JP2016186125A - Aluminum alloy sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet resistant to the peeling of plating, exhibiting high strength and preventing edge cracks in rolling.SOLUTION: An aluminum alloy sheet includes, 4.7-6.0 mass% Mg, 0.20 mass% or less Fe, 0.10 mass% or less Si, at least one of 0.005-0.500 mass% Cu and 0.005-0.400 mass% Zn, with 0.500 mass% or less total content of the Cu and the Zn, and the balance Al with inevitable impurities. A dissolved Mg content is 3.8 mass% or more, and 0.2% yield strength is 250-400 MPa.SELECTED DRAWING: None

Description

  The present invention relates to an aluminum alloy plate, and more particularly, to an aluminum alloy plate that can be used for structural parts such as an inner chassis installed inside an electronic device.

  As can be said for all electronic devices, in particular, there is a great need for weight reduction of various portable devices (portable devices) that are assumed to be portable among electronic devices.

  Therefore, it has been proposed to reduce the weight of the entire electronic device by replacing each component inside the electronic device, which has been configured with a relatively large iron alloy or the like, with an aluminum alloy.

  For example, Patent Document 1 proposes an electrical / electric equipment conductive part material containing 0.5 to 5.0% by weight of Mg and the balance being made of Al and inevitable impurities.

Japanese Unexamined Patent Publication No. 63-96239

According to the description in Patent Document 1, the technique according to Patent Document 1 can be suitably used for conductive parts such as semiconductors, IC lead frames, connectors, and switches.
However, since the detailed needs for each part of electronic equipment differ from part to part, the needs required for the target part are accurately grasped, and a material (aluminum alloy plate) that meets that need is created. There is a need.

  The present inventors paid attention to structural parts such as an inner chassis provided inside an electronic device, and first clarified the performance required for an aluminum alloy plate used for these parts.

Specifically, the inner chassis is often configured to be grounded (grounded) by being fastened to the housing of the electronic device with a bolt or the like, but an oxide film is formed on the surface of the inner chassis. Doing so increases contact resistance and prevents grounding. Therefore, in order to prevent an increase in contact resistance due to the oxide film, the surface of the inner chassis is usually plated (for example, Ni plating). Therefore, the aluminum alloy plate used for the inner chassis is required to have a performance that the plating is difficult to peel off.
Further, the inner chassis is used for the inner chassis because it needs to hold each component such as a substrate and a battery and absorb (protect) the impact to each held component inside the electronic device. Aluminum alloy plates are required to have high strength.
However, if the strength of the aluminum alloy plate is high, the probability of occurrence of ear cracks during rolling increases, which may reduce productivity. Therefore, it is necessary to consider the point which suppresses generation | occurrence | production of an ear crack about an aluminum alloy plate.

  Then, this invention makes it a subject to provide the aluminum alloy plate which can suppress the generation | occurrence | production of the ear crack at the time of rolling while exhibiting high intensity | strength that plating does not peel easily.

  That is, the aluminum alloy plate according to the present invention has Mg: 4.7 to 6.0% by mass, Fe: 0.20% by mass or less, Si: 0.10% by mass or less, and Cu: 0.005 to 0.500% by mass and Zn: at least one of 0.005 to 0.400% by mass, the total content of Cu and Zn is 0.500% by mass or less, the balance being Al and inevitable It is a characteristic impurity, the solid solution Mg amount is 3.8% by mass or more, and the 0.2% proof stress is 250 to 400 MPa.

According to this aluminum alloy plate, the solid solution Mg amount can be set to a predetermined value or more by setting the Si content to a predetermined value or less while keeping the Mg content within a predetermined range. As a result, this aluminum alloy sheet can exhibit the strength required for structural parts such as an inner chassis, and further suppress the occurrence of ear cracks during rolling by making the Fe content not more than a predetermined value. be able to. And according to this aluminum alloy plate, the desired strength can be exhibited more reliably by setting the 0.2% proof stress within a predetermined range.
Moreover, according to this aluminum alloy plate, since content of Cu and Zn is a predetermined range, generation | occurrence | production of peeling of plating can also be suppressed.

