The modelling of a weld is not only related to the heat flow in the thermal part of the simulations. Addition of additive material and the simplification of thermal and mechanical behaviour should be considered. The basic idea is to replace a complex physical process with a much simpler one. This brings not only approximations, but also the need for calibration procedures to determine the heat flow. In the present paper we aim to model the relationship between welding temperature variation depending on the time and depth, and to model the relationship between stress and distance from the heat source (welding).