Numerical Study of the Plastic Behaviour of a Low Alloy Steel during Phase Transformation

IntroductionItiswellknownthaphasetrapsformationsplayanimPortantroleontheresidualstressesandstrainsinducedbythermalprocessessuchasweldingandquenching.lnthispaPer,wefocusourattentiononthebehaviourofsteelsduringphasetransformations.AtheoreticalaPproachhasbeenachievedbyLeblondetal1]andhasledtOamacroscopicmodelinthecaseofideal-plasticphases2]3].Thenthemodelhasbeengeneralizedtotakestrainhardeningphenomenaintoaccount4].ThetheoreticalaPproachhasbeenassessedandcompletedusingflniteelementsimulati…

Numerical Study of the Plastic Behaviour of a Low Alloy Steel during Phase Transformation

Phase transformations in steels play a major role on the generation of residual stresses and distortions during thermal processes such as welding and heat treatments. In this paper, we focus on the influence of phase transformations on the plastic behaviour of a low-alloy steel. It is now well known that the plastic strain rate can then be decomposed as the sum of two terms. The first one corresponds to classical plasticity while the second one is due to the evolution of the transformation and is usually referred to as corresponding to transformation induced plasticity. A theoretical approach of the problem has been achieved (1]2]3]] and a macroscopic model has been proposed in the case of ideal-plastic phases. The theoretical approach has been assessed and completed using micromechanical numerical simulations but these were based on rather coarse 3D meshes due to limited computer capabilities in the 80's. This paper presents new finite element micromechanical calculations using refined meshes to analyse the classical plastic behaviour and transformation induced plasticity. The results of the computations are discussed and compared with the calculations initially performed. Finally improvements of the macroscopic model are proposed.