The aluminum alloy plate according to the present invention is preferably used for a structural part, and more preferably used for an inner chassis. Moreover, the aluminum alloy plate according to the present invention may be used for electrical parts.
Furthermore, the aluminum alloy plate according to the present invention may have a film on the surface, and this film is preferably a plating film.

The aluminum alloy plate according to the present invention has high strength because the content of each alloy component and the solid solution Mg amount are within a predetermined range and the 0.2% proof stress is within a predetermined range, so that the plating is difficult to peel off. In addition, the occurrence of ear cracks during rolling can be suppressed.
Therefore, the aluminum alloy plate according to the present invention can be suitably used for structural parts such as an inner chassis.

  Hereinafter, the form for implementing the aluminum alloy plate which concerns on this invention is demonstrated in detail.

[Aluminum alloy plate]
The aluminum alloy plate according to the present invention has a Mg, Fe, Si content in a predetermined range (or less than a predetermined value), contains at least one of Cu and Zn, and the balance is made of Al and inevitable impurities, and is solid. The amount of dissolved Mg is a predetermined amount or more, and the 0.2% proof stress is in a predetermined range.

  Hereinafter, the reason why the respective alloy components, the solid solution Mg amount, and the 0.2% proof stress of the aluminum alloy plate according to the present invention are numerically limited will be described.

(Mg: 4.7-6.0% by mass)
Mg has an effect of improving strength by solid solution strengthening in an aluminum alloy. By setting the Mg content to 4.7% by mass or more, a desired strength can be obtained. On the other hand, if the Mg content exceeds 6.0% by mass, an Al—Mg-based intermetallic compound is produced, and the possibility of occurrence of ear cracks during rolling increases.
Therefore, the content of Mg is 4.7 to 6.0% by mass, preferably 5.0% by mass or more, and more preferably 5.3% by mass or more.

(Fe: 0.20 mass% or less)
Fe is mixed into the aluminum alloy as a metal impurity, and forms an intermetallic compound together with Mn, Si and the like in the aluminum alloy. When the Fe content exceeds 0.20% by mass, coarse intermetallic compounds such as Al—Fe, Al—Fe—Si, Al—Fe—Mn, and Al—Fe—Mn—Si are generated. As a result, the possibility of occurrence of ear cracks during rolling increases.
Therefore, the Fe content is 0.20% by mass or less (including 0% by mass), and preferably 0.10% by mass or less.

(Si: 0.10 mass% or less)
Si is mixed into the aluminum alloy as a metal impurity, and forms an intermetallic compound together with Mg or the like in the aluminum alloy. If the Si content exceeds 0.10% by mass, a large amount of Mg-Si-based intermetallic compounds will be generated, and the amount of solid solution Mg will decrease. As a result, the desired strength cannot be obtained, and the possibility of ear cracks occurring during rolling increases.
Therefore, the Si content is 0.10% by mass or less (including 0% by mass), and preferably 0.06% by mass or less.

(Cu: 0.005-0.500 mass%, Zn: 0.005-0.400 mass%)
Cu and Zn have an effect of suppressing plating peeling. Specifically, by containing at least one of Cu and Zn in an amount of 0.005% by mass or more, Zn ions in the zincate bath are finely and uniformly deposited on the surface of the aluminum alloy plate in the zincate treatment of the plating pretreatment, By exhibiting the effect of forming the zincate film uniformly, it is possible to suppress the peeling of the plating. On the other hand, the Cu content exceeds 0.500 mass%, the Zn content exceeds 0.400 mass%, or the total content of Cu and Zn exceeds 0.500 mass%. If the Cu and Zn-based intermetallic compounds increase, the possibility of occurrence of plating defects such as nodules (protrusions) and pits increases.
Therefore, about content of Cu and Zn, it contains at least 1 type in Cu: 0.005-0.500 mass% and Zn: 0.005-0.400 mass%, and the total content of Cu and Zn Is 0.500 mass% or less.

