JPH10280111A - Production of aluminum alloy material suppressed in cold aging property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aluminum alloy material suppressed in cold aging properties and capable of suppressing the increase of strength caused by its leaving at ordinary temps., the increase of the amt. of a spring-back and the decrease of formability caused by the increase of the strength. SOLUTION: An aluminum alloy sheet stock essentially consisting of Mg and Si is subjected to solution treatment and quenching of executing solution treatment under heating at 480 to 580 deg.C (louver than burning temp.) at a temp. rising rate of >=100 deg.C/min and executing quenching at a cooling rate of >=100 deg.C/min and is thereafter left standing at a room temp. for >=24 hr. After that, it is heated at a temp. rising rate of >=100 deg.C/min and is held in the temp. range of 200 to 300 deg.C for >=60 sec. Then, it is subjected to quenching at a cooling rate of >=100 deg.C/min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy material suitable for a heat-treated aluminum alloy sheet used for panels such as automobiles, home appliances and machine parts, which increases the strength by utilizing the heating during baking. More specifically, with regard to the manufacturing method, it is possible to suppress an increase in strength due to a change in aging when left at normal temperature (room temperature) and a corresponding increase in springback amount and a decrease in formability due to heat treatment type alloy, The present invention relates to a method for producing an aluminum alloy material which is capable of obtaining the same formability as a non-heat-treating press-working aluminum alloy material and has a reduced room-temperature aging property.

[0002]

2. Description of the Related Art Conventionally, aluminum alloy plates have been used for panels and the like of automobiles, home electric appliances and mechanical parts for the purpose of weight reduction. When an aluminum alloy plate is used for these applications, first, forming processing such as pressing and bending is performed, and then, heat treatment (baking coating, baking) for imparting strength to the coating and the coating film is performed. Such an aluminum alloy plate is a material that has low strength during forming by pressing or the like, is easy to form, and after the forming process, the strength of the aluminum alloy plate itself is significantly improved by heat treatment of baking coating. Is considered ideal. Due to such requirements, Al-Mg-Si heat treatment type aluminum alloy plates are mainly used as this type of aluminum alloy plate.

[0003] However, with the energy saving and the diversification of resin materials, the baking coating temperature tends to be lowered, and it is no longer possible to sufficiently secure the strength of the conventional aluminum alloy plate by baking coating. Accordingly, the present applicant has already proposed an aluminum alloy sheet having excellent bake hardening properties at low temperatures (Japanese Patent Application Laid-Open No. 1-111851 and Japanese Patent Application Laid-Open No.
2-89852). In these aluminum alloy plates, in order to increase the strength after baking at low temperatures,
A method of generating nuclei for precipitation in the matrix is employed. However, when these aluminum alloy sheets are left at room temperature, the strength is increased, the amount of springback is increased, and the formability is deteriorated. If left at room temperature for several months after production, press working becomes difficult, There is a problem that molding is impossible under the immediately following press working conditions.

The present invention has been made in view of the above-mentioned problems, and suppresses an increase in strength due to standing at room temperature and an increase in the amount of springback and a decrease in moldability due to standing at room temperature. It is an object of the present invention to provide a method for manufacturing a manufactured aluminum alloy material.

[0005]

According to the present invention, there is provided a method for producing an aluminum alloy material for suppressing the aging at room temperature, comprising the steps of solution quenching an aluminum alloy material containing Mg and Si as main components, followed by 24 hours at room temperature. Leaving for more than 100 hours, and further heating at a heating rate of 100 ° C./minute or more.
The method is characterized by comprising a step of maintaining the temperature in a temperature range of 00 to 300 ° C. for 0 to 60 seconds, and thereafter, a step of quenching at a cooling rate of 100 ° C./min or more.

Further, another method for producing an aluminum alloy material with reduced aging at room temperature according to the present invention comprises Mg and Si.
Casting a molten aluminum alloy containing aluminum as a main component to produce an aluminum alloy ingot, a step of subjecting the ingot to a homogenizing heat treatment at a temperature equal to or lower than a burning temperature, and a step of hot-pressing the ingot after the homogenizing heat treatment. Rolling and cold-rolling to a predetermined thickness and temper, and heating to 480 to 580 ° C (lower than the burning temperature) at a heating rate of 100 ° C / min or more to perform a solution treatment. Quenching at a cooling rate of 100 ° C./min or more, leaving at room temperature for 24 hours or more, heating at a rate of 100 ° C./min or more, and then increasing the temperature to 200 to 300 ° C. in a temperature range of 0 to 60 ° C. The method is characterized by including a step of holding for a second and then a step of quenching at a cooling rate of 100 ° C./min or more.

As described above, according to the present invention, an aluminum alloy material containing Mg and Si as main components (particularly, a JIS 6000 type aluminum alloy material) is solution-quenched and then left at room temperature (normal temperature) for 24 hours or more. The quenching treatment is carried out at a temperature rising rate of 100 ° C./min or more in a temperature range of 200 to 300 ° C. for 0 to 60 seconds, and thereafter, a quenching treatment is carried out at a cooling rate of 100 ° C./min or more. However, even if left at room temperature for several months, it is possible to prevent an increase in strength, an increase in the amount of springback, and a decrease in formability.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION First of all, the present inventor has firstly proposed the reason why the Al-Mg-Si-based heat-treated aluminum alloy plate which has been practically used for this kind of application is inferior in low-temperature bake hardening properties and has proposed by the applicant. Intensive experimental research was conducted to determine the cause of room temperature aging of the conventional aluminum alloy plate with improved low-temperature bake hardening, and the following results were obtained.

