JPH04259358A - Manufacture of aluminum alloy sheet for forming - Google Patents

Abstract

PURPOSE:To manufacture a sheet good in formability, high in strength after coating and baking and furthermore small in change with lapse of time at a room temp. as an Al-Mg Si(-Cu) series aluminum alloy sheet of a JISNo.6000 series used for land transportation vehicles and electromechanical parts. CONSTITUTION:A rolled sheet is subjected to soln. treatment and is thereafter subjected to heating treatment at 150 to 320 deg.C for <=4min one or >= two times. Or, the rolled sheet is subjected to soln. treatment, is thereafter subjected to stabilizing treatment in the conditional range in the figure and is subjected to heating treatment similar to the above one or >= two times.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a method for manufacturing aluminum alloy plates for forming processing used in various land transportation vehicles, electrical machinery appliances, parts, etc., which has particularly excellent formability and high strength after painting and baking. Moreover, the present invention relates to a method for producing an aluminum alloy plate for forming and processing that exhibits little change over time at room temperature.

0002

[Prior Art] Aluminum alloy sheets have recently been increasingly used as high-strength molded materials for parts of various land transportation vehicles such as automobiles and parts of electrical machinery and equipment due to their light weight and corrosion resistance. ing.

By the way, conventional aluminum alloys for forming processing include Al-Mg based JIS 5182 alloy O material, 5052 alloy O material, or Al-Mg-Si (
-Cu) based AA6009 alloy T4 material, 6010 alloy T
4 materials are widely used.

0004

[Problems to be Solved by the Invention] Among the various molding applications mentioned above, automotive panels, etc. must have good appearance characteristics and good dent resistance. However, conventional Al-Mg alloy soft materials such as 5182 Alloy O material and 5082 Alloy O material are prone to Lüders marks, which easily impairs the appearance quality, and the strength after baking coating is low. These Al-M
G-based alloy soft materials are considered unfavorable for automobile panels and the like.

On the other hand, conventional Al-Mg-Si(-Cu) alloys such as 6009 alloy T4 material and 6010 alloy T4 material do not generate Lüders marks, and it is possible to obtain strength equivalent to steel plates. However, if an attempt is made to obtain a strength equivalent to that of a steel plate after baking the paint, the strength of the material will inevitably increase, resulting in poor formability and, in particular, poor shape fixability during forming. Moreover, these A
The l-Mg-Si(-Cu) alloy T4 material has strong room temperature aging properties after solution treatment, so the material strength gradually increases as time passes after solution treatment, and formability decreases. On the contrary, it tends to gradually deteriorate. However, in general, when a material is manufactured by a material manufacturer and then molded by another press manufacturer, the period from manufacturing the material to pressing is usually different, so There is a major problem in that strength and moldability during molding vary due to changes.

The present invention was made against the background of the above-mentioned circumstances, and is an aluminum alloy sheet for forming processing used for land transportation vehicles, electromechanical parts, etc., which has a lower cost during forming processing than conventional alloy sheets. It has excellent strength and formability, especially shape fixability, and has high strength and excellent dent resistance after paint baking treatment, and changes in material properties over time during the period from material manufacturing to press processing. The purpose of this invention is to provide an aluminum alloy plate with less

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems, as a result of extensive experiments and studies by the present inventors,
The alloy is 6000 series Al-Mg-Si(-Cu
) system alloy, and not only appropriately set the conditions for the solution treatment after rolling, but also one or two stages after the solution treatment.
By applying an appropriate heat treatment at a stage or higher, there is little change over time at room temperature, and the moldability (especially shape freezing ability) and strength after paint baking are high (therefore, excellent dent resistance).
It was discovered that an aluminum alloy plate can be obtained, and the present invention was completed.

Specifically, the method of the invention of claim 1
A rolled Al-Mg-Si aluminum alloy sheet belonging to the IS 6000 series is solution-treated at a temperature within the range of 450 to 580°C, cooled at a cooling rate of 5°C/sec or more, and then Heat treatment at a temperature within the range of ~320°C for 1 minute or more is performed once or twice, and the conductivity after the final heat treatment is 1% IACS or more than the conductivity immediately before the first heat treatment. It is characterized by lowering.