In order to ensure the effect of suppressing the peeling of the plating, the Cu content is preferably 0.010% by mass or more, more preferably 0.100% by mass or more for each of Cu and Zn. The content is preferably 0.010% by mass or more, and more preferably 0.100% by mass or more.
Further, in order to further reduce the possibility of occurrence of plating defects such as nodules (protrusions) and pits, the Cu content is preferably 0.400% by mass or less, and 0.300% by mass or less for each of Cu and Zn. Is more preferable, and the Zn content is preferably 0.300% by mass or less.

(Solution Mg amount: 3.8% by mass or more)
Solid solution Mg has the effect of improving strength as described above. Even if the amount of Mg is large, there is a possibility that the desired strength cannot be obtained if the amount of solid solution Mg is small. Therefore, in the present invention, the amount of solid solution Mg is specified. By setting the solid solution Mg amount to 3.8% by mass or more, a desired strength can be reliably obtained.
Therefore, the solid solution Mg amount is 3.8% by mass or more, and preferably 4.5% by mass or more.
In addition, although the upper limit of the amount of solid solution Mg is not specifically limited, For example, it is 5.9 mass% or less.

About the amount of solid solution Mg, it can measure using the residue extraction method by a hot phenol, for example. Specifically, the amount of Mg contained in the filtrate obtained by the residue extraction method with hot phenol (filter mesh size: 0.1 μm) is measured by ICP emission analysis, and measured from the total amount of Mg contained in the aluminum alloy plate The value obtained by subtracting the value may be used as the solid solution Mg amount.
The solid solution Mg amount can be controlled by adjusting the Mg amount, the Si amount, the heat treatment temperature in the homogenization heat treatment step, and the like.

(Inevitable impurities)
As inevitable impurities, Mn, Cr, Zr, Ti, B, V, Ni, and the like may be contained within a range that does not hinder the effects of the present invention. Specifically, each may be contained in a range of 0.05% by mass or less, preferably 0.01% by mass or less, and a total of 0.15% by mass or less.
And about Mn, Cr, Zr, Ti, B, V, Ni, etc., if not exceeding the above-mentioned predetermined content, it is not only the case where it is contained as an unavoidable impurity but also the case where it is actively added. Even if it exists, the effect of this invention is not prevented. For example, for the purpose of refining crystal grains, Ti or B may be positively added so as to have a content of 0.02 to 0.04% by mass.
Further, Fe and Si that define only the above upper limit value may be positively added, but may be included as an inevitable impurity.
In addition, 0 mass% may be sufficient as content of each element quoted as an unavoidable impurity.

(0.2% proof stress: 250-400 MPa)
When the 0.2% proof stress is 250 MPa or more, the aluminum alloy plate according to the present invention can ensure strength as a structural component such as an inner chassis. On the other hand, if the 0.2% proof stress exceeds 400 MPa, there is a risk that processing cracks may occur during press processing (punching or molding).
Therefore, the 0.2% proof stress of the aluminum alloy plate according to the present invention is 250 to 400 MPa.
The lower limit of 0.2% proof stress is preferably 300 MPa or more, and more preferably 340 MPa or more. The upper limit of 0.2% proof stress is preferably 380 MPa or less, and more preferably 360 MPa or less.

The 0.2% proof stress can be measured by the following method.
A test piece of JIS No. 5 was cut out from an aluminum alloy sheet after stabilization treatment in the production method described later so that the tensile direction was parallel to the rolling direction, and 0.2% proof stress was obtained in accordance with the offset method of JIS Z2241: 2011. taking measurement.
The 0.2% proof stress can be controlled by adjusting the content of each alloy component (particularly Mg, Fe, Si).

