Method for producing aluminum alloy clad material for press molding, aluminum alloy clad material for press molding, and press molded product

Abstract

This method for producing an aluminum alloy clad material for press molding having a core material and a first skin material and second skin material joined to the respective sides of the core material so as to sandwich the core material involves: a step A for preparing a first aluminum alloy by using scrapped aluminum alloy clad material from an automobile heat exchanger containing Si, Fe, Cu, Mn, Mg, Cr, Zn, and Ti as additive elements; a step B for preparing a second aluminum alloy in which the content ratios of at least Si and Cu are smaller than those in the first aluminum alloy; a step C for forming a plate material for the core material by using the first aluminum alloy; a step D for forming a plate material for the first skin material and a plate material for the second skin material independently by using the second aluminum alloy; and a step E for rolling the plate material for the first skin material and the plate material for the second skin material in a state where the plate material for the first skin material and the plate material for the second skin material are arranged so as to sandwich the plate material for the core material.

Description

Manufacturing method of aluminum alloy clad material for press molding, aluminum alloy clad material for press molding, and press molded product

[0001] The present invention relates to a method for manufacturing an aluminum alloy clad material for press forming, an aluminum alloy clad material for press forming, and a press-formed product, and in particular to a method for manufacturing an aluminum alloy clad material for press forming that is more recyclable than conventional methods, an aluminum alloy clad material for press forming manufactured by such a manufacturing method, and a press-formed product manufactured using such an aluminum alloy clad material for press forming.

[0002] In recent years, there has been a growing demand for recycling resources in various fields. Aluminum alloys, which are produced by reducing bauxite, consume a huge amount of electricity, so there is a need to promote recycling from the perspectives of resource conservation and cost reduction.

[0003] For example, Patent Document 1 discloses a recycling method including the steps of melting a recycled aluminum alloy into a liquid metal, adding magnesium, silicon, or copper as an alloying element to the liquid metal to form a modified liquid metal, casting the modified liquid metal, and rolling the cast alloy, wherein the modified liquid metal contains 50% or more of recycled aluminum alloy. According to the recycling method described in Patent Document 1, a high-strength, highly formable metal product can be cast from aluminum alloy scrap.

[0004] Special Publication No. 2020-514556 (Patent No. 7163304)

[0005] The present inventors have investigated ways to improve recycling efficiency by limiting the scrap aluminum alloy materials to be recycled and the aluminum alloy materials to be produced by recycling. However, simply repeatedly recycling the same type of material increases the impurity concentration, and repeatedly recycling the same alloy composition increases the amount of virgin aluminum added, resulting in a problem of reduced recycling efficiency.

[0006] An object of the present invention is to provide a method for producing an aluminum alloy clad material for press forming that can improve recycling efficiency. Another object of the present invention is to provide an aluminum alloy clad material for press forming that can be produced by such a production method, and a press-formed product produced using such an aluminum alloy clad material for press forming.

[0007] According to an embodiment of the present invention, the following solutions are provided:

[0008] [Item 1] A method for producing an aluminum alloy clad material for press molding, having a core material and first and second skin materials joined to either side of the core material so as to sandwich the core material, the method comprising: Step A of preparing a first aluminum alloy using scrap of an aluminum alloy clad material for an automobile heat exchanger, the first aluminum alloy containing Si, Fe, Cu, Mn, Mg, Cr, Zn, and Ti as additive elements; Step B of preparing a second aluminum alloy, the second aluminum alloy having an Si and Cu content lower than that of the first aluminum alloy; Step C of forming a core plate using the first aluminum alloy; Step D of independently forming a first skin plate and a second skin plate using the second aluminum alloy; and Step E of rolling the first skin plate and the second skin plate in a state in which the core plate is sandwiched between them.

[0009] The additive elements contained in the second aluminum alloy may further include, in addition to Si and Cu, at least one element selected from the group consisting of Fe, Mn, Mg, Cr, Zn, and Ti. Mn, Cr, Zn, and Ti contribute to the color tone and / or material strength after anodizing.

