PSI - Issue 35

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ScienceDirect

Procedia Structural Integrity 35 (2022) 10–17 Procedia Structural Integrity 00 (2021) 000–000 Procedia Structural Integrity 00 (2021) 000–000

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© 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IWPDF 2021 Chair, Tuncay Yalçinkaya Abstract The considered highly alloyed TRIP-steel (TRansformation Induced Plasticity–TRIP) exhibits a phase transition from austenite to martensite during large deformation which leads to a remarkable strain hardening capability. However, the martensite evolution highly depends on temperature and stress state. Therefore, especially self heating during deformation has a great influence on the behavior of the material. A thermomechanically coupled viscoplasticity model is applied accounting for strain induced martensite formation and Lode-angle dependent strain hardening. Using fully thermomechanically coupled simulations of tensile and com pression tests the model is able to capture the observed asymmetric hardening behavior of the considered CrMnNi-steel as well as the recorded crossing e ff ect of yield curves at elevated strain rates. c 2021 The Authors. Published by Elsevier B.V. his is an open access article under the CC BY-NC-ND license (http: // creativec mmons.org / licenses / by-nc-nd / 4.0 / ) er-review under responsibility of IWPDF 2021 Chair, Tuncay Yalc¸inkaya. Keywords: strain rate sensitivity ; strain hardening asymmetry ; austenitic stainless steel Martensitic phase transformation (austenite → , α -martensite) and twinning are the main mechanisms behind the strain hardening behavior of metastable austenitic steels, see Rafaja et al. (2020) for a detailed overview. These special deformation mechanisms are surely the reason for many phenomena which have been reported for these steels like extreme ductility, progressive as well as stress state dependent strain hardening (Olson and Cohen (1975); Stout and Follansbee (1986); Miller and McDowell (1996); Iwamoto et al. (1998); Seupel et al. (2016); Seupel and Kuna (2017)) and unusual strain rate sensitivity ( Stout and Follansbee (1986); Andrade-Campos et al. (2005); Kru¨ger et al. (2009); Yoo et al. (2011); Pru¨ger et al. (2014)). The latter observation is the research subject of the present paper. Depending on whether the yield stress increases or drops with increasing strain rate the material shows a positive or negative rate sensitivity, respectively. The positive strain rate sensitivity of mild steels (Langseth et al. (1991)) and dual phase steels (Davaze et al. (2020)), the nearly vanishing (positive) sensitivity of high strength steels (Boyce et al. (2007); Wang et al. (2018)) as well as the negative strain rate sensitivity of TWIP-steels (Yang et al. (2017)) and 2nd International Workshop on Plasticity, Damage and Fracture of Engineering Materials Phenomenological modeling of thermomechanical coupling e ff ects of highly alloyed TRIP-steels at di ff erent stress states Andreas Seupel a, ∗ , Meinhard Kuna a a Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Lampadiusstrasse 4, 09599 Freiberg, Germany Abstract The considered highly alloyed TRIP-steel (TRansformation Induced Plasticity–TRIP) exhibits a phase transition from austenite to martensite during large deformation which leads to a remarkable strain hardening capability. However, the martensite evolution highly depends on temperature and stress state. Therefore, especially self heating during deformation has a great influence on the behavior of the material. A thermomechanically coupled viscoplasticity model is applied accounting for strain induced martensite formation and Lode-angle dependent strain hardening. Using fully thermomechanically coupled simulations of tensile and com pression tests the model is able to capture the observed asymmetric hardening behavior of the considered CrMnNi-steel as well as the recorded crossing e ff ect of yield curves at elevated strain rates. c 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of IWPDF 2021 Chair, Tuncay Yalc¸inkaya. Keywords: strain rate sensitivity ; strain hardening asymmetry ; austenitic stainless steel 1. Introduction Martensitic phase transformation (austenite → , α -martensite) and twinning are the main mechanisms behind the strain hardening behavior of metastable austenitic steels, see Rafaja et al. (2020) for a detailed overview. These special deformation mechanisms are surely the reason for many phenomena which have been reported for these steels like extreme ductility, progressive as well as stress state dependent strain hardening (Olson and Cohen (1975); Stout and Follansbee (1986); Miller and McDowell (1996); Iwamoto et al. (1998); Seupel et al. (2016); Seupel and Kuna (2017)) and unusual strain rate sensitivity ( Stout and Follansbee (1986); Andrade-Campos et al. (2005); Kru¨ger et al. (2009); Yoo et al. (2011); Pru¨ger et al. (2014)). The latter observation is the research subject of the present paper. Depending on whether the yield stress increases or drops with increasing strain rate the material shows a positive or negative rate sensitivity, respectively. The positive strain rate sensitivity of mild steels (Langseth et al. (1991)) and dual phase steels (Davaze et al. (2020)), the nearly vanishing (positive) sensitivity of high strength steels (Boyce et al. (2007); Wang et al. (2018)) as well as the negative strain rate sensitivity of TWIP-steels (Yang et al. (2017)) and 2nd International Workshop on Plasticity, Damage and Fracture of Engineering Materials Phenomenological modeling of thermomechanical coupling e ff ects of highly alloyed TRIP-steels at di ff erent stress states Andreas Seupel a, ∗ , Meinhard Kuna a a Institute of Mechanics and Fluid Dynamics, TU Bergakademie Freiberg, Lampadiusstrasse 4, 09599 Freiberg, Germany 1. Introduction

2452-3216 © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IWPDF 2021 Chair, Tuncay Yal ç inkaya 10.1016/j.prostr.2021.12.042 ∗ Corresponding author. Tel.: + 49-3731-39-3349. E-mail address: Andreas.Seupel@imfd.tu-freiberg.de 2210-7843 c 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review u der responsibility of IWPDF 2021 hair, Tu cay Yalc¸inkaya. ∗ Corresponding author. Tel.: + 49-3731-39-3349. E-mail address: Andreas.Seupel@imfd.tu-freiberg.de 2210-7843 c 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of IWPDF 2021 Chair, Tuncay Yalc¸inkaya.