高载荷作用下Ti6242钛合金低周疲劳和保载疲劳损伤行为分析

Fracture behavior of low cycle fatigue and dwell fatigue of Ti6242 titanium alloy under high load

Ti6242作为一种力学性能优异的近α型钛合金,与其他近α和α+β型钛合金类似,在接近室温时表现出保载疲劳的特征。本研究借鉴钛合金保载疲劳敏感性随测试载荷提升而上升的变化规律,设计高载荷的低周疲劳和保载疲劳力学性能测试,结合微观组织观察、力学性能表征和断口分析,系统分析微观组织和高载荷作用下低周疲劳和保载疲劳损伤行为,建立微观组织与力学性能的联系,总结不同载荷条件下的断口特征与规律,评估高载荷测试条件下Ti6242钛合金保载疲劳敏感性,结果证明通过提高载荷来表征Ti6242钛合金的保载疲劳性能具有可行性。

As one kind of near alpha titanium alloys with excellent mechanical properties, Ti6242 alloy always shows the'dwell fatigue'characteristic, which is similar to other near α or α+β titanium alloys, especially at near room temperature. In this study,the low cycle fatigue and dwell fatigue tests under high load were designed according to the law of dwell fatigue sensitivity rising with the increase of test load. Combining with microstructure observation, mechanical property characterization and failure fracture analysis, the relationship between the microstructure and fracture behavior under high load low cycle fatigue and dwell fatigue tests was analyzed systematically. By summarizing the characteristics of failure fracture under room temperature tensile,high load low cycle fatigue test and high load dwell fatigue test, also comparing the dwell fatigue sensitivity of the Ti6242 alloy in this study with other Ti6242 alloys and other titanium alloys under different loading conditions, it is proved that increasing the fatigue load is a feasible way to characterize the dwell fatigue sensitivity of Ti6242 alloy.