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

T. Tsuchiyama, T. Onomoto, K. Tsuboi, S. 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
    EditorsTara Chandra, Tara Chandra, Tara Chandra, N. Wanderka, N. Wanderka, N. Wanderka, Walter Reimers, Walter Reimers, Walter Reimers, M. Ionescu, M. Ionescu, M. Ionescu
    PublisherTrans Tech Publications Ltd
    Pages3549-3554
    Number of pages6
    ISBN (Print)0878492941, 9780878492947
    DOIs
    Publication statusPublished - 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
    ISSN (Electronic)1662-9752

    Other

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

    All Science Journal Classification (ASJC) codes

    • General Materials Science
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering

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