Numerical simulations of a representative test of welding process are presented in this paper. A French vessel steel, which involves metallurgical phase transformations in solid state is considered in this work. The aim is to validate the thermal-metallurgical-mechanical models taking into account the metallurgical transformations in the finite element codes Sysweld (Framasoft) and Code Aster (EDF). The test is performed on a thin disc submitted to a thermal cycle loading by means of a CO2 laser beam, which leads to metallurgical phase transformations. The thermal, metallurgical and mechanical numerical results have been compared to the experimental results (temperatures, sizes of transformed zones, displacements and residual stresses and strains). The main objective of the numerical analysis is to have some results which enable to give some indications on the ability of the numerical codes to describe the observed phenomena. For that, it is necessary to simulate accurately the thermo-metallurgical history. The comparison of experimental results with the numerical ones leads to some interesting orientations related to the capacities of the considered models to describe the observed phenomena.