Novel ultra-high-strength (ferrite + austenite) duplex lightweight steels achieved by fine dislocation substructures (Taylor lattices), grain refinement, and partial recrystallization

Seok S Sohn, Hyejin Song, Byeong Chan Suh, Jai Hyun Kwak, Byeong Joo Lee, Nack J. Kim, Sunghak Lee

Research output: Contribution to journalArticle

63 Citations (Scopus)

Abstract

Weight reduction from down-gauged high-strength steels has been an important issue in automotive industries to improve fuel efficiency. In addition to lightweight needs, automotive steels require an excellent combination of specific strength and ductility for forming complex shapes as well as improving crashworthiness qualities. Here in the present study, new ultra-high-strength (ferrite + austenite) duplex lightweight steels containing a low-density element of Al, which exhibit strength above 1 GPa and tensile elongation of 46%, have been developed. Improved tensile properties are associated with typical planar glide configurations and high dislocation density walls, configuring Taylor lattices, developed by very fine dislocation structures spaced with intervals between 50 and 100 nm. Deformation twinning having extremely small (about 5 nm) thickness and spacing is also activated, thereby leading to additionally enhanced ductility. The present lightweight steels have outstanding properties of strength and ductility, easy manufacturing process, and costs of alloying elements as well as reduced specific weight for automotive applications.

Original languageEnglish
Pages (from-to)301-310
Number of pages10
JournalActa Materialia
Volume96
DOIs
Publication statusPublished - 2015 Jun 26
Externally publishedYes

Keywords

  • Annealing
  • Duplex lightweight steel
  • Nanometric deformation twinning
  • Partial recrystallization
  • Taylor lattices

ASJC Scopus subject areas

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

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