There is aluminum alloy quenching process that you don’t know
Aluminum alloy quenching is a heat treatment quenching process in which the aluminum alloy is heated to above the critical temperature Ac3 for a period of time to austenite completely or partly, and then rapidly cooled to below Ms for martensite or bainite transformation. Usually the heat treatment process of aluminum alloy, copper alloy, titanium alloy with rapid cooling process is also called quenching. Quenching is a very common heat treatment process, mainly used to improve the hardness of materials. At present, some new quenching processes have appeared.
Rapid quenching of aluminum alloy
Conventional quenching is usually cooled by oil, water or polymer solutions, while rapid quenching is done by water or low concentration brine. Rapid quenching of aluminium alloys is characterized by extremely rapid cooling without fear of excessive distortion and cracking of aluminium alloy steel. When conventional quenching is cooled to the quenchant temperature, the tensile stress or low stress state is formed on the surface of aluminum alloy steel, while rapid quenching is in the middle of cooling, and the cooling stops while the center of the workpiece is still in the hot state, so that the surface of the aluminum alloy steel becomes compressive stress. The supercooled austenite on the surface of steel is subjected to compressive stress of 1200 MPa when the cooling rate of martensitic transformation zone is higher than 30 c/s under rapid quenching condition, which makes the yield strength of Quenched Aluminum alloy steel increase by at least 25%.
Principle of induction heat treatment equipment
After quenching treatment, the retained austenite in the internal structure of aluminum alloy metal material is transformed into martensite, and the dispersed carbide is precipitated in martensite, so the residual stress in martensite can be eliminated, and the martensite matrix can be strengthened, so the hardness and wear resistance of aluminum alloy metal material will be improved. The increase of hardness is due to the transformation of retained austenite into martensite, the increase of strength and toughness is due to the dispersed and fine η-Fe3C precipitation, and the decrease of martensite carbon content, the decrease of lattice distortion and the improvement of plasticity of aluminum alloy metal materials.
Rapid quenching test and properties of quenched aluminum alloy:
The advantages of the rapid quenching method are that the compressive stress is formed on the surface layer, the crack probability of the heat treatment quenching equipment is reduced, and the hardness and strength are improved. The formation of 100% martensite in the surface layer will give the aluminum alloy steel the largest hardening layer. Rapid quenching can also promote the steel to obtain uniform mechanical properties and produce the smallest workpiece distortion.
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Post time: 09-11-2018