[0009] Furthermore, the method of the invention of claim 2 is based on the JIS
A rolled Al-Mg-Si aluminum alloy sheet belonging to No. 6000 series is solution-treated at a temperature within the range of 450 to 580°C, cooled at a cooling rate of 5°C/sec or more, and then horizontally cooled. Point A (0.5 hours, 180°C), point B (0.5
time, 100℃), point C (4 hours, 60℃), point D (2 hours, 60℃),
Each line segment AB, B sequentially connects point E (24 hours, 100℃), point F (4 hours, 180℃)
Stabilization treatment is performed under the time-temperature conditions within the region surrounded by C, CD, DE, EF, and FA (including points on each line segment), and then at a temperature within the range of 150 to 320 °C. It is characterized in that the conductivity after the final heat treatment is lowered by 1% IACS or more than the conductivity immediately before the first heat treatment by performing heat treatment for less than 1 minute once or twice or more. .

0010

[Operation] The alloy used in the manufacturing method of the present invention is basically Al-Mg-Si (-
Any Cu)-based aluminum alloy may be used, and its specific content is not particularly limited, but generally Mg 0.1~
2.0 wt%, Si 0.5 to 2.5 wt% as essential alloy components, and Cu 1.5 as required.
wt% or less, Zn 2.0wt% or less, and further contains Mn 0.6wt% as necessary.
Hereinafter, it is sufficient to contain 0.3 wt% or less of Cr, 0.3 wt% or less of Zr, and the remainder is Al and unavoidable impurities.

[0011] Such desirable components will be explained below.

Mg: Mg is a basic alloy component in JIS 6000 series aluminum alloys, and S
It coexists with i to produce Mg2Si, which contributes to improving strength through precipitation hardening. If the Mg content is less than 0.1 wt%, the strength improvement effect is insufficient, while if it exceeds 2.0 wt%, elongation occurs and formability decreases. Therefore, Mg is 0
．． It is desirable that it be within the range of 1 to 2.0 wt%.

Si: Si is also a basic alloy component in No. 6000 series aluminum alloys, and coexists with Mg to form Mg2Si, which contributes to improving strength through precipitation hardening. Further, if a part of the added Si is present in the Al alloy matrix in the form of metal Si particles, moldability, particularly elongation and bendability, can be improved. Here, it is desirable for the amount of Si added to be in a sufficient excess of the Mg2Si stoichiometric composition and to be in a state where metallic Si is generated, in order to improve the strength.
Si (wt%) > 0.6 x Mg (wt%) + 0.4
(wt%) is desirable. . Note that if the absolute amount of Si is less than 0.5 wt%, the effects of improving strength and moldability cannot be sufficiently obtained;
%, elongation and formability will deteriorate, so the absolute amount of Si is preferably within the range of 0.5 to 2.5 wt %.

Cu, Zn: Both Cu and Zn are elements that contribute to improving strength, and one or both of them may be added as necessary. Of these, Zn is also effective in improving corrosion resistance, and contributes to preventing pitting corrosion by lowering the potential of the matrix. However, Cu is 1
．． If Zn exceeds 5 wt%, moldability and corrosion resistance will deteriorate, and if Zn exceeds 2.0 wt%, corrosion resistance will deteriorate and moldability will decrease due to changes over time at room temperature. Therefore, Cu is 1.5wt% or less, and Zn is 2.0%.
It is preferable to set it within the range of wt% or less.

[0015] Mn, Cr, Zr: All of these elements contribute to making crystal grains finer and reducing the occurrence of flow lines during molding, and one or more of these elements may be used as necessary. is added. However, Mn is 0.6wt
%, Cr exceeds 0.3 wt%, and Zr exceeds 0.3 wt%, coarse intermetallic compounds are formed and formability deteriorates. Therefore, Mn is 0.6wt% or less, and Cr is 0.6wt% or less.
The content of Zr is preferably 3 wt% or less, and Zr is preferably 0.3 wt% or less.

[0016] The remainder of each of the above components may basically be Al and unavoidable impurities, but in addition, a trace amount of B may be used.
e, a trace amount of Ti, or Ti and B may be added. Be forms a dense oxide film to prevent Al and Mg from oxidizing on the surface of the aluminum material, which in turn contributes to a significant improvement in thread rust resistance. However, if the amount of Be added exceeds 0.01 wt%, the effect will be saturated and the cost will only increase, so the amount of Be added should be 0.01 wt%.
It is desirable that it be less than wt%. Furthermore, Ti has traditionally been added together with B as a grain refiner for the ingot structure, but addition of Ti is effective not only for grain refinement but also for improving corrosion resistance. However, the amount of Ti added is 1
．． If it exceeds 0wt%, coarse intermetallic compounds will be generated,
Since it deteriorates rolling properties and formability, the amount of Ti added is 1
．． The content is preferably 0 wt% or less. In addition, if B, which is sometimes added together with Ti, exceeds 0.01wt%, the corrosion resistance will be adversely affected, so 0.01wt%
It is preferable to make it less than.

