Modelling of phase transformations and transformation plasticity of a continuous casted steel 20MnCr5 incorporating segregations

Abstract

Modelling of phase transformations and transformation plasticity of a continuous casted steel 20MnCr5 incorporating segregationsModellierung der Phasenumwandlungen und der Umwandlungsplastizität eines stranggegossenen, geseigerten Stahls 20MnCr5 M. HunkelIn general, material data for heat treatment simulations are assumed to be isotropic and homogeneous (except the carbon dependency for case hardening simulations). But it was found for the conventional continuous casted case hardening steel 20MnCr5 (SAE 5120) that segregations lead to anisotropic and inhomogeneous properties especially during phase transformations. This paper reviews the work within the Collaborative Research Centre SFB 570 "Distortion Engineering" on determination of segregations and its influence on phase transformations and plasticity as well as the subsequent modelling and simulation.Keywords: Segregation / transformation / anisotropy / case hardening steel 20MnCr5 (SAE 5120) / modelling / Im Allgemeinen werden die Materialdaten für die Wärmebehandlungssimulation isotrop und homogen angesetzt (mit Ausnahmen wie der aufgekohlten Randschicht beim Einsatzhärten). Aber für einen konventionellen Einsatzstahl 20MnCr5 hat sich rausgestellt, dass Seigerungen insbesondere während der Phasenumwandlungen zu anisotropen und inhomogenen Materialeigenschaften führen. Diese Veröffentlichung gibt eine Übersicht über die Arbeiten des Sonderforschungsbereichs SFB 570 "Distortion Engineering" zu der Bestimmung von Seigerungen, deren Einfluss auf Phasenumwandlungen und Plastizität sowie die darauf aufbauende Modellbildung und Simulationen.Schlüsselwörter: Seigerungen / Umwandlung / Anisotropie / Einsatzstahl 20MnCr5 / Modellierung /

Some recent developments in modelling of heat‐treatment phenomena in steel within the collaborative research centre SFB 570 “Distortion Engineering”

“…Thus the investigation of phase transformations and TRIP requires additional considerations. We refer to [1].…”

“…In case of macro-segregations like in the steel 20MnCr5, one encounters an anisotropic strain due to stress-free transformations. We refer to [1]. For the TRIP strain e trip we propose (in the case of one forming phase p -for generalisations see [9], e. g.)…”

“…Examples for these steps are: * Primary shaping (casting, e. g.) with possible segregations * Forming (rolling, e. g.) with the formation of fibering and of residual stresses * Cutting (turning, e. g.) with the formation of residual stresses These three process steps will not be dealt with in this paper. In [1], results concerning segregation in steel 20MnCr5 (SAE 5120) and its influence on phase transformations and on plasticity are presented. For distortion-relevant results concerning forming and cutting in the context of the SFB 570 we refer to [4] and [5].…”

“…The chemical composition of 100Cr6 (used in SFB 570) and material parameters are reported in [13]. For the chemical composition of 20MnCr5 we refer to the conference contribution [1] as well as to [12]. Moreover, to study the carbon influence, specimens of 20MnCr5 were carburised up to 0.4 mass-% and 0.5 mass-%.…”

“…More concrete results related to the two steel qualities 100Cr6 (SAE 52100) and 20MnCr5 (SAE 5120) will be reported in [2] and [1], respectively. However, the methods applied, the modelling approaches, the strategies for preparation of experiments needed and data processing, as well as the verification and validation of models are of a more general character.…”