Interaction of carbon partitioning, carbide precipitation and bainite formation during the Q&P process in a low C steel

Farideh HajyAkbary, Jilt Sietsma, Goro Miyamoto, Tadashi Furuhara, Maria Jesus Santofimia

Research output: Contribution to journalArticle

85 Citations (Scopus)

Abstract

Theoretical understanding of the "quenching and partitioning" (Q&P) process allowed developing microstructures consisting of carbon-depleted martensite and retained austenite that deliver superior mechanical properties. Most of the models describing the Q&P process are limited to systems in which carbide precipitation in martensite and decomposition of austenite to bainite are totally suppressed. However, these reactions are often unavoidable, even in low-carbon steels containing a relatively high concentration of Si and Mn. This work investigates interactions between carbon partitioning, carbide precipitation and carbide-free bainite formation during the Q&P process of a 0.3C-1.6Si-3.5Mn (wt.%) steel with non-homogenous distribution of the alloying elements. It was found that prior to the partitioning step ε-carbide forms in martensite. The decomposition of this carbide is required for a full completion of the carbon partitioning from martensite to austenite. Slow kinetics of decomposition of ε-carbide retards the carbon partitioning process. Results show that a fraction of austenite becomes stable by carbon partitioning and does not decompose to bainite. In the specimens quenched to lower temperature, a higher fraction of austenite becomes stable and consequently a lower fraction of bainite is formed.

Original languageEnglish
Pages (from-to)72-83
Number of pages12
JournalActa Materialia
Volume104
DOIs
Publication statusPublished - 2016 Feb 1

Keywords

  • Bainite
  • Carbides
  • Microstructural modelling
  • Quenching and partitioning

ASJC Scopus subject areas

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

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