Aluminum alloy material for cold working, method for producing aluminum alloy material for cold working, aluminum alloy material for hot working, and method for producing aluminum alloy material for hot working

Abstract

To provide an aluminum alloy material for cold working having superior machinability and workability, and a method for producing the same, and an aluminum alloy material for hot working, and a method for producing the same.SOLUTION: An aluminum alloy material for cold working has an alloy composition containing Si in a range of 0.05 mass% or more and 0.2 mass% or less, Fe in a range of 0.3 mass% or more and 0.5 mass% or less, Cu in a range of 0.01 mass% or more and 0.20 mass% or less, Mn in a range of 0.80 mass% or more and 1.09 mass% or less, Mg in a range of 0.05 mass% or less, Ti in a range of 0.01 mass% or more and 0.1 mass% or less, and B in a range of 0.0010 mass% or more and 0.030 mass% or less, with the balance being Al and inevitable impurities. The metal structure is free from needle-like Al-Mn-based compounds having a maximum diameter of 2 μm or more. The Rockwell hardness [HRF] is 57.0 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an aluminum alloy material for cold working, a method for manufacturing an aluminum alloy material for cold working, an aluminum alloy material for hot working, and a method for manufacturing an aluminum alloy material for hot working.

Background Art

[0002] In recent years, aluminum alloys have been increasingly used as structural members of various products by taking advantage of their light weight. For example, steel has been used for general utensils, building materials such as panels, shipbuilding materials, and containers. On the other hand, in recent years, lightweight, corrosion-resistant, and high-strength aluminum alloy materials have been used.

[0003] In these shaped materials, excellent corrosion resistance, high strength, and excellent workability are required. Therefore, Al-Mn-based alloys and the like are widely used as aluminum materials. The Al-Mn-based alloy is an aluminum alloy that enhances strength and weldability without degrading workability and corrosion resistance compared to pure aluminum. Therefore, it is widely used for utensils, building materials, containers, etc. For example, it is used for the body material of fire extinguishers and the container material of secondary batteries. Such Al-Mn-based alloys are manufactured by subjecting them to processing such as extrusion, impact molding, deep drawing, and forging. For example, Patent Document 1 discloses an aluminum alloy that exhibits high strain rate formability at elevated temperatures.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the aluminum alloy composition disclosed in Patent Document 1, since the contents of Fe, Si, and Mn are high, a strong AlFeMnSi compound is coarsened and produced in large quantities, resulting in problems such as a decrease in machinability and workability.

[0006] The present invention has been made in view of such a technical background, and when forming a container or an exterior body by cold working or hot working, it aims to provide an aluminum alloy material for cold working excellent in machinability and workability, a method for manufacturing an aluminum alloy material for cold working, an aluminum alloy material for hot working, and a method for manufacturing an aluminum alloy material for hot working.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention provides the following means.

[0008] (1) An aluminum alloy material for cold working having an alloy composition containing Si in the range of 0.05 mass% or more and 0.2 mass% or less, Fe in the range of 0.3 mass% or more and 0.5 mass% or less, Cu in the range of 0.01 mass% or more and 0.20 mass% or less, Mn in the range of 0.80 mass% or more and 1.09 mass% or less, Mg in the range of 0.05 mass% or less, Ti in the range of 0.01 mass% or more and 0.1 mass% or less, and B in the range of 0.0010 mass% or more and 0.030 mass% or less, with the balance being Al and unavoidable impurities, characterized in that there is no acicular Al-Mn-based compound having a maximum diameter of 2 μm or more in the metal structure, and the Rockwell hardness [HRF] is 57.0 or less.

[0009] (2) The aluminum alloy material for cold working according to (1), characterized in that it is for a pressure-resistant container of a fire extinguisher.

[0010] (3) The aluminum alloy material for cold working according to (1), characterized in that it is for an exterior container of a secondary battery.

[0011] (4) A method for manufacturing an aluminum alloy material for cold working, which is any one of (1) to (3), comprising: an alloy melt forming step of forming an aluminum alloy melt having the same alloy composition as the aluminum alloy material for cold working; a casting step of cooling and solidifying the aluminum alloy melt obtained in the alloy melt forming step to form an aluminum alloy casting; and a homogenization heat treatment step of performing a homogenization heat treatment on the aluminum alloy casting obtained in the casting step, wherein the homogenization heat treatment step includes a first heat treatment stage of holding at a temperature in the range of 590 °C or higher and 615 °C or lower for 4 hours or more to perform the heat treatment, and then a second heat treatment stage of holding at a temperature in the range of 500 °C or higher and 540 °C or lower for 5 hours or more to perform the heat treatment. A method for manufacturing an aluminum alloy material for cold working, characterized by the above.

[0012] (5) An aluminum alloy material for hot working, containing Si in the range of 0.05% by mass or more and 0.2% by mass or less, Fe in the range of 0.3% by mass or more and 0.5% by mass or less, Cu in the range of 0.01% by mass or more and 0.20% by mass or less, Mn in the range of 0.80% by mass or more and 1.09% by mass or less, Mg in the range of 0.05% by mass or less, Ti in the range of 0.01% by mass or more and 0.1% by mass or less, and B in the range of 0.0010% by mass or more and 0.030% by mass or less, with the balance being Al and unavoidable impurities, characterized in that there is no acicular Al-Mn-based compound having a maximum diameter of 2 μm or more in the metal structure, and the Rockwell hardness [HRF] is 57.0 or less.

[0013] (6) The aluminum alloy material for hot working according to (5), characterized by being used for automobile parts.

