Weak zone shift in welded joints for low cycle fatigue
LI Yifei1, CAI Zhipeng1, TANG Zhinan1, PAN Jiluan1, LIU Xia1,2, SUN Lingen2
1. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China;
2. Process Department of Turbine Works, Shanghai Electric Power Generation Equipment Co., Ltd., Shanghai 200240, China
Abstract：Weak zones in welded joints due to low cycle fatigue can affect the safety of welded steam turbine rotors. This study analyzes the low cycle fatigue strength of welded 25Cr2Ni2MoV refractory steel steam turbine rotor joints. The strains in the weak zones of the welded joints are modeled statistically. The reason for the weak zone shift is studied using hardness tests and finite element analyses. The experimental results show that cracks develop in the weld and in tempered regions of the heat affected zone. The weak zone shifts from the weld to tempered regions with decreasing strain. With large strains, the plastic strain concentrates in the weld while with low strains, the weld stays in the elastic range. The large hardness gradient in the tempered region with sandwich construction increases the strain concentration.
李轶非, 蔡志鹏, 汤之南, 潘际銮, 刘霞, 孙林根. 焊接接头低周疲劳性能薄弱区转移[J]. 清华大学学报（自然科学版）, 2015, 55(10): 1056-1060,1066.
LI Yifei, CAI Zhipeng, TANG Zhinan, PAN Jiluan, LIU Xia, SUN Lingen. Weak zone shift in welded joints for low cycle fatigue. Journal of Tsinghua University(Science and Technology), 2015, 55(10): 1056-1060,1066.
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2015, Vol. 55 
