JP4121266B2 - Method for producing semi-molten billet of aluminum alloy for transportation equipment - Google Patents

Description

【００３１】
上記表１に示すアルミニウム合金ビレットを、表２に示す条件で処理し、半溶融成型の成型性、半溶融成型後の初晶α（Ａｌ）相の形状を評価した結果も表２に併記した。
【００３２】
【表２】

【００３３】
表２に示した加工歪み導入時の成型性は、表２で示す成型条件で成型した際に割れが発生せず成型性が良好なものを○とし、割れが見られるものを×で判定した。半溶融成型の成型性は、良好なものを○とし、成型性の悪いものを×と判定した。半溶融成型後の初晶α（Ａｌ）相の形状は、球状化が認められるものを○とし、球状化が不充分であるものを×と判定した。半溶融成型後の初晶α（Ａｌ）相の微細均一化では初晶α（Ａｌ）相のサイズが１００μｍ以下を○とし、１００μｍを越えるサイズのものを×と判定した。
【００３４】
図２は、初晶α（Ａｌ）相の微細均一化が○評価の代表例写真を示す。
【００３５】
【発明の効果】
以上述べて来た如く、本発明によれば、従来の半溶融ビレットよりも工程が簡素化され低コスト化が図れる。また、得られる組織も初晶α（Ａｌ）相サイズが平均１００μｍ以下で、かつ初晶α（Ａｌ）相の面積率５０％の均一球状化組織となっており、自動車部材等の輸送機器用として使用が可能である。
【図面の簡単な説明】
【図１】冷間型枠鍛造の模式図である。
【図２】初晶α（Ａｌ）相の微細均一化が○評価の代表例の顕微鏡組織写真であり、倍率は５０倍である。
【符号の説明】
１ 鍛造用金型
２ 鍛造用金型ポンチ
３ アルミニウム合金ビレット[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a semi-melt molded billet of an aluminum alloy used for transportation equipment.
[0002]
[Prior art]
The thixocast method using a semi-molten billet is a technology that has recently been attracting attention because it has advantages such as fewer casting segregation and defects and a longer die life compared to conventional die casting methods. The billet casting method used for this is a method (method) in which electromagnetic and mechanical stirring is performed in the semi-melting temperature range in order to spheroidize the primary crystal α (Al) phase at the billet stage known as the Pesine Almax method. A) or a method of adding a larger amount of Al-Ti-B than the amount normally added at the time of casting, and raising the temperature to the latter half melting temperature range to spheroidize the primary crystal α (Al) phase (Method B) There is. Further, a method (method C) in which strain is introduced by extrusion / rolling and then heated and spheroidized as in method B is widely known.
[0003]
[Problems to be solved by the invention]
In the case of the conventional semi-molten production method, the method A has a problem that the process is very complicated and the production cost is high.
Moreover, in method B, since a large amount of Al—Ti—B is added, quality instability occurs due to TiB ₂ sedimentation in the melting furnace, and the method of introducing strain by rolling in method C introduces uniform strain. In addition, the extrusion process is cumbersome due to room temperature extrusion, and it is difficult to introduce uniform strain, and both strain introduction methods require product processing after processing, and mass production and cost reduction cannot be achieved. there were.
[0004]
Japanese Patent No. 2976073 discloses an improved method. That is, in the first item, there is described in “the step of deforming a fully solidified metal or metal alloy material at a temperature below its recrystallization temperature, heating the deformable material to cause recrystallization of the microstructure of the material. And partially melting the recrystallized structure to form independent particles in a liquid matrix that exhibits thixotropic behavior by raising the temperature of the material above its solidus temperature. It is a method including the step of
In this method, the deformation material is heated to cause recrystallization of the microstructure of the material, and heating that is called so-called two-step heating in which the temperature of the material is raised to a temperature above the solidus temperature. Is done. Such a method can be said to be an improved technique as compared with the conventional technique, but it still requires two-stage heating, and has a problem that the process is complicated and heating control is difficult.
[0005]
An object of the present invention is to provide a method for producing a semi-molten molded billet of an aluminum alloy for transportation equipment in which the disadvantages of the above prior art are eliminated, the process is simple and cost reduction can be promoted, and the resulting product is homogeneous. To do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the manufacturing method of the semi-molten molded billet of the aluminum alloy for transportation equipment of the present application is Cu 0.40 to 5.5 wt%, Si 13.6 to 25.0 wt%, Zn 1.0 wt% or less, Fe1. 5 wt% or less, Mn 0.65 wt% or less, Ti 0.005 to 0.5 wt% and at least one of B0.0001 to 0.5 wt%, Mg 0.40 to 1.8 wt%, the balance being substantially Al An aluminum alloy having an average particle size of primary Si of 300 μm or less and a dendrite branch interval (DAS) of 200 μm or less is manufactured, and then a strain rate of 5 to 50% and a processing introduction speed of 50 mm / sec. In the following, processing strain is introduced by cold mold forging at a temperature lower than the recrystallization temperature, and then the temperature is raised to the eutectic temperature or higher, and the liquid phase ratio is maintained at a temperature of 20 to 80% and semi-molten. It is a method of processing.
