Synergistic deformation pathways in a TWIP steel at cryogenic temperatures: in situ neutron diffraction

Research output: Contribution to journalArticlepeer-review

Authors

  • Lei Tang
  • Li Wang
  • Huibin Liu
  • Saurabh Kabra
  • Yulung Chiu

Colleges, School and Institutes

External organisations

  • School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.

Abstract

High manganese steels are promising candidates for applications in cryogenic environments. In this study, we investigate the mechanical and microstructural responses of a high manganese twinning induced plasticity (TWIP) steel at a low-temperature range (from 373 to 77 K) via in situ neutron diffraction qualification and correlative microscopy characterization. During plastic deformation, stacking fault probability and dislocation density increased at a faster rate at a lower temperature, hence, higher dislocation density and denser mechanical twins were observed, confirmed by microscopic observation. Stacking fault energy was estimated, dropping linearly from 34.8 mJm−2 at 373 K to 17.2 mJm−2 at 77 K. A small amount of austenite transferred to martensite when deforming at 77 K. The contributions to flow stress from solutes, grain boundary, dislocation, and twinning were determined at different temperatures, which shows that the high work strain hardening capacity of the TWIP steel originates from the synergetic strengthening effects of dislocations and twin-twin networks. These findings reveal the relationship among stacking fault energy, microstructure, and deformation mechanisms at the low-temperature range, paving a way in designing TWIP steels with the superb mechanical performance for cryogenic applications.

Details

Original languageEnglish
Pages (from-to)943-958
Number of pages16
JournalActa Materialia
Volume200
Early online date28 Sep 2020
Publication statusPublished - Nov 2020

Keywords

  • Cryogenic temperatures, Deformation twinning, Neutron diffraction, Deformation pathways