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Effect of Ti additions on micro-alloyed Nb TRIP steel

  • Jaehyuk Jung
  • , Seok Jae Lee
  • , Sungil Kim
  • , B. C. De Cooman*
  • *Corresponding author for this work
  • Pohang University of Science and Technology
  • POSCO

Research output: Contribution to journalJournal articlepeer-review

Abstract

In the present study, the influence of Ti-additions on the mechanical properties of Nb-microalloyed TRIP steel is investigated. Ti micro-alloying additions to multi-phase Nb TRIP steel result in a substantial increase of the yield strength and a reduction of strain hardening. The increase of the yield strength can be attributed mainly to grain refinement with a relatively small contribution of precipitation hardening. Based on general principles and well-known models of alloying strengthening, metallurgical reasons for the observed mechanical behavior of the steel can be formulated. The contribution of precipitation hardening is relatively small as Ti-addition result in the formation of coarse (Nb,Ti)(C,N) particles. The addition of Ti to a Nb-microalloyed TRIP steel leads to a pronounced enhancement of precipitation kinetics of (Nb,Ti)(C,N), thereby increasing their phase fraction. The precipitates coarsen and tend to form groups of aggregates of particles rather than single isolated particles with increasing intercritical annealing time. In addition, Ti-addition to Nb-microalloyed TRIP steel has a direct influence on the chemical composition of the precipitates, which become Ti-rich.

Original languageEnglish
Pages (from-to)857-865
Number of pages9
JournalSteel Research International
Volume82
Issue number7
DOIs
StatePublished - 2011.07

Keywords

  • Micro-alloying
  • Nb
  • Retained Austenite
  • Ti
  • TRIP steel

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