热挤压工艺对Ti-6Al-4V钛合金组织与性能的影响

研究了挤压温度和挤压比对Ti-6Al-4V钛合金挤压型材显微组织、织构及力学性能的影响.挤压温度在相变点T_β以上150~350℃、挤压比λ为25~85范围内时,型材动态再结晶均已完成,形成均匀的魏氏组织.型材的晶粒随挤压温度的降低和挤压比的提高而细化.型材织构在挤压比较低(λ=25)时强度较弱且为随机分布;当挤压比增加时,织构增强并有形成(1219)面纤维织构的趋势;当挤压比提高至85时,形成完整的(1219)面纤维织构.由于织构与晶粒细化的共同作用,使不同挤压条件下得到的Ti-6Al-4V钛合金型材综合力学性能比较稳定,即强度差异均不大于35 MPa,且延伸率和断面收缩率差值均不超过3%. 

Effects of hot extrusion on the microstructure and properties of Ti-6A1-4V titanium alloy

Experiments were performed to investigate the effect of extrusion ratio and temperature on the microstructure, texture and mechanical properties of Ti-6A1-4V titanium alloy. When the extrusion temperature is in the range of 150 to 350℃ above the phase transition temperature (T~) and the extrusion ratio (A) is in the range of 25 to 85, dynamic recrystallization has completed and there is a uniform Widmanst~tten structure in the extruded section. Increasing the extrusion ratio and decreasing the extrusion temperature can refine grains in the extruded section. When the extrusion ratio is low at 25, the texture strength is weak and random distributed. With the extrusion ratio increasing, the texture strengthens and is inclined to evolve into the (1219) fiber texture. The perfect (1219) fiber texture is achieved when the extrusion ratio is 85. The comprehensive performance of the extruded section obtained under different extrusion conditions is stable because of the combined effect of texture and grain refinement, the difference in strength is less than 35 MPa, and the differences in elongation and necking rate are all less than 3%.