[0014] A method for manufacturing an aluminum alloy material for hot working of (7), (5) or (6), comprising: an alloy melt forming step of forming an aluminum alloy melt having the same alloy composition as the aluminum alloy material for hot working; a casting step of cooling and solidifying the aluminum alloy melt obtained in the alloy melt forming step to form an aluminum alloy casting; and a homogenization heat treatment step of performing a homogenization heat treatment on the aluminum alloy casting obtained in the casting step, wherein the homogenization heat treatment step includes a first heat treatment stage of performing heat treatment by holding at a temperature range of 590 ° C or higher and 615 ° C or lower for 4 hours or more, and then a second heat treatment stage of performing heat treatment by holding at a temperature range of 500 ° C or higher and 540 ° C or lower for 5 hours or more. A method for manufacturing an aluminum alloy material for hot working, characterized by having the above steps.

Effects of the Invention

[0015] According to the present invention, when forming a container or an exterior body by cold working or hot working, it is possible to provide an aluminum alloy material for cold working excellent in machinability and workability, a method for manufacturing an aluminum alloy material for cold working, an aluminum alloy material for hot working, and a method for manufacturing an aluminum alloy material for hot working.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the drawings used in the following description may show, for the sake of clarity, parts that are characteristic by being enlarged for convenience, and the dimensional ratios of each component are not necessarily the same as the actual ones. Also, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not necessarily limited thereto, and it can be implemented by appropriately changing them within the range that does not change the effects.

[0018] [Aluminum alloy material for cold working] An aluminum alloy material for cold working according to an embodiment of the present invention (hereinafter simply referred to as an aluminum alloy material) contains Si in the range of 0.05% by mass or more and 0.2% by mass or less, Fe in the range of 0.3% by mass or more and 0.5% by mass or less, Cu in the range of 0.01% by mass or more and 0.20% by mass or less, Mn in the range of 0.80% by mass or more and 1.09% by mass or less, Mg in the range of 0.05% by mass or less, Ti in the range of 0.01% by mass or more and 0.1% by mass or less, and B in the range of 0.0010% by mass or more and 0.030% by mass or less, and the balance is composed of Al and unavoidable impurities. It is an aluminum alloy material for cold working, characterized in that acicular Al-Mn-based compounds having a maximum diameter of 2 μm or more do not exist in the metal structure, and the Rockwell hardness [HRF] is 57.0 or less.

[0019] [Aluminum alloy material for hot working] An aluminum alloy material for hot working according to an embodiment of the present invention (hereinafter simply referred to as an aluminum alloy material) contains Si in the range of 0.05% by mass or more and 0.2% by mass or less, Fe in the range of 0.3% by mass or more and 0.5% by mass or less, Cu in the range of 0.01% by mass or more and 0.20% by mass or less, Mn in the range of 0.80% by mass or more and 1.09% by mass or less, Mg in the range of 0.05% by mass or less, Ti in the range of 0.01% by mass or more and 0.1% by mass or less, and B in the range of 0.0010% by mass or more and 0.030% by mass or less, and the balance is Al and unavoidable impurities. It is an aluminum alloy material for hot working having an alloy composition, and in the metal structure, there is no acicular Al-Mn-based compound having a maximum diameter of 2 μm or more, and the Rockwell hardness [HRF] is 57.0 or less.

[0020] The aluminum alloy material of the present embodiment corresponds to a 3000 series aluminum alloy in that it contains a large amount of Mn.

[0021] (Si: 0.05% by mass or more and 0.2% by mass or less) Si crystallizes as intermetallic compounds such as Al-Mn-Si and Al-Mn-Fe-Si in the aluminum alloy, and has the effect of improving the tensile strength of the aluminum alloy. By setting the content rate of Si within the above range, it is possible to produce a target forged product without deteriorating the machinability and forging workability of the aluminum alloy material. However, if Si is added excessively to the aluminum alloy, there is a risk that the tensile strength of the aluminum alloy will decrease due to the crystallization of coarse primary Si grains. By having the content rate of Si within the above range, the crystallization of primary Si can be suppressed.

[0022] (Fe: 0.3% by mass or more and 0.5% by mass or less) Fe crystallizes as fine precipitates containing intermetallic compounds such as Al-Mn-Fe-Si, Al-Fe-Si, and Al-Mn-Fe in the aluminum alloy, thereby improving the tensile strength of the aluminum alloy. When the content of Fe is within the above range, it is possible to manufacture the target processed product without reducing the machinability and forging workability of the aluminum alloy material.

[0023] (Cu: 0.01 mass% or more and 0.20 mass% or less) Cu has the effect of finely dispersing Mg-Si-based compounds in the aluminum alloy and the effect of improving the tensile strength of the aluminum alloy by precipitating as Al-Cu-based compounds. When Cu is 0.3 mass% or more, the workability is reduced, but when it is 0.01 mass% or more and 0.20 mass% or less, the tensile properties can be improved without reducing the workability.

[0024] (Mn: 0.80 mass% or more and 1.09 mass% or less) Mn forms fine granular precipitates containing intermetallic compounds such as Al-Mn-Fe-Si, Al-Mn-Fe, Al-Mn, and Al-Mn-Si in the aluminum alloy, thereby having the effect of improving the tensile strength of the aluminum alloy. When the content of Mn is within the above range, the mechanical properties of the aluminum alloy material at room temperature can be improved.

[0025] (Mg: 0.05 mass% or less) Mg is mainly in solid solution in the 3000 series aluminum alloy and acts as solid solution strengthening. When the addition amount of Mg is large, the workability is reduced. When Mg is 0.05 mass% or less, it can act with good mechanical properties without reducing the workability. Also, Mg is preferably 0.001 mass% or more.

