JPH05339686A - Manufacture of aluminum alloy excellent in formability - Google Patents

Abstract

PURPOSE:To manufacture an aluminum alloy excellent in formability by executing solution, precipitation and softening treatment at specified temps. to an allay having a specified chemical compsn. subjected to homogenizing treatment and to the subsequent hot and cold rolling. CONSTITUTION:An allay ingot contg., by weight, 0.5 to 1.8% Mg, 0.2 to 1.2% Si, 0.1 to 0.8% Cu and 0.01 to 0.45% Cr, and the balance Al with inevitable impurities is subjected to homogenizing treatment, is thereafter subjected to hot rolling and cold rolling, next subjected to solution treatment at 470 to 550 deg.C, is subsequently cooled, furthermore subjected to precipitating treatment at 120 to 180 deg.C, successively subjected to working of 10 to 50% and is thereafter subjected to softening treatment at 360 to 500 deg.C. In this way, the objective aluminum allay excellent in formability can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum alloy having excellent formability, and more specifically, it is an aluminum alloy containing Mg, Si, etc. represented by a conventional 6000 series alloy and softened. The present invention relates to a method for producing an aluminum alloy that is excellent in formability and that does not cause rough skin even if a forming process is performed after the treatment.

[0002]

2. Description of the Related Art Conventionally forming aluminum alloys such as 6
Alloys such as 061 alloy are used in large quantities as a wide variety of structural materials for railways and land vehicles, and are usually preformed with a soft material, then solution-treated and quenched, and the strength immediately after quenching is applied. It is manufactured by a manufacturing process in which a high-strength aluminum alloy is obtained by performing a finish forming process during low temperature, and then performing an aging treatment.

[0003]

However, the conventional soft material is 20
%, The part that has undergone preforming process has a remarkably coarse recrystallized structure in the subsequent steps such as solutionizing and hardening, and roughening or microcracking occurs on the surface during finish forming process, resulting in performance as an aluminum product. Or it was a cause of reducing the value.

[0004]

In view of the above situation, the present invention has been earnestly studied, and as a result, it has been found that all cold-rolling, such as rolling, drawing, swaging and cold forging, performed on soft materials such as plate materials, pipe materials and bar materials. This is a method for producing an aluminum alloy which has excellent reproducibility and is free from coarse recrystallized grains after hot working and has fine and uniform crystal grains even after finish forming. 0.5-1.8 wt%, Si
0.2-1.2 wt%, Cu 0.1-0.8 wt%, Cr
After homogenizing an alloy ingot containing 0.01 to 0.45 wt% and the balance of Al and unavoidable impurities, hot rolling and cold rolling are performed, and then solution treatment is performed at 470 to 550 ° C. After post-cooling and then 10-50% processing,
A method for producing an aluminum alloy having excellent formability, which is characterized by performing a softening treatment at 360 to 500 ° C.

[0005]

In the present invention, the alloy composition is limited as described above for the following reason. The reason for limiting the content of Mg to 0.5 to 1.8 wt% is that if it is less than 0.5 wt%, sufficient strength cannot be obtained even after solution treatment and aging treatment after molding, and 1.8 wt% This is because if it exceeds 0.1%, the cold rolling property and the formability of the soft material are deteriorated, and further the toughness after the aging treatment is decreased, which is not preferable. The reason for limiting the Si content to 0.2 to 1.2 wt% is that if it is less than 0.2 wt%, sufficient strength cannot be obtained even if solution treatment and aging treatment are performed after molding, %, The amount of insoluble compound in the alloy increases and the toughness decreases, which is not preferable. The content of Cu is limited to 0.1 to 0.8 wt% because if the content is less than 0.1 wt%, sufficient strength cannot be obtained even after solution treatment and aging treatment after the molding process.
This is because if it exceeds 8 wt%, the corrosion resistance is deteriorated, which is not preferable. Cr has an effect of refining crystal grains, but the content is limited to 0.01 to 0.45 wt% by 0.01
If it is less than wt%, the effect of refining the crystal grains is small and 0.45 wt
This is because if it exceeds%, a huge intermetallic compound crystallizes out, which is not preferable. The other contained elements are not particularly limited as long as they are impurities contained in commercially available pure aluminum.

