An Inverse Method For Determining Steel Properties For Simulation Of Phase Transformations During Quenching

Accurate simulation of phase transformation during quenching of steels requires comprehensive knowledge of thermal and physical properties of the material. In case when the reliable material data are not available they can be obtained by two-stage inverse method proposed in the paper. It includes a Jominy test of a specimen with thermocouples. At the first stage, we obtain TTT diagrams by means of analyzing cooling curves for several regions of the specimen obtained from experiment results. The second stage includes correction of material thermo-physical properties, i.e. thermal conductivity and heat capacity for each phase as well as estimation of the latent heat for each phase transformation. Parameters fitting is carried out iteratively by comparing FEM simulation and experiment results. Varying of parameters is performed with evolutionary methods of multi-parameter optimization. The developed method is implemented in QForm commercial software and several experimental case studies are presented.