ZK60镁合金高应变速率锻造成形  

Investigation of the high-strain-rate forging of ZK60 magnesium alloy

作　　者：吴远志[1] 严红革[2] 刘先兰[1] 李理[1] 李鑫[1] 袁丁玲 

机构地区：[1]湖南工学院机械工程学院,湖南衡阳421002 [2]湖南大学材料科学与工程学院,湖南长沙410082

出　　处：《哈尔滨工程大学学报》2017年第3期478-483,共6页Journal of Harbin Engineering University

基　　金：国家自然科学基金项目(51501061);湖南省教育厅科学研究优秀青年项目(14B045);湖南省科技计划项目(2015JC3106);湖南省大学生创新性实验和研究性学习计划项目(20140558)

摘　　要：采用Gleeble-1500对ZK60合金进行锻造模拟,分析了合金高应变速率可锻性;并采用空气锤对合金成功地进行高应变速率多向锻造,研究了其组织演变和力学性能。结果表明:高应变速率(≥10 s-1)锻造成形时,孪生和动态再结晶对变形储能的消耗以及变形温升对散热造成的塑性下降的弥补,可防止合金在高应变速率锻造时产生裂纹。此外,由于再结晶同时在晶界和孪晶上产生,获得了比低应变速率锻造成形更为均匀的再结晶组织,因此高应变速率锻造成形是一种高效可行的镁合金塑性加工工艺。经高应变速率多向锻造成形后,可形成壳状粗晶和核状细晶构成的双峰晶粒组织,应变∑Δε=2.64时,粗晶和细晶组织的平均晶粒尺寸分别为10μm和1μm。由于双峰晶粒组织的形成,合金表现出良好的综合力学性能,抗拉强度和延伸率分别达到330.2 MPa、24.8%,表明高应变速率多向锻造成形是制备高性能镁合金的有效途径。Forging simulation was performed for ZK60 magnesium alloy using Gleeble-1500, and the forging capa-bility during high-strain-rate forging （ HSRF ） was investigated. Moreover, high - strain - rate multiple forging （HSRMF） of the ZK60 alloy was successfully conducted on apneumatic power hammer, and the microstructural evolution and mechanical properties of the alloy were studied. The results show that together with the offset of ductil-ity reduction owing to an increasing temperature,the dissipation of the deformation energy caused by twinning and dynamic recrystallization （ DRX） can prevent the samples from cracking under HSRF （ ≥ 10 s^-1）. A more homoge -nous recrystallization structure was obtained owing to DRX both at the grain boundaries and twins,then made H S R F feasible and more efficient than low-strain-rate forging. A bimodal structure characteristic comprising coarse-grained shells and ultrafine-grained cores formed after H S R M F . T he average grain sizes of the coarse grains and ultrafine grains were 10 and 1pm, respectively,when the accumulated strain （ ΣΔε） was 2. 64. The mechanical properties of the alloy improved significantly owing to the formation of the bimodal structure. An ultimate tensile strength （UTS） of 330. 2 MPa and elongation of 24. 8% were obtained via a mechanical test. Therefore,HSRMF was identi-fied as a potential technique for making the wrought ZK60 alloy stronger and more ductile.

关 键 词：ZK60镁合金 高应变速率锻造 可锻性 多向锻造 双峰组织 力学性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]