High-energy X-ray diffraction study on the temperature-dependent mechanical stability of retained austenite in low-alloyed TRIP steels

R. Blondé*, E. Jimenez-Melero, L. Zhao, J. P. Wright, E. Brück, S. Van Der Zwaag, N. H. Van Dijk

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The stability of the retained austenite has been studied in situ in low-alloyed transformation-induced-plasticity (TRIP) steels using high-energy X-ray diffraction during tensile tests at variable temperatures down to 153 K. A detailed powder diffraction analysis has been performed to probe the austenite-to-martensite transformation by characterizing the evolution of the phase fraction, load partitioning and texture of the constituent phases simultaneously. Our results show that at lower temperatures the mechanically induced austenite transformation is significantly enhanced and extends over a wider deformation range, resulting in a higher elongation at fracture. Low carbon content grains transform first, leading to an initial increase in average carbon concentration of the remaining austenite. Later the carbon content saturates while the austenite still continues to transform. In the elastic regime the probed {h k l} planes develop different strains reflecting the elastic anisotropy of the constituent phases. The observed texture evolution indicates that the austenite grains oriented with the {2 0 0} plane along the loading direction are transformed preferentially as they show the highest resolved shear stress. For increasing degrees of plastic deformation the combined preferential transformation and grain rotation results in the standard deformation texture for austenite with the {1 1 1} component along the loading direction. The mechanical stability of retained austenite in TRIP steel is found to be a complex interplay between carbon concentration in the austenite, grain orientation, load partitioning and temperature.

Original languageEnglish
Pages (from-to)565-577
Number of pages13
JournalActa Materialia
Volume60
Issue number2
DOIs
Publication statusPublished - Jan 2012

Bibliographical note

Funding Information:
We acknowledge the European Synchrotron Radiation Facility for provision of synchrotron radiation facilities and thank the beam line staff for assistance in using beam line ID11. We thank J. Sietsma for useful discussions. This research was carried out under the project number M41.5.08313 in the framework of the Research Program of the Materials innovation institute M2i ( www.m2i.nl ).

Keywords

  • Crystal orientation
  • Martensitic transformation
  • Metastable phases
  • Synchrotron radiation
  • TRIP-assisted steel

ASJC Scopus subject areas

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

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