Novel 1.5 GPa-strength with 50%-ductility by transformation-induced plasticity of non-recrystallized austenite in duplex steels

Seok S Sohn, Hyejin Song, Min Chul Jo, Taejin Song, Hyoung Seop Kim, Sunghak Lee

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Needs for steel designs of ultra-high strength and excellent ductility have been an important issue in worldwide automotive industries to achieve energy conservation, improvement of safety, and crashworthiness qualities. Because of various drawbacks in existing 1.5-GPa-grade steels, new development of formable cold-rolled ultra-high-strength steels is essentially needed. Here we show a plausible method to achieve ultra-high strengths of 1.0~1.5 GPa together with excellent ductility above 50% by actively utilizing non-recrystallization region and TRansformation-Induced Plasticity (TRIP) mechanism in a cold-rolled and annealed Fe-Mn-Al-C-based steel. We adopt a duplex microstructure composed of austenite and ultra-fine ferrite in order to overcome low-yield-strength characteristics of austenite. Persistent elongation up to 50% as well as ultra-high yield strength over 1.4 GPa are attributed to well-balanced mechanical stability of non-crystallized austenite with critical strain for TRIP. Our results demonstrate how the non-recrystallized austenite can be a metamorphosis in 1.5-GPa-grade steel sheet design.

Original languageEnglish
Article number1255
JournalScientific reports
Volume7
Issue number1
DOIs
Publication statusPublished - 2017 Dec 1
Externally publishedYes

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Austenite
Plasticity
Ductility
Steel
Yield stress
Crashworthiness
Mechanical stability
Steel sheet
High strength steel
Automotive industry
Ferrite
Elongation
Energy conservation
Microstructure

ASJC Scopus subject areas

  • General

Cite this

Novel 1.5 GPa-strength with 50%-ductility by transformation-induced plasticity of non-recrystallized austenite in duplex steels. / Sohn, Seok S; Song, Hyejin; Jo, Min Chul; Song, Taejin; Kim, Hyoung Seop; Lee, Sunghak.

In: Scientific reports, Vol. 7, No. 1, 1255, 01.12.2017.

Research output: Contribution to journalArticle

Sohn, Seok S ; Song, Hyejin ; Jo, Min Chul ; Song, Taejin ; Kim, Hyoung Seop ; Lee, Sunghak. / Novel 1.5 GPa-strength with 50%-ductility by transformation-induced plasticity of non-recrystallized austenite in duplex steels. In: Scientific reports. 2017 ; Vol. 7, No. 1.
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