950 ° C.
  • the heated steel pipe is cooled by water cooling or the like and quenched. Note that molding and quenching may be performed at the same time. This is called three-dimensional hot bending quenching (3DQ).
  • 3DQ three-dimensional hot bending quenching
  • a steel pipe is hardened by heating it, deforming it by applying a load, and immediately cooling it by water cooling or the like.
  • the desired hollow hot stamped product can be obtained.
  • the hollow hot stamped product may be used as it is as a part.
  • the application of the hollow hot stamp molded product of the present disclosure is not particularly limited, and examples thereof include various automobile members such as automobile bodies and various members of industrial machines.
  • automobile members include various pillars; reinforcements such as stabilizers, door beams, roof rails and bumpers; frames; and various parts such as arms.
  • the following steel sheets were prepared as steel sheets to be applied to the butt welding steel sheets for use in the test.
  • the prepared steel sheet is a steel sheet having a strength class of 1470 MPa after hot stamping, a quadrangle having a side of 10 cm, and a base steel sheet having a plate thickness of 1.6 mm, which is plated with aluminum.
  • the thickness of the aluminum-plated layer and the thickness of the intermetallic compound layer of this steel sheet are as shown in the area column other than the edge portion in Table 2.
  • the chemical composition of the base steel sheet used for each aluminum-plated steel sheet is as shown in Table 1.
  • the plate thickness shown in Table 2 represents the plate thickness of the base steel plate.
  • the edge portion to be welded was subjected to laser gouging treatment to obtain a steel sheet for butt welding. Specifically, laser gouging treatment was performed on both sides of the edge portion of only one of the four sides over a width of 1.5 mm and a total length of 10 cm.
  • Some aluminum-plated steel sheets were treated by laser ablation instead of laser gouging to obtain steel sheets for butt welding.
  • some steel sheets were made into steel sheets for butt welding by leaving the edges to be welded untreated.
  • Table 2 shows the thickness of the aluminum plating layer and the thickness of the intermetallic compound layer at the edge portion of each butt-welding steel sheet to be welded.
  • the formula (3) is a value obtained from the thickness of the base steel plate, the thickness of the aluminum plating layer per one side, and the thickness of the intermetallic compound layer.
  • the invention example satisfies the formula (3) on both sides.
  • butt-welded steel sheets or untreated butt-welded steel sheets that had been subjected to each treatment were prepared. Then, the end faces of the edges of the butt-welded steel sheets subjected to the above treatment were butted against each other, and butt-welding was performed by laser welding to prepare a tailored blank.
  • the conditions for laser welding were a spot diameter of ⁇ 0.9 mm, a laser output of 3.2 kW, and a laser scanning speed of 3 m / min, using a fiber laser as the oscillator without using a filler wire.
  • the prepared tailored blank was held in a furnace heated to 920 ° C. for 4 minutes, molded with a water-cooled mold, and quenched to prepare a flat plate hot stamped product.
  • the hot stamped product has a tensile strength of 1470 MPa class.
  • the thickness of the aluminum plating layer at the edge connected to the weld metal, the thickness of the intermetallic compound layer (IMC 2 ), and the aluminum plating layer and the intermetallic compound layer (IMC 2 ) were measured.
  • Table 3 shows the plate thickness t 1 of the base steel plate at the position.
  • the processing conditions for laser gouging are as follows.
  • a semiconductor laser was used as the oscillator.
  • a flat nozzle was followed from behind the laser irradiation unit, and nitrogen was injected at 5.5 kgf / cm 2 .
  • a line beam having a width of 1.5 mm and a length of 1 mm was used.
  • the laser output was adjusted appropriately at 0.6 kW to 2.1 kW and the laser scanning speed was adjusted at 3 m / min to 8 m / min. No. Taking No. 6 as an example, the laser output was 0.7 kW and the laser scanning speed was 5 m / min.
  • the front and back surfaces of the edge to be butt welded were treated. By the treatment, the aluminum plating layer of Al—Si metal was not present, and the intermetallic compound layer grew to a thickness of 17 ⁇ m.
  • the conditions for laser ablation are as follows. A Q-switched laser was used as the process by laser ablation.
  • the processing conditions are a pulse width of 60 ns, a nominal output of 300 W, a pulse energy of 30 mJ, and a laser scanning speed of 10 m / min.
  • Laser ablation is a phenomenon in which constituent substances on a solid surface are explosively released by irradiation with laser light.
  • Laser gouging is a phenomenon in which molten metal is removed by high-speed gas by irradiation with laser light.
  • test plate was 65 mm in length and 100 mm in width (the welded portion is in the center of the width).
  • the automobile parts appearance corrosion test JASO M610-92 was used to evaluate the corrosion resistance after painting under the corrosion condition after 360 cycles (120 days).
  • the ratio of red rust is defined as the red rust occurrence rate, and the following criteria are visually observed for the area excluding the periphery of the weld metal (corresponding to the area other than the edge of the butt welding steel plate), the periphery of the weld metal, and the weld metal. I went there.
  • the red rust occurrence rate is a value rounded to the nearest whole number. Up to evaluation B is allowed around the weld metal, and up to evaluation B is allowed for the weld metal.
  • C Red rust occurrence rate 51% to 75%
  • D Red rust occurrence rate 76% to 100%
  • the periphery of the weld metal represents the following.
  • the periphery of the weld metal is adjacent to the weld metal formed after welding and up to the region where the increase in the thickness of the intermetallic compound layer is saturated among the parts where the edge of the butt-welding steel plate is subjected to laser gouging treatment. Show the part.
  • the periphery of the weld metal indicates a portion adjacent to the weld metal and up to the region where the intermetallic compound layer is exposed. When untreated, the portion up to the region corresponding to the region where the increase in the thickness of the intermetallic compound layer in the laser gouging treatment is saturated is shown.
  • the thickness of the intermetallic compound layer (IMC 0 ) satisfies the range of 3 mm to 10 mm (that is, the above-mentioned range of the formula (2) is satisfied).
  • the thickness of the intermetallic compound layer (IMC 1) is greater than the thickness of the intermetallic compound layer (IMC 0) (i.e., satisfies the scope of formula (1) above).
  • the range of the above-mentioned equation (3) is satisfied. Therefore, in all regions (around the weld metal, around the weld metal, and the weld metal), the corrosion resistance and the tensile strength after painting were excellent. And these satisfy the range of the above-mentioned equations (4) and (5).