Next, each process in the manufacturing method of the present invention will be explained.

In the manufacturing method of the present invention, the steps before solution treatment are not particularly limited, but the following processes are generally applied.

First, a molten alloy having the above-mentioned composition is cast. As the casting method here, a DC casting method (semi-continuous casting method) or a continuous casting rolling method (thin plate continuous casting method) may be applied.

[0020] The aluminum alloy ingot obtained by DC casting is subjected to homogenization treatment at a temperature within the range of 450°C to 570°C. By performing such homogenization treatment, it is possible to improve moldability and stabilize recrystallized grains. The homogenization temperature is
Below 450°C, the above effects cannot be obtained; on the other hand, 570
If the temperature exceeds .degree. C., eutectic melting may occur. Note that the time for the homogenization treatment is preferably 1 to 48 hours. If the treatment time is less than 1 hour, the above-mentioned effects cannot be sufficiently obtained, while treatment for a long time exceeding 48 hours is not economical. After such homogenization treatment, hot rolling is performed according to a conventional method to obtain a hot rolled plate having a desired thickness. Thereafter, if necessary, cold rolling is performed to obtain the final thickness.

On the other hand, in the case of a continuously cast thin plate obtained by the continuous casting and rolling method, it is not necessary to particularly perform hot rolling, but it may be subjected to the same homogenization treatment as in the case of the DC casting ingot described above. Also in this case, if necessary, cold rolling may be performed to obtain the final plate thickness.

[0022] Furthermore, when cold rolling is carried out as described above,
If necessary, intermediate annealing may be performed before cold rolling or during cold rolling. This intermediate annealing is performed for the purpose of improving rollability and controlling the structure, and either batch annealing or continuous annealing may be applied, and the conditions are not particularly limited.
It is sufficient to heat the material to a temperature within the range of ~450°C for 0.5 to 24 hours, and for continuous annealing, heat to a temperature within the range of 300°C to 580°C and apply conditions of no holding or holding for 5 minutes or less. Good.

[0023] When batch annealing is applied as intermediate annealing, if the temperature is less than 250°C, the rolling properties will not be improved and it is meaningless, while if it exceeds 450°C, the recrystallized grains will become coarse, The thickness of the surface oxidation layer increases, and thread rust resistance decreases. Furthermore, if the holding time is less than 0.5 hours, the rolling properties will not be sufficiently improved, while if it exceeds 24 hours, it will not only become uneconomical but also increase the thickness of the surface oxidation layer.
Thread rust resistance decreases.

In addition, when continuous annealing is applied as intermediate annealing, if the heating temperature is less than 300°C, the rolling properties will not be improved and it is meaningless, whereas if it exceeds 580°C, there is a risk of eutectic melting and As the crystal grains become coarser, the thickness of the surface oxidized layer increases, and the thread rust resistance decreases. Furthermore, if the holding time exceeds 5 minutes, the recrystallized grains become coarse and the thickness of the surface oxidized layer increases, resulting in a decrease in thread rust resistance.

The rolled plate having the final thickness as described above is subjected to solution treatment. This solution treatment is performed at 60%
Mg, Si, Cu, which are strengthening elements in 00 series alloys
, Zn is dissolved in the matrix to obtain sufficient strength after the subsequent paint baking treatment, and at the same time, it is recrystallized to refine and stabilize the crystal grains and to improve formability. It is a process.

[0026] The conditions for this solution treatment are 450~
It is necessary to hold the temperature within the range of 580° C. for no more than 120 minutes. If the temperature of solution treatment is less than 450°C, the effect of solution treatment is insufficient, and recrystallization is not completed.
Moldability deteriorates. On the other hand, if the temperature exceeds 580°C, there is a risk of eutectic melting, and the recrystallized grains will become coarser, resulting in rough skin, resulting in poor appearance and reduced formability, and furthermore, the thickness of the surface oxidation layer will increase. There is a risk that thread rust resistance may decrease. Here, as a guideline for preventing coarsening of recrystallized grains, it is sufficient to set the recrystallized grain size to 150 μm or less. Furthermore, if the solution treatment time exceeds 120 minutes, not only the solution treatment effect will be saturated, but also the thickness of the surface oxidation layer will increase, leading to a risk that corrosion resistance and thread rust resistance will deteriorate. Note that for this solution treatment, either a batch type heat treatment furnace or a continuous type heat treatment furnace may be applied. Further, rapid cooling is performed after the solution treatment, and it is sufficient if the cooling rate is higher than forced air cooling. Specifically, 5℃
A cooling rate of /sec or more is appropriate.

