WO2019167469A1

WO2019167469A1 - Al-mg-si system aluminum alloy material

Info

Publication number: WO2019167469A1
Application number: PCT/JP2019/001614
Authority: WO
Inventors: 克彦塩月
Original assignee: 本田技研工業株式会社
Priority date: 2018-03-01
Filing date: 2019-01-21
Publication date: 2019-09-06
Also published as: JPWO2019167469A1; JP7044863B2

Abstract

The present invention provides an Al-Mg-Si system aluminum alloy material which has both high strength and good corrosion resistance at the same time. This Al-Mg-Si system aluminum alloy material contains from 0.1% by mass to 2.0% by mass (inclusive) of Si, from 0.3% by mass to 1.5% by mass (inclusive) of Mg, from 0.05% by mass to 3.0% by mass (inclusive) of Cu, and more than 0.05% by mass but 2.3% by mass or less of Ni, while optionally containing one or more elements that are selected from the group consisting of Fe, Mn, Cr, Zn and Ti in an amount of 1.0% by mass or less, with the balance being made up of Al and unavoidable impurities.

Description

Al-Mg-Si aluminum alloy material

The present invention relates to an Al—Mg—Si based aluminum alloy material containing Cu and Ni.

In recent years, there has been a demand for further weight reduction of vehicles such as automobiles, and aluminum alloys have been adopted as materials for vehicle structural materials. As materials for body panels and undercarriages, heat-treatment type 6000 series aluminum alloys (Al-Mg-Si series aluminum alloys) that have excellent strength and corrosion resistance and have bake hardness that hardens when painted and baked are used. In order to improve the strength and formability, alloys to which Cu is added have been developed.

Structural materials such as vehicle body panels and undercarriages are generally manufactured by aging treatment of materials formed by press molding, forging, etc., and Al-Mg-Si based materials used as materials for structural materials Aluminum alloys are required to have high elongation for forming in addition to strength. Therefore, various studies including chemical composition have been made in order to develop an Al—Mg—Si aluminum alloy having both high strength and elongation.

For example, Patent Document 1 discloses an aluminum alloy material suitable for manufacturing an automobile body panel, and Si: 0.6 to 1.2 wt%, Mg: 0.7 to 1 based on the total weight of the aluminum alloy material. .3 wt%, Zn: 0.25 to 0.8 wt%, Cu: 0.02 to 0.20 wt%, Mn: 0.01 to 0.25 wt%, Zr: 0.01 to 0.20 wt%, and the rest An aluminum alloy material that contains Al and ancillary elements and satisfies the inequality of 2.30 wt% ≦ (Si + Mg + Zn + 2Cu) ≦ 3.20 wt% is described.

Special table 2016-522320 gazette

Al-Mg-Si-based aluminum alloy materials used as vehicle structural materials and the like are required to have higher strength from the viewpoint of achieving both vehicle weight reduction and collision safety. As the Al—Mg—Si based aluminum alloy, there is a relatively large amount of Cu added, and in addition to the 6111 alloy that improves the bake hardness while securing elongation, the 6061 alloy that suppresses the amount of Cu added, etc. is there. However, in any alloy, when strengthening is performed by increasing the amount of Cu or the like, corrosion resistance deteriorates, and thread corrosion, stress corrosion cracking, and the like are liable to occur, so that the durability of the structural material is impaired.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an Al—Mg—Si based aluminum alloy material having both high strength and good corrosion resistance.

In order to solve the above-mentioned problems, the Al—Mg—Si-based aluminum alloy material according to the present invention includes Si: 0.1% by mass to 2.0% by mass, Mg: 0.3% by mass to 1.5% by mass. %: Cu: 0.05% by mass or more and 3.0% by mass or less, Ni: more than 0.05% by mass and 2.3% by mass or less, and Fe, Mn, Cr, Zn and Ti One or more selected elements are optionally contained in an amount of 1.0% by mass or less, and the balance consists of Al and inevitable impurities.

