Crystal-plasticity finite-element simulations of two-step loading of a ferrite-martensite dual phase steel sheet
Takayuki HAMA, Yuto NAKATA, Naoki MIYAZAWA, Takashi MATSUNO, Yoshitaka OKITSU
Abstract. Ferrite-martensite dual-phase (DP) steel sheets are widely used for structural components of automobiles. The macroscopic mechanical properties, including the yield stress and work hardening, of DP steel sheets are strongly affected by the microstructural properties, including the mechanical properties, volume fraction, and grain geometries of each phase. When DP steel sheets are subjected to tension in the rolling direction followed by tension in the transverse direction, the stress level after the strain-path change becomes smaller than that under monotonic tension in the transverse direction. However, the deformation mechanism of this behavior is not understood and open to discussion. In this study, experiments and crystal plasticity finite-element simulations of the two-step loading of a DP980 steel sheet are conducted, and the mechanisms that induce the stress decrease after the strain-path change are discussed. The results of crystal plasticity finite-element simulations well reproduced the experimental results of the stress-strain curves and the stress decrease after the strain-path change. The simulation results showed that the stress decrease occurred because of the following mechanisms. The tensile stresses during the first loading in the rolling direction were much smaller in the ferrite phase than in the martensite phase, which yielded compressive deviatoric stresses in the ferrite phase after unloading. This stress reversal in the ferrite phase upon unloading assisted macroscopic yielding after the strain-path change, decreasing the stress level.
Keywords
Dual-Phase Steel, Two-Step Loading, Internal Stress
Published online 5/7/2025, 6 pages
Copyright © 2025 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Takayuki HAMA, Yuto NAKATA, Naoki MIYAZAWA, Takashi MATSUNO, Yoshitaka OKITSU, Crystal-plasticity finite-element simulations of two-step loading of a ferrite-martensite dual phase steel sheet, Materials Research Proceedings, Vol. 54, pp 957-962, 2025
DOI: https://doi.org/10.21741/9781644903599-102
The article was published as article 102 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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