Numerical Investigation on Heat Transfer and Residual Stress in a Butt Welded Plate

It is a well known fact that during welding, the metal at the welding zone gets melted and then solidifies, which results in shrinkage in all directions. Residual strain and stress distributions coming from shrinking are largely influenced by the nature and configuration of the welding process, metallurgical characteristics of weld, and the geometrical shape of the weld joint. The residual stress mainly depends on the thermal history cycle through which the specimen undergoes in the welding process. So these thermal history cycles are to be known in order to get a better knowledge of the welding phenomenon and to minimize the risk of failures. In this work, a detailed analysis has been carried out for predicting the heat flow pattern and stress distribution in an aluminum alloy plate during welding. In this study, the modified double ellipsoidal heat source distribution pattern is modeled and considered for the weld pool design. Elastic-plastic material properties at various temperatures are also considered for simulation. A detailed finite element analysis is carried out to predict the welding residual stress. In this, thermal analysis is carried out for actual variable welding speed and these transient thermal histories at various locations were numerically predicted and compared with experimental results. Further, these thermal results are used to predict the residual stress on the weld plate using finite element method.