According to the present invention, it is possible to provide an Al—Mg—Si aluminum alloy material having both high strength and good corrosion resistance.

2 is a transmission electron microscope image of a test material made of an Al—Mg—Si—Cu-based aluminum alloy. 3 is a transmission electron microscope image of a test material made of an Al—Mg—Si—Cu-based aluminum alloy with Ni added.

Hereinafter, an Al—Mg—Si based aluminum alloy material according to an embodiment of the present invention will be described. In the following description, the Al—Mg—Si based aluminum alloy material according to the present embodiment may be simply referred to as “aluminum alloy material”.

<Al-Mg-Si-based aluminum alloy material>
The Al—Mg—Si-based aluminum alloy material according to this embodiment has a chemical composition in which Cu and Ni are further added to an aluminum-based alloy to which Mg and Si are added. That is, this aluminum alloy material corresponds to an Al—Mg—Si—Cu-based aluminum alloy to which Ni is added. By adding Ni, it is possible to increase the strength without increasing the amount of Cu that lowers the corrosion resistance of the parent phase. Therefore, an aluminum alloy material having both high strength and good corrosion resistance can be obtained. Here, the details of the chemical composition of the aluminum alloy material will be described.

[Si: 0.1 to 2.0% by mass]
The amount of Si in the aluminum alloy material is 0.1% by mass or more and 2.0% by mass or less. Si contributes to precipitation strengthening by forming an Mg ₂ Si-based β ″ phase or β ′ phase or an AlMgSiCu-based Q ′ phase. Also, the addition of Si improves the flow of molten metal during casting. If the amount of Si is less than 0.1% by mass, the molten metal flow may deteriorate and sufficient strength may not be obtained due to precipitation strengthening. If the amount exceeds 0% by mass, elongation and formability may be deteriorated, whereas if the amount of Si is within the above range, both high strength and good elongation can be achieved.

The amount of Si may be 0.2% by mass or more, 0.4% by mass or more, or 0.6% by mass or more from the viewpoint of increasing strength and the like. The amount of Si may be 1.8% by mass or less, 1.6% by mass or less, or 1.4% by mass or less from the viewpoint of increasing elongation. Note that Si can be positively added to the aluminum alloy material, and may be included in advance in the waste or the like used as a raw material for the aluminum alloy material.

[Mg: 0.3 to 1.5% by mass]
The amount of Mg in the aluminum alloy material is 0.3 mass% or more and 1.5 mass% or less. Mg contributes to precipitation strengthening by forming Mg ₂ Si-based β ″ phase or β ′ phase or AlMgSiCu-based Q ′ phase. If the amount of Mg is less than 0.3% by mass, On the other hand, if the amount of Mg exceeds 1.5% by mass, hot workability may be deteriorated, whereas the amount of Mg is within the above range. Thus, both high strength and good hot workability can be achieved.

The amount of Mg may be 0.4% by mass or more, 0.5% by mass or more, 0.6% by mass or more from the viewpoint of increasing strength and the like. It is good also as 8 mass% or more, and good also as 1.0 mass% or more. The amount of Mg may be 1.3% by mass or less, 1.1% by mass or less, or 0.9% by mass or less from the viewpoint of improving hot workability. .

[Cu: 0.05 to 3.0% by mass]
The amount of Cu in the aluminum alloy material is 0.05 mass% or more and 3.0 mass% or less. Cu strengthens the Al phase by solid solution, and mainly contributes to precipitation strengthening by forming an AlMgSiCu-based Q ′ phase. If the amount of Cu is less than 0.05% by mass, there is a possibility that sufficient strength cannot be obtained by addition of Cu. On the other hand, when the amount of Cu exceeds 3.0% by mass, the corrosion resistance deteriorates. On the other hand, if the amount of Cu is within the above range, it is possible to increase the strength within a range that does not significantly impair the corrosion resistance of the aluminum alloy material.

The amount of Cu may be 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more from the viewpoint of increasing the strength. Further, the amount of Cu may be 2.0% by mass or less, 1.0% by mass or less, or 0.5% by mass or less from the viewpoint of increasing the corrosion resistance.

