热处理对Ti65钛合金板材的显微组织、织构及拉伸性能的影响

研究了不同热处理条件下Ti65钛合金板材的显微组织和织构的变化规律,分析了板材织构的类型和热处理影响拉伸强度的机制。结果表明,热处理对板材的显微组织和织构类型具有显著的影响。通过热处理可分别得到具有等轴组织、双态组织或片层组织的板材。等轴组织板材的织构为晶体c轴与板材RD方向呈现70°~90°夹角的B/T型织构,双态组织和片层组织板材的主要织构类型与等轴组织类似,且出现晶体学c轴与RD方向平行的织构。双态组织板材内的位错和亚结构使板材的室温拉伸强度提高,但是对高温拉伸变形的阻碍能力有限。板材中的织构是影响合金力学性能各向异性的主要因素。经980℃/1 h/AC+700℃/4 h/AC热处理后的板材横、纵向拉伸强度的差异最小,且都具有较高的室温拉伸性能和最佳的650℃拉伸性能。

Effects of Heat Treatment on Microstructure,Texture and Tensile Properties of Ti65 Alloy

Microstructure- and texture-evolution of Ti65 Ti-alloy plate were investigated, and the tensile deformation mechanism of the plate after heat treatment with different texture were discussed. The results show that heat treatment has a significant influence on the evolution of microstructure and texture of the plate. Equiaxed-, duplex- and lamellar-microstructure would be obtained after different heat treatment. The plate with equiaxed microstructure presented a B/T texture, while the c-axis of the α-phase and the rolling direction (RD) met at a 70°~90° angle; similar texture could be found in duplex- and lamellar-microstructure, meanwhile a new texture that the c-axis of the α-phase paralleled to RD could be found in the alloy. Room temperature tensile strength of plates with duplex microstructure could be enhanced by the dislocations and sub-structures, while had little effect on tensile properties at high temperature. Texture was found to be the main factor affecting the anisotropy of tensile properties of Ti65 plates, the plate would possess good tensile properties without obvious anisotropy in tensile strength after heat treatment of 980℃/1 h/AC+700℃/4 h/AC.