CN112126830B - Preparation and heat treatment process of a high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate - Google Patents

Abstract

A preparation and heat treatment process of a novel aluminum alloy plate with high strength and high plasticity Al-Mg-Si-Sc belongs to the technical field of metal alloys. The preparation method comprises the following steps: preparing a metal cast ingot by adopting a casting mode, carrying out homogenization heat treatment on the cast ingot, and finally carrying out hot rolling and cold rolling on a rolling mill. The homogenization heat treatment process comprises the following steps: the ingot was incubated at 560℃for 6 hours. The rolling process comprises the following steps: before hot rolling, the ingot is firstly kept at 400 ℃ for 20 minutes, then hot rolled, then cold rolled, immediately cooled by water after each rolling, and the final rolling thickness is about 2mm. The solution heat treatment process comprises the following steps: the ingot was incubated at 550℃for 1 hour and immediately cooled to room temperature by water. The aging heat treatment process comprises the following steps: immediately after the ingot is subjected to solution treatment, aging heat treatment is performed at 170 ℃. The alloy treated by the method is aged for 10 hours at 170 ℃, the engineering stress of the alloy reaches 300MPa, and the engineering strain reaches 32.5%; aging at 170 ℃ for 192 hours, the engineering stress of the alloy reaches 300MPa, and the engineering strain reaches 28%.

Description

Preparation and heat treatment of a high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate craft

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-plasticity Al-Mg-Si-Sc aluminum alloy plate.

Background technique

Al-Mg-Si alloys are widely used in transportation fields, such as vehicles, aircraft, and high-speed rail, due to their very attractive specific strength, formability, weldability, and corrosion resistance. 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 undergoes solid solution treatment to form a supersaturated solid solution. During the subsequent artificial aging heat treatment, precipitates with high number density and uniform distribution are precipitated, and the precipitates significantly hinder 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 alloys decreases with the increase in strength, which seriously affects its application range, for example, it cannot be processed into parts with more complex shapes. The present invention prepares Al-Mg-Si-Sc aluminum alloy with engineering stress up to 300MPa and engineering strain up to 32.5% by adding rare earth element Sc (0.4wt%), aging at 170°C for 192 hours, the engineering stress of the alloy can also be Maintained at 300MPa, engineering strain up to 28%.

Contents of the invention

The purpose of the present invention is to provide a high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate preparation and heat treatment process to solve the problems raised in the above-mentioned background technology.

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

A high-strength and high-plasticity Al-Mg-Si-Sc 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. Its preparation method is as follows: firstly, pure aluminum ingot and aluminum-magnesium, aluminum-silicon, aluminum-scandium intermediate alloy are smelted into molten aluminum, then poured into aluminum ingot, secondly, the aluminum ingot is homogenized, and then the aluminum ingot is hot-rolled and cold-rolled rolling, and finally the rolled plate is subjected to solution treatment and aging treatment.

The outstanding advantages of the present invention are:

1. The time required for the peak aging of the alloy is shortened by half, aging at 170°C 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°C 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 to exhibit excellent heat resistance and corrosion resistance.

Description of drawings

Fig. 1 is the age hardening curve of a high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate according to the present invention aged at 170°C for different times.

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

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

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

Fig. 5 is a low-magnification transmission view of a high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate according to the present invention aged at 170° C. for 10 hours.

Fig. 6 is a high-magnification transmission image of a high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate according to the present invention aged at 170° C. for 10 hours.

Fig. 7 is a low-magnification transmission view of a high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate according to the present invention aged at 170° C. for 192 hours.

Fig. 8 is a high-magnification transmission image of a high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate according to the present invention aged at 170° C. for 192 hours.

Detailed ways

First prepare the Al-2%Sc, Al-10%Mg, Al-10%Si master alloys and 99.99% pure aluminum, first put the Al-Sc master alloy into the graphite crucible in the resistance furnace, and heat it at 640°C Keep warm for 2 hours, then put pure aluminum, aluminum-magnesium, and aluminum-silicon intermediate alloys into a graphite crucible in another resistance furnace, and keep warm at 800°C for 1 hour, and finally mix the two aluminum liquids, and stir rapidly during the mixing process , ensure uniform mixing, and add 0.3wt% hexachloroethane to remove the gas and impurities contained in the aluminum liquid, heat it at 800° C. for 1 hour and then cast it into an aluminum ingot. In order to eliminate defects such as segregation produced 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, mill off the scale on the surface with a milling machine, then keep warm at 400°C for 20 minutes for hot rolling, and immediately cool with water after each hot rolling. Cold rolling is carried out after the hot rolling is finished, and water is cooled to room temperature immediately after each cold rolling, and finally rolled into a plate with a thickness of 2 mm. The bound plate is subjected to solution heat treatment at 550°C for 1 hour, and immediately quenched with water to room temperature, and the plate is quickly subjected to aging heat treatment at 170°C.