[0026] (Ti: 0.01 mass% or more and 0.1 mass% or less) Ti has the effect of refining the crystal grains of the aluminum alloy and improving the stretch formability. When the Ti content is less than 0.01% by mass, the effect of refining the crystal grains may not be sufficiently obtained. On the other hand, when the Ti content exceeds 0.1% by mass, coarse precipitates may be formed, and the stretch formability may decrease. In addition, when a large amount of coarse precipitates containing Ti are mixed into the aluminum alloy material, the toughness may decrease. Therefore, the content of Ti is preferably 0.012% by mass or more and 0.035% by mass or less, more preferably 0.015% by mass or more and 0.050% by mass or less.

[0027] (B: 0.0010% by mass or more and 0.030% by mass or less) B has the effect of refining the crystal grains of the aluminum alloy and improving the stretch formability. By adding B to the aluminum alloy together with the above-mentioned Ti, the effect of refining the crystal grains is improved. When the content of B is less than 0.0010% by mass, the effect of refining the crystal grains may not be sufficiently obtained. On the other hand, when the content of B exceeds 0.030% by mass, coarse precipitates may be formed and may be mixed into the aluminum alloy material as inclusions. In addition, when a large amount of coarse precipitates containing B are mixed into the final product of the aluminum alloy, the toughness may decrease. Therefore, the content of B is 0.0010% by mass or more and 0.030% by mass. The content of B is preferably 0.0050% by mass or more and 0.025% by mass.

[0028] (Inevitable impurities) Inevitable impurities are impurities that are inevitably mixed into the aluminum alloy from the raw materials or the manufacturing process. Examples of inevitable impurities include Ni, Sn, Be, etc. The content of these inevitable impurities preferably does not exceed 0.1% by mass.

[0029] (There is no acicular Al-Mn compound with a maximum diameter of 2 μm or more in the metal structure) In the alloy structure of the cross-section of the aluminum alloy material, needle-shaped Al-Mn compounds with a size of 2 μm or more are not precipitated. The presence of such needle-shaped Al-Mn compounds may particularly inhibit machining, and there is a concern that machinability, cold workability, and hot workability may deteriorate.

[0030] (Rockwell hardness [HRF] after homogenization treatment is 57.0 or less) When measuring the hardness of the aluminum alloy material subjected to the homogenization treatment described below, if the Rockwell hardness using the HRF scale (60 kg - 1 / 16” steel ball) is 60.0 or more, cold workability deteriorates, and it is necessary to perform reheat treatment (O material treatment). Therefore, in order to ensure cold workability, it is necessary to make the Rockwell hardness [HRF] 57.0 or less.

[0031] As described above, according to the aluminum alloy material for cold working and the aluminum alloy material for hot working of the present embodiment, their respective compositions are within the ranges described above, there are no needle-shaped Al-Mn-based compounds with a maximum diameter of 2 μm or more in the metal structure, and the Rockwell hardness [HRF] is 57.0 or less. Thus, for example, it is possible to realize an aluminum alloy material for cold working and an aluminum alloy material for hot working in which Al-Fe-Mn-Si-based compounds are difficult to form and which have excellent machinability.

[0032] Such an aluminum alloy material for cold working has excellent machinability and cold workability. Therefore, for example, it can be used as a processing material for a pressure-resistant container of a fire extinguisher for storing a fire extinguishing agent in a pressurized state, or as a processing material for an exterior container for storing a power generation laminate of a secondary battery typified by a lithium-ion battery.

[0033] In addition, the aluminum alloy material for hot working of the present embodiment has excellent machinability, hot workability, and forging properties, and thus can be used as a processing material for automotive parts, for example, a suspension arm.

[0034] [Manufacturing method of aluminum alloy material for cold working, Manufacturing method of aluminum alloy material for hot working] Next, an example of a method for manufacturing an aluminum alloy material for cold working and a method for manufacturing an aluminum alloy material for hot working according to this embodiment will be described. The method for manufacturing the aluminum alloy material according to this embodiment includes a molten metal forming step, a casting step, and a homogenization heat treatment step.

[0035] (Molten metal forming step) The molten metal forming step is a step of obtaining an aluminum alloy molten metal by melting raw materials and preparing a composition. The composition of the aluminum alloy molten metal may be the same as the composition of the aluminum alloy material. That is, Si is in the range of 0.05% by mass or more and 0.2% by mass or less, Fe is in the range of 0.3% by mass or more and 0.5% by mass or less, Cu is in the range of 0.01% by mass or more and 0.20% by mass or less, Mn is in the range of 0.80% by mass or more and 1.09% by mass or less, Mg is in the range of 0.05% by mass or less, Ti is in the range of 0.01% by mass or more and 0.1% by mass or less, and B is in the range of 0.0010% by mass or more and 0.030% by mass or less, respectively, and the balance is adjusted to an alloy composition consisting of Al and unavoidable impurities to obtain a molten metal of a 3000 series aluminum alloy. By performing the subsequent steps using the aluminum alloy molten metal having the above composition, an aluminum alloy material suitable for cold working and hot working can be obtained in which acicular Al-Mn-based compounds having a maximum diameter of 2 μm or more do not exist in the metal structure and the Rockwell hardness [HRF] is 57.0 or less.

[0036] The aluminum alloy molten metal can be obtained by heating and melting an aluminum alloy. Alternatively, a mixture containing elements that are the raw materials of the aluminum alloy or compounds containing two or more elements at a ratio that produces the target aluminum alloy may be melted and formed. For example, for the purpose of controlling the crystal grain size of the aluminum alloy in the casting step, Ti and B may be mixed as crystal grain refining materials such as an Al-Ti-B rod.

