Numerical Simulation of Welding for Residual Stress Prediction of Low Carbon Steel

Abstract

Residual stress in welded structures causes distortion. Severe problems in welded structures leading to failure can be due to uneven distribution of plastic and thermal strain. In the present investigation, Gas Metal Arc Welding of carbon steel (ASTM 36) has been simulated and analysed using Numerical methods. Finite element software ANSYS workbench has been used for the analysis of butt welding of two similar plates. 3-D FEM has been carried out to predict the temperature profile, residual stress distribution and distortion produced during single-pass GMAW process. Also, the effect of variation of convective film coefficients (h) on the distribution and magnitude of the welding residual stresses has been simulated. The analysis includes a time-varying moving heat source, material deposition, temperature-dependent material properties, temperature-dependent plasticity and elasticity properties, transient heat transfer and mechanical behaviour. The temperature-dependent properties of ASTM 36 have been taken from standard data source and that are described up to liquid phase. A 20 node tetrahedral (solid 90) thermal solid has been considered for the thermal analysis, whereas an 8 node (solid 185) solid is used for structural analysis. Both the effects of conduction and convection have been considered in the present work. A sequential coupled thermo-mechanical analysis has been used in this study, and to simulate the filler material deposition, “element birth and death technique” which is introduced to incorporate non-linearity in the model, has been adopted. From this present analysis, the angular distortions have been seen due to the clamping constraint used in the model, but they are insignificant. The lowest value of equivalent stress and the maximum value of angular distortion has been found out for the same value of convective film coefficients (h) which is 500 W/m² °C.