Example 1

First put the aluminum-scandium master alloy into a graphite crucible in a resistance furnace, and keep it warm at 640°C for 2 hours, then put pure aluminum, aluminum-magnesium, and aluminum-silicon master alloy into another graphite crucible in a resistance furnace, and Insulate at 800°C for 1 hour, mix the two aluminum liquids after they are completely dissolved, stir rapidly during the mixing process to ensure uniform mixing, and add 0.3wt% hexachloroethane, wrap the hexachloroethane with aluminum foil, Then remove the gas and impurities contained in the molten aluminum, and finally keep it at 800°C for 1 hour and then cast it into an aluminum ingot. Put the ingot into the muffle furnace for homogenization heat treatment at 560°C for 6 hours, and then cool with the furnace. Before rolling, first mill off the scale on the surface with a milling machine, then keep warm at 400°C for 20 minutes, and carry out hot rolling. After each hot rolling, immediately cool with water, and the number of hot rolling passes is 2-4 times. Carry out cold rolling after the hot rolling is finished, and immediately cool to room temperature with water after each cold rolling, and finally roll into a plate with a thickness of 2 mm, and the cold rolling passes are 4-6 times. Al-Mg-Si-Sc alloy plates can be obtained by subjecting the bound plates to solution heat treatment at 550° C. for 1 hour and then water-cooling to room temperature.

Example 2

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

Example 3

The Al-Mg-Si-Sc alloy plate was first aged at 300°C for 36 hours, and then aged at 170°C for different times. The age 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 Al3Sc precipitates are formed, which inhibits the recrystallization of the alloy, and the grain refinement is obvious and Equiaxed crystals are 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-plasticity Al-Mg-Si-Sc aluminum alloy plate, its preparation process is as follows: first, pure aluminum ingots and aluminum-magnesium, aluminum-silicon, aluminum-scandium master alloys are smelted into aluminum liquid, and then Pouring into aluminum ingots, followed by homogenization of the aluminum ingots, hot rolling and cold rolling of the aluminum ingots, and finally solution treatment and aging treatment of the rolled plates; Before rolling, use a milling machine to mill off the scale on the surface, then keep warm at 400°C for 20 minutes, and carry out hot rolling. After each hot rolling, immediately cool with water. The number of hot rolling passes is 2-4 times. After hot rolling Carry out cold rolling, cool to room temperature with water immediately after each cold rolling, and finally roll into a 2mm thick plate, and the cold rolling pass is 4-6 times; The alloy composition of the high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate is: Mg: 0.45-0.9%, Si: 0.2-0.6%, Sc: 0.4%, and the balance is aluminum. 2. The preparation and heat treatment process of the high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy sheet according to claim 1, characterized in that, the melting method is: first heat the aluminum-scandium master alloy at 640°C for 2 hours , followed by keeping pure aluminum, aluminum-magnesium, and aluminum-silicon intermediate alloys at 800°C for 1 hour, and finally mixing the two aluminum liquids, adding 0.3wt% hexachloroethane for degassing and slag removal, stirring rapidly during the mixing process, Make sure to mix evenly, keep warm at 800°C for 1 hour and then pour into aluminum ingots. 3. The preparation and heat treatment process of the high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate according to claim 1, characterized in that, the homogenization heat treatment is held at 560° C. for 6 hours, and then cooled with the furnace. 4. According to the preparation and heat treatment process of the high-strength and high-plasticity Al-Mg-Si-Sc aluminum alloy plate according to claim 1, it is characterized in that the solution treatment is 550 ° C for 1 hour, immediately water-cooled to room temperature, and then quickly The aging treatment was carried out at 170° C. for 10 hours in an oil bath furnace.