[0037] Further, as raw materials for the molten aluminum alloy, 10% or more of scrap materials of aluminum alloys of the 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, and 7000 series may be used, and the balance is new aluminum ingots and those being the above-described additive elements. These may be melted to obtain a molten aluminum alloy having a prepared composition. Here, the new aluminum ingot referred to herein is aluminum having a concentration of 99% by mass or more obtained by performing electrolysis called electrolytic refining on alumina produced from minerals.

[0038] (Casting process) In the casting process, the molten aluminum alloy (liquid phase) is cooled and solidified into a solid (solid phase) to obtain an aluminum alloy casting. For the casting process, for example, a horizontal continuous casting method can be used.

[0039] Here, a horizontal continuous casting apparatus that can be used for manufacturing the aluminum alloy material of the present embodiment is shown in FIGS. 1 and 2. Note that FIG. 1 is a cross-sectional view showing an example near the mold 12 of the horizontal continuous casting apparatus 10. FIG. 2 is an enlarged cross-sectional view of a main part near the cooling water cavity 24 of the horizontal continuous casting apparatus 10.

[0040] The horizontal continuous casting apparatus 10 shown in FIGS. 1 and 2 includes a molten metal receiving part (tundish) 11, a hollow cylindrical mold 12, and a refractory plate-like body (heat insulating member) 13 disposed between one end side 12a of the mold 12 and the molten metal receiving part 11.

[0041] The molten metal receiving part 11 is composed of a molten metal inflow part 11a that receives the molten aluminum alloy M obtained in the above-described molten metal forming process, a molten metal holding part 11b, and an outflow part 11c to the hollow part 21 of the mold 12.

[0042] The molten metal receiving part 11 maintains the level of the upper liquid surface of the molten aluminum alloy M at a position higher than the upper surface of the hollow part 21 of the mold 12, and in the case of multi-strand casting, stably distributes the molten aluminum alloy M to each mold 12.

[0043] The molten aluminum alloy M held in the molten metal holding part 11b in the molten metal receiving part 11 is poured into the hollow part 21 of the mold 12 from the pouring passage 13a provided in the refractory plate-like body 13. Then, the molten aluminum alloy M supplied into the hollow part 21 is cooled and solidified by a cooling device 23 described later, and is pulled out from the other end side 12b of the mold 12 as an aluminum alloy rod B which is a solidified ingot.

[0044] It is sufficient that a drawing drive device (not shown) for drawing out the cast aluminum alloy rod B at a constant speed is installed at the other end side 12b of the mold 12. Further, it is also preferable that a synchronous cutting machine (not shown) for cutting the continuously drawn aluminum alloy rod B into an arbitrary length is installed.

[0045] The refractory plate-like body 13 is a member that blocks heat transfer between the molten metal receiving part 11 and the mold 12, and may be composed of materials such as calcium silicate, alumina, silica, a mixture of alumina and silica, silicon nitride, silicon carbide, graphite, etc. Such a refractory plate-like body 13 can also be composed of a plurality of layers having different constituent materials.

[0046] In this embodiment, the mold 12 is a hollow cylindrical member, and is formed of a material selected from one or a combination of two or more of, for example, aluminum, copper, or their alloys. For the material of such a mold 12, an optimal combination may be selected from the viewpoints of thermal conductivity, heat resistance, and mechanical strength.

[0047] The hollow part 21 of the mold 12 is formed to have a circular cross-section in order to make the aluminum alloy rod B to be cast into a cylindrical rod shape, and the mold 12 is held such that the mold central axis (central axis) C passing through the center of the hollow part 21 is substantially along the horizontal direction.

[0048] The inner peripheral surface 21a of the hollow portion 21 of the mold 12 is formed at an elevation angle of 0° to 3° (more preferably 0° to 1°) with respect to the mold central axis C toward the casting direction of the aluminum alloy rod B (see FIG. 1). That is, the inner peripheral surface 21a is configured in a tapered shape that opens in a conical shape toward the casting direction. And the angle formed by the taper is the elevation angle.

[0049] When the elevation angle is less than 0°, when the aluminum alloy rod B is pulled out from the mold 12, casting may become difficult because it receives resistance at the other end side 12b which is the mold outlet. On the other hand, when the elevation angle exceeds 3°, the contact of the inner peripheral surface 21a with the molten aluminum alloy M becomes insufficient, and the heat extraction effect from the molten aluminum alloy M or the solidified shell formed by its cooling and solidification to the mold 12 decreases, which may cause insufficient solidification. As a result, a remelted texture may occur on the surface of the aluminum alloy rod B, or casting troubles such as the ejection of the non-solidified molten aluminum alloy M from the end of the aluminum alloy rod B may occur, which is not preferable.

[0050] In addition, the cross-sectional shape of the hollow portion 21 of the mold 12 (the planar shape when the hollow portion 21 of the mold 12 is viewed from the other end side 21b) may be selected according to the shape of the aluminum alloy rod to be cast, such as a shape having a cross-sectional shape other than circular in this embodiment, for example, a triangular or rectangular cross-sectional shape, a polygon, a semi-circle, an ellipse, or a shape having an irregular cross-sectional shape without an axis of symmetry or a plane of symmetry.

