In this project, the simulation done in the paper: "Solid-state phase transformation and strain hardening on the residual stresses in S355 steel weldments" [Sun et al., 2019] will be recreated, and - if possible - improved. This is done by using LSDyna’s material model MAT_UHS_STEEL, and since the efficiency was not given in the paper, it had to be found by trial and error. The efficiency was found to be 50% which is quite low according to the sources Jeberg [2005]; Karkhin [2013]. There were some differences between the data and the simulation done in [Sun et al.,2019], which was fist attributed to a wrong convection boundary condition. This was tested by lowering the convection constant to a fourth, but since this did not produce a significant change, this could not be the reason. Thereafter, it was found that if the efficiency was raised to 75%, there simulation fit the data well, and it could be used to predict the grain structure with a accuracy of 5%, where Sun et al. [2019] had an accuracy of 9%. Therefore it was concluded that this was an improvement of the original model.