Three-dimensional finite element analysis to predict the different zones of microstructure in submerged arc welding

The temperature distribution and cooling rate during the welding process have significant effects on the mechanical and metallurgical properties of a weldment. The change in microstructure, grain growth, hardness and residual stress in a weldment are very dependent on the temperature distribution and cooling rate. In the present work a three-dimensional transient finite element analysis of heat transfer in arc welding has been done to predict the different zones of microstructures. The problem was solved by taking several important factors into consideration (such as temperature dependence of material properties, a Gaussian distribution for the welding arc, enthalpy, etc.). The model was indirectly verified by conducting some experiments on submerged arc welding. The weld metal zone, coarse-grained zone and fine-grained zone were theoretically estimated by using three-dimensional finite element analysis and compared with the experimentally measured values. It was found that theoretically estimated zones corresponded well to the experimentally measured zones. A correlation was also developed to estimate the arc radius from the weld metal zone.