(1. 湖南科技大学 高温耐磨材料及制备技术湖南省国防科技重点实验室,湘潭 411201;
2. 湖南工学院 汽车零部件技术研究院,衡阳 421002)
摘 要: 对铸态AZ31镁合金进行温度350~450 ℃、平均应变速率为2.26~8.3 s-1的中高应变速率轧制,研究轧制后镁板的边裂和组织性能。研究结果表明:随着平均应变速率增加,轧制边裂得到改善;轧后镁板室温拉伸断裂方式具有韧-脆性断裂向韧性断裂转变的趋势,在拉伸断口中观察到拉长形孔洞和夹着韧窝的层状结构;镁合金抗拉强度受细晶强化和孪晶强化的共同作用,建立了考虑细晶强化和孪晶强化叠加的本构关系。
关键字: AZ31镁合金;中高应变速率轧制;边裂;组织;断裂方式
(1. Key Laboratory of High Temperature Wear Resistant Materials Preparation Technology of Hunan Province, Hunan University of Science and Technology, Xiangtan 411201, China;
2. Research Institute of Automobile Parts Technology, Hunan Institute of Technology, Hengyang 421002, China)
Abstract:The medium-high strain rate rolling was carried out on as-casting AZ31 magnesium alloys over the temperature ranges from 350 to 450 ℃ with average strain rates of 2.26-8.3 s-1. The edge cracks, microstructures and mechanical properties were investigated. The results show that the edge crack is improved and the fracture mechanism of magnesium rolling sheet tends to transform from ductile-brittle fracture to ductile fracture with increasing average strain rate. The tensile fracture displays elongated holes and laminar structure with dimples. The tensile strength of magnesium alloy is affected by fine-grain strengthening and twins strengthening. A constitutive relation considering the fine-grain strengthening and twins strengthening was built.
Key words: AZ31 magnesium alloy; medium-high strain rate rolling; edge crack; microstructure; fracture mechanism