Note that if forced air cooling or water quenching is performed after solution treatment, the plate is likely to warp. In order to remove this, light cold working such as skin pass, leveling, stretching, etc. may be performed as strain forced working after cooling.

[0028] The method of the present invention applies the following method to a rolled plate that has been subjected to solution treatment as described above, or to a rolled plate that has been subjected to light cold working for straightening after solution treatment. Apply heat treatment. That is, 15 for the rolled plate.
Heat treatment for less than 1 minute at a temperature within the range of 0 to 320℃
After applying the stabilization treatment once or twice or more (the invention of claim 1), or after performing the stabilization treatment under the conditions within the range shown in FIG. The following heat treatment is performed once or twice or more.

Such heat treatment after solution treatment is a fundamentally important part of the method of the present invention, and conventional heat treatment type alloys are generally not particularly subjected to heat treatment after solution treatment. Met. FIG. 2 shows four typical examples of process patterns of such heat treatment after solution treatment. In FIG. 2, A and B are process patterns of heat treatment according to the invention of claim 1, and C and D are process patterns of heat treatment according to the invention of claim 2. The difference between the process patterns A and B in FIG. 2 from the process patterns C and D in FIG. 2 is that the stabilization process 12 is not performed.
, B. In the case of the process pattern B, in an industrial production line, after the solution treatment, a certain amount of time passes after being left at room temperature before the next heat treatment 21 is performed, so the numbers in parentheses in FIG. As mentioned above, it can be said that room temperature aging 11 has been carried out.

[0030] Here, the overall effect of the heat treatment after the solution treatment as described above will be explained.

[0031] By room temperature aging 11 or stabilization treatment 12 after the solution treatment, precipitates are generated which are effective as precipitation sites during subsequent coating baking. That is, a part of the precipitates generated by the room temperature aging 11 or the stabilization treatment 12 becomes a precipitation site for the precipitates that are formed during the subsequent baking of the paint and greatly contribute to the strength. However, in such room temperature aging 11 or stabilization treatment 12,
At the same time, unnecessary fine precipitates, ie, fine precipitates that do not serve as precipitation sites during paint baking, are also generated, and such fine precipitates increase material strength and reduce formability. Therefore, after room temperature aging 11 or stabilization treatment 12, heat treatment 21 is performed to dissolve unnecessary fine precipitates again into solid solution, thereby lowering the strength, that is, improving formability. In the case of process patterns B and D, after the first heat treatment 21, a second heat treatment 22 is further performed to further reduce the subsequent room temperature aging property. That is, in addition to simply redissolving unnecessary fine precipitates in the first heat treatment 21, the second heat treatment 22
This reduces the apparent excess pores introduced by quenching (rapid cooling) during solution treatment, reduces the diffusion rate of additive elements such as Mg, Si, and Cu, and further reduces room temperature aging properties.

[0032] Each condition in the heat treatment after the solution treatment as described above will be explained next.

In the process patterns A and B in FIG. 2, the product is simply left at room temperature and aged at room temperature, thereby generating precipitates that are effective as precipitation nucleation sites during the subsequent paint baking process. In order to further stabilize the precipitation site during the process, in process patterns C and D,
The stabilization process 12 is actively performed under the time-temperature conditions within the area surrounded by the line segments AB, BC, CD, DE, EF, and FA in FIG. 1 (including points on each line segment).

[0034] The temperature in this stabilization treatment 12 is 60°C.
If it is less than (below the line segment CD), the precipitation rate is slow and a sufficient amount of precipitate cannot be obtained. Furthermore, if the temperature exceeds 180°C (above line segment FA), precipitation hardening will be too large, strength will increase and formability will decrease, and paint baking properties will also deteriorate due to the formation of coarse precipitates. . On the other hand, the processing time is too short on the left side of the line segments AB and BC in FIG.
The precipitation sites required during paint baking are not sufficiently generated, and on the right side of the lines DE and EF in Figure 1, the processing time is too long, precipitation hardening is too large, and the strength is high, resulting in poor formability. At the same time, coarse precipitates are formed and paint baking properties are also deteriorated. Therefore, the conditions for stabilization processing are line segments AB, BC, CD, DE, EF, F in Fig. 2.
Within the area surrounded by A (including points on each line segment)
time-temperature conditions.