[0007]
In this case, for homogenization of component segregation and release of casting stress, it is preferable to perform a homogenization treatment at a temperature of 450 to 550 ° C. for 1 to 10 hours before introducing processing strain.
[0008]
Moreover, in order to achieve the said objective, the manufacturing method of the semi-molten shaping | molding billet of the aluminum alloy for transportation apparatuses of this application is Cu0.40-5.5 wt%, Si10.0-25.0 wt%, Zn1.0 wt% or less Fe 1.5 wt% or less, Mn 0.65 wt% or less, Ti 0.005 to 0.5 wt%, and B0.0001 to 0.5 wt%, at least one of Mg, 0.40 to 1.8 wt%, Ni 0.05 to 1 An aluminum alloy containing 0.7 wt%, the balance being substantially composed of Al, the primary crystal Si having an average particle diameter of 300 μm or less and a dendrite branch interval (DAS) of 200 μm or less is manufactured, and then the distortion rate 5 to 50%, processing introduction speed 50 mm / sec. In the following, processing strain is introduced by cold mold forging at a temperature lower than the recrystallization temperature, and then the temperature is raised to the eutectic temperature or higher, and the liquid phase ratio is maintained at a temperature of 20 to 80% and semi-molten. It is a method of processing.
[0009]
In this case, for homogenization of component segregation and release of casting stress, it is preferable to perform a homogenization treatment at a temperature of 450 to 550 ° C. for 1 to 10 hours before introducing processing strain.
[0010]
Furthermore, in order to achieve the said objective, the manufacturing method of the semi-molten shaping | molding billet of the aluminum alloy for transport equipment of this application is the alloy used by the method mentioned above, and also contains the aluminum alloy which contains P0.003-0.150 wt%. Sometimes used.
[0011]
Also in this case, in order to homogenize the component segregation and release the casting stress, it is preferable to perform a homogenization treatment at a temperature of 450 to 550 ° C. for 1 to 10 hours before introducing processing strain.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, various numerical limitation reasons such as numerical limitation of the amount of aluminum alloy components used in the present invention will be described in detail.
[0013]
The Cu component improves not only mechanical properties but also hardness, machinability, and castability. However, the effect is small if it is less than 0.40 wt%, while corrosion resistance decreases if it exceeds 5.5 wt%. 0.40 to 5.5 wt%.
[0014]
The Si component has an effect of improving the wear resistance. However, if the content is less than 10.0 wt%, the effect is small. On the other hand, if it exceeds 25.0 wt%, the elongation / toughness deteriorates and the cold forging workability deteriorates. It was set to 10.0-25.0 wt%.
[0015]
The Mg component precipitates Mg ₂ Si and contributes to the improvement of mechanical properties. However, the effect is small when the content is less than 0.40 wt%, while the cold forgeability deteriorates when the content exceeds 1.8 wt%. 40-1.8 wt%.
[0016]
The Fe component produces an Al component and an intermetallic compound, and if it is contained in a large amount, it becomes an Al—Fe—Si compound and adversely affects elongation, toughness, and corrosion resistance.
[0017]
The Ti component refines the ingot structure and prevents the occurrence of ingot cracking, but the effect is small if it is less than 0.005 wt%, while the TiAl ₃ giant crystallized material is exceeded if it exceeds 0.5 wt%. The generation is promoted and causes cracking during cold forging and deterioration of mechanical properties of transport equipment parts, so 0.005 to 0.5 wt% was set.
[0018]
The B component also refines the structure of the ingot together with the Ti component to prevent the occurrence of ingot cracking, but the effect is small if it is less than 0.0001 wt%, while it exceeds the 0.5 wt% during cold forging. Since it causes cracks and deterioration of mechanical properties of parts for transportation equipment, the content is set to 0.0001 to 0.5 wt%.
[0019]
The Zn component improves the castability but deteriorates the corrosion resistance.
[0020]
The Mn component is set to 0.65 wt% or less because it causes a decrease in toughness due to the formation of coarse intermetallic compounds.
[0021]
The Ni component contributes to the improvement of the high-temperature strength, but the effect is small if it is less than 0.05 wt%, while the corrosion resistance deteriorates if it exceeds 1.7 wt%, so it was made 0.05 to 1.7 wt%.