[0010] [Item 2] The manufacturing method according to Item 1, wherein the scrap of the aluminum alloy clad material of the automotive heat exchanger contains Si: 0.50% by mass or more, Fe: 0.10% by mass or more, Cu: 0.10% by mass or more, Mn: 0.50% by mass or more, Mg: 0.05% by mass or more, Cr: 0.01% by mass or more, Zn: 0.10% by mass or more, and Ti: 0.01% by mass or more.

[0011] [Item 3] The manufacturing method according to Item 1 or 2, wherein the first aluminum alloy contains 10 mass% or more of the scrap.

[0012] [Item 4] The manufacturing method according to item 1 or 2, wherein the first aluminum alloy contains 50 mass% or more of the scrap.

[0013] [Item 5] The manufacturing method according to any one of Items 1 to 4, wherein the step A includes adding any of the additional elements and / or virgin aluminum ingot so that the first aluminum alloy contains 0.50% by mass or more of Si, 0.05% by mass or more of Fe, 0.12% by mass or more of Cu, 0.60% by mass or more of Mn, 0.30% by mass or more of Mg, 0.01% by mass or more of Cr, 0.11% by mass or more of Zn, and 0.01% by mass or more of Ti, with the balance consisting of aluminum and inevitable impurities.

[0014] [Item 6] The manufacturing method according to Item 5, wherein the step A includes adding any of the additional elements and / or a new aluminum ingot so that the first aluminum alloy contains 2.00% by mass or less of Si, 1.00% by mass or less of Fe, 1.00% by mass or less of Cu, 1.80% by mass or less of Mn, 0.80% by mass or less of Mg, 0.03% by mass or less of Cr, 1.50% by mass or less of Zn, and 0.30% by mass or less of Ti.

[0015] [Item 7] The manufacturing method according to any one of Items 1 to 6, wherein the first skin plate and the second skin plate are formed by dividing one skin plate formed using the second aluminum alloy.

[0016] [Item 8] An aluminum alloy clad material for press forming, comprising a core material and first and second skin materials joined to either side of the core material so as to sandwich the core material, wherein the core material is formed of an aluminum alloy containing, as additive elements, at least 0.50% by mass of Si, at least 0.05% by mass of Fe, at least 0.12% by mass of Cu, at least 0.60% by mass of Mn, at least 0.30% by mass of Mg, at least 0.01% by mass of Cr, at least 0.11% by mass of Zn, and at least 0.01% by mass of Ti, with the balance being aluminum and inevitable impurities, and the first skin material and the second skin material are each independently formed of an aluminum alloy having at least an Si content and an Cu content that are less than the content in the core material.

[0017] The first skin material and the second skin material may further contain at least one element selected from the group consisting of Fe, Mn, Mg, Cr, Zn, and Ti, in addition to Si and Cu.

[0018] [Item 9] The aluminum alloy of the core material contains Si: 2.00% by mass or less, Fe: 1.00% by mass or less, Cu: 1.00% by mass or less, Mn: 1.80% by mass or less, Mg: 0.80% by mass or less, Cr: 0.03% by mass or less, Zn: 1.50% by mass or less, and Ti: 0.30% by mass or less. Clad material according to item 8.

[0019] [Item 10] A press-molded product manufactured using the aluminum alloy clad material for press molding according to item 8 or 9.

[0020] [Item 11] The manufacturing method according to any one of Items 1 to 7, wherein scrap of the press-molded product according to Item 10 is used instead of the scrap of the aluminum alloy clad material of the automotive heat exchanger.

[0021] According to an embodiment of the present invention, there is provided a method for producing an aluminum alloy clad material for press forming that can improve recycling efficiency. According to another embodiment of the present invention, there are provided an aluminum alloy clad material for press forming that can be produced by such a production method, and a press-formed product produced using such an aluminum alloy clad material for press forming.

[0022] Hereinafter, a method for producing an aluminum alloy clad material for press forming, an aluminum alloy clad material for press forming, and a press-formed product according to embodiments of the present invention will be described.