The above-described room temperature aging 11 or stabilization treatment 12 can be said to be a kind of preliminary aging. After such preliminary aging, heat treatment is performed once or twice or more in order to appropriately control solid solution and precipitation.

[0036] As already mentioned, the first heat treatment 21 is to re-dissolve into the matrix fine precipitates that do not become precipitation sites during paint baking, among the precipitates formed during pre-aging. The temperature is 1
If the temperature is lower than 50°C, the effect of solid solution cannot be sufficiently obtained, while if the temperature exceeds 320°C, coarse precipitates are formed due to over-aging, and the strength after baking of the paint is reduced. Also, the heat treatment time is 1
If the temperature exceeds 10 minutes, the strength of the material increases due to age hardening and the formability decreases. Therefore, the conditions for this first heat treatment 21 need to be such that the temperature is maintained within the range of 150 to 320° C. for 1 minute or less. Note that this heat treatment essentially requires rapid heating, and a heating rate of 1° C./sec or more is desirable. Furthermore, since the dissolution rate of small precipitates that do not become precipitation sites during paint baking is extremely fast, the holding time may be zero.

In process patterns B and D in FIG. 2, after the first heat treatment 21 as described above, a second heat treatment 22 is performed to further reduce the room temperature aging property. The conditions for this second heat treatment 22 may be the same as those for the first heat treatment 21, at a temperature within the range of 150 to 320° C. for less than 1 minute. If this temperature is less than 150°C, the effect of reducing room temperature age hardening cannot be obtained, and if it exceeds 320°C, coarse precipitates are generated due to over-aging, which reduces formability and reduces the strength after painting baking. Moreover, even if the treatment time exceeds 1 minute, the material strength increases due to age hardening, and the formability decreases.

Although not shown in FIG. 2, it goes without saying that the above heat treatment may be performed three or more times. In addition, when heat treatment is performed two or more times, the temperature of the first heat treatment and the second and subsequent heat treatments must be at least 20°C lower than the temperature of the first heat treatment. It is desirable to provide such a temperature difference.

Furthermore, in the method of the present invention, in order to judge the effectiveness of the heat treatments 21 and 22 as described above, the electrical conductivity after the final heat treatment (that is, if the heat treatment is performed only once, the conductivity of the first heat treatment is determined) The conductivity after the heat treatment (or the conductivity after the final heat treatment if heat treatment is performed two or more times) is 1 higher than the conductivity immediately before the first heat treatment.
It was defined as a decrease of %IACS or more. In other words, the electrical conductivity of a material is an effective index for determining the amount of solid solution and precipitation of alloying elements, and is particularly useful for A, which is the target of this invention.
In heat treatable alloys such as l-Mg-Si(-Cu) alloys, the change in electrical conductivity before and after heat treatment is an effective index for evaluating solid solution/precipitation during the heat treatment process. In the method of the present invention, as mentioned above, the conductivity after the final heat treatment is 1 greater than the conductivity immediately before the first heat treatment.
%IACS or more, the effect of the heat treatment will not be sufficiently obtained, the strength after baking of the paint will decrease, and the change in room temperature over time after the heat treatment will increase.

[0040]

[Example] As shown in Table 1, an alloy with code A corresponding to JIS 6061 alloy and an alloy with code B corresponding to AA6010 alloy were DC cast according to the conventional method, and the obtained ingots were homogenized at 500°C. After the treatment, hot rolling was carried out according to a conventional method to obtain a hot rolled sheet with a thickness of 4 mm, and then a sheet with a thickness of 1 m.
It was cold rolled to m. Thereafter, it was subjected to solution treatment at 535° C. for 40 minutes and water quenched. After that, heat treatment number 1~ in Table 2
Heat treatment was performed under various conditions as shown in 7. Here, the solution treatment was performed in an electric furnace, and in each heat treatment shown in Table 2, rapid heating was performed using an infrared heater, and water quenching was performed.

After each heat treatment shown in Table 2 was carried out, the mechanical properties and moldability were examined after being left at room temperature for one week. Similarly, after being left at room temperature for one week, it was heated at 177° C. for 1 hr as a treatment equivalent to paint baking, and the strength after paint baking was examined. Furthermore, the amount of decrease in conductivity after the final heat treatment with respect to the conductivity immediately before the first heat treatment shown in Table 2 was investigated. These results are shown in Table 3.

