CN112126830A - Preparation and heat treatment process of novel high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate - Google Patents

Abstract

The invention discloses a preparation and heat treatment process of a high-strength and high-plastic Al-Mg-Si-Sc new aluminum alloy sheet, which belongs to the technical field of metal alloys. The preparation method is as follows: a metal ingot is prepared by casting, and then the ingot is subjected to a homogenization heat treatment, and finally hot rolling is performed on a rolling mill and then cold rolling is performed. The homogenization heat treatment process is as follows: the ingot is kept at 560° C. for 6 hours. The rolling process is as follows: before hot rolling, the ingot is kept at 400°C for 20 minutes, then hot rolled, and then cold rolled. After each rolling, it is cooled with water immediately, and the final rolling thickness is about 2 mm. The solution heat treatment process is as follows: the ingot is kept at 550°C for 1 hour, and then water-cooled to room temperature immediately. The aging heat treatment process is: aging heat treatment at 170° C. immediately after the solution treatment of the ingot. The alloy treated by the invention is aged at 170°C for 10 hours, the alloy engineering stress reaches 300MPa and the engineering strain reaches 32.5%; when aged at 170°C for 192 hours, the alloy engineering stress reaches 300MPa and the engineering strain reaches 28%.

Description

Preparation and heat treatment process of a new high-strength and high-plastic Al-Mg-Si-Sc aluminum alloy sheet

technical field

The invention belongs to the technical field of metal alloys, in particular to a preparation and heat treatment process of a high-strength and high-plastic Al-Mg-Si-Sc new aluminum alloy plate.

Background technique

Because of its attractive specific strength, formability, weldability and corrosion resistance, Al-Mg-Si alloys are widely used in transportation fields, such as vehicles, aircraft, and high-speed rail. Since the solid solution precipitation strengthening mechanism was proved to have a very attractive effect on improving the strength of aluminum alloys (1906), this strengthening mechanism has been widely used in the research of various aluminum alloys. The solid solution precipitation strengthening mechanism means that the aluminum alloy is subjected to solid solution treatment to form a supersaturated solid solution. During the subsequent artificial aging heat treatment process, a high number density and uniformly distributed precipitation phase is precipitated. The precipitation phase significantly hinders the movement of dislocations through pinning , thereby increasing the strength of the aluminum alloy. However, there are a large number of literature reports that the plasticity of Al-Mg-Si alloy decreases with the increase of strength, which seriously affects its application range. For example, it cannot be processed into parts with complex shapes. By adding rare earth element Sc (0.4wt%), the present invention prepares a new Al-Mg-Si-Sc aluminum alloy with engineering stress of 300 MPa and engineering strain of 32.5%, aging at 170°C for 192 hours, and the engineering stress of the alloy is also It can be maintained at 300MPa and the engineering strain reaches 28%.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation and heat treatment process of a new high-strength and high-plastic Al-Mg-Si-Sc aluminum alloy sheet, so as to solve the problems raised in the above background technology.

To achieve the above object, the present invention provides the following technical solutions:

A high-strength and high-plastic Al-Mg-Si-Sc new type of aluminum alloy plate, the alloy composition of which is: Mg: 0.45-0.9%, Si: 0.2-0.6%, Sc: 0.4%, and the balance is aluminum. The preparation method is as follows: firstly, pure aluminum ingot and aluminum-magnesium, aluminum-silicon, aluminum-scandium intermediate alloy are smelted into aluminum liquid, then poured into aluminum ingot, secondly, the aluminum ingot is homogenized, and then the aluminum ingot is hot-rolled and cooled. Rolling, and finally the rolled sheet is subjected to solution treatment and aging treatment.

The outstanding advantages of the present invention are:

1. The time required for peak aging of the alloy is shortened by half, and when the alloy is aged at 170 ℃ for 10 hours, the engineering stress of the alloy reaches 300MPa, and the engineering strain reaches 32.5%.

2. It has excellent heat resistance. The alloy is aged at 170℃ for 192 hours, the engineering stress of the alloy reaches 300MPa, and the engineering strain reaches 28%.

3. The alloy is first aged at 300 °C for 36 hours, and then aged at 170 °C for different times, showing excellent heat resistance and corrosion resistance.

Description of drawings

Fig. 1 is the aging hardening curve of a new type of Al-Mg-Si-Sc aluminum alloy sheet with high strength and high plasticity according to the present invention aged at 170°C for different time periods.

Fig. 2 is the aging hardening curve of a new high-strength and high-plastic Al-Mg-Si-Sc aluminum alloy sheet according to the present invention aged at 300°C for 36 hours, and then aged at 170°C for different times.

3 is a stress-strain curve of a new type of Al-Mg-Si-Sc aluminum alloy sheet with high strength and high plasticity according to the present invention aged at 170° C. for 10 hours.

4 is a stress-strain curve of a new type of Al-Mg-Si-Sc aluminum alloy sheet with high strength and high plasticity according to the present invention aged at 170° C. for 192 hours.

FIG. 5 is a low-power transmission diagram of a new type of Al-Mg-Si-Sc aluminum alloy sheet with high strength and high plasticity according to the present invention, which is aged at 170° C. for 10 hours.

6 is a high-power transmission diagram of a new type of Al-Mg-Si-Sc aluminum alloy sheet with high strength and high plasticity according to the present invention aged at 170° C. for 10 hours.

7 is a low-power transmission diagram of a new type of Al-Mg-Si-Sc aluminum alloy sheet with high strength and high plasticity according to the present invention, which is aged at 170° C. for 192 hours.