(State of aluminum alloy plate)
The aluminum alloy plate according to the present invention basically refers to an alloy plate that has been subjected to the stabilization treatment in the production method described below and before the surface treatment, but the alloy after the stabilization treatment. Also includes a surface-treated plate.
Here, “surface-treated” means that the alloy plate after stabilization treatment is pretreated (mechanical pretreatment such as sandblasting and polishing, degreasing, zincate treatment, double zincate treatment, chemical treatment before etching, etc. That have been subjected to surface treatment, such as plating treatment, chemical conversion treatment (phosphate chromate treatment, chromate chromate treatment, etc.), anodization treatment, etc. is there.
Note that when the above-described surface treatment (for example, plating treatment) is performed on the aluminum alloy plate, a film (for example, a plating film) is formed on the surface of the aluminum alloy plate.

(Use)
The aluminum alloy plate according to the present invention can be suitably used for structural parts installed inside electronic equipment.
Here, the structure part is a part (electric part) that becomes a framework or a framework that forms the structure (shape) of the electronic device, and includes an inner chassis (also referred to as an inner frame or an internal frame).
The electronic device is not particularly limited, and examples thereof include various portable devices (portable devices) such as mobile phones, smart devices (smartphones, tablet terminals, etc.) and portable game machines that are required to be reduced in weight. Can do.

  The aluminum alloy plate according to the present invention exerts an effect that the plating is difficult to peel off. However, the “plating” is not particularly limited, but is usually Ni applied to the surface of a structural component such as an inner chassis. This assumes plating and the like.

  The aluminum alloy plate according to the present invention is as described above, but the other characteristics that are not clearly specified are not particularly limited as long as they are conventionally known and exhibit the effects obtained by the characteristics. Needless to say.

[Method for producing aluminum alloy sheet]
Next, the manufacturing method of the aluminum alloy plate concerning this invention is demonstrated.
The aluminum alloy sheet according to the present invention is manufactured by performing a casting process, a homogenizing heat treatment process, a hot rolling process, a cold rolling process, and a stabilization processing process. In the cold rolling process, intermediate annealing may be performed.
Moreover, you may manufacture the aluminum alloy plate which concerns on this invention by performing a surface treatment process after the stabilization process.
Hereinafter, the respective steps will be mainly described.

(Casting process)
In the casting process, the aluminum alloy having the above-described composition is melted, cast by a known casting method such as a DC casting method, cooled to below the solidus temperature of the aluminum alloy, and a predetermined thickness (for example, 400 (About 600 mm).

(Homogenization heat treatment process)
In the homogenization heat treatment step, the homogenization heat treatment is performed at a predetermined temperature before rolling the ingot cast in the casting step. By subjecting the ingot to homogenization heat treatment, internal stress is removed, solute elements segregated at the time of casting are homogenized, and intermetallic compounds precipitated at the time of casting cooling and thereafter grow.
The heat treatment temperature in this homogenization heat treatment step may be 400 to 550 ° C., for example. By setting the heat treatment temperature to the above lower limit value or more, the above-described homogenization effect can be obtained. On the other hand, when the heat treatment temperature exceeds the upper limit, the ingot is melted and an aluminum alloy plate cannot be obtained. However, in order to increase the solid solution Mg amount, the high temperature range is preferable among the above temperature ranges.
The heat treatment time may be 1 to 24 hours, for example.

In the homogenization heat treatment step, even after “homogeneous heat treatment” after the homogenization heat treatment, the hot rolling is performed without cooling. ) Even after “2 times soaking” in which hot rolling is carried out after reheating after chamfering and chamfering, after the homogenization heat treatment, it is cooled to the hot rolling start temperature and hot rolling “Two-stage soaking” may be performed.
Here, when performing “one-time soaking” and “two-stage soaking”, it is only necessary to chamfer before the homogenization heat treatment step.

(Hot rolling process)
In the hot rolling step, the homogenized ingot is hot rolled.
The rolling start temperature in this hot rolling process may be 400 to 550 ° C., for example, and the rolling end temperature may be 250 to 380 ° C. By setting the rolling start temperature to the lower limit value or more, an aluminum alloy plate can be appropriately obtained. On the other hand, if the rolling start temperature exceeds the above upper limit, the ingot melts, and an aluminum alloy plate cannot be obtained, or even if an aluminum alloy plate is obtained, a seizure pattern may occur. There is. Moreover, an aluminum alloy plate can be obtained appropriately by setting the rolling end temperature to be equal to or higher than the lower limit. On the other hand, when the rolling end temperature exceeds the upper limit, the crystal grain size may become coarse or a seizure pattern may occur.
In addition, it can be set as the hot rolled sheet (hot coil) of desired plate | board thickness by performing the hot rolling which consists of a several path | pass.