First, in the case of a conventional material having low low-temperature bake hardenability, quenching is performed after a normal solution treatment, and then the substrate is left at room temperature. When left at room temperature, precipitates (aggregates) consisting of vacancies called clusters and solute atoms such as Mg and Si are generated from the solid solution state immediately after quenching. When such clusters are formed, the formation of β′-Mg ₂ Si is hindered, so that the bake hardness at low temperatures is reduced.

On the other hand, in a conventional aluminum alloy material having improved low-temperature bake hardenability, a nucleus for precipitation is generated in a matrix by performing high-temperature quenching after solution quenching as described above. Therefore, even at a low temperature for a short time, the nucleus of this precipitation (nucleus of β′-Mg ₂ Si) easily grows and becomes an aging precipitate, so that excellent low-temperature bake hardening properties can be obtained. However, since the formation of clusters similar to that of a normal quenched material occurs at room temperature, an increase in strength due to standing at room temperature, an increase in the amount of springback, and a decrease in formability occur.

Based on the above findings, the present inventor has conducted sincere studies to improve the method proposed above. As a result, in order to suppress room-temperature aging and simultaneously obtain excellent low-temperature bake hardening properties, it is necessary to melt precipitates such as clusters and β′-Mg ₂ Si nuclei in aluminum, and therefore, It was found that a heat treatment process for re-dissolving these precipitates was provided and that the heat treatment conditions were important. That is, after solution quenching, 2
After leaving for more than 4 hours to precipitate the cluster once, as a heat treatment to re-dissolve the precipitate such as cluster,
It is an optimal condition that the aluminum alloy material is heated at a heating rate of 100 ° C./min or more, kept at a temperature range of 200 to 300 ° C. for 0 to 60 seconds, and quenched at a cooling rate of 100 ° C./min or more. I found something. This allows
An increase in the strength of the aluminum alloy material due to normal temperature aging in the T4 state can be suppressed, and at the same time, excellent low-temperature bake hardenability can be obtained. The present invention has been completed based on such findings.

Hereinafter, the composition and heat treatment conditions of the present invention will be described. First, the composition of the aluminum alloy of the present invention will be described. The feature of the present invention is the suppression of precipitates, and the elements constituting these precipitates, Mg, Si
Are Mg: 0.3 to 1.0% by weight, Si: 0.5, respectively.
It is preferably from 1.5 to 1.4% by weight. At this time, the content of Mg ₂ Si is 0.9 to 1.3% by weight, and the amount of Si is excessive with respect to the amounts of Mg and Si constituting Mg ₂ Si. 0% by weight
It is preferable to set the amounts of Mg and Si such that

Further, in order to improve the moldability, the M
Mn: 0.02 to 0.20% by weight in addition to g and Si
Can be added. If necessary, Zr: 0.3% by weight or less, Cr: 0.3% by weight or less, Ti: 0.1% by weight in these Al-Mg-Si-based or Al-Mg-Si-Mn-based alloys % Or less and B: 0.1% or less, one or more kinds may be contained. Furthermore,
It is preferable that Fe as an impurity is restricted to 0.3% by weight or less.

However, since the feature of the present invention is the suppression of precipitates due to the heat treatment, the so-called 6 mainly containing Mg and Si is used.
The present invention can be applied to any 000 series alloy.

If the content of other elements is less than 0.1% by weight, the characteristics of the present invention are not affected, and thus the content of such elements is acceptable. For example, impurities such as aluminum or the like mixed from a base metal and return scrap may be contained.

The reasons for adding the components of the aluminum alloy of the present invention and the reasons for limiting the components will be described below.

Mg: 0.3 to 1.0% by weight Mg itself has a solid solution strengthening action, and further forms an aging precipitate β′-Mg ₂ Si by co-addition with Si, ie, precipitation hardening. Is an element that contributes to improving the strength of the aluminum alloy. The amount of β′-Mg ₂ Si deposited depends on the Mg content. Therefore, the Mg content is 0.3% by weight.
If the strength is less than the sufficient strength (hereinafter, the strength
It refers to the proof stress after baking at 0 ° C. ) Cannot be obtained, and if more than 1.0% by weight is added, the equilibrium phase Mg
₂ Si grows as crystallized substances, elongation is lowered and moldability is remarkably reduced. Therefore, the Mg content is 0.3 to 1.
A range of 0% by weight is desirable.

Si: 0.5 to 1.4% by weight Si mainly forms an aging precipitate β′-Mg ₂ Si by synergistic action by co-addition with Mg, and contributes to strength improvement by precipitation hardening. Element. .beta. '-Mg ₂ Si precipitation amount depends on the Si content. Therefore, if the Si content is less than 0.5% by weight, sufficient strength cannot be obtained, and S
When the i content exceeds 1.4% by weight, the equilibrium phase Mg ₂ Si
Crystallizes, greatly reduces elongation, and deteriorates moldability. Therefore, the Si content is desirably in the range of 0.5 to 1.4% by weight.

