热挤压WE43镁合金的高温断裂行为研究

Study on High Temperature Fracture behavior of Hot-extruded WE43 Magnesium Alloy

采用Gleeble-3800热模拟试验机在350℃以0.001 s^(-1)、0.01 s^(-1)、0.1 s^(-1)和1 s^(-1)的应变速率对热挤压WE43镁合金进行了拉伸试验随后氩气淬火。拉伸试验后采用光学显微镜和扫描电子显微镜检测了试样的显微组织和断口形貌。结果表明:WE43镁合金在350℃已发生再结晶,以这四种应变速率拉伸试验的WE43合金的真应力-真应变曲线均为典型的动态再结晶曲线;以0.01~1 s^(-1)的应变速率拉伸试验的WE43合金的流变应力对应变速率变化不敏感,而以0.001~0.01 s^(-1)的应变速率拉伸试验的WE43合金的流变应力对应变速率的变化较敏感;以0.01 s^(-1)的应变速率拉伸试验时WE43合金的塑性最好,应变达0.385;以1 s^(-1)的应变速率拉伸试验时试样为准解理断裂,而以0.001~1 s^(-1)的应变速率拉伸试验时试样为韧性断裂;第二相粒子对WE43镁合金的高温断裂行为有显著影响。

Hot-extruded WE43 magnesium alloy was subjected to tensile tests which were performed at 350 C at strain rates of 0.001 s^(-1),0.01 s^(-1),0.1 s^(-1) and 1s^(-1) by a Gleeble-3800 thermal simulation tester,followed by quenching in argon gas.After tensile tests the specimens were tested for microstructure and pattern of fracture by means of optical scanning electron microscopes.The results showed that(a)the WE43 magnesium alloy has recrystallized at 350 C,and the true stress-true strain curves of WE43 alloy subjected to tensile testes at these four strain rates all were typical dynamic recrystallization curves;(b)the flow stress of WE43 alloy during tensile tests at strain rates of 0.01 to 1 s^(-1) was insensitive to the change in strain rate,whereas the flow stress of WE43 alloy during tensile tests at strain rates of 0.001 to 0.01 s^(-1) was sensitive to the change in strain rate;(c)WE43 alloy exhibited the best plasticity during tensile test at strain rate of 0.01 s^(-1),and its strain reached 0.385;(d)the specimen was quasi-cleavage fracturing during tensile test at strain rate of 1 s^(-1),and ductile fracturing during tensile test at strain rate of 0.001 s^(-1);and(e)the second phase particles had an significant influence on the high-temperature fracture behavior of WE43 magnesium alloy.