[0051] A fluid supply pipe 22 for supplying a lubricating fluid into the hollow portion 21 of the mold 12 is arranged at one end side 12a of the mold 12. The lubricating fluid supplied from the fluid supply pipe 22 can be any one or two or more kinds of lubricating fluids selected from gas lubricants and liquid lubricants. When supplying both a gas lubricant and a liquid lubricant, it is preferable to provide separate fluid supply pipes respectively. The lubricating fluid pressurized and supplied from the fluid supply pipe 22 is supplied into the hollow portion 21 of the mold 12 through the annular lubricant supply port 22a.

[0052] In this embodiment, the pumped lubricating fluid is supplied from the lubricant supply port 22a to the inner peripheral surface 21a of the mold 12. Note that the liquid lubricant may be configured to be heated to become a decomposed gas and supplied to the inner peripheral surface 21a of the mold 12. Further, a porous material may be disposed at the lubricant supply port 22a, and the lubricating fluid may be exuded to the inner peripheral surface 21a of the mold 12 through this porous material.

[0053] Inside the mold 12, a cooling device 23, which is a cooling means for cooling and solidifying the molten aluminum alloy M, is formed. The cooling device 23 of this embodiment has a cooling water cavity 24 that houses cooling water W for cooling the inner peripheral surface 21a of the hollow portion 21 of the mold 12, and a cooling water injection passage 25 that communicates the cooling water cavity 24 with the hollow portion 21 of the mold 12.

[0054] The cooling water cavity 24 is formed in an annular shape so as to surround the hollow portion 21 outside the inner peripheral surface 21a of the hollow portion 21 inside the mold 12, and the cooling water W is supplied through a cooling water supply pipe 26.

[0055] The inner peripheral surface 21a of the mold 12 is cooled by the cooling water W accommodated in the cooling water cavity 24, so that the heat of the molten aluminum alloy M filled in the hollow portion 21 of the mold 12 is taken from the surface in contact with the inner peripheral surface 21a of the mold 12, and a solidified shell is formed on the surface of the molten aluminum alloy M.

[0056] Further, the cooling water injection passage 25 directly applies the cooling water W from the shower opening 25a facing the hollow portion 21 toward the aluminum alloy rod B at the other end side 12b of the mold 12 to cool the aluminum alloy rod B. The longitudinal cross-sectional shape of such a cooling water injection passage 25 may be, for example, a semi-circle, a pear shape, or a horseshoe shape in addition to the circular shape of this embodiment.

[0057] In this embodiment, the cooling water W supplied through the cooling water supply pipe 26 is first stored in the cooling water cavity 24 to cool the inner peripheral surface 21a of the hollow portion 21 of the mold 12, and then the cooling water W in the cooling water cavity 24 is sprayed from the cooling water injection passage 25 toward the aluminum alloy rod B. However, these can also be supplied by separate cooling water supply pipes for each system.

[0058] The length from the position where the extension line of the central axis of the shower opening 25a of the cooling water injection passage 25 hits the surface of the cast aluminum alloy rod B to the contact surface between the mold 12 and the refractory plate-like body 13 is referred to as the effective mold length L. This effective mold length L is preferably, for example, 10 mm or more and 40 mm or less. If this effective mold length L is less than 10 mm, casting becomes impossible because a good film cannot be formed. If it exceeds 40 mm, the effect of forced cooling becomes low, solidification by the mold wall becomes dominant, the contact resistance between the mold 12 and the molten aluminum alloy M or the aluminum alloy rod B increases, and there is a risk that the casting skin cracks or breaks inside the mold, making the casting unstable, which is not preferable.

[0059] It is preferable that the supply of the cooling water W to the cooling water cavity 24 and the injection of the cooling water W from the shower opening 25a of the cooling water injection passage 25 can be controlled in operation by control signals from a control device (not shown).

[0060] The cooling water cavity 24 is formed such that the inner bottom surface 24a near the hollow portion 21 of the mold 12 is parallel to the inner peripheral surface 21a of the hollow portion 21 of the mold 12.

[0061] Here, the term "parallel" includes the case where the inner peripheral surface 21a of the hollow portion 21 of the mold 12 is formed at an elevation angle of 0° to 3° with respect to the inner bottom surface 24a of the cooling water cavity 24, that is, the case where the inner bottom surface 24a is inclined with respect to the inner peripheral surface 21a by more than 0° and up to 3°.

[0062] As shown in FIG. 1, the cooling wall portion 27 of the mold 12, which is the portion where the inner bottom surface 24a of such a cooling water cavity 24 and the inner peripheral surface 21a of the hollow portion 21 of the mold 12 face each other, has a heat flux value per unit area from the molten aluminum alloy M in the hollow portion 21 to the cooling water W in the cooling water cavity 24, for example, 10×10 5 W / m 2 or more and 50×10 5 W / m 2 or less within the following range.

[0063] The thickness t of such a cooling wall portion 27 of the mold 12, that is, the interval between the inner bottom surface 24a of the cooling water cavity 24 and the inner peripheral surface 21a of the hollow portion 21 of the mold 12, is, for example, within the range of 0.5 mm or more and 3.0 mm or less, preferably 0.5 mm or more and 2.5 mm or less, and the mold 12 may be formed accordingly. Also, the forming material of the mold 12 may be selected so that the thermal conductivity of at least the cooling wall portion 27 of the mold 12 is within the range of 100 W / m·K or more and 400 W / m·K or less.

[0064] In FIG. 1, the molten aluminum alloy M in the molten metal receiving portion 11 is supplied from one end side 12a of the mold 12 held so that the mold central axis C is substantially horizontal through the refractory plate-like body 13, and is forcibly cooled at the other end side 12b of the mold 12 to become the aluminum alloy rod B.