Mg ₂ Si: 0.9 to 1.3% by weight, excess
Excess Si amount: 0.5 to 1.0% by weight In the above-mentioned contents of Mg and Si, it is preferable that Si is excessively added to Mg. Then, Mg and Si form Mg ₂ Si as an aging precipitate, and a predetermined amount of the Mg ₂ Si precipitates and hardens, thereby improving the strength of the aluminum alloy material. Mg and S
The aging precipitate β′-Mg ₂ Si formed by combining i is a compound capable of improving the strength of the aluminum alloy material and further improving the strength after baking. If the total content of Mg ₂ Si is less than 0.9% by weight, the strength is low and the paint baking curability cannot be obtained. On the other hand, if the content of Mg ₂ Si exceeds 1.3% by weight, elongation is reduced and formability is reduced. Therefore, the total content of Mg ₂ Si formed by combining Mg and Si is preferably 0.9 to 1.3% by weight.

Since Si is excessively added to Mg, Si not contained in Mg ₂ Si (residual Si)
Is contained in the Al alloy. This residual Si has an effect of improving formability. That is, when the remaining Si is dissolved in the T4 state, the strength is improved by solid solution hardening. If the total content of residual Si is less than 0.5% by weight, the above-mentioned effect cannot be sufficiently obtained, while if the content of residual Si exceeds 1.0% by weight,
Since the strength becomes too high, the moldability decreases. Therefore, the content of residual Si is 0.5 to 1.0% by weight in total.
It is preferred that As described above, the amounts of Mg and Si are appropriately blended in consideration of the amount of Mg ₂ Si and the amount of residual Si.

When the following elements are added to the aluminum alloy material of the present invention, the strength or formability of the aluminum alloy material can be further improved.

Mn: 0.02 to 0.20% by weight Mn forms a second phase MnAl ₆ together with Al.
nAl ₆ precipitates and suppresses recrystallization of the alloy structure, refines crystal grains, and contributes to improvement in formability and strength. Also,
When the solution treatment is sufficiently performed and Mn is dissolved in the Al alloy, the strength can be further improved. If the content of Mn is less than 0.02% by weight, the effect of refining the crystal grains cannot be obtained, and the precipitation of the second phase MnAl ₆ is insufficient, so that the formability and strength can be improved. Can not. On the other hand, when Mn exceeds 0.20% by weight, a coarse crystallized substance is formed and the formability is reduced. Therefore, the content of Mn is preferably set to 0.02 to 0.20% by weight. When Mn is added within this content range, even if the solution heat treatment is sufficiently performed to increase the strength of the material, A
The crystal grain size in the alloy 1 is 35 μm or less, so that a decrease in formability can be prevented.

Cr: 0.3 wt% or less Cr forms an intermetallic compound, and the refined compound suppresses recrystallization and refines crystal grains, so that formability can be improved. If the Cr content exceeds 0.3% by weight, the intermetallic compound grows and becomes coarse, the elongation is reduced, and the formability is reduced. Therefore, the content of Cr is preferably 0.3% by weight or less.

Zr: 0.3 wt% or less Zr forms an intermetallic compound in the same manner as Cr, and the refined compound suppresses recrystallization and refines crystal grains, thereby improving formability. Can be. If the total content of Zr exceeds 0.3% by weight, the intermetallic compound grows and becomes coarse, the elongation decreases, and the formability decreases. Therefore, the content of Zr is preferably 0.3% by weight or less.

Ti: 0.1 wt% or less Ti is an element that refines crystal grains of an ingot and improves formability. If the content of Ti exceeds 0.1% by weight, the crystallized product becomes coarse and the formability decreases. Therefore, the content of Ti is preferably 0.1% by weight or less.

B: 0.1 wt% or less B can be added simultaneously with Ti to promote the effect of refining Ti crystal grains. However, if B is excessive, a coarse compound is formed, which causes surface flaws and pinholes. Therefore, it is preferable to contain B in an amount of 0.1% by weight or less.

Fe: not more than 0.3% by weight Fe is an impurity which is usually mixed from metal and scrap, but may be contained in a small amount for the purpose of improving the strength and formability of the aluminum alloy material. However, Fe
When the content exceeds 0.3% by weight, the formation of crystallized substances and the coarsening of the crystallized substances are remarkable, the crystal grains are coarsened further, and the formability of the aluminum alloy material is significantly reduced. Therefore, the Fe content is desirably 0.3% by weight or less.

Next, the manufacturing process of the aluminum alloy material will be described. First, an aluminum alloy material having a predetermined composition is melted and cast to produce an aluminum alloy ingot.
Next, a homogenization treatment is performed at a temperature equal to or lower than the burning temperature, and thereafter, hot rolling is performed, and intermediate annealing is further performed as necessary. Thereafter, cold rolling is performed to a predetermined thickness. Thereafter, a heat treatment, which is a feature of the present invention, is performed.

That is, after the solution quenching of the aluminum alloy material, the aluminum alloy material is left at room temperature for 24 hours or more, and further kept at a temperature rising rate of 100 ° C./min or more in a temperature range of 200 to 300 ° C. for 0 to 60 seconds. The quenching treatment is performed at a cooling rate of not less than ° C / min. By the above processing, as described above, the precipitates such as clusters and β′-Mg ₂ Si nuclei are melted, and T
In the four states, normal-temperature aging can be suppressed, an increase in strength and a decrease in moldability can be suppressed, and in addition, relatively high strength can be obtained with respect to low-temperature bake hardenability. If the homogenization heat treatment is performed before the solution heat treatment, the size and volume content of the dispersed precipitate can be adjusted to appropriate values.

Next, each heat treatment condition will be described. First, a JIS 6000 series Al alloy is melted by an ordinary method and then cast to obtain an aluminum alloy ingot. Thereafter, the aluminum alloy ingot is subjected to a homogenizing heat treatment.
In the homogenization heat treatment, it is preferable to homogenize the aluminum alloy ingot under the following conditions.