Next, the manufacturing method is limited as described above.
The reason is as follows. First, after performing homogenization treatment, hot rolling and cold rolling, and then performing solution treatment at 470 to 550 ° C. and cooling, the solute element is solid-solved in the matrix, or G. P phase or β'-Mg ₂
This is because the Si intermediate phase is deposited. If it is less than 470 ° C, it cannot be sufficiently dissolved, and if it exceeds 550 ° C, eutectic melting occurs, which is not preferable. The holding time at this time may be several minutes, but if possible, it is desirable to hold it for a sufficient time. The cooling rate is preferably 30 ° C./sec. Or higher, and water quenching is desirable if possible.

Next, the precipitation treatment is carried out at a temperature of 120 to 180 ° C. as described in G. This is because the precipitation of the P phase or β′-Mg ₂ Si intermediate phase is appropriately promoted and the coarsening of recrystallized grains is hindered. If the temperature is lower than 120 ° C, the precipitation is not promoted and the temperature is 180 ° C.
This is because if it exceeds, the phase transformation of the precipitated phase will occur, which is not preferable. The holding time at this time is preferably 40 hours or less.

Next, the processing of 10% to 50% is carried out in order to introduce a proper amount of dislocations necessary for obtaining fine recrystallized grains. If it is less than 10%, the amount of dislocations is small, and if it is 50%.
If it exceeds, the amount of dislocations increases and the recrystallized grains increase in either case, which is not preferable.

Next, the softening treatment is carried out at 360 to 500 ° C. in order to distribute the dislocations introduced by processing as a fine and uniform cell structure, and to obtain a fine recrystallized structure by using them as nuclei. If it is less than 360 ° C, it is not sufficiently softened, and it is 500
If the temperature exceeds ℃, crystal grains will grow remarkably, which is not preferable.
The heating rate at this time was 40 ° C / hr. The above is desirable.
The holding time is several minutes to several hours on the high temperature side, and up to about 6 hours is sufficient on the low temperature side. Further, the cooling after softening is preferably slow cooling.

[0010]

[Examples] Alloy ingots having the compositions shown in Table 1 were cast by an ordinary melting method, face-shaved, homogenized at 540 ° C for 24 hours, and then hot-rolled, cold-rolled, 2mm thick plate material. Samples were obtained by subjecting this plate material to the treatment conditions according to the method of the present invention and the comparative method shown in Table 2 and the conventional annealing treatment (softening treatment). In either case, after the solution treatment, the solution was cooled to room temperature with water, and the softening treatment was performed at 80 ° C./hr. After heating at 25 ° C / hr. It was gradually cooled at the cooling rate of.
In order to try the performance of the inventive material, comparative material and conventional material thus obtained, preforming processing (L and LT direction tension) shown in Table 3 was performed, and then solution hardening was performed. Immediately after the treatment (530 ° C. × 1 hr. Water cooling), finish molding (2 to 10% L and tensile in LT direction) was performed to confirm the rough skin condition.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

As is apparent from Table 3, the sample No. of the present invention material
For Nos. 1 to 8, no skin roughness was observed after finish molding at any molding processing rate after the softening treatment. In contrast,
Comparative material sample No. with low solution heat treatment temperature 9, comparative material sample No. with a low processing rate after precipitation treatment No. 10, Comparative material sample No. with low softening temperature 11. Comparative material sample No. 11 having a high precipitation treatment temperature and a high softening treatment temperature. 12 and conventional material sample No. 1
Nos. 3 and 14 had rough skin or cracks.

[0015]

As described above, according to the method of the present invention, the portion which has been preformed with the softening treated material has a uniform fine recrystallized structure even if the solution hardening treatment is performed in the subsequent step. ,
It is possible to produce an aluminum alloy having excellent formability that does not cause surface roughening even after the finish forming process, and it has a remarkable industrial effect.

Claims (1)

[Claims] 1. Mg 0.5-1.8 wt%, Si 0.2-
1.2 wt%, Cu 0.1-0.8 wt%, Cr 0.01-
An alloy ingot containing 0.45 wt% and the balance of Al and unavoidable impurities is homogenized, hot-rolled and cold-rolled, and then solution-treated at a temperature of 470 to 550 ° C and cooled. Then, a precipitation treatment is performed at a temperature of 120 to 180 ° C., and then a processing of 10 to 50% is performed.
A method for producing an aluminum alloy having excellent formability, which comprises performing a softening treatment at ˜500 ° C.