室温复合加工及热处理对Ti-53Nb组织及性能的影响

Effects of Composite Processing at Room Temperature and Heat Treatment on Microstructure and Mechanical Properties of Ti-53Nb Alloy

采用室温ECAP+冷轧+冷旋锻复合变形方法制备了Ti-53Nb合金棒材,通过金相显微镜、扫描电子显微镜、单向拉伸试验等研究了合金室温及热处理后组织演变及β晶粒的长大行为,并分析了加工硬化和细晶强化效应。结果表明:室温抗拉强度由变形前的380 MPa,提升到了变形后的553 MPa,提高了45.53%,延伸率也在16%以上。随固溶温度升高,β晶粒长大速率加快;晶粒尺寸对合金的强化作用满足Hall-Petch关系式。在700℃,保温60 min的条件下,组织均匀呈细小等轴状,可以获得良好的强塑性匹配。

The bars of Ti-53Nb alloy were prepared by combined deformation method of room temperature equal channel bending channel deformation(ECAP)+cold rolling+cold rotary swaging. The evolution of microstructure and β-crystal growth were studied by metallographic microscope(MM), scanning electron microscope(SEM) and uniaxial tensile test after preparing process. The effects of work hardening and fine grain strengthening were analyzed with dislocation strengthening theory and Hall-Petch theory. The results show that the tensile strength increases from 380 MPa to 553 MPa before and after deformation and heat treatment, increased by 45.53%, and the elongation reaches 16%. The growing speed of β-crystal is accelerated with increasing the solid solution temperature, and the grain size dependence of strengthening follows the Hall-Petch equation. The microstructure exhibits uniform equiaxed grains after annealing at 700 ℃ for 60 min, which can match the requirement of strong plastic characteristics in applications.