Homogenization heat treatment temperature: 480 to 580 ° C. The homogenization heat treatment is a heat treatment performed to uniformly disperse the segregation of the added element and to control the size and volume content of the dispersed precipitate. If the temperature of the homogenization heat treatment is lower than 480 ° C., the intermetallic compound composed of the additional element does not form a solid solution, and the volume content of the remaining intermetallic compound increases, so that the moldability decreases. On the other hand, the homogenization heat treatment temperature is 580 ° C
If it exceeds, burning occurs and cracks occur during hot rolling. Therefore, the temperature in the homogenization heat treatment is preferably set to 480 to 580 ° C. Depending on the composition of the aluminum alloy, burning may occur at 580 ° C. or lower, and the homogenizing heat treatment temperature is preferably set as high as possible according to the composition within a range in which burning does not occur. Further, the holding time is appropriately determined.

Next, a hot rolling process and a cold rolling process are performed. If an intermediate annealing process is performed between the hot rolling process and the cold rolling process, the formability can be further improved. This intermediate annealing treatment is performed by adding 300 parts of the aluminum alloy material.
It is preferable to heat to a temperature of from 450 to 450 ° C. Then, after the aluminum alloy material is reduced to a predetermined thickness by cold rolling, a solution heat treatment is performed.

Next, the conditions of the solution heat treatment will be described.

Heating rate: 100 ° C./min or more In the solution heat treatment, if the heating rate is less than 100 ° C./min, the added elements do not form a solid solution, the strength is reduced, and the bake hardenability is not sufficient. Therefore, in the solution heat treatment, the heating rate is set to 100 ° C./min or more.

Solution heat treatment temperature: 480 to 580 ° C
If the solution heat treatment temperature is lower than 480 ° C. (below the burning temperature), the intermetallic compound consisting of the added element does not form a solid solution and the intermetallic compound remains, so that the formability is reduced. On the other hand, if the solution temperature exceeds 580 ° C., burning occurs and plate cracks occur. Therefore, the temperature in the solution heat treatment is set to 480 to 580 ° C. Depending on the composition of the aluminum alloy, burning may occur at 580 ° C. or lower, and the solution heat treatment temperature is preferably as high as possible depending on the composition within a temperature range in which burning does not occur. Further, the holding time is appropriately determined.

Quenching cooling rate: 100 ° C./min or more In quenching after solution heat treatment, the cooling rate is 100
If the temperature is lower than ℃ / minute, a solid solution element is precipitated, and sufficient strength cannot be obtained, and the moldability is lowered. Therefore, the cooling rate is set to 100 ° C./min or more.

Leaving at room temperature: 24 hours or more Then, as a normal temperature aging treatment after solution heat treatment and quenching, the aluminum alloy material is left at normal temperature for 24 hours or more to precipitate precipitates such as clusters. If the next step (heat treatment for re-solid solution) is performed without performing the normal-temperature aging treatment, the strength of the aluminum alloy material rapidly increases in the T4 state, and the formability and bendability are reduced. Connect. Therefore, before the heat treatment for re-solid solution, normal temperature aging treatment is performed under the above conditions.

Heating rate during re-solid solution heat treatment: 100 ° C./min
After natural aging or, in order to melt the aging precipitation was subjected to heat treatment for redissolved. In this heat treatment, if the heating rate is less than 100 ° C./min, the precipitates are insufficiently melted, and stable phase precipitates are generated depending on the conditions, resulting in insufficient bake hardening at low temperatures. . Therefore,
The heating rate during the re-solid solution heat treatment is 100 ° C./min or more.

Heat treatment temperature: 200 to 300 ° C. The heat treatment for re-solid solution is a heat treatment for melting the aging precipitate (precipitate at room temperature or artificial aging) again in the aluminum alloy. If the heat treatment temperature is lower than 200 ° C., the precipitates are not sufficiently melted, and the aging at ordinary temperature cannot be suppressed. On the other hand, when the heat treatment temperature exceeds 300 ° C., precipitates of a stable phase are generated, so that the bake hardness at low temperatures becomes insufficient. Therefore, the heat treatment temperature for re-solid solution is set to 200 to 300 ° C.

Heat treatment holding time: not more than 60 seconds If the holding time of the heat treatment exceeds 60 seconds, precipitates of a stable phase are generated, so that the bake hardness at low temperatures becomes insufficient. Therefore, the heat treatment holding time is set to 60 seconds or less. Note that the time for maintaining the heat treatment temperature may be 0 seconds, that is, it is not necessary to maintain the heat treatment temperature.

Cooling rate: 100 ° C./min or more In the quenching after heat treatment for re-solid solution, if the cooling temperature is set to less than 100 ° C./min, the precipitation is insufficiently melted and the stable phase Precipitates are generated and bake hardening at low temperatures becomes insufficient. Therefore, the cooling rate is set to 100 ° C./min or more.

[0042]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples that fall outside the scope of the claims of the present invention. Examples 1 to 3 were compared with Comparative Examples in which the heat treatment conditions were out of the range of the present invention, and Example 4 was compared with Comparative Examples in which the composition was out of the range of the present invention.