[0065] Since the aluminum alloy rod B is pulled out at a constant speed by a drawing drive device (not shown) installed near the other end side 12b of the mold 12, it is continuously cast to form a long aluminum alloy rod B. The pulled-out aluminum alloy rod B is cut to a desired length by, for example, a synchronous cutting machine (not shown).

[0066] Incidentally, the composition ratio of the cast aluminum alloy rod B can be confirmed by a method using a photoelectric emission spectroscopic analyzer (device example: PDA - 5500 manufactured by Shimadzu Corporation, Japan) as described in, for example, "JIS H 1305".

[0067] The height difference between the liquid level of the molten aluminum alloy M stored in the molten metal receiving part 11 and the upper inner peripheral surface 21a of the mold 12 is preferably 0 mm to 250 mm (more preferably 50 mm to 170 mm). By setting it within such a range, the pressure of the molten aluminum alloy M supplied into the mold 12, the lubricating oil, and the gas formed by vaporization of the lubricating oil are preferably balanced, so that the castability is stabilized.

[0068] As the liquid lubricant, vegetable oil which is a lubricating oil can be used. For example, rapeseed oil, castor oil, and salad oil can be mentioned.

[0069] The lubricating oil supply amount is preferably 0.05 mL / min to 5 mL / min (more preferably 0.1 mL / min or more and 1 mL / min or less). If the supply amount is too small, the molten aluminum alloy M of the aluminum alloy rod B may leak from the mold 12 without solidifying due to insufficient lubrication. If the supply amount is too large, the excess may mix into the aluminum alloy rod B and cause internal defects.

[0070] The casting speed, which is the speed at which the aluminum alloy rod B is pulled out from the mold 12, is preferably 200 mm / min or more and 1500 mm / min or less (more preferably 400 mm / min or more and 1000 mm / min or less). This is because if the casting speed is within this range, the network structure of the crystallized products formed by casting becomes uniform and fine, the resistance to deformation of the aluminum stock at high temperatures increases, and the high-temperature mechanical strength is improved.

[0071] The amount of cooling water sprayed from the shower opening 25a of the cooling water injection passage 25 is preferably, for example, 10 L / min or more and 50 L / min or less per mold (more preferably 25 L / min or more and 40 L / min or less). If the amount of cooling water is less than this, the molten aluminum alloy M may leak from the mold 12 without solidifying. Also, the surface of the cast aluminum alloy rod B may remelt and form a non-uniform structure, which may remain as an internal defect. On the other hand, if the amount of cooling water is more than this range, the heat extraction of the mold 12 may be too large and solidification may occur halfway.

[0072] The average temperature of the molten aluminum alloy M flowing from inside the molten metal receiving part 11 into the mold 12 is preferably, for example, 650°C or higher and 750°C or lower (more preferably 680°C or higher and 720°C or lower). If the temperature of the molten aluminum alloy M is too low, there is a risk of forming coarse crystallites in the mold 12 and in front of it and being incorporated as internal defects inside the aluminum alloy bar B. On the other hand, if the temperature of the molten aluminum alloy M is too high, a large amount of hydrogen gas is likely to be incorporated into the molten aluminum alloy M, and it may be incorporated as porosity in the aluminum alloy bar B, resulting in internal cavities.

[0073] And in the cooling wall part 27 of the mold 12, the heat flux value per unit area from the molten aluminum alloy M in the hollow part 21 towards the cooling water W in the cooling water cavity 24 is 10×10 5 W / m 2 or more and 50×10 5 W / m 2 or less. By setting it within this range, seizure of the aluminum alloy bar B can be prevented.

[0074] The cooling wall part 27 of the mold 12 receives heat by heat extraction from the molten aluminum alloy M, and heat exchange is performed by cooling this heat with the cooling water W contained in the cooling water cavity 24. Regarding the state of this heat exchange, as shown in the explanatory diagram of FIG. 3, attention was paid to the heat flux per unit area. The heat flux per unit area is expressed by the following formula (1) according to Fourier's law. Q=-k×(T1-T2) / L···(1) Q: Heat flux k: Thermal conductivity (W / m·K) of the location where heat passes (in this embodiment, the cooling wall part 27 of the mold 12) T1: Low-temperature side temperature of the location where heat passes (in this embodiment, the inner bottom surface 24a of the cooling water cavity 24) T2: High-temperature side temperature of the location where heat passes (in this embodiment, the inner peripheral surface 21a of the hollow part 21 of the mold 12) L: Section length (mm) of the location where heat passes (in this embodiment, the thickness t of the cooling wall part 27 of the mold 12)

[0075] Based on the quality, thickness, and temperature measurement data of the cast material, even when reducing the lubricating oil amount during casting, the heat flux value per unit area is 10×10 5 W / m 2 or more. By configuring the cooling wall portion 27 of the mold 12 in this way, sticking of the cast aluminum alloy bar B can be prevented. Also, it is preferable that the heat flux value per unit area is 50×10 5 W / m 2 or less.

[0076] To make the cooling wall portion 27 of the mold 12 within such a heat flux value range, the mold 12 may be formed such that the thickness t of the cooling wall portion 27 of the mold 12 is, for example, in the range of 0.5 mm or more and 3.0 mm or less. Also, the thermal conductivity of at least the cooling wall portion 27 of the mold 12 may be in the range of 100 W / m·K or more and 400 W / m·K or less.

[0077] When manufacturing the aluminum alloy bar B, using the above-described horizontal continuous casting apparatus 10, the aluminum alloy melt M stored in the melt receiving portion 11 is continuously supplied into the hollow portion 21 from one end side 12a of the mold 12. Also, cooling water W is supplied to the cooling water cavity 24, and a lubricating fluid, for example, lubricating oil, is supplied from the fluid supply pipe 22.