(Cold rolling process)
In the cold rolling step, the hot rolled plate is cold rolled at a temperature lower than the recrystallization temperature (for example, room temperature).
The rolling reduction in this cold rolling process may be 50 to 90%, for example.
And in this cold rolling process, you may give intermediate annealing (for example, 300-450 degreeC, 1 to 12 hours). The intermediate annealing may be continuous annealing (CAL) or batch annealing (box annealing).

(Stabilization process)
In the stabilization process, low-temperature heating is performed on the rolled sheet after the cold rolling process.
The heating temperature in the stabilization process may be, for example, 100 to 250 ° C. By setting the heating temperature to the lower limit value or more, the effect of stabilization treatment (inhibition of softening of strength over time) can be obtained. On the other hand, when the heating temperature exceeds the above upper limit value, the aluminum alloy sheet is softened, so that it falls below the desired proof stress value.
The heating time may be 1 to 12 hours, for example.

(Surface treatment process)
In the surface treatment step, surface treatment is performed on the rolled plate after the stabilization treatment step.
Surface treatments in the surface treatment process include “pretreatment” (mechanical pretreatment such as sandblasting and polishing, degreasing, zincate treatment, double zincate treatment, chemical pretreatment such as etching), “plating treatment”, and “chemical conversion treatment”. ”(Phosphoric acid chromate treatment, chromic acid chromate treatment, etc.),“ anodic oxidation treatment ”and the like are generally performed surface treatments.

  The method for producing an aluminum alloy plate according to the present invention is as described above. However, in carrying out the present invention, other processes are performed between or before and after each process within a range that does not adversely affect each process. May be included. For example, after the stabilization treatment step or the surface treatment step, a processing step of cutting or punching the aluminum alloy plate into a predetermined size or processing into a predetermined shape (bending, punching, etc.) May be included.

  In addition, as for conditions that are not clearly shown in the respective steps, it is sufficient to use conventionally known conditions, and it is needless to say that the conditions can be appropriately changed as long as the effects obtained by the processing in the respective steps are exhibited.

  Next, the aluminum alloy plate according to the present invention will be specifically described by comparing an example satisfying the requirements of the present invention with a comparative example not satisfying the requirements of the present invention.

[Production of test materials]
Aluminum alloys having the compositions shown in Table 1 were melted, and ingots were produced by semi-continuous casting (about 4 tons by weight). This ingot is subjected to homogenization heat treatment (samples 1 to 8, 12 to 19 are 480 ° C, sample materials 9, 10, and 20 are 550 ° C, sample material 11 is 400 ° C, and sample material 21 is 380 ° C. Sample material 22 was 580 ° C.). Then, hot rolling (starting temperature: specimens 1-8, 12-19 are 400 ° C., specimens 9-11, 20-22 are the same temperature as soaking temperature, finishing temperature: 330 ° C., starting plate (Thickness: 580 mm, final plate thickness: 2 mm). Thereafter, cold rolling (final plate thickness: 0.4 mm) is performed, and stabilization treatment (heating temperature: 175 ° C., heating time: 4 hours) is performed to prepare a test material, Samples for evaluation were collected from the central portion of the width. In addition, about the aluminum plate coil after the said last cold rolling, coil rewinding was performed, the sample of 1 m length was each taken from the outer peripheral part, the center part, and the inner peripheral part, and it was used for the ear crack evaluation.

