Study On The High-Cycle Fatigue Properties Of SUS301L Stainless Steel Welded Joint

In recent years,stainless steel is widely used in engineering structures,compared with traditional steel,stainless steel has better mechanical properties.In the field of rail transit,with the continuous development of China's high-speed railway development,the SUS301 L stainless steel was used to manufacture the train body due to its unique advantages.In the manufacturing process of the train body,welding is a common material connection method.The fatigue performance of welded joints affec ts the safety service life of the train.Therefore,the study on the fatigue performance of SUS301 L stainless steel welded joints has very important engineering significance and value.In this paper,the residual stress of SUS301 L stainless steel Laser-MAG hybrid welded joint specimen was tested.the high cycle fatigue test was carried out,at the same time,the effect of stress ratio and welding root on the fatigue life of t he joint was taken into account.then,the fatigue life of the joint was evaluated.The main work of the paper is as follows:(1)The test results show that the residual stress of sample joints is at a low level,and the closing effect of residual stress on fatigue crack propagation is weakened.Therefore,the influence of stress ratio should be considered in the high cycle fatigue test.(2)The high cycle fatigue test of SUS301 L stainless steel welded joint was carried out,and the effects of different stress ratios and removal of welding roots on fatigue life were discussed.The results show that the fatigue life of the joint decreases with the increase of the stress ratio.Removal of the weld root will cause the fatigue failure position to change and increase the S-N curve represented by nominal stress.(3)The fatigue life of sample joints was evaluated by using nominal stress method,structural hot spot stress method and notch stress method.In addition,when the hot spot stress and notch stress were used as fatigue damage parameters to characterize the fatigue life of the sample joints,the effect of removing welding roots on the fatigue life disappeared.(4)The modified design curve considering the effect of stress ratio in the IIW specification cannot accurately evaluate the fatigue life of the specimen joints studied in this paper.Considering the effect of stress ratio,the introduction of Walker equivalent stress can give a more reasonable evaluation and prediction of fatigue life of specimen joints.