The Influence Of Post-treatment Process On Welding Residual Stress State Of Joints

Along with the development of trains forward to high-speed and light-weight, thematerial and property of the bogies, especially fatigue strength is facing great challenge. Theresidual stress is the utmost factor of the bogies fatigue strength with T-joint. Based oncurrently production process of bogies, the process of TIG remelting for welding toe+chilling treatment after welding has been studied to improve residual stress state of weldingtoe and then improve fatigue strength of the joint. By optimizing the model of finite element,this paper further research for the influence of TIG remelting for welding toe+chillingtreatment on residual stress state of T-joint welding toe of steel and aluminum alloy. Andmeasure the residual stress values of welding toe region in different state of treatment byusing the blind-hole method, which are compared with caculation values.For the T-joint of steel, use the Finite Element Method to calculate the residual stressdistribution of welding state, TIG remelting state for welding toe region with different heatinput,spray treatment state for TIG remelting region with same chilling intensty but differenttemperature, spray treatmeng state for TIG remelting region with same temperature butdifferent chilling intensity. The results show that: comparing to the welding state, there is nosignificant change of residual stress of TIG remelting state for welding toe region; with theincrease of TIG remelting heat input,the longitudinal residual stress is increased gradually andstable at last, the width and depth of remelting zone is also increased and make the surface ofwelding toe transited smoothly;as the initial temperature of spraying treatment and chillingintensity increased,the longitudinal and transverse residual stress is decreased, and bothtranstied gradually from tensile residual stress to compressive residual stress, and the depth ofcompressive stress layer formed at welding toe region increases.For the T-joint of aluminum alloy, the results show that: comparing to the welding state,the residual stress of TIG remelting state for welding toe region is decreased; spraying treatedjoint under different temperature, the redidual stress values at welding toe region haspresented compressive stress from200℃;as the initial temperature increased,the longitudinaland transverse compressive residual stress is increased; with the increase of chilling intensityat300℃, the longitudinal and transverse compressive residual stress at welding toe isgradually increased, and the depth of compressive stress layer formed in welding toe regionincreases.