316L 焊接接头不同区域低周疲劳特性与寿命预测方法

In this paper, the high-temperature low-cycle fatigue characteristics of three types of materials: 316L base metal, welded material, and welded joints were systematically studied. By introducing a fatigue life reduction coefficient into the traditional life prediction model, the low-cycle fatigue life prediction of different regions of the welded joints has been achieved. The results show that during the low-cycle fatigue process, all three materials undergo initial rapid hardening, then enter a stable cyclic state, and finally experience a rapid decrease in peak stress followed by failure. Among them, the base metal has the longest duration of hardening, while the hardening duration of the welded material and welded joints is relatively shorter. With the increase of strain amplitude, the fatigue life of the three materials significantly decreases. The fatigue life of the base metal is significantly higher than that of the welded material and welded joints, while the fatigue lifes of the welded material and welded joints are similar. Based on the low-cycle fatigue life of the base metal, the fatigue lifes of different materials are equivalently processed using a life reduction coefficient. Multiple life prediction models are selected to predict and evaluate the isothermal fatigue life of the three materials. It is found out that Generalized Strain Energy Damage Function (GSEDF) method can achieve the best agreement with measured result.