应变速率对Al-Zn-Mg合金室温拉伸性能的影响

摘要

研究了应变速率对Al-Zn-Mg合金室温拉伸性能的影响.结果表明,随着试验过程中应变速率的增加,Al-Zn-Mg合金的极限抗拉强度(Rm)略有增加,屈服强度(RP0.2)明显上升,伸长率(A%)显著下降.断口显微分析表明,在应变速率较低时,Al-Zn-Mg合金材料的断口中韧窝组织较多,主要以韧性断裂为主;随着应变速率不断增加,表现出韧性断裂和脆性断裂.金相显微分析表明,随着应变速率的增加,断口的纵剖面晶粒伸长减少,并出现一些细小的析出相.此外,基于Fields-Backofen本构方程模型,定量分析计算了应变速率对Al-Zn-Mg合金拉伸性能的影响.%The effects of strain rate on the tensile properties of Al-Zn-Mg alloy were analyzed.The results show that the ultimate tensile strength slightly rises, the yield strength dramatically increases, and the elongation significantly decreases with the increase of strain rate.The fracture analysis shows that the dimple increases with strain rate decreasing, which was mainly ductile rupture.The fracture was mainly ductile and brittle rupture with the increase of strain rate.The metallographic analysis indicates the elongation of crystal grain decreased and tiny precipitated phase appeared with strain rate increasing.Besides, the effect of strain rate is calculated based on the Fields-Backofen equation in Al-Zn-Mg alloy.