7075铝合金深冷轧制及时效处理微观组织和性能

Microstructure evolution and mechanical properties of AA7075 sheets via cryorolling and ageing

采用深冷轧制和室温轧制及峰值时效处理制备了不同厚度的7075铝合金板材,利用硬度测试、拉伸试验、X射线衍射、扫描电子显微镜和透射电子显微镜分析了轧制板材的力学性能和微观组织演变。结果表明:与室温轧制板材发生了严重边裂不同,深冷轧制板材始终未发生边裂。轧制强化效果随压下率增加而提高,80%压下率的深冷轧制样品屈服强度和抗拉强度较固溶样品分别提高155%和44%。深冷轧制样品在峰值时效后强度和塑性同时提升。20%、40%、60%和80%压下率的深冷轧制+峰值时效样品与室温轧制+峰值时效样品相比,断裂伸长率分别提高8.7%、18.5%、45.5%和57.4%,这是时效引起的位错湮灭、深冷轧制更均匀的变形和深冷轧制+峰值时效样品中细小析出相的共同作用。

7075 aluminum alloy sheets with different thickness were prepared by cryorolling and roomtemperature rolling respectively,and subsequent peak aging treatment.Mechanical properties and microstructure evolution of rolled plates were analyzed by hardness tests,tensile tests,X-ray diffraction,scanning electron microscope and transmission electron microscope.The results show that no edge cracks have occurred in cryorolled sheets,which are different from the serious edge cracks of room-temperature rolled sheets with 60%and 80%reduction.The strengthening effect of rolling increases with the increase of deformation,compared with solid solution sample,the yield strength and ultimate tensile strength of cryorolling sample with 80%deformation are increased by 155%and 44%respectively.After aging,the strength and plasticity of cryorolled samples are improved simultaneously.The elongation to failure of aged cryorolled sample with 20%,40%,60%and 80%deformation increases by 8.7%,18.5%,45.5%and 57.4%,respectively compared with the aged room-temperature rolled sample.