Li元素对热轧及退火态AZ31镁合金板材的组织及力学性能的影响

摘要

The microstructure and mechanical properties of rolled and annealed AZ31 alloy with different Li addition were studied by optical microscopy, SEM, and tensile test. The results show that with the increase of lithium additions, the microstructures of rolled alloy with lithium addition exhibit much twins. After annealed at 150℃ for 30 min, the LAZ131(Mg-1Li-3Al-1Zn) sheet exhibit higher tensile strength of 335 MPa along TD, with lower elongation of 14.6%. After annealing at 300℃ for 30 min, the lower anisotropy and optimal comprehensive mechanical property are achieved in LAZ131(Mg-1Li-3Al-1Zn), with ultimate tensile strength of 259 MPa, yield strength of 174 MPa and elongation of 23.1%. This is attributed to the modification of basal texture due to Li addition and recrystallization when annealing at 300℃.%通过OM、SEM、拉伸实验研究添加不同含量的Li元素对轧制及退火态AZ31镁合金组织和力学性能的影响.结果表明:添加Li元素的合金板材在热轧后均有大量孪晶出现.经过不同温度退火处理后,合金板材的力学性能得到不同程度的改善.LAZ131(Mg-1Li-3Al-1Zn)合金在经过150℃退火30 min,其沿TD方向拉伸时力学性能最佳,抗拉强度、屈服强度、伸长率分别为335 MPa、261 MPa、14.6%.而LAZ131合金在经过300℃退火30 min后的力学性能各向异性最小,且合金的组织为均匀细小的等轴晶,总的力学性能较好,抗拉强度、屈服强度及伸长率分别为259 MPa、174 MPa、23.1%.这是由于Li元素的添加对基面织构的改善以及在300℃退火时的再结晶所导致.