[en] Highlights: • A Finite Element Method was developed to simulate welding residual stresses in dual phase steel. • The residual stresses through the welded joint can be evaluated by FEM. • The coupled effects with thermal, metallurgical and mechanical behaviours were uncovered. • The validated FEM gives insights into the whole process of laser beam heat flux. • Experimental approach by neutron diffraction confirms the numerical approach. This study aimed at characterizing the residual stresses distribution of a DP600 undergoing a laser beam welding. The residual stresses in the ferritic phase have been experimentally determined by the use of the neutron diffraction technique. The results confirmed a gradient of residual stresses among different zones both on the top and below surfaces but also through the thickness of the fusion zone. Low compressive stresses were observed in the BM (Base metal) close to the HAZ zone (heat affected zone) whereas high tensile stresses were observed in the FZ (fusion zone). Two numerical modelling strategies were conducted: first with elastic plastic model (EP) and then with a visco-elastic plastic model (VEP) which takes into account the effect of phase transformation-induced volumetric strain. Both models allowed highlighting the residual stresses evolution through the different zones. Numerical results showed a difference in the residual stresses distribution depending on the model used. In the end, it appears that the high temperature, specific to the laser beam, is the main factor governing the residual stresses. When comparing simulation results with experimental data, the values converge well in some zones, in particular the FZ and the others less.