FIG. 8 is a high-power transmission diagram of a new type of Al-Mg-Si-Sc aluminum alloy sheet with high strength and high plasticity according to the present invention, which is aged at 170° C. for 192 hours.

Detailed ways

First prepare Al-2%Sc, Al-10%Mg, Al-10%Si master alloy and 99.99% pure aluminum, first put the aluminum scandium master alloy into the graphite crucible in the resistance furnace, and at 640 ℃ Incubate for 2 hours, then put pure aluminum, aluminum-magnesium, and aluminum-silicon intermediate alloy into a graphite crucible in another resistance furnace, and keep it at 800 ° C for 1 hour. Finally, mix the two aluminum liquids, and stir quickly during the mixing process. , ensure uniform mixing, add 0.3 wt % hexachloroethane to remove gas and impurities contained in the aluminum liquid, keep the temperature at 800° C. for 1 hour and then cast it into an aluminum ingot. In order to eliminate the segregation and other defects generated during the cooling process of the ingot, the alloy needs to be subjected to a homogenization heat treatment at 560 °C for 6 hours, and then cooled with the furnace. Before rolling, the oxide scale on the surface is milled off with a milling machine, and then kept at 400 ° C for 20 minutes for hot rolling. After each hot rolling, it is cooled with water immediately. After the hot rolling, cold rolling was performed, and after each cold rolling, it was cooled to room temperature with water immediately, and finally rolled into a 2 mm thick plate. The bound plate was subjected to solution heat treatment at 550°C for 1 hour, immediately quenched with water to room temperature, and rapidly subjected to aging heat treatment at 170°C.

Example 1

First, put the aluminum-scandium master alloy into the graphite crucible in the resistance furnace, and keep it at 640 °C for 2 hours. Incubate at 800°C for 1 hour, mix the two aluminum liquids after they are completely dissolved, stir quickly during the mixing process to ensure uniform mixing, and add 0.3 wt% hexachloroethane, which is wrapped with aluminum foil, Then, the gas and impurities contained in the molten aluminum are removed, and finally it is kept at 800° C. for 1 hour and then cast into an aluminum ingot. The ingot is put into a muffle furnace for homogenization heat treatment at 560°C for 6 hours, and then cooled with the furnace. Before rolling, use a milling machine to mill off the oxide scale on the surface, and then keep it at 400 ° C for 20 minutes to carry out hot rolling. After each hot rolling, it is immediately cooled with water. After the hot rolling, cold rolling is carried out. After each cold rolling, it is cooled to room temperature with water immediately, and finally rolled into a plate with a thickness of 2 mm. The number of cold rolling passes is 4-6 times. Al-Mg-Si-Sc alloy plate can be obtained by performing solution heat treatment at 550° C. for 1 hour and then cooling to room temperature with water.

Example 2

The Al-Mg-Si-Sc alloy sheet was aged at 170 °C for different time periods. Figure 1 shows the aging hardening curve of the Al-Mg-Si-Sc alloy at 170 °C. It can be seen from Figure 1 that with the increase of aging time, the hardness of the alloy increases rapidly. When the aging time is 10 hours, the Vickers hardness of the alloy reaches its peak value. As the time continues to increase to 192 hours, the alloy hardness does not decrease significantly and maintains the peak value. The hardness plateau indicates that the alloy has good heat resistance.

Example 3

The Al-Mg-Si-Sc alloy sheet was first aged at 300 °C for 36 hours, and then aged at 170 °C for different times. The aging hardening curve is shown in Figure 2. It can be seen from Figure 2 that the peak hardness of the alloy is slightly lower than the hardness of the alloy aged at 170 °C for 10 hours, but by observing the internal structure of the alloy, it is found that a large number of Al ₃ Sc precipitates are formed, which inhibits the recrystallization of the alloy and the grain refinement. The equiaxed grains are obvious and mainly present, and the corrosion resistance of the alloy is significantly enhanced.

Claims (4)

1. a preparation and heat treatment process of a high-strength and high-plastic Al-Mg-Si-Sc new aluminum alloy sheet, the preparation process is: first pure aluminum ingot and aluminum-magnesium, aluminum-silicon, aluminum-scandium master alloy are smelted into molten aluminum, Then, it is casted into an aluminum ingot, and then the aluminum ingot is homogenized, and then the aluminum ingot is subjected to hot rolling and cold rolling, and finally the rolled plate is subjected to solution treatment and aging treatment. 2. the preparation and heat treatment process of the high-strength and high-plastic Al-Mg-Si-Sc new aluminum alloy sheet according to claim 1, it is characterized in that, described smelting method is: first heat preservation of aluminum-scandium master alloy at 640 ℃ for 2 Second, pure aluminum, aluminum-magnesium, and aluminum-silicon master alloy were kept at 800 °C for 1 hour. Finally, the two aluminum liquids were mixed, and 0.3 wt% hexachloroethane was added for degassing and slag removal, and rapid stirring during the mixing process. , to ensure uniform mixing, hold at 800 ° C for 1 hour and then cast into aluminum ingots. 3. The preparation and heat treatment process of the high-strength and high-plastic Al-Mg-Si-Sc new aluminum alloy sheet according to claim 1, wherein the homogenization heat treatment is 560° C. for 6 hours, and then cooled with the furnace. 4. the preparation and heat treatment process of the high-strength and high-plastic Al-Mg-Si-Sc new aluminum alloy sheet according to claim 1, it is characterized in that, described solution treatment is 550 ℃ of insulations for 1 hour, immediately water-cooled to room temperature, then The aging treatment was rapidly carried out at 170°C for 10 hours in an oil bath furnace.

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