[0022]
The P component refines the primary Si of the high Si alloy and contributes to the improvement of mechanical properties, but the effect is small if it is less than 0.003 wt%, while the fluidity of the molten aluminum alloy exceeds 0.015 wt%. Or 0.003 to 0.015 wt% because the filling property is deteriorated and the castability is impaired.
[0023]
A billet with a dendrite branch interval (DAS) of 200 μm or less is cast, but when the dendrite branch interval (DAS) exceeds 200 μm, the primary α (Al) phase becomes uniform and fine spheroidized when heated to the semi-melting temperature range. In addition, when the homogenization process is performed, the homogenization process takes time, so the dendrite branch interval (DAS) is set to 200 μm or less. Further, when the average grain size of primary Si exceeds 300 μm, the mechanical properties deteriorate, so it is set to 300 μm or less.
[0024]
By homogenizing the billet obtained by casting, crystallized substances such as Al ₂ Cu and Mg ₂ Si crystallized at the crystal grain boundaries during casting are dissolved in the matrix. In addition, eutectic Si and primary Si are spheroidized to reduce deformation resistance during cold forging. If the homogenization temperature is less than 450 ° C. or a heating time that does not reach 1 hour, sufficient solid solution cannot be obtained, and spheroidization of eutectic Si or primary crystal Si or removal of casting strain is insufficient. However, if the processing temperature exceeds 550 ° C., eutectic melting occurs and the workability during forging is impaired. On the other hand, when the heating time exceeds 10 hours, the effect of homogenization corresponding to the long heating time is not observed, and heating energy is lost. For this reason, the homogenization treatment conditions were heating at a temperature of 450 to 550 ° C. for 1 to 10 hours.
[0025]
Next, processing strain is introduced by cold forging so that the process can be simplified and strain is effectively introduced at a low processing rate, and strain is uniformly introduced into the entire forging billet. Formwork forging. When the strain rate is less than 5%, the introduction of strain is small, so even if the temperature is raised to the semi-melting temperature range, uniform spheroidization of the primary crystal α (Al) phase cannot be achieved. In addition to no change in the α (Al) phase size, cracks occur during cold forging, so the content was set to 5 to 50%. The distortion rate here is (L ₁ −L ₂ ) / L ₁ × 100 (%), where L ₁ is the original length of the forging billet and L ₂ is the length of the billet after forging. Defined.
[0026]
The processing introduction speed can be significantly increased by adding grain refinement of the billet ingot, refinement of eutectic Si, refinement of primary Si and homogenization treatment. In terms of productivity, it is preferable that the processing introduction speed is as fast as possible. However, 50 mm / sec. Exceeds 50 mm / sec., Because cracking occurs during forging and distortion is not uniformly introduced into the forged dead zone. It was as follows. Further, when the billet temperature during cold mold forging is higher than the recrystallization temperature, the introduction of strain for the predetermined processing rate is insufficient, and even when the temperature is raised to the semi-melting temperature, the primary α (Al) phase has a granular structure. Therefore, it was set below the recrystallization temperature.
[0027]
Thereafter, the billet is heated to a temperature equal to or higher than the eutectic temperature and held at a temperature at which the liquid phase ratio becomes 20 to 80%, and semi-molten molding is performed. However, when the liquid phase ratio is less than 20%, the primary α (Al) phase is uniform. Sphericalization cannot be achieved, and the deformation resistance of semi-molten molding is large, and pressure molding becomes difficult. On the other hand, if it exceeds 80%, a molded product having a uniform structure cannot be obtained. For this reason, the liquid phase ratio in the semi-melting temperature range above the eutectic temperature was set to 20 to 80%.
[0028]
【Example】
Specific examples of the present invention are shown below.
FIG. 1 is a schematic view of cold mold forging used in the method of the present invention, in which 1 is a forging die, 2 is a forging die punch, and 3 is an aluminum alloy billet.
[0029]
The molten metal was adjusted so that Cu, Si, Mg, Zn, Fe, Ti, B, Ni, and P each had a composition as shown in Table 1 below, and an aluminum alloy billet was cast by continuous casting.
[0030]
[Table 1]

