Cu addition effects on TRIP to TWIP transition and tensile property improvement of ultra-high-strength austenitic high-Mn steels

Jin Hyeok Choi, Min Chul Jo, Hyungsoo Lee, Alireza Zargaran, Taejin Song, Seok S Sohn, Nack J. Kim, Sunghak Lee

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Austenitic high-Mn steels have been nominated as desirable ultra-high-strength cold-rolled steels whose mechanical properties are greatly improved by powerful deformation mechanisms of transformation- and twinning-induced plasticity (TRIP and TWIP). In this study, an austenitic high-Mn TRIP steel was suggested to achieve a good strength-ductility balance, and 1–2 wt.% Cu was added as an element for increasing stacking fault energy (SFE) as well as an austenite stabilizer to exploit a transition from TRIP to TWIP. The non-Cu-added steel showed the highest yield and tensile strengths (502 MPa and 1137 MPa, respectively) and the lowest elongation (34.6%) with a serrated flow. Yield and tensile strengths decreased with increasing Cu content, while the elongation was the highest in the 1%-Cu-added steel. TRIP and TWIP mechanisms showed good agreements with calculated SFEs in consideration of (Mn,Cu)-segregated bands. In the non-Cu-added steel, the TRIP occurred step by step as localized deformation bands passed through the specimen gage section to activate the serrated flow, which were reduced (or improved) by the transition from TRIP to TWIP with increasing Cu content. In the 1%-Cu-added steel, overall tensile properties were improved (yield strength; 461 MPa, tensile strength; 1093 MPa, elongation; 65.1%) as both TRIP and TWIP were well homogenized to produce synergic effects.

Original languageEnglish
Pages (from-to)246-260
Number of pages15
JournalActa Materialia
Volume166
DOIs
Publication statusPublished - 2019 Mar 1
Externally publishedYes

Keywords

  • (Mn,Cu)-segregated band
  • Austenitic high-Mn steel
  • Serrated flow
  • Transformation-induced plasticity (TRIP)
  • TRIP to TWIP transition
  • Twinning-induced plasticity (TWIP)

ASJC Scopus subject areas

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

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