时效制度对2099铝锂合金力学和应力腐蚀性能的影响

采用透射电镜,拉伸性能测试和慢应变拉伸等手段研究时效制度对2099铝锂合金微观组织和力学及应力腐蚀性能的影响。研究采用1组T6(175℃/48 h)制度和2组T8制度对试样进行处理。实验发现,T8状态下试样的抗拉强度均高于T6态。同时T8态中双级时效制度(2.5%预变形,120℃/12 h+150℃/48 h)相比于单级时效制度(2.5%预变形,150℃/48 h)具有更优异的综合性能。对2099合金进行应力腐蚀测试,试样并未发生强度损失现象,然而失效却加速。合金经过T8双级时效后,抗拉强度、屈服强度和延伸率分别为590 MPa、570 MPa,9.3%。

Effects of aging treatment on mechanical and stress corrosion properties of 2099 alloy

The influence of the aging treatment on microstructures and mechanical properties of 2099 Al-Li alloy were investigated by means of transmission electron microscopy, tensile properties measurement and slow strain rate test. There were one T6 temper and two T8 tempers in this study. The value of tensile strength in T8 tempers were both higher than that in T6 temper. With pre-deformation before the aging treatment, it increased the dislocation density, and therefore the number of T1 precipitate in matrix. Meanwhile, the duplex aging in T8 temper was equipped with better comprehensive property. In investigated of slow strain rate test of 2099 alloy, the loss of strength did not happen in this study. However, compared with samples tested in the air, the failure time rapidly decreased when samples tested in aqueous solution. The tensile strength, yield strength and elongation of alloy in T8 duplex aging condition were 590 MPa, 570 MPa, and 9.3%, respectively. 2099 alloy had excellent stress corrosion cracking resistance and no stress loss happened.