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Hot forging processes are influenced by numerous thermo-mechanical-metallurgical material phenomena, which interact strongly. In particular, the strains due to transformation-induced plasticity (TRIP) occurring during the forming process have a considerable influence on the distortion and residual stresses of the components. As TRIP strains are anisotropic they depend on the orientation and magnitude of the stress states superimposed to the phase transformation during cooling. By numerical modelling the impact of the TRIP effect can be analysed and taken into account during process design. However, required material data are poorly accessible to non-existent in literature. Therefore, this work focuses on the determination of characteristic values of TRIP for the material AISI 52100 considering dynamic effects. Tests were performed using hollow specimens which were thermo-mechanically loaded. An external stress was applied shortly before the start of the transformation and, in the case of reversible transformation plasticity, selectively released during the transformation phase. In this way, it was possible to determine phase-specific as well as load-dependent reversible transformation plasticity effects. The determined values for TRIP effect with and without backstress were transferred to a FE simulation and successfully validated with an experimental comparison. The material models and subroutines created are now to be validated on the basis of experimental forging tests by comparing distortion and residual stresses.
Keywords: Hot forging, FE-simulation, phase transformation, transformation-induced plasticity, AISI 52100© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.