Example 1 First, Si: 1.0% by weight, Mg: 0.6% by weight, M
n: 0.06% by weight, Ti: 0.03% by weight, Fe:
0.15% by weight, the content of Mg ₂ Si consisting of Mg and Si is 0.95% by weight, and the remaining S
An aluminum alloy material having an i content of 0.65% by weight and the balance consisting of Al and unavoidable impurities was melted and cast by an ordinary method to obtain an ingot having a thickness of 50 mm. Next, this alloy ingot was heated at a temperature of 560 ° C. for 4 hours, subjected to a homogenizing heat treatment, and hot-rolled immediately after hot rolling to obtain a hot-rolled material having a thickness of 5 mm. continue,
After leaving this hot-rolled material at room temperature,
After performing a heat treatment at a temperature of 500 ° C. at a heating rate of / hour for 5 seconds to perform an intermediate annealing treatment, cold rolling was performed at room temperature to obtain a rolled material having a thickness of 1 mm. The rolled material was subjected to a solution heat treatment under the conditions shown in Table 1 below (the quenching method was water quenching).

[0044]

[Table 1]

Then, it is left at room temperature for 24 hours to perform aging treatment at room temperature.
The temperature was raised to 200 ° C. at a heating rate of 0 ° C./min and held for 5 seconds. Then, quenching was performed at a cooling rate of 200 ° C./min to obtain a T4 material. Then, this T4 material was added for 7 days and 3
An aluminum alloy material (Al alloy plate) was prepared by leaving it at room temperature for a month, and a test was performed under the following conditions and evaluated.

Test of Strength and Formability and Evaluation Method Thereof A test piece was cut from the Al alloy material subjected to the above-described steps,
Each test piece was subjected to a tensile test by an autograph (manufactured by Shimadzu). Regarding the evaluation of strength, 7
Al alloy material subjected to normal temperature aging treatment for 7 days (material that has passed for 7 days)
And 0.2% proof stress (hereinafter simply referred to as “proof stress”) of each of the Al alloy materials (materials aged 3 months) that have been subjected to the normal temperature aging treatment for 3 months, and from these values of the proof stress (σ _0.2 ). ((Σ _0.2 months old material)-(7 days old material)
_0.2 )), the change in proof stress (σ _0.2 ) (hereinafter, this change in proof stress is referred to as a proof stress difference) was evaluated. In addition, the case where the value of the proof stress difference was 15 N / mm ² or less was regarded as good. Further, after aged for 7 minutes at a temperature of 180 ° C. for a material aged 7 days and a material aged 3 months, a tensile test was performed, and the values of these proof stresses were evaluated as bake hardness (hereinafter, referred to as bake hardness). This proof stress is called BH proof stress). This BH proof stress value is 2
The case where it was 00 N / mm ² or more was regarded as good.

The formability was evaluated by the Erichsen test B method specified in JIS-Z2247 using an Erichsen tester. , This value is referred to as the Er value). From these Er values, ((3
Er value of material aged for months)-(Er value of material aged for 7 days))
(Hereinafter, this change in Er value is referred to as E
The Erichsen value is 9.8 mm or more even after 3 months, and when the Erichsen value is 9.8 mm or more, the formability is similar to that of the conventional Al-Mg alloy for non-heat treatment type press working. It was judged to be excellent.

Table 2 below shows the results of these tests.
The proof stress, BH proof stress value, and Er value of the material that has passed for three days and the material that has passed for three months are shown. Table 3 below shows the proof stress difference and the Er value difference. In addition, when the evaluation of the proof stress difference and the BH proof strength in the strength is good and the evaluation of the Erichsen value in the moldability is good, “○” is given, and any one of the proof stress difference, the BH proof strength and the Erichsen value is used. If there is a defect, it is shown in Table 3 below as “×”.

[0049]

[Table 2]

[0050]

[Table 3]

Example 2 An Al alloy material having the same composition as in Example 1 was subjected to the cold rolling process in the same manner as in Example 1 to obtain a rolled material having a thickness of 1 mm. Next, the rolled material was heated to a temperature of 530 ° C. at a heating rate of 200 ° C./min, held for 30 seconds to perform solution heat treatment, and then water-quenched at a cooling rate of 200 ° C./min.
Then, normal temperature aging treatment was performed under the conditions shown in Table 4 below.

[0052]

[Table 4]

Then, as heat treatment for re-solid solution, 20
The temperature was raised to 200 ° C. at a heating rate of 0 ° C./min and held for 5 seconds. Then, quenching was performed at a cooling rate of 100 ° C./min to obtain a T4 material. Then, this T4 material was added for 7 days and 3
Example 1 An Al alloy material left at room temperature for months was prepared.
The test was performed under the conditions shown in (1) and evaluated by the evaluation method.

Table 5 below shows the results of these tests.
The proof stress, BH proof stress value, and Er value of the material aged for three days and the material aged for three months are shown, and the proof stress difference and the Er value difference are shown in Table 6 below. In the same manner as in Example 1, when the evaluation of the proof stress difference and the BH proof stress in the strength was good and the evaluation of the Erichsen value in the moldability was good, the evaluation was “O”, and the proof stress difference, the BH proof strength and the Erichsen strength were evaluated. When there is a defect among the values, it is shown in Table 6 below as “×”.

[0055]

[Table 5]

[0056]

[Table 6]

Example 3 An Al alloy material containing the same chemical components as in Example 1 was subjected to a cold rolling process in the same manner as in Example 1 to obtain a rolled material having a thickness of 1 mm. Next, the rolled material was heated to a temperature of 530 ° C. at a heating rate of 300 ° C./min, held for 30 seconds to perform solution heat treatment, and then water-quenched at a cooling rate of 300 ° C./min. Then, after standing at room temperature for 24 hours, the following Table 7
The T4 material was obtained by performing a heat treatment and a quenching treatment for re-solid solution under the following conditions.

