The effects of N on the microstructures and tensile properties of Fe-15Mn-0.6C-2Cr-xN twinning-induced plasticity steels

Yeon Seung Jung, Singon Kang, Kookhyun Jeong, Jae Gil Jung, Young Kook Lee

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Three Fe-15Mn-0.6C-2Cr-xN (wt.%) twinning-induced plasticity (TWIP) steels with N concentrations of 0.02%, 0.09% and 0.21% were fabricated using a pressure-induction furnace. The variations in tensile properties and deformed microstructure as a function of N concentration were investigated. The yield and tensile strengths of the steels increased without a loss of total elongation as the concentration of N increased. The strain hardening rates (SHR) of the TWIP steels with 0.02% and 0.09% N decreased gradually as the true strain increased until failure. The SHR of the TWIP steel with 0.21% N decreased sharply until a strain of approximately 0.07 and increased with further strain, exhibiting the highest value at a strain of over 0.15. The addition of N delayed the kinetics of mechanical twinning, particularly secondary twinning. The TWIP steel with 0.02% N had many intersections between primary and secondary twins, at which α′ martensite formed. The TWIP steel with 0.09% N possessed few intersections because primary twins obstructed the growth of secondary twins. The TWIP steel with 0.21% N had primary twins with few secondary twins and intersections. The addition of N increased the critical strain for triggering serrations on the tensile stress-strain curves, indicating a reduction in dynamic strain aging (DSA). The TWIP steel with 0.21% N exhibited the highest SHR at large strains, despite the reduced twinning and DSA, because of both the thinning of the mechanical twins and the hardening of the twin boundaries as the N concentration increased.

Original languageEnglish
Pages (from-to)6541-6548
Number of pages8
JournalActa Materialia
Volume61
Issue number17
DOIs
Publication statusPublished - 2013 Oct 1

All Science Journal Classification (ASJC) codes

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

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