[Ni: 0.05 to 2.3% by mass]
The amount of Ni in the aluminum alloy material exceeds 0.05% by mass and is 2.3% by mass or less. Ni mainly contributes to precipitation strengthening by forming Mg ₂ Si-based β ″ phase or β ′ phase or AlMgSiCu-based Q ′ phase. In general Al—Mg—Si—Cu-based aluminum alloys, these The intermediate phase of Mg is formed of Mg, Si, and Cu. When an effective amount of Ni of 0.025 to 1.0 at% (about 0.05 to 2.3 mass%) is added, Ni becomes β ″ phase. In addition, β ′ phase and Q ′ phase are formed, and high strength can be achieved without increasing the amount of Cu. However, when the amount of Ni is 0.05% by mass or less, there is a high possibility that the effect of adding Ni cannot be significantly obtained. On the other hand, when the amount of Ni exceeds 2.3% by mass, the elongation decreases due to excessive increase of crystallized materials, and the tensile breaking elongation of the aluminum alloy material may be less than 10% required for various applications. high. On the other hand, if the amount of Ni is within the above range, precipitation strengthening can be achieved without depending on the amount of Cu, and both high strength and good elongation can be achieved without impairing the corrosion resistance of the aluminum alloy material. Can be made.

The amount of Ni may be 0.1% by mass or more, 0.3% by mass or more, or 0.5% by mass or more from the viewpoint of increasing the strength. Further, the amount of Ni may be 2.0% by mass or less, 1.8% by mass or less, or 1.6% by mass or less from the viewpoint of increasing elongation.

[Fe, Mn, Cr, Zn, Ti]
The aluminum alloy material may optionally contain one or more elements selected from the group consisting of Fe, Mn, Cr, Zn, and Ti in an amount of 1.0% by mass or less. That is, Fe, Mn, Cr, Zn, and Ti may be included as inevitable impurities due to raw materials, manufacturing processes, and the like, and are actively added as long as the content is 1.0% by mass or less. It may be.

Fe contributes to suppression of seizure at the time of casting, improvement of strength, and the like, but it can deteriorate elongation when a coarse or large amount of crystallized matter is formed. The amount of Fe is preferably 0.7% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less. It is particularly preferable that Fe is not added actively but is in the range of 0.1 to 0.2% by mass or less which may be included as an inevitable impurity.

Mn is allowed to be added because it contributes to the refinement of crystal grains and the suppression of stress corrosion cracking. The amount of Mn is preferably 0.7% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, still more preferably 0.15% by mass or less, and still more preferably 0.05% by mass. It is not more than mass%, particularly preferably not more than 0.03% by mass.

Since Cr contributes to refinement of crystal grains and suppression of stress corrosion cracking, addition thereof is allowed. The amount of Cr is preferably 0.7% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.35% by mass or less, still more preferably 0.25% by mass or less, and further preferably 0.15%. It is not more than mass%, more preferably not more than 0.05 mass%, particularly preferably not more than 0.03% by mass.

Zn can be added for various purposes, but it is preferable not to add Zn actively. The amount of Zn is preferably 0.7% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.25% by mass or less, still more preferably 0.20% by mass or less, and further preferably 0.10%. It is not more than mass%, more preferably not more than 0.05 mass%, particularly preferably not more than 0.03% by mass.

Ti is allowed to be added because it refines crystal grains and contributes to prevention of casting cracks. The amount of Ti is preferably 0.20% by mass or less, more preferably 0.10% by mass or less.

[Inevitable impurities]
The aluminum alloy material may contain other elements as inevitable impurities caused by raw materials, manufacturing processes, and the like. Examples of inevitable impurities include Ga, V, B, Zr, Co, Ag, Bi, Pb, and Sn. The amount allowed as an inevitable impurity is 0.05% by mass or less, preferably 0.01% by mass or less, more preferably 0.005% by mass or less for each element. Further, the amount allowed for the total of the elements is preferably 0.15% by mass or less, more preferably 0.10% by mass or less.

