T5热处理对Mg-Gd-Y-Zr合金筒形件拉压 不对称性的影响

Influence of T5 heat treatment on tension-compression asymmetry for Mg-Gd-Y-Zr-Ag alloy cylindrical parts

通过力学性能测试、背散射电子衍射、X射线衍射、透射电子表征等手段分析大尺寸Mg-9.17Gd-1.98Y-0.43Zr-0.11Ag镁合金筒形件的组织性能不均匀性和拉压不对称性,并通过时效处理调控合金组织,提高材料力学性能。研究发现:从内部到外部,筒形件组织呈不均匀分布,平均晶粒尺寸从12.9μm粗化至20.1μm,抗拉强度从327 MPa降至280 MPa,屈服强度从223 MPa降至157 MPa。经225℃×21 h峰时效处理后,β′相作为主要析出相,抑制了压缩载荷下孪晶的产生,大幅提高了筒形件的强度并降低其伸长率,压缩屈服强度和拉伸屈服强度的比值从内部到外部分别为1.06、1.17和1.02。T5热处理后筒形件内部的力学性能最好,抗拉强度、屈服强度和伸长率分别为407 MPa、293 MPa和12%。

The inhomogeneity of microstructure and the properties and the tension-compression asymmetry for large-sized Mg-9.17Gd1.98Y-0.43Zr-0.11Ag magnesium alloy cylindrical part were analyzed by mechanical property testing,backscattered electron diffraction,X-ray diffraction and transmission electron characterization,and the mechanical properties of material were improved by aging treatment to regulate the alloy microstructure.The results show that from the inside to the outside,the microstructure of cylinder part is unevenly distributed,the average grain size is coarsened from 12.9μm to 20.1μm,the tensile strength is reduced from 327 MPa to 280 MPa,and the yield strength is reduced from 223 MPa to 157 MPa.After peak aging at 225°C×21 h,as the main precipitation phase,β′phase inhibits the generation of twins under compression load,greatly increases the strength of cylinder part and reduces its elongation,and the ratio of compressive yield strength to tensile yield strength is 1.06,1.17 and 1.02 from the inside to the outside,respectively.After T5 heat treatment,the internal mechanical properties of cylindrical part are the best with the tensile strength of 407 MPa,the yield strength of 293 MPa and the elongation of 12%.