时效工艺对Al-Zn-Mg-Cu铝合金组织与性能的影响

向Al-Zn-Mg-Cu合金中添加0.22%的过渡族元素Ti,通过一级时效、二级时效与三级时效工艺处理,研究了时效工艺对含Ti铝合金的组织与性能的影响。利用光学显微镜(OM)、扫描电镜(SEM)、微控万能试验机、显微硬度计等测试合金铸态组织及相析出分布形态、时效后力学性能与断口形貌等。结果表明:添加Ti元素可以细化晶粒、改善枝晶偏析并强化合金;一级时效态合金具有最高强度586 MPa,三级时效态合金具有最大硬度与最长伸长率,强度与一级时效态相当,分别为183.2 HV0.1、8.8%和579 MPa。三级时效对合金的力学性能提高最显著。

Influence of aging processes on microstructure and properties of Al-Zn-Mg-Cu aluminium alloy

The influence of aging processes (including one-step, two-step and three-step aging) on the microstructure and properties of Al-Zn-Mg-Cu aluminium alloy with Ti addition was studied by alloy preparation and heat treatments. The as-cast microstructure, distribution patterns of phase precipitation, mechanical properties after aging and fracture morphology of the alloy were studied by OM, SEM, microcomputer controlled universal testing machine and microhardness tester. The results show that adding Ti can refine the grain size, reduce the dendritic segregation and strengthen the alloy. The strength of the alloy reaches its maximum of 586 MPa in the one-step aging process. But in the three-step aging process, the alloy has the highest hardness (183.2 HV0.1) and the best elongation (8.8%) with the strength (579 MPa) equivalent to that in the one-step aging process. It is revealed that the three-step aging treatment can achieve the most significant improvement in the mechanical properties of the alloy.