时效工艺对电磁成形7075铝合金组织与性能的影响

Influence of aging process on microstructure and properties of 7075 aluminum alloy by electromagnetic forming

为了探究人工时效处理时间对电磁成形7075铝合金组织及性能的影响规律,开展了电磁成形单向拉伸试样的时效处理工艺实验。对成形后的零件进行切样,通过拉伸实验、金相显微镜、扫描电镜、透射电镜等手段,研究了时效时间对电磁成形7075铝合金的时效析出行为及力学性能的影响。结果表明:电磁成形产生的位错,有利于η’沉淀析出相的形核、析出及长大,随着时效时间的增加,位错密度降低,η’沉淀析出相数量减少,η沉淀析出相数量增多且尺寸增大。时效时间为9 h时,基体中同时析出了大量细小弥散的η’和η沉淀析出相,材料综合性能最优,其抗拉强度、屈服强度、伸长率、硬度分别为598.3 MPa、568.36 MPa、4.48%、178.3 HV。

In order to explore the influence law of aging treatment time on the microstructure and properties of 7075 aluminum alloy in electromagnetic forming,the aging treatment process experiment of unidirectional tensile specimens by electromagnetic forming was carried out.Then,the formed parts were cut,and the influences of aging time on the aging precipitation behavior and mechanical properties of 7075 aluminum alloy in electromagnetic forming were studied by methods of tensile tests,optical microscope,scanning electron microscope,transmission electron microscope and so on.The results show that the dislocations produced by electromagnetic forming are conductive to the nucleation,precipitation and growth ofη’precipitated phase.With the increasing of aging time,the dislocation density decreases,the number ofη’precipitated phase reduces,and the number and size ofηprecipitated phase increase.When the aging time is 9 h,a large number of fine-dispersedη’andηprecipitated phases precipitate at the same time in the matrix,and the comprehensive properties of material are the best with the tensile strength of 598.3 MPa,the yield strength of 568.36 MPa,the elongation of 4.48%and the hardness of 178.3 HV.