[0023] The method for producing an aluminum alloy clad material for press molding according to an embodiment of the present invention improves recycling efficiency by using scrap aluminum alloy clad material from automotive heat exchangers as the recycled aluminum alloy raw material.

[0024] The aluminum alloy clad material for press molding manufactured by the manufacturing method according to an embodiment of the present invention has a core material and a first skin material and a second skin material joined to either side of the core material so as to sandwich the core material. The manufacturing method according to an embodiment of the present invention includes the following steps.

[0025] A first aluminum alloy is prepared using scrap of an aluminum alloy clad material for an automobile heat exchanger, the aluminum alloy containing Si, Fe, Cu, Mn, Mg, Cr, Zn, and Ti as additive elements. A core plate for forming a core material is formed using the first aluminum alloy.

[0026] A second aluminum alloy is prepared, the content of at least Si and Cu being less than the content of Si and Cu in the first aluminum alloy. A first skin sheet for forming the first skin and a second skin sheet for forming the second skin are formed using the second aluminum alloy. The second aluminum alloys for forming the first skin sheet and the second skin sheet can be independently selected. That is, the compositions of the first skin sheet and the second skin sheet may be different or the same. From the viewpoint of productivity, it is preferable to form the first skin sheet and the second skin sheet by dividing a single skin sheet formed using the second aluminum alloy.

[0027] The first skin sheet and the second skin sheet are arranged so as to sandwich the core sheet, and then rolled. The rolling process may be a hot rolling process and / or a cold rolling process. After the rolling process, an aluminum alloy clad material for press forming is obtained, which has a core material, a first skin material, and a second skin material. The obtained aluminum alloy clad material for press forming may be subjected to a heat treatment, if necessary.

[0028] Examples of heat treatments include a homogenization treatment performed after ingot casting and before the hot rolling process, an intermediate heat treatment performed after the hot rolling process and before the cold rolling process, a solution treatment performed after the cold rolling process, and an artificial aging treatment performed after the solution treatment. Note that the intermediate heat treatment may be omitted.

[0029] The heat treatment is carried out so that small crystal precipitates are uniformly dispersed in order to improve the formability of the aluminum alloy sheet for press forming.

[0030] The homogenization treatment is carried out, for example, at a temperature of about 500°C to about 600°C, which is higher than the solubility line, for about 24 hours or less. If the treatment time exceeds about 24 hours, the crystal precipitates may become coarse. If the treatment temperature is lower than about 500°C, the treatment takes too long and the throughput decreases.

[0031] The intermediate heat treatment is carried out, for example, at about 300°C or higher and about 500°C or lower, preferably about 400°C. The heat treatment time is, for example, about 2 hours or higher and about 24 hours or lower. The intermediate heat treatment reduces the size of crystal precipitates formed in the hot rolling process, and also reduces distortion caused in the hot rolling process, allowing for recrystallization. The intermediate heat treatment may be omitted.

[0032] Solution treatment is performed to heat the crystal precipitates generated by rolling or the like to fully dissolve them. The solution treatment is preferably performed at a temperature lower than the solidus and preferably higher than the solubility limit line. The heat treatment time is, for example, more than about 0 seconds and not more than 12 hours. After the solution treatment, it is preferable to cool the material by air or water to prevent the dissolved crystal precipitates from re-precipitation.

[0033] Artificial aging is performed at a temperature of about 100° C. to about 200° C. for about 4 hours to about 24 hours. By performing artificial aging, elements contained in a solid solution in a supersaturated state are precipitated, thereby achieving a desired strength.

[0034] The process of preparing a first aluminum alloy is described below. The first aluminum alloy is used to form a core plate material that will become the core material of an aluminum alloy clad material for press forming. Scrap of an aluminum alloy clad material for an automotive heat exchanger is used, which contains the first aluminum alloy and additional elements Si, Fe, Cu, Mn, Mg, Cr, Zn, and Ti. The scrap of the aluminum alloy clad material for an automotive heat exchanger contains, for example, 0.50 mass% or more of Si, 0.10 mass% or more of Fe, 0.10 mass% or more of Cu, 0.50 mass% or more of Mn, 0.05 mass% or more of Mg, 0.01 mass% or more of Cr, 0.10 mass% or more of Zn, and 0.01 mass% or more of Ti. The composition of the scrap is determined by melting the scrap and following a method in accordance with JIS H 1351-1972.

