锻造方式对ZK21镁合金显微组织和力学性能的影响  

Effects of forging technique on microstructure and mechanical properties of ZK21 magnesium alloy

作　　者：吴远志[1,2] 严红革[3] 朱素琴[3] 刘先兰[1,2] 刘安民[1,2] 张蓉[1,2] 

机构地区：[1]湖南工学院机械工程学院,湖南衡阳421002 [2]汽车零部件制造与绩效提升技术湖南省应用基础研究基地,湖南衡阳421002 [3]湖南大学材料科学与工程学院,湖南长沙410082

出　　处：《中南大学学报（自然科学版）》2015年第2期444-451,共8页Journal of Central South University:Science and Technology

基　　金：湖南省自然科学基金资助项目(14JJ6047);湖南省教育厅科学研究青年项目(14B045)(Project(14JJ6047)~~

摘　　要：采用空气锤对ZK21合金进行高应变速率锻造成形,对比研究单向、双向和三向锻造合金的显微组织和力学性能。研究结果表明:锻造成形时通过改变载荷方向可以提高合金所能承受的累积应变,从而获得良好的晶粒细化效果和优异的综合力学性能。双向锻造时,再结晶机制主要为孪生诱发动态再结晶,合金最终锻造组织为平均晶粒粒径约为0.3μm的超细晶粒组织;而三向锻造时,再结晶机制主要为旋转动态再结晶和孪生诱发动态再结晶,合金最终锻造组织为平均晶粒粒径为15μm的蜂窝状粗大再结晶组织和平均晶粒粒径约为0.3μm的岛状细小再结晶组织。累积应变为2.64时,双向锻造合金的抗拉强度、屈服强度和伸长率分别为355.7 MPa,295 MPa和16.6%,三向铸造合金的抗拉强度、屈服强度和伸长率分别为341.6 MPa,270.7 MPa和25.1%。The high strain rate forging of ZK21 magnesium alloy was conducted on the pneumatic power hammer, and the microstructure and mechanical properties of the forged alloys processed by different forging techniques including uniaxial forging （UF）, biaxial forging （BF） and triaxial forging （TF） were investigated. The results show that higher strain should be accumulated on ZK21 alloy by alternating the loading direction, which consequently results in extensive grain refinement and excellence mechanical properties. Twinning induced dynamic recrystallization （TDRX） is the main DRX mechanism of BF, which consequently results in ultrafme grains with average grain size of 0.3 μm. However, both rotation DRX （RDRX） and TDRX are responsible for the DRX during TF, which consequently results in a novel mixed structure of honeycombe-like coarse DRX grains with average grain size of 15μm and island-like ultrafine grains with average grain size of 0.3 μm. An excellent combination of mechanical property is achieved in biaxial forged and triaxial forged alloys at accumulated strain of 2.64. The ultimate tensile strength （UTS）, yield strength （YS） and elongation of biaxial forged alloy are 355.7 MPa, 295 MPa and 16.6%, respectively. The VTS, YS and elongation of triaxial forged alloy are 341.6 MPa, 270.7 MPa and 25.1%, respectively.

关 键 词：ZK21镁合金 高应变速率锻造 锻造方式 显微组织 力学性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]