[Measurement item]
(Solution Mg amount)
About the amount of solid solution Mg of a test material, it measured with the following method.
The test material (aluminum alloy plate) produced by the above method was dissolved with hot phenol, and diluted by adding benzyl alcohol and suction filtered. Filtration was performed by suction filtration on a membrane filter having a pore size of 0.1 μm to obtain a filtrate from which crystallized substances and fine precipitates were removed. The amount of Mg in the filtrate was measured by ICP emission analysis, and the value obtained by subtracting the measured value from the total amount of Mg contained in the test material was taken as the solid solution Mg amount.
When troubles such as clogging occur, the crystallized product is removed by passing the solution once through a PTFE (tetrafluorostyrene resin) type membrane filter having a pore size of 1.0 μm, Subsequently, a second suction filtration was performed with a membrane filter having a pore diameter of 0.1 μm.

(0.2% yield strength)
The 0.2% proof stress of the test material was measured by the following method.
A test piece of JIS No. 5 was cut out from the specimen prepared by the above method so that the tensile direction was parallel to the rolling direction, and in accordance with the offset method of JIS Z2241: 2011, Shimadzu Corporation Co., Ltd. A tensile test was performed with a stationary universal tensile tester AG-I, and a 0.2% yield strength (MPa) was measured.
The crosshead speed was 5 mm / min. The test was performed at a constant speed until the test piece broke, and the average value was calculated by measuring each time five times.

(Ear cracking)
Regarding the judgment of the ear cracking property of the test material (degree of suppression of the occurrence of ear cracks during rolling), the aluminum alloy plate (plate thickness: 0.4 mm, width: 1300 mm) after the final cold rolling of each test material. ) Was evaluated (evaluation was performed on three parts of the outer peripheral part, the central part, and the inner peripheral part).
(Double-circle): The ear crack was not recognized in all the site | parts.
O: Ear cracks were observed in any part, but the crack propagation length from the edge (end in the width direction) toward the inner side in the width direction was within 20 mm.
X: Ear cracks were observed in any part, and the crack propagation length from the edge (end in the width direction) toward the inner side in the width direction exceeded 20 mm.

(Plating adhesion)
The plating adhesion (degree of difficulty of peeling of plating) of the test material was evaluated by the following method.
The specimen prepared by the above method was degreased with AD-68F at 70 ° C. for 5 minutes, acid-etched with AD-101F at 68 ° C. for 2 minutes, and desmutted with 30% nitric acid. Then, after performing a zincate treatment at 20 ° C. and 30 seconds with AD-301F-3X, a zincate peeling treatment at 20 ° C. and 30 seconds with 30% nitric acid was performed, and then again at 20 ° C. and 30 seconds with AD-301F-3X. A zincate treatment was performed, and a double zincate treatment was performed. Furthermore, electroless nickel plating was performed using SEK-797 to form a Ni plating film having a thickness of about 2 μm. The AD-68F, AD-101F, and AD-301F-3X are plating pretreatment solutions, and the SEK-797 is a plating solution, all of which are manufactured by Nippon Kanisen Co., Ltd.
Then, a plating adhesion test was performed on the test material on which the Ni plating film was formed based on the peel test method (tape test method) of JISH8504: 1999. In this test, after making a streak (a streak specified in 15.1.4c of JISH8504: 1999), a tape peeling operation (JISH8504: 1999 15.1.4 of a prescribed condition) was made. The operations specified in a) and b) were performed.

Further, the presence or absence of plating defects (pits, nodules, etc.) was determined by observing the surface of the test material at a magnification of 200 times using a Scopeman MS-900HD (stereoscopic microscope, manufactured by Moritex Co., Ltd.). When defects such as pits or nodules having a width of 10 μm or more were found on the surface of the test material on which the Ni plating film was formed (2.5 mm × 1.5 mm in total 10 fields of view), it was determined that there was a plating defect.
In addition, the presence or absence of the plating defect was determined before the plating adhesion test (before applying the tape).

The evaluation criteria for plating adhesion are as follows.
◯: There was no peeling of plating (no adhesion of plating on the adhesive surface of the tape), and there were no plating defects (pits, nodules, etc.).
Δ: There was no peeling of the plating, but there was a plating defect.
X: Plating was peeled off.

