Microstructure, phase composition and hardness evolution in 316L stainless steel processed by high-pressure torsion

Jeno Gubicza, Moustafa El-Tahawy, Yi Huang, Hyelim Choi, Heeman Choe, János L. Lábár, Terence G. Langdon

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

A 316L stainless steel was processed by high-pressure torsion (HPT) to evaluate the grain refinement and phase transformation. The initial material was essentially a single phase γ-austenite with a coarse-grained microstructure of ~42μm but the grain size was reduced to ~45nm after 10 turns of HPT. In addition, there was a phase transformation and the initial γ-austenite transformed initially to ε-martensite and finally to α'-martensite with increasing strain. The dislocation density increased to an exceptionally high value, of the order of ~1016m-2, in the main α'-martensite phase after 10 HPT revolutions. The formation of the multiphase nanocrystalline microstructure yielded a four-fold increase in hardness to reach an ultimate value of ~6000MPa. The Hall-Petch behaviour of the HPT-processed alloy is compared directly with coarse-grained materials.

Original languageEnglish
Pages (from-to)215-223
Number of pages9
JournalMaterials Science and Engineering A
Volume657
DOIs
Publication statusPublished - Mar 7 2016

Keywords

  • Grain refinement
  • Hardness
  • Nanostructured materials
  • Phase transformation
  • Steel

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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