Optimizing microstructure and mechanical properties of heat-treated Al-Zn-Mg-Cu alloy by indirect hot deformation technology

利用间接热成形技术优化热处理Al-Zn-Mg-Cu合金的微观组织和力学性能

In this paper,the indirect thermal tensile experiments of 7075 aluminum alloy including the pre-deformation process at room temperature and the final heat tensile process were carried out,the plastic deformation behavior and forming limit of the material in the compound forming process were investigated considering three pre-deformation amounts 4%,9%,14%,two strain rates 0.001 s^(-1),0.01 s^(-1) and four forming temperatures 300℃,350℃,400℃,450℃.In the indirect hot forming process,the material is sensitive to the pre-deformation,strain rate,and forming temperature,when the strain rate is 0.01 s^(-1),the pre-deformation amount is 4%,and the forming temperature is 400℃,respectively,the maximum tensile deformation is 50 mm.Finally,taking the process in which the forming temperature is 450℃ as an example,according to the observation of the microstructure appearance of fracture,the fracture type in the hot forming process was judged as the ductile fracture.By analyzing the microstructure of the specimen treated with the quenching and artificial aging process,the eutectic T(AlZnMgCu)phase and α(Al)matrix formed a network of non-equilibrium alpha binary eutectic.

本文开展了7075铝合金的间接热拉伸试验和材料塑性变形行为研究,同时包含间接热成形和热处理技术。试验过程考虑了3种预变形量,2种应变速率和4种成形温度。在间接热成形过程中,材料对预变形,应变速率和成形温度是敏感的。当应变速率为ε=0.01 s,预变形量为ε=4%,成形温度为T=400℃时,材料的最大拉伸变形量为50 mm。以成形温度为450℃的情况为例,通过断口微观形貌的观察,材料在热成形过程的断裂形式为塑性断裂。通过观察经过淬火和时效处理后的试样微观组织可知,T(AlZnMgCu)共晶体与基体α(Al)形成了网状的非平衡二元共晶体。