<Method for producing Al-Mg-Si aluminum alloy material>
The Al—Mg—Si-based aluminum alloy material according to the present embodiment can be obtained by forming into an appropriate shape according to the application. The mechanical properties required for each application can be obtained by artificial aging treatment, natural aging, and age hardening by paint baking. Specifically, the method for producing an Al—Mg—Si based aluminum alloy material according to the present embodiment includes a molding step of molding a molded body made of an aluminum alloy adjusted to the chemical composition, and a solution of the molded body. It includes at least a solution treatment step to be processed and an aging treatment step for aging the solution-treated molded body.

In the forming step, the aluminum alloy adjusted to the chemical composition is formed into a shape according to the intended use of the aluminum alloy material. For example, the forming may be performed using any one of a rolling process, a press process, an extrusion process, a forging process, and a casting process using a mold. Although the shape of the molded body depends on the use of the aluminum alloy material, it may be a general wrought material shape such as a plate, a net shape, or a near net shape. May be. Before or after the aging treatment step, it is possible to add a process for obtaining a net shape and other processes required for each application.

For example, as shown below, aluminum alloy materials used as materials for automobile body panels, etc., are manufactured by forming the material into a plate shape and subjecting the plate material to a solution treatment process, a press working process, and an aging treatment process in this order. can do. The plate material is made of, for example, Al ingot, Al-containing waste, etc., and an alloy containing an additive element such as Ni, to cast an ingot, and the cast ingot is subjected to homogenization heat treatment to be homogenized. It can be obtained by rolling the heat-treated ingot. The molten metal in which the metal is melted is cast using various general casting methods such as semi-continuous casting method (direct chill casting method), horizontal continuous casting method, hot top casting method, electromagnetic field casting method, etc. It is possible. The homogenization heat treatment can be performed at a general holding temperature and holding time. The homogenization heat treatment may be omitted when the concentration of the additive element is low.

The rolling process for forming the plate material may be performed using any one of hot rolling, cold rolling, and a combination thereof, but after hot rolling the ingot to several mm in thickness. The hot-rolled rolled sheet is preferably cold-rolled at a sufficient cold rolling rate, for example, 50% or more. When cold rolling is performed at a sufficient cold rolling rate, alloy components such as Ni are easily dissolved in the solution treatment, so that the effect of aging precipitation can be obtained more reliably. Note that intermediate annealing may be performed between hot rolling and cold rolling, or rolling may be performed continuously without performing intermediate annealing.

In addition, the plastic working performed to obtain the plate material can be performed with an appropriate working degree according to mechanical properties finally required for the aluminum alloy material, tempering conditions by heat treatment, and the like. Further, instead of the above casting, homogenization heat treatment, and rolling, a direct casting and rolling method such as a roll type or a belt type may be used. When the direct casting and rolling method is used, a plate material can be obtained directly from the molten metal.

In the solution treatment step, the plate material formed by rolling in the forming step is heated and held at a temperature above the temperature at which the precipitated phase is dissolved in the solid solution and below the temperature of the solidus. When the solution treatment is performed, the amount of solute atoms in the matrix is increased, so that the effect of aging precipitation can be increased. The holding temperature of the solution treatment is usually 450 ° C. or higher and 590 ° C. or lower, but is not particularly limited. Moreover, the retention time of the solution treatment can be, for example, from 10 minutes to 24 hours, but is not particularly limited. The solution treated plate material is preferably cooled by water quenching from the viewpoint of suppressing precipitation of precipitates at the grain boundaries. After cooling, the plate material may be subjected to a stabilization treatment, for example, by holding at 80 ° C. or higher and 120 ° C. or lower.

