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用光学显微镜和拉伸试验研究了退火温度(Ta)对Ti-50.8Ni-0.3Cr合金显微组织和拉伸行为的影响。结果表明,合金原始态为拉拔纤维组织,退火时发生回复与再结晶。Ta=350～500℃时,为回复阶段,组织呈纤维状。Ta=550～590℃时,为再结晶阶段,纤维组织逐渐变成无畸变等轴晶粒,再结晶温度在570℃左右。Ta=600～800℃时,为晶粒长大阶段,显微组织呈粗大不均匀等轴晶。Ta对合金在低温(8℃)下的拉伸行为有显著影响,随Ta升高,应力诱发马氏体相变临界应力先降低后升高;350～500℃退火态合金的加工硬化能力和抗拉强度大于550～700℃退火态合金,而后者的延伸率则显著大于前者。当Ta大于650℃后合金的延伸率因晶粒粗化而减小。
The effect of annealing temperature (Ta) on the microstructure and tensile properties of Ti-50.8Ni-0.3Cr alloy was investigated by optical microscope and tensile test. The results show that the original state of the alloy is drawing the fiber structure, and annealing and recrystallization occur during annealing. Ta = 350 ~ 500 ℃, the recovery stage, the organization was fibrous. Ta = 550 ~ 590 ℃, the recrystallization stage, the fibrous tissue gradually become undistorted equiaxed grains, recrystallization temperature of about 570 ℃. Ta = 600 ~ 800 ℃, the grain growth phase, the microstructure was coarse heterogeneous equiaxed. Ta has a significant effect on the tensile behavior of the alloy at low temperature (8 ℃). With the increase of Ta, the critical stress of stress-induced martensitic transformation first decreases and then increases. The work hardening ability of annealed alloy at 350-500 ℃ and Tensile strength greater than 550 ~ 700 ℃ annealed alloy, while the latter the elongation was significantly greater than the former. When Ta is greater than 650 ℃, the elongation of the alloy decreases due to grain coarsening.