Microstructural evolution and mechanical properties of short-term thermally exposed 9/12Cr heat-resistant steels

Wei Wang, Wei Yan, Wei Sha, Yiyin Shan, Ke Yang

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    11 Citations (Scopus)

    Abstract

    The microstructural evolution during short-term (up to 3000 hours) thermal exposure of three 9/12Cr heat-resistant steels was studied, as well as the mechanical properties after exposure. The tempered martensitic lath structure, as well as the precipitation of carbide and MX type carbonitrides in the steel matrix, was stable after 3000 hours of exposure at 873 K (600 °C). A microstructure observation showed that during the short-term thermal exposure process, the change of mechanical properties was caused mainly by the formation and growth of Laves-phase precipitates in the steels. On thermal exposure, with an increase of cobalt and tungsten contents, cobalt could promote the segregation of tungsten along the martensite lath to form Laves phase, and a large size and high density of Laves-phase precipitates along the grain boundaries could lead to the brittle intergranular fracture of the steels.
    Original languageEnglish
    Pages (from-to)4113-4122
    Number of pages10
    JournalMetallurgical and Materials Transactions A
    Volume43
    Issue number1
    Early online date13 Jun 2012
    DOIs
    Publication statusPublished - Nov 2012

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