[0058]

[Table 7]

Then, an Al alloy material was prepared by leaving the T4 material at room temperature for 7 days and 3 months, and a test was conducted under the conditions shown in Example 1 and evaluated by an evaluation method.

Table 8 below shows the results of these tests.
The proof stress, BH proof stress value, and Er value of the material aged for three days and the material aged for three months are shown, and the proof stress difference and the Er value difference are shown in Table 9 below. In addition, when the evaluation of the proof stress difference and the BH proof stress in the strength is good and the evaluation of the Erichsen value in the moldability is good, it is marked with “○”, and when the proof stress difference, the BH proof stress and the Erichsen value are defective. In Table 9 below.

[0061]

[Table 8]

[0062]

[Table 9]

Example 4 An Al alloy material having the composition shown in Tables 10 and 11 below was melted and cast by a usual method to obtain an alloy ingot having a thickness of 50 mm.

[0064]

[Table 10]

[0065]

[Table 11]

Then, the cold rolling treatment was performed under the same conditions as in Example 1 to obtain a rolled material having a thickness of 1 mm. Next, the rolled material was held at a temperature of 530 ° C. for 30 seconds, subjected to a solution heat treatment, and then water-quenched. Then, after leaving at room temperature for 24 hours, a heat treatment for re-solid solution was performed at 200 ° C. /
The temperature was raised to 200 ° C. at a heating rate of 1 minute and held for 5 seconds.
Then, a quenching treatment is performed at a cooling rate of 200 ° C./min, and T
Four materials were obtained. Then, the T4 material was left at room temperature for 7 days and 3 months to prepare an Al alloy material, and a test was performed under the conditions shown in Example 1 and evaluated.

Test of Strength and Formability and Evaluation Method Thereof A test piece was cut from the Al alloy material subjected to the above-described steps,
Each test piece was subjected to a tensile test by an autograph (manufactured by Shimadzu). Regarding the strength evaluation, the strength (proof stress σ _0.2 and tensile strength σ _B ) of the Al alloy material aged at room temperature for 7 days (material aged 7 days) and the Al alloy material aged at room temperature for 3 months (material aged 3 months) Was measured respectively. Then, from the value of the proof stress (σ _0.2 ), ((σ _{0.2 of the} material passed for 3 months) − (7
The proof stress difference indicating the change in the proof stress (σ _0.2 ) calculated by σ _0.2 )) of the material passed through the day was evaluated. In addition, the value of the proof stress difference is 15 N /
The case where mm ² or less was considered good.

The moldability was evaluated by the Erichsen test B method specified by JIS-Z2247 using an Erichsen tester, and the Er value was measured using the material aged 7 days and the material aged 3 months. did. Note that these E
An Er value difference calculated from the r value by ((Er value of material aged 3 months) − (Er value of material aged 7 days)) was also evaluated. When the Erichsen value was 9.8 mm or more, it was judged that the formability was excellent as in the case of the conventional Al—Mg alloy for non-heat treatment type press working. Also, 7
The ear ratio (δ%) was also evaluated for the day-aged material and the 3-month-old material, respectively.

Table 12 below shows the results of these tests.
3 shows the proof stress, tensile strength, ear ratio, and Er value of the material aged 7 days and the material aged 3 months.
The r value difference is shown.

[0070]

[Table 12]

[0071]

[Table 13]

[0072]

[Table 14]

The test results in the above table will be described below. First, Example 1 shown in Tables 2 and 3 will be described.
With respect to Nos. 1 to 4 of Example 1, all have a BH proof strength of 200 N / mm ² or more, and can be said to have good bake hardening properties. In addition, the difference in proof stress indicating the change in proof stress was 15 N /
mm ² or less, which means that an increase in strength due to aging at normal temperature can be suppressed. Furthermore, the Erichsen value is 9.8 mm or more even after aging at room temperature for 3 months, and it can be said that the moldability is excellent without lowering the moldability. In contrast, Table 2 above,
As shown in No. 3, the Erichsen value of No. 1 of Comparative Example 1 was a good result, but the heating rate in the solution heat treatment was less than a predetermined value.
The strength decreased, and the value of the BH proof stress decreased. The difference in proof stress indicating the change in proof stress was also 16 N / mm ² , and the strength was slightly increased by aging at room temperature. For No. 2 of Comparative Example 1, the treatment time was too long, so the Erichsen value was low, and the strength was also increased by aging at room temperature. For No. 3 of Comparative Example 1, since the solution heat treatment temperature was lower than the predetermined value, the intermetallic compound remained, the Erichsen value was lowered, the moldability was reduced, and the bake hardness was also reduced. For No. 4 of Comparative Example 1, since the solution heat treatment temperature was higher than a predetermined value, burning occurred, and
The Al alloy plate was cracked.

Next, a second embodiment shown in Tables 5 and 6 will be described. With respect to Nos. 1 to 3 of Example 2, the BH proof stress was 200 N / mm ² or more, and the bake hardening property was good. Further, the difference in proof stress indicating a change in proof stress is also 15 N / mm ² or less, and it can be said that an increase in strength due to normal temperature aging can be suppressed. Furthermore, the Erichsen value is 9.8 mm or more even after aging at room temperature for 3 months, and it can be said that the moldability is excellent without lowering the moldability. On the other hand, as shown in Tables 5 and 6, with respect to Nos. 1 to 3 of Comparative Example 2, the BH proof stress was 200 N / mm ² or more and the bake hardening property was good, but the room temperature aging treatment was performed. Since the time was shorter than the predetermined value, the strength of the Al alloy increased in the T4 state, the formability was reduced, and the Erichsen value was low.

