Fusion Zone and HAZ Prediction Through 3-D Simulation of Welding Thermal Cycle

Abstract

An implicit centre difference scheme with a simplified heat source model has been implemented to simulate the transient 3-D thermal cycle. The parameters defining the heat source model, presented in this work, can easily be estimated unlike in the case of ellipsoidal or Gaussian heat source models. The transient temperature distribution was obtained with convection boundary conditions on all the three plate boundaries and top and bottom surfaces. The governing equations were represented in a finite difference form following centre difference implicit scheme. Jacobi iteration scheme with under-relaxation has been implemented to solve the system of difference equations. The temperature dependence of the thermo-physical properties have been incorporated by an iterative process subject to a predefined convergence criterion. The Jacobi iteration and iteration to accommodate variation of thermo-physical properties with temperature run simultaneously. The entire code has been written in VC++ environment. The numerical results for the fusion zone dimensions compared fairly well with those of experiments. Increase in plate thickness indicated increase in cooling rate. For thicker plate, cooling rate stabilised faster as compared to thinner plate.