Residual stress on the run out table accounting for multiphase transitions and transformation induced plasticity

International audienceThe development of harder and thinner new steel grades necessitates reasonably fast numerical simulations of forming processes in order to optimize industrial conditions through parametric studies. This paper focuses on the evolution of residual stresses of thin strips during cooling on the run out table. Since the problem involves multiphysics and non-linear processes, comprehensive and fully coupled numerical approaches may be difficult to use to design or optimize industrial conditions because of extensive computation times. Therefore, a simplified numerical simulation has been developed and consists in solving first the thermal problem coupled with multiphase transitions and then the mechanical problem accounting for thermal expansion, metallurgical deformation and transformation induced plasticity. Residual stress profiles through the strip thickness are also computed in order to evaluate classic flatness defects such as crossbow and longbow. A post-processing is also included in order to quantify out of plane displacements that would take place if the strip were cut off the production line. It consists in computing at finite strain the relaxation of residual stresses when the tension applied by the coiler is released. The proposed numerical strategy has been tested on common industrial conditions