[0035] Any of the additive elements and / or virgin aluminum ingot is added to the scrap so that the first aluminum alloy contains, for example, 0.50 mass% or more of Si, 0.05 mass% or more of Fe, 0.12 mass% or more of Cu, 0.60 mass% or more of Mn, 0.30 mass% or more of Mg, 0.01 mass% or more of Cr, 0.11 mass% or more of Zn, and 0.01 mass% or more of Ti, with the remainder consisting of aluminum and unavoidable impurities. In addition, any of the above-mentioned additional elements and / or new aluminum ingot are added to the scrap so that the first aluminum alloy contains, for example, 2.00 mass% or less of Si, 1.00 mass% or less of Fe, 1.00 mass% or less of Cu, 1.80 mass% or less of Mn, 0.80 mass% or less of Mg, 0.03 mass% or less of Cr, 1.50 mass% or less of Zn, and 0.30 mass% or less of Ti.

[0036] The first aluminum alloy preferably contains 10% by mass or more of scrap, more preferably 30% by mass or more, and even more preferably 50% by mass or more of scrap. The greater the mass fraction of scrap, the less virgin aluminum metal can be added.

[0037] The content of at least Si and Cu in the second aluminum alloy (sometimes referred to as the second content) is less than the content in the first aluminum alloy (sometimes referred to as the first content). The at least Si and Cu in the second aluminum alloy include at least Si and Cu whose content increases due to scrap of press-molded products manufactured using the aluminum alloy clad material for press molding. The additive elements in the second aluminum alloy may further include at least one element selected from the group consisting of Fe, Mn, Mg, Cr, Zn, and Ti in addition to Si and Cu. In this case, the content (second content) of any one or more additive elements selected from the group consisting of Fe, Mn, Mg, Cr, Zn, and Ti in the second aluminum alloy may be lower than the content (first content) in the first aluminum alloy, and the content of at least one element selected from the group consisting of Fe, Mn, Mg, Cr, Zn, and Ti other than Si and Cu does not have to be lower than the first content.

[0038] According to the above manufacturing method, an aluminum alloy clad material for press molding can be obtained, which has a core material and first and second skin materials joined to either side of the core material so as to sandwich the core material, wherein the core material contains, as additive elements, at least 0.50% by mass of Si, at least 0.05% by mass of Fe, at least 0.12% by mass of Cu, at least 0.60% by mass of Mn, at least 0.30% by mass of Mg, at least 0.01% by mass of Cr, at least 0.11% by mass of Zn, and at least 0.01% by mass of Ti, with the remainder being formed of an aluminum alloy consisting of aluminum and unavoidable impurities, and the first and second skin materials are each independently formed of an aluminum alloy whose Si and Cu contents are at least less than those in the core material. The aluminum alloy of the core material contains, for example, Si: 2.00 mass% or less, Fe: 1.00 mass% or less, Cu: 1.00 mass% or less, Mn: 1.80 mass% or less, Mg: 0.80 mass% or less, Cr: 0.03 mass% or less, Zn: 1.50 mass% or less, and Ti: 0.30 mass% or less.

[0039] The content of at least Si and Cu among the additive elements of the first aluminum alloy in the entire press-formable aluminum alloy clad material is adjusted so as not to exceed the upper limit of the first content. Therefore, even if impurities are contained in scrap of a press-formed product produced using the press-formable aluminum alloy clad material and the content of at least Si and Cu in the scrap increases, the content exceeding the upper limit of the first content can be suppressed or the amount by which the content exceeds the upper limit of the first content can be reduced. Therefore, in the above-mentioned method for producing a clad material, by using scrap of a press-formed product produced using the press-formable aluminum alloy clad material instead of scrap of an aluminum alloy clad material for an automotive heat exchanger, it is possible to reduce the amount of virgin aluminum ingot required to prepare the first aluminum alloy, and to improve recycling efficiency.

