双级时效对7050铝合金组织和性能的影响

Effect of duplex aging on microstructure and properties of 7050 aluminium alloy

采用力学性能和电导率测试及透射电镜组织观察的方法,研究了7050合金挤压带板的单级时效、双级时效及两级时效之间处理条件对合金组织和性能的影响。结果表明:7050合金在120℃时效有很高的抗过时效能力,抗拉强度超过619 MPa,但电导率较低仅为32.3%IACS;采用第二级时效温度为165℃的双级时效,合金可获得强度为551 MPa和电导率为40.6%IACS的配合;双级时效过程的两级时效之间处理条件对合金的强度有明显的影响,间断时效和第一级时效后快冷有利于提高合金的强度;经过第一级时效后空冷再进行165℃、16 h时效,合金的强度和电导率分别为559 MPa和40.2%IACS。

The effects of single aging, duplex aging and conditions between the first and second step agings on the microstructures and properties of the extruded plate of 7050 aluminium alloy were investigated, by means of TEM, tensile and conductivity tests. The results show that 7050 aluminium alloy aged at 120℃ can obtain tensile strength of 619 MPa and conductivity of 32.3%IACS, and its overaging at that temperature needs long time. 7050 aluminium alloy after duplex aging with the second-step aging at 165℃ can obtain the combinations of the tensile strength of 551 MPa and the conductivity of 40. 6%IACS. Obvious effects of the treatment conditions exist between the first and second step agings on the tensile strength of 7050 aluminium alloy during duplex aging. The tensile strength of 7050 aluminium alloy can be increased as stop aging or quick cooling after the first step aging during duplex aging. 7050 alloy can obtain tensile strength of 559 MPa and conductivity of 40.2%IACS when it is aged at 165℃for 16 h after air cooling following the first step aging.