双重时效对Ti1023合金低周疲劳行为的影响

研究了双重时效对Ti-10V-2Fe-3Al合金低周疲劳行为的影响。结果显示,高应变幅(△εt/2=1.5%,1.2%,1.0%)下,合金表现为循环软化;低应变幅(△εt/2=0.8%,0.6%)下,则表现为循环应力饱和。疲劳寿命测试结果表明,双重时效疲劳寿命和直接时效疲劳寿命相当,疲劳总应变幅和疲劳寿命满足Coffin-Manson方程。SEM断口形貌显示,双重时效后疲劳裂纹稳定扩展区有明显的疲劳条纹,疲劳裂纹以穿晶方式扩展,并伴随着撕裂棱和二次裂纹,但二次裂纹较直接时效大量减少。TEM形貌显示,不论是双重时效还是直接时效,疲劳后变形组织都很均匀。虽然双重时效和直接时效具有相当的疲劳寿命,但是这种工艺缩短了时效时间,节约了能源,能更好地满足实际工业生产需求。

Effect of Duplex Aging on Low Cycle Fatigue Behavior in Ti-10V-2Fe-3Al Alloy

The effect of duplex aging on low cycle fatigue behavior of Ti-10V-2Fe-3Al alloys was investigated. The cyclic stress response curves show that the cyclic softening occurs at the high strain amplitude of 1.5%, 1.2% and 1.0%. However, when the strain amplitude decreases to 0.8% and 0.6%, cyclic stress saturation appears. Low cycle fatigue life of duplex aging is similar to that of simplex aging. The relationship between cycle total strain amplitude and fatigue life fits to classic Coffin-Manson equation. The fractography analyses suggest that transgranular fracture with well-developed fatigue striations is the predominant failure mode. The plastic deformation traces and secondary cracks are also observed. TEM examination reveals that fatigue deformed microstructures are homogeneous for both duplex aging and simplex aging. Due to shortening operated time and saving energy, duplex aging is more beneficial to actual industrial production than simplex aging.