In the pressing process, the plate material is pressed to obtain a net-shaped or near-net-shaped plate-shaped compact. The press working may be performed using any one of a warm press, a cold press, and a combination thereof. The warm pressing can be performed, for example, at 230 ° C. or higher and 300 ° C. or lower. In addition, the board | plate material with which it uses for a press work process may be pre-aged at the appropriate holding temperature previously, and may be naturally aged at room temperature. That is, a T4 material prepared in advance may be used as a plate material to be pressed.

In the aging treatment step, in order to age harden the Al—Mg—Si—Cu based aluminum alloy to which Ni has been added, the solution after the solution treatment is maintained at a temperature equal to or higher than the temperature at which the precipitation phase is generated. As the aging treatment, either natural aging treatment for natural aging hardening at room temperature or artificial aging treatment for artificial aging hardening by heat treatment may be performed. Further, any of peak aging treatment for obtaining the maximum strength, sub-aging treatment for obtaining the strength before the peak aging, and overaging treatment for obtaining the strength after the peak aging may be performed. In addition, two-stage aging may be performed in the aging treatment process, two-stage aging may be performed by aging the T4 material, etc. in the aging treatment process, or after natural aging is performed as the aging treatment process, aluminum The surface of the alloy material may be baked and cured in a paint baking process in which a resin paint is applied and baked.

The holding temperature in the artificial aging treatment is not particularly limited, but can be, for example, 100 ° C. or higher, preferably 140 ° C. or higher, more preferably 160 ° C. or higher. The holding temperature can be, for example, 250 ° C. or lower, preferably 220 ° C. or lower, more preferably 200 ° C. or lower. At such a holding temperature, a precipitated phase is formed in a state in which solute atoms are easily diffused, so that it is possible to obtain better mechanical properties with higher uniformity. The artificial aging treatment can be performed with an appropriate holding time using an appropriate heat treatment furnace such as a batch furnace or a continuous furnace.

In addition, an aluminum alloy material used as a material for an automobile suspension arm or the like is manufactured, for example, by forming a net shape or near net shape molded body and subjecting the molded body to a solution treatment step and an aging treatment step in this order. Can do. The molded body is, for example, Al ingot, Al-containing waste, etc. and an alloy containing an additive element such as Ni are cast into an ingot, and the cast ingot or extrusion into the ingot It can obtain by performing the forging process after performing the homogenization heat processing to the extrusion material which gave, and performing a homogenization heat processing. Note that the casting and the homogenization heat treatment can be performed in the same manner as in the case of obtaining the plate material. As the casting method, an irregular continuous casting method may be used.

The forging process for forming the formed body may be performed using any of hot forging, warm forging, cold forging, and combinations thereof, but the ingot is at a temperature below the melting point. Hot forging is preferred. When plastic working is performed at a sufficient working rate, an alloy component such as Ni is easily dissolved in the solution treatment, so that the effect of aging precipitation can be obtained more reliably. Forging may be performed, for example, by die forging using a hydraulic press, vertical press, horizontal press, screw press, or the like, or may be performed by free forging. The number of forgings, presence or absence of preforming or reheating, presence or absence of closed forging or deburring forging are not particularly limited.

In addition, the molded body may be obtained by casting in the case of a chemical composition that can ensure hot water flowability, resistance to casting cracking, and the like. For example, Al ingots, Al-containing wastes, and alloys containing additive elements such as Ni are melted to form a molten metal, and a molded body can be obtained using a die casting method, a sand mold casting method, or the like. . As the casting method, a low pressure casting method in which a low pressure of about 0.05 MPa or less is applied, a high pressure casting method in which a high pressure of about several tens of MPa is applied, a gravity casting method, or the like may be used.

In the solution treatment step, the compact formed in the molding step is heated and held at a temperature equal to or higher than the temperature at which the precipitated phase dissolves in the solid solution and equal to or lower than the solidus temperature. Thereafter, in the aging treatment step, the compact after the solution treatment is maintained at a temperature equal to or higher than the temperature at which the precipitated phase is generated. The solution treatment and aging treatment of the molded body can be performed under the same conditions as in the case of the plate material or plate-shaped molded body, and the degree of plastic working, the progress of recrystallization, and the required mechanical properties Depending on the conditions, etc., appropriate conditions can be set.

