两种显微组织的Ti600合金低周疲劳行为

Low Cycle Fatigue Behavior of Ti600 Titanium Alloy with Two Types of Microstructure

利用扫描电子显微镜和激光共聚焦显微镜研究了Ti600合金在不同组织类型下的疲劳行为。结果表明,Ti600合金在总应变幅±0.6%～±1.0%范围内,无论是片层(LM)组织还是双态(BM)组织的试样均呈现循环软化现象。在相同的总应变幅条件下,BM组织的试样具有长的疲劳寿命。LM组织试样断口附近侧表面的裂纹易于发生连接,致使循环应力响应的有效面积快速减小,因此LM组织试样在较低的循环应力下发生疲劳断裂。

Effects of microstructural type on the low cycle fatigue behavior of Ti600 alloy were investigated by Laser Scanning Confocal Microscope（LSCM） and Scanning Electron Microscope（SEM）.The results demonstrate that whether specimens with LM（lamellar microstructure） or BM（bimodal microstructure） show cyclic softening within a total strain amplitude range from ±0.6% to ±1.0%.At the same total strain amplitude,the fatigue life of BM specimens is longer than that of LM specimens.The joint of cracks near the lateral surface of fatigue fracture specimens with LM lead to rupture quickly under lower cyclic stress,since the effective area for cyclic stress response is decreased rapidly.