[0078] Then, the aluminum alloy melt M supplied into the hollow portion 21 is cooled and solidified under the condition that the heat flux value per unit area in the cooling wall portion 27 is 10×10 5 W / m 2 or more to cast the aluminum alloy bar B. Also, when casting the aluminum alloy bar B, it is preferable that the wall surface temperature of the cooling wall portion 27 of the mold 12 cooled by the cooling water W is 100°C or less.

[0079] The thus obtained aluminum alloy bar B has a heat flux value per unit area in the cooling wall portion 27 of 10×10 5 W / m 2By cooling and solidifying under the above conditions, the adhesion of reaction products, such as carbides, due to the contact between the lubricating oil gas and the molten aluminum alloy M is suppressed. As a result, it is not necessary to cut and remove carbides and the like on the surface of the aluminum alloy rod B, and the aluminum alloy rod B can be manufactured with a high yield.

[0080] The casting process for obtaining a casting from the molten aluminum alloy M is not limited to the above-described horizontal continuous casting method, and known continuous casting methods such as the vertical continuous casting method can be used. The vertical continuous casting method is classified into a float method and a hot top method depending on the supply method of the molten aluminum alloy M to the mold (casting mold 12). Hereinafter, the case of using the hot top method will be briefly described.

[0081] The casting apparatus used in the hot top method includes a mold, a molten metal receiving vessel (header), and the like. The molten metal supplied to the molten metal receiving portion passes through the outlet port and through the header to adjust the flow rate, and enters a cylindrical mold installed substantially horizontally, where it is forcibly cooled to form a solidified shell on the outer surface of the molten metal.

[0082] Furthermore, cooling water is directly radiated onto the casting drawn out from the mold, and the casting is continuously drawn out while the solidification of the metal proceeds to the inside of the casting. Generally, a metal member having good thermal conductivity is used for the mold, and it has a hollow structure for introducing a refrigerant therein.

[0083] The refrigerant to be used may be appropriately selected from those that are industrially available, but water is recommended from the viewpoint of ease of use.

[0084] The mold used in the present embodiment is appropriately selected from metals such as copper and aluminum or graphite from the viewpoints of heat transfer performance and durability at the contact portion with the molten metal. The header is generally made of a refractory and is installed above the mold. The material and size of the header may be appropriately selected according to the component range of the alloy to be cast and the dimensions of the casting, and there are no particular restrictions.

[0085] The average cooling rate during casting may be appropriately selected from a generally recommended range such as, for example, 10 to 300 °C / second. The casting speed may be appropriately selected from a general range in horizontal continuous casting, for example, it may be appropriately selected from the range of 200 to 600 mm / minute.

[0086] By the casting method described above, even for medium to large-sized castings, a uniform metal structure can be obtained. The diameter of the target casting is not particularly limited, and it is preferably used for bars with a diameter of 30 to 100 mm.

[0087] (Homogenization heat treatment process) The homogenization heat treatment process is a process of performing homogenization heat treatment on the aluminum alloy casting obtained in the casting process to homogenize the microsegregation caused by solidification, precipitate supersaturated solid solution elements, and change metastable phases to equilibrium phases.

[0088] In this embodiment, the homogenization heat treatment process is performed by two-stage heat treatment. First, the casting obtained in the casting process is heat-treated by holding it in the temperature range of 590 °C or higher and 615 °C or lower for 4 hours or more (the first heat treatment stage). Subsequently, it is heat-treated by holding it in the temperature range of 500 °C or higher and 540 °C or lower for 5 hours or more (the second heat treatment stage). By performing the homogenization heat treatment process by such two-stage heat treatment with different temperature ranges and holding times, the precipitation of acicular Al-Mn compounds is prevented. Thereby, the machinability, cold workability, and hot workability during cutting can be improved.

[0089] Through the above steps, an aluminum alloy material of this embodiment can be manufactured in which acicular Al-Mn-based compounds with a maximum diameter of 2 μm or more do not exist in the metal structure and the Rockwell hardness [HRF] is 57.0 or less.

Examples

[0090] Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

[0091] [Examples 1 - 8 and Comparative Examples 1 - 8] (Production of Continuous Casting Products) First, aluminum alloy materials with the alloy compositions shown in Table 1 below (the balance being aluminum) were prepared. Using the prepared aluminum alloy materials, continuous casting products with a circular cross - section of 82 mm in diameter were produced.

[0092]

Table 1

[0093] (Manufacture of Aluminum Alloy Materials) Next, a homogenization heat treatment process was performed on the obtained continuous casting products to obtain aluminum alloy materials. The conditions of the homogenization heat treatment process are shown in Table 2 below. In Examples 1 - 8, two - stage heat treatment was used, and in Comparative Examples 1 - 8, one - stage heat treatment was used.

[0094]

Table 2

[0095] [Evaluation] Regarding the aluminum alloy materials of Examples 1 - 8 and Comparative Examples 1 - 8 obtained as described above, the following evaluations were performed. The results of these evaluations are shown in Table 3 below. Also, photographs of the SEM - EBSD images of Example 1 and Comparative Example 1 are shown in Figure 4.

[0096] [Rockwell Hardness [HRF]] On the cross - section of the aluminum alloy materials obtained through the homogenization heat treatment process, the Rockwell hardness [HRF] using the HRF scale was measured 10 times for 1 sample, and the average value was taken as the measurement result for each sample. (Judgment Criteria) “〇”... The Rockwell hardness [HRF] is 57.0 or less. “×”... The Rockwell hardness [HRF] exceeds 57.0.

