Enhancement of fracture strain during abrupt orthogonal strain- path changes in ferrite/martensite dual phase steel

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Enhancement of fracture strain during abrupt orthogonal strain- path changes in ferrite/martensite dual phase steel

MATSUNO Takashi, KINOSHITA Nanami, HOKIMOTO Keisuke, HAMA Takayuki, HONDA Yoshiaki

Abstract In multistage press forming, the scrutiny of work-hardening behavior attributed to abrupt strain path changes in deformation paths has been pivotal in the context of press formability. However, applying this method to stretch flanging presents a formidable complexity. In such scenarios, substantial deformations resulting from shear-cut processing and subsequent stretch-flange formation significantly influence the local fracture strains, a critical determinant of process success. Therefore, our investigation examined the impact of deformation path variations on the fracture strain of dual-phase steel sheets. A crucial facet of our experimental approach involved manipulating the strain level during the initial tensile deformation. Tensile deformation was extended beyond the onset of necking, culminating in the emergence of microvoids within the material. Following this preliminary extensive strain, successive tensile tests were conducted on diminutive round-bar specimens, subject to a 90º change in the deformation path, to investigate their influence on work hardening and fracture strain. The outcomes of the diameter-measuring tensile tests unveiled a pronounced cross effect during the early stages of deformation, particularly concerning work-hardening behavior. However, as the deformation advanced, the results conformed to the stress-strain curve observed in the same direction of tension. Notably, the fracture strain exhibited an approximately 10% enhancement attributable to the abrupt strain path change, thereby having the potential to augment the practical stretch flangeability.

Keywords
Ductile Fracture, Strain-Path Change, Post-Necking, Dual Phase Steel

Published online 4/24/2024, 6 pages
Copyright © 2024 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA

Citation: MATSUNO Takashi, KINOSHITA Nanami, HOKIMOTO Keisuke, HAMA Takayuki, HONDA Yoshiaki, Enhancement of fracture strain during abrupt orthogonal strain- path changes in ferrite/martensite dual phase steel, Materials Research Proceedings, Vol. 41, pp 1074-1079, 2024

DOI: https://doi.org/10.21741/9781644903131-118

The article was published as article 118 of the book Material Forming

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

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