A third embodiment shown in Tables 8 and 9 will be described. Regarding Nos. 1 to 4 of Example 3, the BH proof stress was 200 N / mm ² or more, and the bake hardening property was good. Further, the difference in proof stress indicating a change in proof stress is also 15 N / mm ² or less, and it can be said that an increase in strength due to normal temperature aging can be suppressed. Furthermore, the Erichsen value is 9.8 mm or more even after aging at room temperature for 3 months, and it can be said that the moldability is excellent without lowering the moldability. On the other hand, as shown in Tables 8 and 9, for No. 1 of Comparative Example 3, since the heating rate in the heat treatment step for re-solid solution was smaller than a predetermined value, precipitates remained and the BH proof stress decreased. , The bake hardness was reduced. Also, after three months, the moldability was reduced and the Erichsen value was also reduced. With respect to Nos. 2 and 3 of Comparative Example 3, since the heat treatment temperature for re-solid solution was lower than the predetermined value, normal-temperature aging could not be suppressed, and the proof stress difference indicating a change in proof stress exceeded 15 N / mm ² . With respect to No. 4 of Comparative Example 3, the Erichsen value was 9.8 mm or more, and the moldability was excellent without being deteriorated. However, since the heat treatment temperature for re-solid solution was higher than a predetermined value, the precipitate became an equilibrium phase. Precipitation resulted in low BH proof strength and low bake hardening properties. With respect to No. 5 of Comparative Example 3, since the treatment time was too long with respect to the predetermined value, precipitates were precipitated, so that the moldability was lowered and the Erichsen value was lowered. For No. 6 of Comparative Example 3, since the cooling rate in the heat treatment step for re-solid solution was smaller than a predetermined value, the precipitate was deposited as an equilibrium phase, so that the BH proof strength was reduced and the bake hardening property was reduced. Also, after 3 months, the Erichsen value was low, and the moldability was also low.

Next, a fourth embodiment shown in Tables 12, 13, and 14 will be described. For Nos. 1 to 3 of Example 4, the BH proof stress was 200 N / mm ² or more,
It can be said that the bake hardness is good. The difference in proof stress indicating a change in proof stress is also 15 N / mm ² or less, and it can be said that an increase in strength due to normal temperature aging can be suppressed. Furthermore, the Erichsen value is 9.8 mm or more even after aging at room temperature for 3 months, and it can be said that the moldability is excellent without lowering the moldability. On the other hand, in Comparative Example 4, the proof stress difference indicating a change in proof stress was 15 N / mm ² or less, and it can be said that the increase in strength due to normal temperature aging could be suppressed.
The ear ratio and Erichsen value were slightly lower than Nos. 1 to 3. That is, in Nos. 1 and 2 of Comparative Example 4, the content of Mn was out of the range of the predetermined amount, and No. 1 having a small content of Mn was unable to obtain a crystal grain refining effect, and
Since the precipitation of MnAl ₆ was insufficient, the Erichsen value was slightly lowered, and the moldability was slightly lowered. In No. 2 having a large Mn content, a crystallized product was formed, the Erichsen value and the ear rate were slightly lowered, and the moldability was slightly lowered. With respect to No. 3 of Comparative Example 4, since the content of Cr was slightly larger than the predetermined amount, the intermetallic compound grew and became coarse, the Erichsen value and ear ratio were slightly lowered, and the elongation and the formability were slightly lowered. . In No. 4 of Comparative Example 4, since the content of Zr was slightly higher than the predetermined amount, the Erichsen value was slightly lower, and the moldability was slightly lower. In No. 5 of Comparative Example 4, since the Fe content was slightly larger than the predetermined amount, the crystallized product was coarsened, so that the Erichsen value was slightly lowered and the moldability was slightly lowered. In No. 6 of Comparative Example 4, since the content of Ti was larger than the predetermined amount, the crystallized product was coarsened, so that the Erichsen value was slightly lowered and the moldability was slightly lowered.
In No. 7 of Comparative Example 4, since the Si content was slightly larger than the predetermined amount, the equilibrium phase Mg ₂ Si crystallized and became coarse.
The Erichsen value was slightly lower, and the moldability was slightly lower. In No. 8 of Comparative Example 4, since the content of Si was slightly smaller than the predetermined amount, the precipitation hardening of the aging precipitate was insufficient, the strength was slightly reduced, and the tensile strength and proof stress were slightly lowered. In No. 9 of Comparative Example 4, since the Mg content was slightly larger than the predetermined amount, the crystallized matter of the equilibrium phase Mg ₂ Si was coarsened, the Erichsen value was slightly lowered, and the moldability was slightly lowered. In No. 10 of Comparative Example 4, since the amount of Mg ₂ Si was smaller than the predetermined amount, the tensile strength and the proof stress were low.

However, in Comparative Example 4 manufactured by the manufacturing method according to the present invention, it can be said that the increase in strength due to normal temperature aging can be suppressed regardless of the content of the component elements of the Al alloy. Therefore, unlike the past, M
It can be said that the growth of precipitates such as g ₂ Si is suppressed. Therefore, it can be said that in the Al alloy sheet manufactured by the manufacturing method according to the present invention, the aging at normal temperature is suppressed, and the increase in strength and the decrease in formability can be prevented as compared to the case of manufacturing by the conventional method. Further, Nos. 1 to 3 of the fourth embodiment
When using an Al alloy plate having a predetermined component composition as described above, it is possible to reliably prevent an increase in strength and a decrease in formability due to aging at normal temperature.