[0042] In the moldability evaluation, the Erichsen test was carried out using graphite grease lubrication according to the JIS-B method. Further, the stretching test was conducted using a ball-head punch with a diameter of 100 mm, with the PVC film attached. Furthermore, the LDR (limit drawing ratio) was investigated by conducting a drawing test with a φ50 mm punch under Johnson wax lubrication with 600 kg of wrinkle suppression added. In addition, the bendability is 18
Evaluation was made using the minimum bending radius in the 0° bending test. Furthermore, an eddy current type sigma tester was used to measure the conductivity before and after the heat treatment. Further, ΔYS in the column of strength after paint baking in Table 3 indicates the amount of increase in YS after the paint baking equivalent treatment with respect to the YS of the base material before the paint baking equivalent treatment.

On the other hand, Table 4 shows the results of examining changes over time at room temperature after the heat treatment shown in Table 2, especially changes over time in mechanical properties (TS, YS, EL) and formability (Erichsen value). show. Here, regarding changes over time, characteristics were examined at each time point of 1 day, 1 week, 1 month, and 3 months after the heat treatment.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

Heat treatment number 4 among the heat treatments shown in Table 2
Heat treatment number 5 is a comparative example in which the stabilization treatment time was too long, heat treatment number 5 is a comparative example in which the first heat treatment temperature was too high, and heat treatment number 6 is a comparative example in which the first heat treatment time was too long. ,
In these cases, the strength before paint baking was too high, resulting in poor formability, and the strength improvement by paint baking was not sufficient. In addition, heat treatment number 7 is a conventional example in which heat treatment was not performed after solution treatment. There were significant changes in mechanical properties and formability over time.

On the other hand, in the case of heat treatment numbers 1 to 3 according to the method of the present invention, the strength before paint baking is low and the formability is excellent, and at the same time, the strength improvement due to paint baking is sufficient and high strength is achieved after painting baking. was obtained, and furthermore, it was confirmed that changes in mechanical properties and formability over time at room temperature after the final heat treatment were extremely small.

[0050]

Effects of the Invention As is clear from the above embodiments, according to the method of the present invention, when manufacturing an aluminum alloy plate made of JIS 6000 series alloy, low At the same time, it is possible to obtain a board that has excellent strength and formability, has sufficient strength after baking the paint, and has little change in mechanical properties and formability over time when left at room temperature after final heat treatment. In particular, it is possible to actually produce on a mass production scale a board that has excellent shape fixability during molding and dent resistance after paint baking, and has little change over time at room temperature. Therefore, the method of the present invention is most suitable for producing aluminum alloy plates for applications such as parts for land transportation vehicles such as automobile bodies, parts for electric machines, etc., which are subjected to forming processing and paint baking.

[Brief explanation of the drawing]

FIG. 1 is a coordinate diagram showing time-temperature coordinates defining time-temperature conditions for stabilization treatment in the method of the present invention.

FIG. 2 is a flowchart showing four typical process patterns of heat treatment after solution treatment in the method of the present invention.

Claims (2)

[Claims] [Claim 1] Al belonging to JIS 6000 series
-4 for Mg-Si based aluminum alloy rolled plate
Solution treatment at a temperature within the range of 50-580℃
Cool at a cooling rate of 150 to 32
Heat treatment for less than 1 minute at a temperature within the range of 0°C is performed once or twice, and the conductivity after the final heat treatment is reduced to 1.
A method for producing an aluminum alloy plate for forming, which exhibits little change over time at room temperature and has excellent formability and strength after paint baking, characterized by reducing the conductivity by 1% or more IACS compared to the conductivity immediately before the second heat treatment. [Claim 2] Al belonging to JIS 6000 series
-4 for Mg-Si based aluminum alloy rolled plate
Solution treatment at a temperature within the range of 50-580℃
Figure 1: After cooling at a cooling rate of sec or more, the horizontal time axis is on a logarithmic scale and the vertical temperature axis is on an evenly spaced scale.
Point A (0.5 hours, 1
80°C), point B (0.5 hours, 100°C), point C (4
time, 60℃), point D (24 hours, 60℃), point E (24 hours, 60℃),
Each line segment AB, BC, CD, DE, EF, FA sequentially connects each point of point F (4 hours, 180℃)
Within the area surrounded by (including points on each line segment)
Stabilization treatment is performed under the time-temperature conditions of 1%I higher than the conductivity immediately before the first heat treatment
A method for producing an aluminum alloy plate for forming, which exhibits little change over time at room temperature and has excellent formability and strength after paint baking, which is characterized by reducing the ACS or more.