[0031]
The aluminum alloy billet shown in Table 1 was processed under the conditions shown in Table 2, and the results of evaluating the moldability of semi-melt molding and the shape of the primary crystal α (Al) phase after semi-melt molding are also shown in Table 2. .
[0032]
[Table 2]

[0033]
The moldability at the time of introducing the processing strain shown in Table 2 was judged as “Good” when the mold did not generate a crack when molded under the molding conditions shown in Table 2 and the moldability was good. . Regarding the moldability of the semi-melt molding, a good one was evaluated as “good”, and a poor one was determined as “poor”. The shape of the primary crystal α (Al) phase after semi-melt molding was evaluated as “◯” when spheroidization was observed, and “×” when the spheroidization was insufficient. In the fine homogenization of the primary crystal α (Al) phase after semi-melt molding, the primary crystal α (Al) phase size was evaluated as ○ when the size of the primary crystal α (Al) phase was 100 μm or less, and × when the size exceeded 100 μm.
[0034]
FIG. 2 shows a photograph of a representative example in which fine homogenization of the primary crystal α (Al) phase is evaluated as o.
[0035]
【The invention's effect】
As described above, according to the present invention, the process is simplified and the cost can be reduced as compared with the conventional semi-molten billet. The resulting structure also has a uniform spheroidized structure with an average primary crystal α (Al) phase size of 100 μm or less and an area ratio of primary crystal α (Al) phase of 50%. It can be used as
[Brief description of the drawings]
FIG. 1 is a schematic diagram of cold mold forging.
FIG. 2 is a photomicrograph of a representative example of evaluation of fine homogenization of primary crystal α (Al) phase, with a magnification of 50 times.
[Explanation of symbols]
1 Forging die 2 Forging die punch 3 Aluminum alloy billet

Claims (6)

Cu 0.40 to 5.5 wt%, Zn 1.0 wt% or less, Fe 1.5 wt% or less, Mn 0.65 wt% or less, Ti 0.005 to 0.5 wt%, and B 0.0001 to 0.5 wt%, Mg 0.40 to 1.8 wt% , Si 10.0 to 25.0 wt% , the balance is composed of unavoidable impurities and Al, the average grain size of primary Si is 300 μm or less, and the dendrite branch spacing is 200 μm The following aluminum alloy is manufactured, and then a strain rate of 5 to 50% and a processing introduction speed of 50 mm / sec. In the following, processing strain is introduced by cold mold forging at a temperature lower than the recrystallization temperature, and then the temperature is raised to the eutectic temperature or higher, and the liquid phase ratio is maintained at a temperature of 20 to 80% and semi-molten. A method for producing a semi-melt molded billet of an aluminum alloy for transport equipment, characterized by processing.   The aluminum alloy semi-molten molded billet for transportation equipment according to claim 1, wherein the aluminum alloy is manufactured and homogenized at a temperature of 450 to 550 ° C for 1 to 10 hours before introducing processing strain. Manufacturing method. Cu 0.40 to 5.5 wt%, Zn 1.0 wt% or less, Fe 1.5 wt% or less, Mn 0.65 wt% or less, Ti 0.005 to 0.5 wt%, and B 0.0001 to 0.5 wt%, Mg0.40-1.8wt%, Ni0.05-1.7wt% , Si10.0-25.0wt% , the balance is composed of inevitable impurities and Al, and the average grain size of primary Si is 300μm In the following, an aluminum alloy having a dendrite branch interval of 200 μm or less is manufactured, and then a strain rate of 5 to 50% and a processing introduction speed of 50 mm / sec. In the following, processing strain is introduced by cold mold forging at a temperature lower than the recrystallization temperature, and then the temperature is raised to the eutectic temperature or higher, and the liquid phase ratio is maintained at a temperature of 20 to 80% and semi-molten. A method for producing a semi-melt molded billet of an aluminum alloy for transport equipment, characterized by processing.   The aluminum alloy semi-molten molded billet for transportation equipment according to claim 3, wherein the aluminum alloy is homogenized at a temperature of 450 to 550 ° C for 1 to 10 hours before producing the aluminum alloy and introducing processing strain. Manufacturing method.   The method for producing a semi-molten molded billet of an aluminum alloy for transportation equipment according to claim 1 or 3, further comprising using an aluminum alloy containing 0.003 to 0.150 wt% of P.   6. The aluminum alloy semi-molten molded billet for transport equipment according to claim 5, wherein the aluminum alloy is manufactured and homogenized at a temperature of 450 to 550 [deg.] C. for 1 to 10 hours before introducing processing strain. Manufacturing method.

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