The aluminum alloy material obtained by being subjected to the aging treatment process can be subjected to other processing and surface treatment depending on the application. Aluminum alloy materials include, for example, processing to form a joint for joining a structural material and another member, diffusion joining for joining to another member, processing such as welding, polishing to smooth the surface, etc. Processing may be given. The surface may be subjected to a surface treatment such as a chemical conversion treatment, an anodizing treatment, or a plating treatment, or a paint baking treatment.

According to the method for producing an Al—Mg—Si aluminum alloy material according to this embodiment, an Al—Mg—Si aluminum alloy material that has been subjected to an aging treatment can be obtained. The obtained aluminum alloy material has an aging structure in which a precipitated phase containing Ni exists, and has high strength and good corrosion resistance. In addition, the dispersion of the crystallized product makes it easy to sever the chips generated during cutting and makes it difficult for the chips to wrap around the cutting tool or the like, so that an aluminum alloy material with improved machinability is obtained.

The production method of the Al—Mg—Si-based aluminum alloy material is not limited to the production methods exemplified above, and other appropriate forming, processing, heat treatment, etc. as long as the chemical composition satisfies the above range. It is possible to produce an Al—Mg—Si-based aluminum alloy material in an appropriate form.

<Mechanical properties of Al-Mg-Si-based aluminum alloy materials>
The Al—Mg—Si-based aluminum alloy material according to the present embodiment has a Cu content after age-hardening due to the addition of Ni, compared to a general Al—Mg—Si—Cu-based aluminum alloy. Higher maximum strength and hardness can be obtained without dependence. By adding Ni, the effect of improving the mechanical properties of an arbitrary part can be obtained without significantly impairing the corrosion resistance.

Specifically, the aluminum alloy material can have a tensile strength measured for an arbitrary part after the aging treatment, for example, 350 MPa or more by controlling the amount of components such as Ni and the crystal structure, and is 360 MPa or more. It can be. Moreover, the 0.2% yield strength measured about the arbitrary site | parts after an aging treatment can be 330 Mpa or more, for example by control of the amount of components, such as Ni, and crystal structure, and can be 350 Mpa or more. Further, when the tensile strength is in the range of about 360 to 370 MPa, a tensile breaking elongation of 10% to 13% can be obtained.

The tensile strength, 0.2% proof stress and tensile elongation at break in Al-Mg-Si-based aluminum alloy materials are determined according to the test piece, tester and test conditions specified in JIS Z 2241: 2011 after age hardening. It can obtain | require by performing the used tensile test.

<Applications of Al-Mg-Si-based aluminum alloy materials>
The Al—Mg—Si based aluminum alloy material according to the present embodiment can be used as a structural material for vehicles such as automobiles and motorcycles. Examples of structural materials for vehicles include exterior structural materials such as door inner panels, door outer panels, roof panels, bonnets, trunks, fenders, various beams, and suspension structural materials such as suspension arms. Is mentioned. When an Al-Mg-Si-Cu-based aluminum alloy with Ni added is used as the structural material, the strength can be increased without significantly damaging the corrosion resistance. Thus, it is possible to obtain a highly durable structural material that combines good corrosion resistance.

Hereinafter, the present invention will be described in detail with reference to examples of the present invention. However, the technical scope of the present invention is not limited to this.

The Al—Mg—Si-based aluminum alloy material according to the present embodiment was prepared by changing the amount of nickel added, and for each of the prepared test materials, the influence of the amount of nickel added, age hardenability, and mechanical properties Was evaluated.

As a test material, an Al—Mg—Si—Cu-based aluminum alloy indicated as “no additive” in Table 1 is used as a basic composition, and the target value of the atomic concentration of nickel is changed within a range of 0.025 to 1.0 at%. A wrought material (sample Nos. 1 to 5) was prepared and used. Table 1 shows the basic composition of the test material (“no addition”) and the measured values of the components.

