多级固溶对7A04铝合金的力学性能和剥落腐蚀性能的影响

摘要

通过金相显微镜(OM)、扫描电子显微镜(SEM)、室温拉伸及腐蚀剥落性能测试,研究多级固溶处理对7A04铝合金的微观组织、力学性能及剥落腐蚀行为的影响.研究结果表明:7A04铝合金经三级固溶(470℃/2h+480℃/l h+490℃/0.5 h)后第二相含量较单级与双级固溶分别减少了36.9％和28.2％;120℃/24 h时效后,抗拉强度Rm,屈服强度Rpo.2和伸长率A分别达到718.8 MPa,660.3 MPa和10.6％;当固溶处理工艺从单固溶处理升级到三级固溶处理时,剥蚀敏感性降低,铝合金的耐剥蚀性能等级由EC提高到EA.%The effects of multi-stage solid-solution treatment on the mechanical properties,microstructure and exfoliation corrosion behavior of 7A04 aluminum alloy were investigated by optical microscopy(OM),scanning electron microscopy (SEM),tensile test and exfoliation corrosion test.The results show that compared with single-stage and two-stage solid-solution treatment,the second phase particles fraction of the 7A04 aluminum alloy after triple-stage solid-solution (470 ℃/2 h+480 ℃/1 h+490 ℃/0.5 h) has decreased by 36.9％ and 28.2％.And the ultimate tensile strength Rm,yield strength Rp0.2 of the samples by triple-stage solid-solution and peak aging (120 ℃/24 h) are 718.8 MPa,660.3 MPa,respectively,with approximately 10.6％ elongation.When the solid solution stages increase to the triple,the exfoliation susceptibility of the alloy has reduced and the scale of the exfoliation corrosion resistance has improved from EC to EA-.