Numerical simulation of distortion and residual stresses of dual phase steels weldments

Due to the welding of low alloyed dual phase steels the local heat-input may lead to distortions and residual stresses that may influence the component production and in-service behaviour. In order to better characterize the component behaviour with respect to deformation and residual stresses, experimental and numerical investigations have been performed on sheet metals. Two different methods of consideration of phase transformation were considered, the use of the Koistinen-Marburger law while cooling as well as a direct method which uses the measured thermal strains as function of temperature characterizing also the phase transformation. Both methods show comparable results. The numerically determined transient temperature filed during welding was adjusted to the measured temperature profiles. The calculated distortions and experimental results show good agreement using the material data of base and weld metal for laser beam welds. The numerical simulation of the welding process was demonstrated as a powerful tool for the prediction of distortions and residual stresses of low alloyed dual phase steels in to be used in welded structures.