JPH06287725A - Method for heat-treating al-mg-si aluminum alloy extruded material - Google Patents

Abstract

PURPOSE:To obtain an Al-Mg-Si aluminum alloy extruded material having sufficient strength after artificial aging treatment and furthermore excellent in formability by subjecting an Al Mg Si aluminum alloy extruded material to high temp.short time heating by induction heating immediately after press hardening. CONSTITUTION:An Al-Mg-Si aluminum alloy extruded material (such as a JIS6063 alloy) is subjected to press hardening and is immediately subjected to induction heating at about 100 to 280 deg.C, preferably at about 250 to 280 deg.C for about 5sec to 2hr heating time, preferably for about 5 to 15sec. In this way, acicular G.P. zones are precipitated to prevent the generation of clusters in the process of cold aging treatment, by which the strength of the Al-Mg-Si aluminum alloy is improved, and its formability is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method for extruded Al-Mg-Si aluminum alloys.

[0002]

2. Description of the Related Art Al-Mg-Si-based aluminum alloys are heat-treatable alloys, and their properties can be controlled in various ways by heat treatment. Utilizing this fact, the extruded materials are used for household appliances, construction materials, Widely used for automobile parts and aircraft parts. This Al-Mg-Si based aluminum alloy extruded material is often used in a T5 state in which it is subjected to artificial aging treatment after being quenched by quenching from high temperature processing during extrusion. In the case of further forming such as bending after extrusion, after the solution treatment, it is processed in the T4 state aged at room temperature or the T5 state, but when the degree of processing is severe, the T4 state is processed. In this case, artificial aging treatment is applied after processing to obtain high strength. In any case, before the artificial aging treatment is carried out after quenching, a room temperature aging treatment period of keeping the temperature at room temperature for several days to several months is required before it can be used.

This room temperature aging treatment is about 1 wt% or more of Mg ₂
There is a problem that the artificial aging treatment has a negative effect on the Al-Mg-Si-based aluminum alloy containing Si, and the strength obtained by the subsequent artificial aging treatment decreases.
Further, there is also a problem that the aging treatment at room temperature causes age hardening to some extent, and as time elapses, the formability at the time of forming in the T4 state decreases.

The aging precipitation process in an Al-Mg-Si system aluminum alloy is as follows: supersaturated solid solution → cluster → acicular G. P. It is a process of zone → rod-like intermediate phase β ′ → plate-like stable phase β, and the highest strength is acicular G.I. P. Obtained by zone. The reason why the strength cannot be obtained by the artificial aging treatment after the room temperature aging treatment is that clusters are generated during the room temperature aging treatment after the solution treatment, and most of them are acicular G.
P. It is said that it is not possible to move to the zone.

Therefore, by the preliminary aging treatment, the clusters generated during the room temperature aging treatment were formed into needle-shaped G.I. P. After shifting to the zone, there is a method of performing artificial aging treatment to improve the strength. However, even with this heat treatment method, all the clusters are acicular G.
P. It does not move to the zone and the strength cannot be improved sufficiently.

Immediately after the solution treatment, a high temperature (about 100 to 1
Pre-aging treatment is performed at 80 ° C., and needle G. P. There is also a heat treatment method of precipitating zones and preventing the formation of clusters during the subsequent room temperature aging treatment. However, in this heat treatment method, heat treatment must be performed twice after quenching, there is a cost problem, and pre-aging treatment must be performed at a high temperature within several hours after quenching. There is also a problem in the production process that a heat treatment furnace must be prepared in advance.

[0007]

In view of the above situation, the present invention provides an Al-Mg-Si based aluminum alloy extruded material having sufficient strength after artificial aging treatment and excellent formability. It was made for the purpose of developing a heat treatment method for an extruded Al-Mg-Si aluminum alloy.

[0008]

That is, the present invention is directed to Al-M.
It is a heat treatment method for an Al-Mg-Si based aluminum alloy extruded material, characterized by heating the g-Si based aluminum alloy extruded material at a high temperature for a short time by induction heating immediately after press hardening.

[0009]

The present invention is directed to an Al-Mg-Si-based aluminum alloy extruded material, and solution treatment and quenching can be performed by so-called press quenching in which quenching is performed immediately after extrusion. Although the extrusion temperature is usually lower than the solution heat treatment temperature of the alloy, the temperature rises near the die due to heat generation during processing, solute atoms can be solid-soluted during extrusion processing.

In the present invention, heating at a high temperature for a short time immediately after the press hardening is performed by heating at a high temperature for a short time. P. This is to prevent the formation of clusters during the normal temperature aging treatment by precipitating zones. The heating temperature is preferably 100 to 280 ° C., and the heating time is preferably 5 seconds to 2 hours. The reason is that the needle-shaped G.I. P. Zone does not precipitate and exceeds 280 ℃
Alternatively, if it exceeds 2 hours, the plate-like stable phase precipitates and the strength decreases. Furthermore, considering productivity, a very short heating time is desired, so at 250 to 280 ° C, 5
Heating for about 15 seconds is more desirable.

Induction heating is convenient and suitable for heating at high temperature for a short time.

The Al-Mg-Si type aluminum alloy to which the present invention can be applied includes JIS6063 alloy and JIS.
Most of 6000 series alloys such as 6N01 alloy and JIS6061 alloy can be mentioned.

Al which is a step before the heat treatment method of the present invention is applied.
The melting, casting, homogenization treatment, preheating before extrusion, and extrusion of the —Mg—Si aluminum alloy may be performed as usual.

[0014]

EXAMPLES The present invention will now be described in more detail with reference to Examples. JIS6063 alloy having the alloy composition shown in Table 1,
JIS6N01 alloy and JIS6061 alloy were respectively water-cooled into ingots having an outer diameter of 200 mm, and after homogenization treatment at 540 ° C. for 8 hours, extrusion temperature 500 ° C., extrusion speed 10 m
/ Min, hot extrusion was performed. As the extrusion equipment, an induction heating furnace was installed after the water spray as shown in FIG. The extruded shape is a plate shape of 3 × 120 mm. For cooling after extrusion, water spray was used to rapidly cool to room temperature. Immediately after that, the heating shown in Table 2 was performed in the induction heating furnace. Then, after 30 days of normal temperature aging treatment at room temperature, artificial aging treatment of 175 ° C. × 8 hours was performed, and then JIS 5 tensile test pieces were processed and subjected to a tensile test. The results are shown in Table 2. This result is N = 3
Is the average value of.

[0015]

[Table 1]

[0016]

[Table 2]

As is apparent from Table 2, the method according to the present invention has improved tensile strength and yield strength as compared with the method according to the conventional method, and the elongation has not decreased.

[0018]

As described above, according to the present invention, it is possible to improve the strength and maintain formability of an Al-Mg-Si based aluminum alloy without changing the alloy composition. It has a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of extrusion equipment used in the present invention.

[Explanation of symbols]

 1 Extrusion Press 2 Water Spray 3 Induction Heating Furnace 4 Extruded Material

Claims (1)

[Claims] 1. A heat treatment method for an Al-Mg-Si-based aluminum alloy extruded material, which comprises heating the Al-Mg-Si-based aluminum alloy extruded material at a high temperature for a short time by induction heating immediately after press hardening.