Effect of heat treatment temperature and quenching cooling rate on mechanical properties of wrought Al-Mg-Si alloy (6082Al)

Due to a series of excellent properties, aluminum alloy materials are widely used in aerospace, transportation, building decoration, packaging containers, machinery and electrical appliances, electronic communications, petrochemicals, energy power, sports and health and other industries, and become an important basic material for the development of the national economy. . Therefore, in recent decades, deformed aluminum alloys have generally developed in two directions. One is to develop new high-strength and high-toughness aluminum alloy materials to meet the needs of aviation and aerospace; the other is to develop a series of civilian aluminum that can meet various conditions of utilization of alloy. Therefore, the improvement and development of aluminum alloy materials is always accompanied by heat treatment and composition development. Heat treatment is one of the most important means to improve the process performance and service performance of the alloy and give full play to the potential of the material. The most commonly used heat treatments for wrought aluminum alloys are annealing, solution treatment, and aging. Deformation heat treatment is also used, and chemical heat treatment is less used. In the production process of aluminum alloy materials, it is necessary to master the basic principles and influencing factors of various heat treatments in order to correctly specify the production process, solve the relevant problems in production, and achieve high quality and high yield. In the end, 6082 aluminium alloy’s quenching sensitivity of for rail transport was studied by using end quenching (JEQ) experiment, using JMatpro7.0 simulation software, combined with hardness, tensile property testing and transmission electron microscopy (TEM) observations. The results show that: (1) The TTT curve simulated by JMatpro7.0 shows that the quenching sensitive temperature range of 6082 aluminum alloy is 220~425oC, and the nose peak temperature of β and β'' phases is 375oC. The CCT curve of the alloy shows that so as toinhibit the precipitation of β' (metastable phase) during the quenching process, the quenching cooling rate of the alloy must be greater than 6 °C/s; (2) With the increase of the end quenching distance D, the aging of 6082 aluminum alloy The as-state hardness and strength decreased, and the hardening depth was 23 mm; (3) With the decrease of the quenching cooling rate, the quenching-induced precipitation phase β was preferentially precipitated on the α-(AlMnFeSi) phase at the heterogeneous nucleation site, and in the succeeding aging process doesthe β phase grow and absorb the surrounding solute atoms so that the β'' of theprecipitation-strengthening phase in the grain decreases; (4) In the sluggish cooling process, the vacancy concentration near the grain boundary reduces, and the precipitation-free precipitation zone (PFZ) at the grain boundary expands.