Impact of Si and Al on Microstructural Evolution and Mechanical Properties of Lean Medium Manganese Quenching and Partitioning Steels

Simone Kaar*, Daniel Krizan, Reinhold Schneider, Christof Sommitsch

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Herein, the investigation of the tensile behavior of lean medium Mn Quenching and Partitioning (Q&P) steels containing 0.2 wt% C, 4.5 wt% Mn, and additions of 1.5 wt% Si or 1.3 wt% Al is concentrated upon. By the variation of the quenching temperature (TQ), different volume fractions of primary martensite (α′prim) are adjusted, influencing the subsequent microstructural evolution during Q&P processing. Using scanning electron microscopy (SEM), the final microstructure consisting of tempered martensite (α″), retained austenite (RA), partially bainitic ferrite (αB), and final martensite (α′final) is characterized. Furthermore, interrupted tensile tests at gradually increased strains are conducted to investigate the stability of RA against strain-induced martensite transformation (SIMT) and overall tensile behavior of lean medium Mn Q&P steels. The investigations manifest the formation of larger amounts of αB and consequently lower RA contents, when Si is substituted by Al. As an aftermath, the tendency to form α′final is significantly lower, compared with the Si-alloyed composition, reflected in the overall stress–strain behavior. Especially in case of the Si-alloyed samples containing RA fractions exceeding 15 vol%, an over-accelerated SIMT is observed, inducing failures occurring prior to necking, whereas for the Al-alloyed samples, a wider process window is obtained.

Original languageEnglish
Article number2000181
JournalSteel Research International
Volume91
Issue number10
DOIs
Publication statusPublished - 1 Oct 2020

Keywords

  • lean medium Mn Q&P steels
  • retained austenite stabilities
  • stress–strain behaviors

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry

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