Residual stresses of laser-welded pressure vessel steel determined by X-ray and neutron diffraction

To gain insight into the quality of the laser weld, information about the residual stress state across the weld is very useful. In this contribution, the residual stress profiles for low-alloy carbon steel plates of P355NL1 grade, which were laser welded from both sides, are presented. To separate the effects of the production of plates from the welding process, the samples were annealed for stress relieving. Using X-ray and neutron diffraction, the surface and bulk RS profiles were obtained. From the obtained data, first, the difference in the character of the longitudinal (parallel to the weld axis) and the transversal component of the RS tensor can be seen. The longitudinal component has a tensile character with a maximum value approximately 500 MPa. Values and character of the transversal component vary strongly with depth and distance from the weld axis.