Figure 12 Numerical-experimental comparison of HAZ, during the first (A) and the second pass (B).
By comparing the numerical results with the experimental ones, it is possible to state that the used methodology is suitable to predict very accurately the temperatures distribution in the welded joint, without the need to perform a tuning process to opportunely calibrate the heat source.17,27,32,33,34,44
3.2 Mechanical analysis
The longitudinal residual stressesσy , induced from the longitudinal expansion and contraction of the material during the welding process, along thex -direction at the midsection (y = 124 mm, z = 4 mm) are shown in Figure 13A (line with marker). The self-equilibrium of the weldment is such that the tensile and compressive residual stresses are present at the weld seam and away from the welding line respectively. High tensile residual stresses are present in correspondence of the zones nearby the Welding Centre Line (WCL), due to the contraction resistance of the material as the cooling phase begins. Then, they decreased to zero, as the distance from the (WCL) increases, becoming compressive for the zones far from the weld seam. The transversal residual stresses σx along thex -direction in the midsection (y = 124 mm, z = 4 mm) are shown in Figure 13B. Tensile residual stresses are present in correspondence of the zones nearby the (WCL). Subsequently, they decreased as the distance from the (WCL) increased, up to 0, almost.