Solid-state phase transformation incorporated welding simulation and prediction of residual stresses and deformations of ultra-high strength steel Strenx®960 MC
Ghafouri, Mehran (2018)
Julkaisun pysyvä osoite on
This study investigates prediction of transverse residual stresses as well as angular and bending distortions in bead on plate welding of the low carbon ultra-high strength steel Strenx®960 MC by developing a three-dimensional sequentially-coupled thermal, metallurgical and mechanical finite element model in ABAQUS. Modelling the heat source was carried out considering a volumetric heat source based on the Goldak’s double ellipsoidal heat source model implemented in DFLUX user subroutine. Modelling the heat loss was accomplished using the FILM user subroutine. The effect of solid-state phase transformation during welding was included in numerical model through applying volumetric changes induced by austenitic, bainitic and martensitic transformations based on dilatometric tests and continuous cooling transformation (CCT) diagram of the material under investigation. User subroutine USDFLD was developed to determine volume fraction of present phases based on the available mathematical kinetics models for diffusive and dispalcive transformations. Modification of thermal expansion coefficient was performed using user subroutine UEXPAN in ABAQUS in which volumetric changes during phase transformations were incorporated. The results of simulations indicate that distortions and residual stresses in particular, are significantly affected by solid-state bainitic and martensitic transformations.