[0078]

As described above, according to the present invention,
By performing the predetermined heat treatment, it is possible to prevent an increase in strength due to normal temperature aging and an increase in the amount of springback accompanying the aging while maintaining excellent bake hardness at a low temperature, and to reduce moldability. Can be prevented. Therefore, after manufacturing the Al alloy plate, it is not necessary to change the processing conditions even after being left at room temperature for a long time, so that the manufacturing process is simplified, the yield is improved, and the manufacturing cost is reduced. Furthermore, since this Al alloy plate has excellent low-temperature bake hardening properties, when this alloy plate is used for automobiles, home appliances and machine parts, it is possible to reduce the weight of these automobiles, home appliances and machine parts. it can. Then, application to general-purpose industrial products is possible.

Further, by setting the composition of the aluminum alloy to a predetermined one, it is possible to reliably prevent an increase in strength and a decrease in formability due to aging at ordinary temperature.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22F 1/00 691 C22F 1/00 691A 691B 692 692A

Claims (12)

[Claims] 1. A solution quenching step of an aluminum alloy material containing Mg and Si as main components,
The method includes a step of standing for 4 hours or more, a step of heating to a temperature range of 200 to 300 ° C. at a heating rate of 100 ° C./min or more, and a step of quenching at a cooling rate of 100 ° C./min or more. A method for producing an aluminum alloy material in which aging at normal temperature is suppressed. 2. A step of solution quenching a 6000 series aluminum alloy material containing Mg and Si as main components, a step of standing at room temperature for 24 hours or more,
Heating at a heating rate of at least one minute and then maintaining the temperature in a temperature range of 200 to 300 ° C. for 60 seconds or less;
A step of quenching at a cooling rate of not less than ° C./min. Wherein Mg ₂ Si contained in the aluminum alloy material before molding is 0.9 to 1.3%, and Mg ₂
3. The method for producing an aluminum alloy material according to claim 1, wherein Si is present in excess of 0.5 to 1.0% by weight with respect to the amounts of Mg and Si constituting Si. 4. A step of casting an aluminum alloy melt containing Mg and Si as a main component to produce an aluminum alloy ingot, a step of subjecting the ingot to a homogenizing heat treatment at a temperature equal to or lower than a burning temperature, and a step of homogenizing. Hot-rolling the ingot after the heat treatment, and further cold-rolling to obtain a predetermined plate thickness and temper; and 480 to 580 ° C. at a temperature rising rate of 100 ° C./min or more.
(Below the burning temperature) for solution treatment, quenching at a cooling rate of 100 ° C./min or more, leaving at room temperature for 24 hours or more, and heating rate of 100 ° C./min or more A method for producing an aluminum alloy material in which room temperature aging is suppressed, comprising a step of heating to a temperature range of 200 to 300 ° C. and a step of quenching at a cooling rate of 100 ° C./min or more. 5. A step of casting a molten metal of a 6000 series aluminum alloy containing Mg and Si as main components to produce an aluminum alloy ingot, and a step of subjecting the ingot to a homogenizing heat treatment at a temperature equal to or lower than a burning temperature. A step of hot rolling the ingot after the homogenization heat treatment and further cold rolling to a predetermined thickness and temper, and 480 to 580 ° C. at a heating rate of 100 ° C./min or more (below the burning temperature) A step of heating to a solution treatment, a step of quenching at a cooling rate of 100 ° C./min or more, a step of leaving at room temperature for 24 hours or more,
Heat at a heating rate of 0 ° C./min or more and then 200 to 30
A step of keeping the temperature range of 0 ° C. for 60 seconds or less, and thereafter,
A step of quenching at a cooling rate of 100 ° C./min or more. 6. The method for producing an aluminum alloy material according to claim 4, wherein intermediate annealing is performed before and / or during the cold rolling. 7. The Mg ₂ Si contained in the aluminum alloy material before the forming process is 0.9 to 1.3% by weight, and the amount of Si is 0.1 to the amount of Mg and Si constituting Mg ₂ Si.
The method for producing an aluminum alloy material according to claim 4 or 5, wherein the excess amount is 5 to 1.0% by weight. 8. The method according to claim 1, wherein the aluminum alloy material is Mg: 0.1.
8. The semiconductor device according to claim 1, wherein the composition contains 3 to 1.0% by weight and Si: 0.5 to 1.4% by weight.
The method for producing an aluminum alloy material according to the above item. 9. The method according to claim 9, wherein the aluminum alloy material is Mg: 0.1.
3 to 1.0% by weight, Si: 0.5 to 1.4% by weight,
Mn: 0.02 to 0.20% by weight, with the balance being A
The method for producing an aluminum alloy material according to any one of claims 1 to 7, wherein the method comprises aluminum and unavoidable impurities. 10. Ti: 0.3% by weight or less and B: 0.
The method for producing an aluminum alloy material according to claim 8 or 9, wherein the method contains at least one element selected from the group consisting of 1% by weight or less. 11. Cr: 0.3% by weight or less and Zr:
2. The composition according to claim 1, wherein the composition contains at least one element selected from the group consisting of 0.3% by weight or less.
0. The method for producing an aluminum alloy material according to any one of items 0 to 10. 12. The method for producing an aluminum alloy material according to claim 8, wherein Fe: 0.3% by weight or less is regulated.