An investigation into the reverse transformation mechanisms in the heat treatment of austenitic stainless steel

D. O’Sullivan, R. Raghavendra, M. Cotterell, I. Mészáros, D. A. Tanner

Research output: Contribution to journalArticle

Abstract

Cold working of austenitic stainless steel results in the formation of α0-martensite (ferromagnetic) within the host material (paramagnetic). The role of α0-martensite and carbide precipitation in the reverse transformation mechanism during the heat treatment of AISI 304 is presented. A magnetic Barkhausen noise (MBN) measurement technique was employed to characterize the transformation mechanisms. MBN was found to be an effective tool for studying the transformation mechanisms of austenite to α0-martensite during material deformation as MBN and the ferromagnetic phase showed a good correlation. AISI 304 specimens plastically strained to 51 % were subjected to annealing heat treatment (from 100°C to 1,100°C) for 30 minutes. The α0-martensite to austenite reversion mechanisms were found to have a significant effect on residual stress and materials magnetic properties, thus limiting MBN effectiveness in studying the reverse transformation process. Residual stresses go from tensile to compressive between 500°C and 600°C as a result of the transformation mechanisms, as the austenitic phase is larger than α0-martensite and therefore compresses the remaining α0-martensite. It is suggested that ε-martensite has a significant role in the dislocation structural mechanisms in the heat treatment of AISI 304.

Original languageEnglish
JournalMaterials Performance and Characterization
Volume7
Issue number4
DOIs
Publication statusPublished - Jun 14 2018

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Keywords

  • A-Martensite
  • Austenitic stainless steel
  • Carbide precipitation
  • Magnetic Barkhausen noise
  • Residual stress

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials
  • Polymers and Plastics
  • Metals and Alloys

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