Simulation of hot stamping considering self-tempering

The application of ultra-high-strength steel plates to automobile bodies has progressed to achieve weight reduction and collision safety, with expanding applications of hot stamping (HS) technology for components with tensile strengths of 1.5 GPa or more. HS simulations considering phase transformat...

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Main Authors: Mori Keitaro, Kubo Masahiro, Okamura Kazuo
Format: Article
Language:English
Published: EDP Sciences 2025-01-01
Series:MATEC Web of Conferences
Subjects:
Online Access:https://www.matec-conferences.org/articles/matecconf/pdf/2025/02/matecconf_iddrg2025_01003.pdf
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author Mori Keitaro
Kubo Masahiro
Okamura Kazuo
author_facet Mori Keitaro
Kubo Masahiro
Okamura Kazuo
author_sort Mori Keitaro
collection DOAJ
description The application of ultra-high-strength steel plates to automobile bodies has progressed to achieve weight reduction and collision safety, with expanding applications of hot stamping (HS) technology for components with tensile strengths of 1.5 GPa or more. HS simulations considering phase transformation for predicting formability, hardenability, and shape accuracy have been reported. The hardness of HS components obtained via die quenching is lower than that of martensitic structures obtained via water quenching, due to self-tempering from the temperature history below the martensite-transformation temperature (Ms point). Few HS simulations consider self-tempering. We established a material model to reproduce self-tempering behaviour accurately and verified hardness prediction after HS. Results: 1) The hardness of water-quenched martensite after tempering was measured, and the activation energy of the tempering reaction was calculated. Then, it became possible to linearly approximate the self-tempering martensite hardness during continuous cooling using the cumulative tempering parameter.2) We developed simulation technology of hot stamping that incorporates the effects of phase transformation, transformation plasticity, and self-tempering. By calculating the tempering parameters at each time step below the Ms point, the accuracy of hardness prediction after HS was confirmed.
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spelling doaj-art-cdca1eb81ad14959a2ce9cb5784fb7e22025-08-20T02:26:02ZengEDP SciencesMATEC Web of Conferences2261-236X2025-01-014080100310.1051/matecconf/202540801003matecconf_iddrg2025_01003Simulation of hot stamping considering self-temperingMori Keitaro0Kubo Masahiro1Okamura Kazuo2Kyusyu R&D Laboratory, Nippon Steel CorpSteel research Laboratory, Nippon Steel CorpGraduate School of Engineering, Osaka Univ.The application of ultra-high-strength steel plates to automobile bodies has progressed to achieve weight reduction and collision safety, with expanding applications of hot stamping (HS) technology for components with tensile strengths of 1.5 GPa or more. HS simulations considering phase transformation for predicting formability, hardenability, and shape accuracy have been reported. The hardness of HS components obtained via die quenching is lower than that of martensitic structures obtained via water quenching, due to self-tempering from the temperature history below the martensite-transformation temperature (Ms point). Few HS simulations consider self-tempering. We established a material model to reproduce self-tempering behaviour accurately and verified hardness prediction after HS. Results: 1) The hardness of water-quenched martensite after tempering was measured, and the activation energy of the tempering reaction was calculated. Then, it became possible to linearly approximate the self-tempering martensite hardness during continuous cooling using the cumulative tempering parameter.2) We developed simulation technology of hot stamping that incorporates the effects of phase transformation, transformation plasticity, and self-tempering. By calculating the tempering parameters at each time step below the Ms point, the accuracy of hardness prediction after HS was confirmed.https://www.matec-conferences.org/articles/matecconf/pdf/2025/02/matecconf_iddrg2025_01003.pdfhot stampingself-temperingsimulationphase transformation
spellingShingle Mori Keitaro
Kubo Masahiro
Okamura Kazuo
Simulation of hot stamping considering self-tempering
MATEC Web of Conferences
hot stamping
self-tempering
simulation
phase transformation
title Simulation of hot stamping considering self-tempering
title_full Simulation of hot stamping considering self-tempering
title_fullStr Simulation of hot stamping considering self-tempering
title_full_unstemmed Simulation of hot stamping considering self-tempering
title_short Simulation of hot stamping considering self-tempering
title_sort simulation of hot stamping considering self tempering
topic hot stamping
self-tempering
simulation
phase transformation
url https://www.matec-conferences.org/articles/matecconf/pdf/2025/02/matecconf_iddrg2025_01003.pdf
work_keys_str_mv AT morikeitaro simulationofhotstampingconsideringselftempering
AT kubomasahiro simulationofhotstampingconsideringselftempering
AT okamurakazuo simulationofhotstampingconsideringselftempering