[0097] <Distribution of acicular Al-Mn compounds with a maximum diameter of 2 μm or more in the metal structure> In the cross-section of the aluminum alloy material obtained through the homogenization heat treatment process, a plate-like body (2 mm thick) for preparing a test piece for structure evaluation was sampled. The obtained plate-like body was cut into 7 mm squares to obtain test pieces for structure evaluation with dimensions of 7 mm × 7 mm × 2 mm thick. Regarding the surface of the obtained test pieces for structure evaluation, the distribution of acicular Al-Mn compounds with a maximum diameter of 2 μm or more was measured using SEM-EBSD (scanning electron microscope - electron backscatter diffraction apparatus). (Judgment criteria) “〇”... There are no acicular Al-Mn compounds. “×”... There are acicular Al-Mn compounds.

[0098] <Overall evaluation> The Rockwell hardness and the evaluation results of the distribution of acicular Al-Mn compounds were evaluated based on the following judgment criteria. (Judgment criteria) “O”... Both of the two evaluation items are “O”. “×”... At least one of the two evaluation items is “×”.

[0099]

Table 3

[0100] As shown in Table 3, according to the aluminum alloy material of this embodiment, it was confirmed that it is possible to realize an aluminum alloy material for cold working and an aluminum alloy material for hot working, which have excellent machinability and workability, with a Rockwell hardness [HRF] of 57.0 or less and no acicular Al-Mn compounds with a maximum diameter of 2 μm or more.

Explanation of symbols

[0101] 10… Horizontal continuous casting apparatus 11… Molten metal receiving part (tundish) 11a… Molten metal inflow part 11b… Molten metal holding part 11c… Outflow part 12…Mold 12a…One end side 12b…The other end side 13…Refractory plate-like body (heat insulation member) 13a…Pouring passage 21…Hollow part 21a…Inner peripheral surface 21b…The other end side 22…Fluid supply pipe 22a…Lubricant supply port 23…Cooling device 24…Cooling water cavity 24a…Inner bottom surface 25…Cooling water injection passage 25a…Shower opening 26…Cooling water supply pipe 27…Cooling wall part B…Aluminum alloy rod M…Molten aluminum alloy W…Cooling water

Claims

1. An aluminum alloy material for cold working, having an alloy composition containing Si in the range of 0.05% by mass or more and 0.2% by mass or less, Fe in the range of 0.3% by mass or more and 0.5% by mass or less, Cu in the range of 0.01% by mass or more and 0.20% by mass or less, Mn in the range of 0.80% by mass or more and 1.09% by mass or less, Mg in the range of 0.05% by mass or less, Ti in the range of 0.01% by mass or more and 0.1% by mass or less, and B in the range of 0.0010% by mass or more and 0.030% by mass or less, with the balance being Al and inevitable impurities, wherein there is no acicular Al-Mn-based compound having a maximum diameter of 2 μm or more in the metal structure, and the Rockwell hardness [HRF] is 57.0 or less.

2. The aluminum alloy material for cold working according to claim 1, which is used for a pressure-resistant container of a fire extinguisher.

3. The aluminum alloy material for cold working according to claim 1, which is used for an outer container of a secondary battery.

4. A method for manufacturing an aluminum alloy material for cold working according to any one of claims 1 to 3, comprising an alloy melt forming step of forming an aluminum alloy melt having the same alloy composition as the aluminum alloy material for cold working, a casting step of cooling and solidifying the aluminum alloy melt obtained in the alloy melt forming step to form an aluminum alloy casting, and a homogenization heat treatment step of performing a homogenization heat treatment on the aluminum alloy casting obtained in the casting step, wherein the homogenization heat treatment step includes a first heat treatment stage of performing heat treatment by holding at a temperature range of 590 °C or more and 615 °C or less for 4 hours or more, and a second heat treatment stage of performing heat treatment by holding at a temperature range of 500 °C or more and 540 °C or less for 5 hours or more.

5. An aluminum alloy material for hot working, containing Si in the range of 0.05% by mass or more and 0.2% by mass or less, Fe in the range of 0.3% by mass or more and 0.5% by mass or less, Cu in the range of 0.01% by mass or more and 0.20% by mass or less, Mn in the range of 0.80% by mass or more and 1.09% by mass or less, Mg in the range of 0.05% by mass or less, Ti in the range of 0.01% by mass or more and 0.1% by mass or less, and B in the range of 0.0010% by mass or more and 0.030% by mass or less, with the balance being Al and inevitable impurities, An aluminum alloy material for hot working, characterized in that there is no acicular Al-Mn-based compound having a maximum diameter of 2 μm or more in the metal structure and the Rockwell hardness [HRF] is 57.0 or less.

6. The aluminum alloy material for hot working according to claim 5, characterized in that it is for automobile parts.

7. A method for manufacturing the aluminum alloy material for hot working according to claim 5 or 6, comprising: An alloy melt forming step of forming an aluminum alloy melt having the same alloy composition as the aluminum alloy material for hot working; A casting step of cooling and solidifying the aluminum alloy melt obtained in the alloy melt forming step to form an aluminum alloy casting; A homogenization heat treatment step of performing a homogenization heat treatment on the aluminum alloy casting obtained in the casting step, and The homogenization heat treatment step includes a first heat treatment stage of performing heat treatment by holding at a temperature range of 590 °C or more and 615 °C or less for 4 hours or more, and then a second heat treatment stage of performing heat treatment by holding at a temperature range of 500 °C or more and 540 °C or less for 5 hours or more. A method for manufacturing an aluminum alloy material for hot working, characterized by this.

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