  Detailed components of the aluminum alloy and the results of the measurement items are shown in Table 1. In Table 1, those not satisfying the configuration of the present invention are indicated by underlining the numerical values. In addition, “-” in Table 1 indicates that the element is not added.

[Examination of results]
About the test materials 1-11, since the requirements prescribed | regulated by this invention are satisfy | filled, while exhibiting sufficient intensity | strength (0.2% yield strength) to apply to structural components, such as an inner chassis, plating As a result, the adhesiveness was excellent and the occurrence of ear cracks during rolling could be suppressed. In addition, the specimen 7 having a particularly low Fe content and the specimen 8 having a particularly low Si content were particularly excellent in terms of suppressing the occurrence of ear cracks during rolling.

On the other hand, in the test material 12, since the Mg content exceeded the upper limit value of the numerical range defined in the present invention, the occurrence of ear cracks during rolling could not be sufficiently suppressed.
Since the amount of solute Mg was less than the lower limit of the numerical range defined in the present invention, the test material 13 could not obtain sufficient strength (0.2% yield strength).

Since the sample material 14 was less than the lower limit of the numerical range defined in the present invention, the Cu and Zn contents were inferior in plating adhesion.
Since the sample material 15 had a Cu content exceeding the upper limit of the numerical range defined in the present invention, the result was that the plating adhesion was not sufficient.
Since the total content of Cu and Zn exceeded the upper limit of the numerical value range prescribed | regulated by this invention, the test material 16 was a result that plating adhesiveness was not enough.
In the test material 17, since the Zn content exceeded the upper limit of the numerical range defined in the present invention, the occurrence of ear cracks during rolling cannot be sufficiently suppressed, and the plating adhesion is not sufficient. The result was not.

In the test material 18, since the Fe content exceeded the upper limit of the numerical range defined in the present invention, the generation of the ear cracks during rolling could not be sufficiently suppressed.
In the test material 19, the Si content exceeded the upper limit of the numerical range defined in the present invention, and the solid solution Mg amount was less than the lower limit of the numerical range defined in the present invention. Further, the occurrence of ear cracks during rolling could not be sufficiently suppressed, and sufficient strength could not be obtained.
Since the sample material 20 had a Mg content and a solid solution Mg content that were less than the lower limit of the numerical range defined in the present invention, sufficient strength (0.2% yield strength) could not be obtained. It was.
Since the test material 21 had a low heat treatment temperature during the homogenization heat treatment and the solid solution Mg amount was less than the lower limit of the numerical range defined in the present invention, sufficient strength could not be obtained.
The test material 22 was too high in the temperature of the homogenization heat treatment, and could not be processed after the hot rolling.

  From the above results, it has been found that the aluminum alloy plate according to the present invention is excellent in strength and plating adhesion, suppresses the occurrence of ear cracks during rolling, and improves productivity. Therefore, it turned out that the aluminum alloy plate which concerns on this invention can be used suitably for structural components, such as an inner chassis.

Claims (6)

Mg: 4.7 to 6.0 mass%, Fe: 0.20 mass% or less, Si: 0.10 mass% or less, Cu: 0.005 to 0.500 mass%, and Zn: 0.005 ~ At least one of 0.400 mass%, the total content of the Cu and Zn is 0.500 mass% or less, the balance is Al and inevitable impurities,
The solid solution Mg amount is 3.8% by mass or more,
An aluminum alloy plate having a 0.2% proof stress of 250 to 400 MPa.   The aluminum alloy sheet according to claim 1, wherein the aluminum alloy sheet is used for a structural part.   It uses for an inner chassis, The aluminum alloy plate of Claim 1 or Claim 2 characterized by the above-mentioned.   The aluminum alloy plate for electrical parts according to any one of claims 1 to 3.   The aluminum alloy plate according to any one of claims 1 to 4, wherein the aluminum alloy plate has a film on the surface.   The aluminum alloy plate according to claim 5, wherein the film is a plating film.