Effects of solute segregation on tensile properties and serration behavior in ultra-high-strength high-Mn TRIP steels

Min Chul Jo, Jin Hyeok Choi, Hyungsoo Lee, A. Zargaran, Joo Hyun Ryu, Seok S Sohn, Nack J. Kim, Sunghak Lee

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Austenitic high-Mn TWinning- and Transformation-Induced Plasticity (TWIP and TRIP) steels are strong candidates for GPa-grade cold-rolled steel sheets. The reduction in C or Mn content from high-Mn TWIP steels help generate a TRIP mechanism and prevent serration. However, these high-Mn TRIP steels show low yield strength because of the inherent characteristics of austenite, and often contain a band-shaped segregation of solutes, making the steels acts as hetero-structural materials. Therefore, in this study, we investigate the effects of compositionally-segregated microstructures on tensile properties and serration behavior in precipitation-hardened high-Mn TRIP steels. The present TRIP steels showed high yield strength (778–824 MPa) and an excellent strength-ductility balance, along with serration in their stress-strain curves which could not be explained by existing theories of dynamic strain aging. A considerable amount of martensite was formed step by step as localized deformation bands passed through the specimen gage section, which implied that the serration occurred only when the transformation rate increased substantially. In microstructural aspects, the martensitic transformation occurred sequentially along Mn-segregated bands due to differences in austenite stability and Mn content between high- and low-Mn bands, thereby leading to discontinuous transformation and consequently the serrated flow.

Original languageEnglish
Pages (from-to)16-27
Number of pages12
JournalMaterials Science and Engineering A
Volume740-741
DOIs
Publication statusPublished - 2019 Jan 7
Externally publishedYes

Keywords

  • Austenitic high-Mn steel
  • Segregation
  • Serration
  • Transformation-Induced Plasticity (TRIP)
  • Twinning-Induced Plasticity (TWIP)

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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