[0040] The first content rate and the second content rate in the method for producing an aluminum alloy clad material for press molding according to an embodiment of the present invention depend on the thickness of the core material, the thickness of the first skin material and the second skin material, and the properties required of the core material, the first skin material and the second skin material, as well as the content rate of the additive elements including at least Si and Cu that will be contained in excess in the scrap.

[0041] The thickness of the core material is, for example, 0.1 mm to 10.0 mm, and the thicknesses of the first skin material and the second skin material are each independently, for example, 0.005 mm to 3 mm. The thickness of the skin material is, for example, about 5% to about 30% of the thickness of the core material.

[0042] The composition of the first aluminum alloy is, for example, Si: 0.50 mass% or more and 2.00 mass% or less, Fe: 0.05 mass% or more and 1.00 mass% or less, Cu: 0.12 mass% or more and 1.00 mass% or less, Mn: 0.60 mass% or more and 1.80 mass% or less, Mg: 0.30 mass% or more and 0.80 mass% or less, Cr: 0.01 mass% or more and 0.03 mass% or less, Zn: 0.11 mass% or more and 1.50 mass% or less, and Ti: 0.01 mass% or more and 0.30 mass% or less.

[0043] When the additional elements that will be contained in the first aluminum alloy due to the use of scrap are Si and Cu, the composition of the second aluminum alloy is, for example, Si: 0.20 mass% or more and 1.00 mass% or less, Fe: more than 0.0 mass% and 0.50 mass% or less, Cu: more than 0.0 mass% and 0.30 mass% or less, and Mg: 0.20 mass% or more and 1.00 mass% or less.

[0044] When improving the press formability (surface quality) and / or the surface treatability of the first skin material and the second skin material, the composition of the second aluminum alloy can be adjusted, for example, as follows: Si: 0.30% by mass or more and 0.70% by mass or less, Fe: more than 0.0% by mass and 0.40% by mass or less, Cu: more than 0.0% by mass and 0.15% by mass or less, Mg: 0.30% by mass or more and 0.70% by mass or less.

[0045] The second aluminum alloy does not need to contain any of the above-mentioned additive elements. Furthermore, the second aluminum alloy only needs to have a lower content of one or more additive elements that will be contained in excess in the scrap than the content of the one or more additive elements in the first aluminum alloy. Depending on the properties desired for the first skin material and the second skin material, the second aluminum alloy may contain one or more additive elements (e.g., Zn, Mn, Cr, Ti, Ga, or Ni) whose content is higher than that of the first aluminum alloy. Furthermore, the first aluminum alloy and the second aluminum alloy may contain additive elements other than the exemplified additive elements.

[0046] The press-molding aluminum alloy clad material according to the embodiment of the present invention can be produced by a known method (see, for example, Japanese Patent Application Laid-Open No. 01-252759). The entire disclosure of Japanese Patent Application Laid-Open No. 01-252759 is incorporated herein by reference. The melting (dissolution), casting, rolling, and heat treatment (annealing, etc.) of the aluminum alloy raw material including the scrap can be carried out by a known method.

[0047] The aluminum alloy clad material for press forming according to the embodiment of the present invention can be suitably used for producing various press-formed products (e.g., automobile housings such as bumpers and front panels, housings for electronic devices such as smartphones, tablet terminals, and laptop computers, etc.) Furthermore, scrap from press-formed products produced using the aluminum alloy clad material for press forming according to the embodiment of the present invention can be suitably used for producing the aluminum alloy clad material for press forming according to the embodiment of the present invention.

[0048] The method for producing an aluminum alloy clad material for press forming, the aluminum alloy clad material for press forming, and the press-formed product according to the embodiments of the present invention can improve the recycling efficiency of aluminum alloy materials. The embodiments of the present invention can also be used in combination with known recycling methods, such as the recycling method described in Patent Document 1.

