Investigation Of TIG Remelting Technical To T Joints Weld Toe For High Speed Bogies

Along with the sixth railway rising up the speed, the fatigue problem of the bogies looms large. This paper research of T-MAG joints which are common used in bogies by using new compound treatment, which is adding TIG remelting procedure to the temporal manufacture procedure. TIG remelting procedure is using tungsten argon arc welding at the transition zone of the weld joints, which can make transition between the base metal and weld smoothly. IIW recommend this procedure to improve the weld structure fatigue strength, now it be used abroad in ocean flat roof, shipping, motor body and steel structure bridge.Through five group test sample three bending experiment ,which is weld ,annealing ,annealing and shot peening ,TIG remelting , TIG remelting and annealing and shot peening ,we get the S-N curve result. The reasons of new procedure which can improve the fatigue strength can be concluded to three points. Firstly it can reduce the weld toe stress concentration coefficient. Secondly it changes the weld exterior .Lastly it can refine the weld crystal. Due to residual stress is the main factor of the weld fatigue strength,we use ANSYS to simulate the T-MAG and T-TIG residual stress. The research found that TIG remelting modifies the residual stress of weld and weld toe, which can enhance the portrait tensile stress, this result provides the theory foundation to add annealing and spot peening after TIG remelting.From the research we can get a conclusion that TIG remelting can improve the T joints fatigue strength obviously, and it satisfies the demand of fatigue strength.