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Published January 2014 | public
Journal Article

Deformation response of ferrite and martensite in a dual-phase steel

Abstract

Deformation response of ferrite and martensite in a commercially produced dual-phase sheet steel with a nominal composition of 0.15% C–1.45% Mn–0.30% Si (wt.%) was characterized by nanoindentation and uniaxial compression of focused ion beam-milled cylindrical micropillars (1–2 μm diameter). These experiments were conducted on as-received and pre-strained specimens. The average nanoindentation hardness of ferrite was found to increase from ∼2 GPa in the as-received condition to ∼3.5 GPa in the specimen that had been pre-strained to 7% plastic tensile strain. Hardness of ferrite in the as-received condition was inhomogeneous: ferrite adjacent to ferrite/martensite interface was ∼20% harder than that in the interior, a feature also captured by micropillar compression experiments. Hardness variation in ferrite was reversed in samples pre-strained to 7% strain. Martensite in the as-received condition and after 5% pre-strain exhibited large scatter in nanoindentation hardness; however, micropillar compression results on the as-received and previously deformed steel specimens demonstrated that the martensite phase in this steel was amenable to plastic deformation and rapid work hardening in the early stages of deformation. The observed microscopic deformation characteristics of the constituent phases are used to explain the macroscopic tensile deformation response of the dual-phase steel.

Additional Information

© 2013 Acta Materialia Inc. Published by Elsevier Ltd. Received 2 June 2013; received in revised form 30 September 2013; accepted 2 October 2013; Available online 28 October 2013. Brown University acknowledges support from Arcelor- Mittal Global R&D East Chicago. Mechanical testing of the micropillars and post-deformation microstructural characterization were performed at Brown University using the Experimental Shared Facilities that is supported by the NSF-MRSEC on Micro- and Nano-Mechanics of Structural and Electronic Materials (NSF Grant DMR-0520651) at Brown University. J.R.G. and R.M. acknowledge the infrastructure and support of the Kavli Nanoscience Institute, the Alexander von Humboldt Foundation for the financial support to R.M. (and R.M.'s host, G.M. Pharr) and J.R.G.'s ONR Grant (N000140910883).

Additional details

Created:
August 22, 2023
Modified:
October 25, 2023