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

H. Ghassemi-Armaki, R. Maaß, S. P. Bhat, S. Sriram, J. R. Greer, K. S. Kumar

Research output: Contribution to journalArticlepeer-review

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 lm 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% prestrain 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.

Original languageEnglish (US)
Pages (from-to)197-211
Number of pages15
JournalActa Materialia
Volume62
Issue number1
DOIs
StatePublished - Jan 2014
Externally publishedYes

Keywords

  • Dual-phase steel
  • Electron microscopy
  • Mechanical behavior
  • Micropillar compression
  • Nanoindentation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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