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Indexed by:期刊论文

Date of Publication:2015-04-01

Journal:MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

Included Journals:SCIE、EI、Scopus

Volume:629

Page Number:1-7

ISSN No.:0921-5093

Key Words:Hot forming; Boron steel; Advanced high strength steel; Martensite transformation; Martensite start temperature

Abstract:Non-isothermal tension and compression tests of 22MnB5 boron steel were carried out in this study. How different stress state influences the martensitic transformation of advanced high strength steel (AHSS) parts was analyzed. The analysis reveals that the martensitic transformation starting temperature (M-s) changes with different stress states. Specifically, the M-s temperature rises with increasing tensile stress, however, it rises first and then drops with increasing compressive stress. Moreover, a higher initial forming temperature leads to a higher M-s temperature under the same stress. Simulation of an actual hot-formed AHSS B-pillar together with the microscopic metallography, hardness and martensitic content shows that in higher tensile stress dominated area, the martensitic content and hardness are usually higher than in other areas. Although the stress can promote the M-s temperature, a lower cooling rate may lead to less martensite fraction. (C) 2015 Elsevier B.V. All rights reserved.