Effect of grain refinement on mechanical properties in 25Cr-1N austenitic steel

Toshihiro Tsuchiyma, T. Onomoto, K. Tsuboi, Setsuo Takaki

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

The Fe-25Cr-1N alloy produced by solution nitriding possesses extremely high yield strength owing to the solid solution strengthening by nitrogen. However, it was found that the steel exhibited an insufficient elongation because of the brittle intergranular fracture caused during the uniform tensile deformation. This is due to the marked stress concentration at grain boundaries, which is derived from the grain coarsening caused during long time solution nitriding and the development of planar dislocation structure characteristic of high nitrogen austenitic steels. The most effective way to reduce the stress concentration at grain boundary during deformation should be grain refinement. In this study, grain refinement was attempted by the two-step heat treatment for the Fe-25Cr-1N(-Mn) alloy, and then the mechanical properties were investigated by means of tensile tests and fatigue tests. The two-step heat treatment resulted in the grain refinement of austenite to 20 microns in diameter. The intergranular fracture was greatly suppressed from 70% (as-solution-nitrided) to 10% (grain-refined) in area fraction by the grain refinement. In addition, elongation was markedly increased with local necking. The yield stress and tensile strength were also increased, and thus, the fatigue limit is also raised by more than 30%.

Original languageEnglish
Title of host publicationTHERMEC 2009
Pages3549-3554
Number of pages6
DOIs
Publication statusPublished - Feb 9 2010
Event6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2009 - Berlin, Germany
Duration: Aug 25 2009Aug 29 2009

Publication series

NameMaterials Science Forum
Volume638-642
ISSN (Print)0255-5476

Other

Other6th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2009
CountryGermany
CityBerlin
Period8/25/098/29/09

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All Science Journal Classification (ASJC) codes

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

Cite this

Tsuchiyma, T., Onomoto, T., Tsuboi, K., & Takaki, S. (2010). Effect of grain refinement on mechanical properties in 25Cr-1N austenitic steel. In THERMEC 2009 (pp. 3549-3554). (Materials Science Forum; Vol. 638-642). https://doi.org/10.4028/www.scientific.net/MSF.638-642.3549