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Coating With Molten Metal (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
  • Heat Treatment Of Articles (AREA)
  • Arc Welding In General (AREA)

Abstract

L'invention concerne une tôle d'acier dans laquelle une couche de composé intermétallique contenant du fer et de l'aluminium et une couche de placage d'aluminium sont disposées dans cet ordre sur les deux surfaces d'une tôle d'acier de base, et qui satisfait l'expression (1) : b1 (µm) > b0 (µm), l'expression (2) : 3 µm ≤ b0 (µm) ≤ 10 µm, et l'expression (3) : 0,8 % ≤ {2 x (a1 (µm) + b1 (µm))/t0 (µm)} x 100 ≤ 3,5 %, l'épaisseur de la couche de placage d'aluminium et l'épaisseur de la couche de composé intermétallique (IMC0) par surface au niveau d'une partie autre que la partie de bord de la tôle d'acier étant définies comme a0 µm et b0 µm, respectivement, l'épaisseur de la couche de placage d'aluminium et l'épaisseur de la couche de composé intermétallique (IMC1) par surface au moins au niveau d'une partie de la partie de bord de la tôle d'acier étant définies comme a1 µm et b1 µm, respectivement, et l'épaisseur de tôle de la tôle d'acier de base au niveau de la partie autre que la partie de bord étant définie comme t0 µm.
PCT/JP2019/014687 2019-04-02 2019-04-02 Tôle d'acier, flan personnalisé, produit moulé pressé à chaud, tuyau en acier et produit moulé trempé creux WO2020202474A1 (fr)

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PCT/JP2019/014687 WO2020202474A1 (fr) 2019-04-02 2019-04-02 Tôle d'acier, flan personnalisé, produit moulé pressé à chaud, tuyau en acier et produit moulé trempé creux
JP2019530107A JP6601598B1 (ja) 2019-04-02 2019-04-02 鋼板、テーラードブランク、熱間プレス成形品の製造方法、鋼管、及び中空状焼入れ成形品の製造方法

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009534529A (ja) * 2006-04-19 2009-09-24 アルセロールミタル・フランス 被覆積層板から非常に高い機械的特性を有する溶接部品を製造する方法
JP2017514694A (ja) * 2014-04-25 2017-06-08 アルセロールミタル 溶接され、次いでプレス硬化されるアルミニウムめっき鋼板の製造方法
JP2017518438A (ja) * 2014-03-31 2017-07-06 アルセロールミタル 高い生産率でのプレス焼き入れおよび被覆鋼部品の製造方法
WO2018096387A1 (fr) * 2016-11-24 2018-05-31 Arcelormittal Tôle d'acier laminé à chaud et revêtu pour estampage à chaud, pièce d'acier revêtu estampé à chaud, et ses procédés de fabrication

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009534529A (ja) * 2006-04-19 2009-09-24 アルセロールミタル・フランス 被覆積層板から非常に高い機械的特性を有する溶接部品を製造する方法
JP2017518438A (ja) * 2014-03-31 2017-07-06 アルセロールミタル 高い生産率でのプレス焼き入れおよび被覆鋼部品の製造方法
JP2017514694A (ja) * 2014-04-25 2017-06-08 アルセロールミタル 溶接され、次いでプレス硬化されるアルミニウムめっき鋼板の製造方法
WO2018096387A1 (fr) * 2016-11-24 2018-05-31 Arcelormittal Tôle d'acier laminé à chaud et revêtu pour estampage à chaud, pièce d'acier revêtu estampé à chaud, et ses procédés de fabrication

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