Effects of Cr addition on Charpy impact energy in austenitic 0.45C-24Mn-(0,3,6)Cr steels

Seok Gyu Lee, Bohee Kim, Min Cheol Jo, Kyeong Min Kim, Junghoon Lee, Jinho Bae, Byeong Joo Lee, Seok Su Sohn, Sunghak Lee

Research output: Contribution to journalArticle

Abstract

Effects of Cr addition (0, 3, and 6 wt%) on Charpy impact properties of Fe-C-Mn-Cr-based steels were studied by conducting dynamic compression tests at room and cryogenic temperatures. At room temperature, deformation mechanisms of Charpy impacted specimens were observed as twinning induced plasticity (TWIP) without any transformation induced plasticity (TRIP) in all the steels. At cryogenic temperature, many twins were populated in the Cr-added steels, but, interestingly, fine ε-martensite was found in the 0Cr steel, satisfying the Shoji-Nishiyama (S[sbnd]N) orientation relationship, {111}γ//{0002}ε and < 101 >γ//< 112¯0 >ε. Even though the cryogenic-temperature staking fault energies (SFEs) of the three steel were situated in the TWIP regime, the martensitic transformation was induced by Mn- and Cr-segregated bands. In the 0Cr steel, SFEs of low-(Mn,Cr) bands lay between the TWIP and TRIP regimes which were sensitively affected by a small change of SFE. The dynamic compressive test results well showed the relation between segregation bands and the SFEs. Effects of Cr were known as not only increasing the SFE but also promoting the carbide precipitation. In order to identify the possibility of carbide formation, a precipitation kinetics simulation was conducted, and the predicted fractions of precipitated M23C6 were negligible, 0.4–1.1 × 10−5, even at the low cooling rate of 10 °C/s.

Original languageEnglish
Pages (from-to)21-30
Number of pages10
JournalJournal of Materials Science and Technology
Volume50
DOIs
Publication statusPublished - 2020 Aug 1

Keywords

  • Austenitic high-Mn steels
  • Charpy impact energy
  • Split Hopkinson pressure bar
  • Stacking fault energy (SFE)
  • Transformation induced plasticity (TRIP)
  • Twinning induced plasticity (TWIP)

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials
  • Mechanical Engineering
  • Polymers and Plastics
  • Metals and Alloys
  • Materials Chemistry

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