双级时效对7085铝合金组织和性能的影响

摘要

The effect of two-step aging treatment on microstructure and properties of 7085 aluminum alloy was investigated by hardness, conductivity, mechanical testing, slow strain rate testing and transmission electron microscopy. The results show that the GP zones andη′phase are the mainly precipitation phases of pre-aging, and the pre-aging time is less impact on the hardness and electrical conductivity. The strength after two-step aging process first increases, and then decreases, while the ability of stress corrosion resistance increases with the extension of the second step of aging time. With the size of grain boundary precipitates coarsening, and the distribution of grain boundary precipitates from continuous to non-continuous. The strength of the alloy significantly decreases with the increases of the second step aging temperature. The optimal of the two-step aging process is (110℃, 6 h)+(160℃, 12 h), the tensile strength, yield strength, elongation and conductivity of alloy are 515 MPa, 487 MPa, 11.7%, 38%(IACS), respectively.%采用硬度、电导率、力学拉伸、慢应变速率拉伸试验及透射电镜等测试分析方法，研究双级时效对7085铝合金组织和性能的影响。结果表明：预时效热处理主要析出相为GP 区和η′相，预时效时间对合金硬度和电导率的影响较小。随着第二级时效时间的延长，合金的抗拉强度和屈服强度先增大后减小，电导率和抗应力腐蚀性能提高，晶界析出相由连续分布变为非连续分布。第二级时效温度越高，合金强度随时效时间的延长，降低得越显著。采用(110℃,6 h)+(160℃,12 h)双级时效热处理，合金的抗拉强度、屈服强度、伸长率及电导率分别为515 MPa、487MPa、11.7%、38%(IACS)。