Welding Journal - May 2012

A durability assessment of a weld joint needs the knowledge of residual stresses and distortion (Ref. 1). Thermal cycle history during welding is a necessary input for simulation of residual stresses. Many investigators have studied heat flow during arc welding analytically, numerically, and experimentally (Refs. 2–6). Analytical methods developed are capable of computing temperature distribution with reasonable accuracy. An approximate analytical solution for plate with finite thickness using Green’s function and effective heat source to compensate for Neumann boundary condition (Ref. 2) has provided a very efficient tool to quickly simulate the transient thermal cycle during welding. This closed form solution has a distinct advantage over a finite element procedure and doesn’t need a tedious procedure of modeling and discretization to be followed. This solution can be extended to multipass welding using the principle of superposition; however, a closed form solution considering convection and radiation heat losses is very difficult to achieve. Neglecting convection and radiation heat loss for the weld pool gives relatively high peak temperature values. Numerical techniques such as the finite element method are used increasingly by researchers particularly for complex weld geometries but this requires “tuning” or calibration of the heat source to get a solution with acceptable accuracy. In the present research work, a method to extend an approximate analytical solution for multipass welding is proposed and a temperature correction term is derived to account for convection and radiation heat loss from the weld. The authors have verified the proposed analytical solution experimentally and also with finite element simulation results obtained from ABAQUS to an acceptable accuracy of 90% for the problem being investigated.