First, age hardening of each specimen was evaluated based on the peak hardness during T6 treatment. The solution treatment was performed at 575 ° C. for 1 hour. In addition, the artificial aging treatment was performed by water quenching the solution-treated specimen and holding it at 200 ° C. And the micro Vickers hardness (HV0.1) by the test force 0.98N of the test material which carried out artificial aging treatment for every different holding time was measured. Table 2 shows the measurement results of the peak hardness.

As shown in Table 2, as a result of the measurement, it was confirmed that the peak hardness tends to improve depending on the amount of nickel added. Compared with the test material of the basic composition to which nickel is not added (“no addition”), when the target value is 0.025 at% or more, significant age hardening is recognized, and the hardness increases as the amount of Ni increases. Improved. However, the test material No. 1 was set to a target value exceeding the solid solubility limit of nickel (about 0.3 at%). In 3 to 5, the increase in hardness was small, and the peak hardness of each other was substantially the same.

FIG. 1 is a transmission electron microscope image of a test material made of an Al—Mg—Si—Cu-based aluminum alloy. FIG. 2 is a transmission electron microscope image of a specimen made of an Al—Mg—Si—Cu-based aluminum alloy to which Ni is added.
FIG. 1 is a result of observing an aging structure of a cross section of a specimen having a basic composition to which Ni is not added (“no addition”) with a transmission electron microscope. Further, FIG. 2 shows the test material No. 1 in which the target value of nickel is 0.2 at%. It is the result of having observed the aging structure | tissue of 2 cross sections with the transmission electron microscope.

As shown in FIGS. 1 and 2, a large number of precipitates were confirmed in the parent phase of the aluminum alloy. The structure of the test material with the basic composition to which Ni was not added (“no addition”) and the test material No. with Ni added. When comparing with the structure of Sample No. 2, It was confirmed that No. 2 produced a state in which many precipitates were finely dispersed. As a result of separately analyzing the composition of the precipitate in such a state, nickel distribution was observed.

Next, the mechanical properties of each test material after age hardening were evaluated. The solution treatment was performed at 575 ° C. for 1 hour. In addition, the artificial aging treatment was performed by water quenching the solution-treated specimen and holding it at 200 ° C. for 100 minutes. The test material after the artificial aging treatment was subjected to a tensile test according to JIS Z 2241: 2011, and the tensile strength, 0.2% proof stress, and tensile breaking elongation were measured. The results are shown in Table 3. The “reference value” is a value based on the standard values specified in JIS H 4000, 4040, 4080, 4100, 4140, etc., and the lower limit value set based on the overall standard values of the 6061-T6 material. Show.

As shown in Table 3, when the target value of nickel is 0.025 at% to 1.0 at%, there is a tendency that the strength generally increases as the amount of Ni increases. On the other hand, the tensile elongation at break is the test material No. 1 in which the target value of nickel is 1.0 at%. 5 was below the reference value. The amount of Ni in the aluminum alloy material according to the present invention is suitably 0.025 to 1.0 at% (about 0.05 to 2.3 mass%), and the nickel solid solubility limit (about 0.3 at%) is satisfied. In consideration, it has been confirmed that it is effective to set the amount to 0.025 to 0.3 at% or 0.3 at% or more depending on the required mechanical properties.

Claims

Si: 0.1% by mass to 2.0% by mass, Mg: 0.3% by mass to 1.5% by mass, Cu: 0.05% by mass to 3.0% by mass, Ni: 0.05 It contains more than 2.3% by mass and more than 1% by mass, optionally containing one or more elements selected from the group consisting of Fe, Mn, Cr, Zn and Ti at 1.0% by mass or less, with the balance being An Al—Mg—Si aluminum alloy material comprising Al and inevitable impurities.
2. The Al—Mg—Si-based aluminum alloy material according to claim 1, wherein the tensile strength is 350 MPa or more, the 0.2% proof stress is 330 MPa or more, and the tensile breaking elongation is 10% or more.