AZ80-Ag镁合金环轧件的组织及力学性能各向异性

Microstructure and anisotropy of mechanical properties in ring rolled AZ80-Ag alloy

本文研究了AZ80-Ag镁合金环轧件显微组织及拉伸强度和拉伸蠕变的各向异性。环件在轧向比横向有更高的强度,织构分析结果表明基面织构偏转导致沿轧向有更好的拉伸性能。通过拉伸蠕变试验发现,当蠕变应力在70~80 MPa时,轧向比横向的蠕变抗性差,会产生更高的蠕变应变和稳态蠕变速率。轧向和横向的蠕变应力指数n分别为1.13和3.86,分别对应扩散蠕变和位错攀移蠕变机制。在蠕变过程中,环件会析出不连续Mg_(17)Al_(12)相,并且它们的体积分数随应力增加而增加。

The microstructure,anisotropy in tensile strength and tensile creep resistance of the ring rolled AZ80-Ag alloy were studied.The ring exhibited higher strength along rolling direction(RD)than transverse direction(TD).The microstructure characterization and texture analysis demonstrated that the tilted basal texture was responsible for the higher tensile performance along RD.Investigations on the creep anisotropy revealed that the samples along RD had lower creep resistance,higher creep strain and higher steady creep rate at 70−80 MPa,compared with that along TD.The nominal creep stress exponent(n)values,1.13 for RD and 3.86 for TD,indicated that diffusional creep and dislocation climb were the two corresponding creep mechanisms.During creep of the alloy,Mg_(17)Al_(12) phase discontinuous precipitations were witnessed and their volume fraction enhanced with increasing stress.