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用示差扫描量热仪、X射线衍射仪、拉伸实验和循环实验研究了退火温度、形变温度和应力--应变循环对 Ti-50.8Ni-0.3Cr超弹性(SE)合金丝和弹簧相变、形变及应力循环特性的影响. 350-600 ℃退火态Ti--50.8Ni--0.3Cr合金 室温下呈SE特性, 室温组织由母相B2和TiNi$_{3}$组成. 退火温度显著影响合金的相变类型, 随退火温度升高, 合金的马 氏体相变温度升高, R相变温度先升高后降低, 应力诱发马氏体应力先降低后升高; 随形变温度的升高, SE弹簧的应力 诱发马氏体切应力增加; 随应力循环次数增加, SE弹簧的应变恢复率先快速衰减后趋于稳定. 预循环训练可增加弹簧SE 特性的稳定性. 要使该合金弹簧具有良好的SE特性, 退火温度应为400-550 ℃, 使用温度应在室温以上.

Effects of annealing and deforming temperatures, and the stress-strain cycle on the transformation, deformation and stress cycling characteristics of Ti-50.8Ni-0.3Cr superelastic (SE) alloy wires and coil springs were investigated with differential scanning calorimetry, X-ray diffraction, tensile test, and cycling test. The 350—600 ℃ annealing Ti-50.8Ni-0.3Cr alloy shows SE property at the room temperature, and the microstructure at the room temperature consists of parent phase. The annealing temperatures influence remarkably transformation type of the alloy. With increasing the annealing temperature the martensitic (M) transformation temperature increases, the R transformation temperature increases firstly then decreases, and the stress-induced M stress decreases firstly then increases. With increasing the deforming temperature the stress-induced M critical shear stress of the SE spring increases. The decline of recovery ratio is quick at the beginning of the stress-strain cycle, and the ratio is slow with the increasing of cycle number. The prior cyclic training can enhance the SE stability of the alloy spring. To obtain stable SE property for the alloy spring, the annealing temperature should be 400—550 ℃, and the using temperature should be over room temperature.