Claims

1. A method for producing an aluminum alloy clad material for press molding, having a core material and a first skin material and a second skin material joined to either side of the core material so as to sandwich the core material, comprising: step A of preparing a first aluminum alloy using scrap of an aluminum alloy clad material for an automobile heat exchanger, the first aluminum alloy containing Si, Fe, Cu, Mn, Mg, Cr, Zn and Ti as additive elements; step B of preparing a second aluminum alloy having an Si and Cu content at least less than that in the first aluminum alloy; step C of forming a core material plate from the first aluminum alloy; step D of independently forming a first skin material plate and a second skin material plate from the second aluminum alloy; and step E of rolling the first skin material plate and the second skin material plate arranged so as to sandwich the core material plate.

2. The manufacturing method of claim 1, wherein the scrap of the aluminum alloy clad material of the automotive heat exchanger contains Si: 0.50 mass% or more, Fe: 0.10 mass% or more, Cu: 0.10 mass% or more, Mn: 0.50 mass% or more, Mg: 0.05 mass% or more, Cr: 0.01 mass% or more, Zn: 0.10 mass% or more, and Ti: 0.01 mass% or more.

3. The manufacturing method described in claim 1 or 2, wherein the first aluminum alloy contains 10 mass% or more of the scrap.

4. The manufacturing method described in claim 1 or 2, wherein the first aluminum alloy contains 50 mass% or more of the scrap.

5. A manufacturing method as described in claim 1 or 2, wherein step A includes a step of adding any of the additive elements and / or new aluminum ingot so that the first aluminum alloy contains Si: 0.50 mass% or more, Fe: 0.05 mass% or more, Cu: 0.12 mass% or more, Mn: 0.60 mass% or more, Mg: 0.30 mass% or more, Cr: 0.01 mass% or more, Zn: 0.11 mass% or more, and Ti: 0.01 mass% or more, with the remainder consisting of aluminum and unavoidable impurities.

6. The manufacturing method of claim 5, wherein step A includes a step of adding any of the additive elements and / or new aluminum ingot so that the first aluminum alloy contains not more than 2.00 mass% Si, not more than 1.00 mass% Fe, not more than 1.00 mass% Cu, not more than 1.80 mass% Mn, not more than 0.80 mass% Mg, not more than 0.03 mass% Cr, not more than 1.50 mass% Zn, and not more than 0.30 mass% Ti.

7. A manufacturing method as described in claim 1 or 2, wherein the first skin plate material and the second skin plate material are formed by dividing a single skin plate material formed using the second aluminum alloy.

8. An aluminum alloy clad material for press molding, comprising a core material and first and second skin materials joined to either side of the core material so as to sandwich the core material, wherein the core material is formed of an aluminum alloy containing, as additive elements, the following: Si: 0.50% by mass or more, Fe: 0.05% by mass or more, Cu: 0.12% by mass or more, Mn: 0.60% by mass or more, Mg: 0.30% by mass or more, Cr: 0.01% by mass or more, Zn: 0.11% by mass or more, and Ti: 0.01% by mass or more, with the remainder being aluminum and unavoidable impurities, and the first skin material and the second skin material are each independently formed of an aluminum alloy having at least an Si and Cu content less than the content in the core material.

9. The clad material according to claim 8, wherein the aluminum alloy of the core material contains Si: 2.00% by mass or less, Fe: 1.00% by mass or less, Cu: 1.00% by mass or less, Mn: 1.80% by mass or less, Mg: 0.80% by mass or less, Cr: 0.03% by mass or less, Zn: 1.50% by mass or less, and Ti: 0.30% by mass or less.

10. A press-molded product manufactured using the aluminum alloy clad material for press molding according to claim 8 or 9.

11. The manufacturing method according to claim 1, wherein scrap of the press-molded product according to claim 10 is used in place of the scrap of the aluminum alloy clad material of the heat exchanger for an automobile.