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Effect of Microstructure on the Heat Affected Zone Toughness of High Nitrogen Containing Ni-Free Austenitic Stainless Steel(Materials, Metallurgy & Weldability)

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Abstract

This work was undertaken to examine the influence of Cr-nitride on impact property in heat-affected zone of high nitrogen containing Ni-free austenitic stainless steel. Cr-nitride precipitation of HAZ was simulated using the isothermal test and the Gleeble test by varying holding time and cooling rate, respectively. Impact toughness was determined by testing Charpy V-notch type impact specimens (55×10×5mm) between room temperature and 77K. Isothermal test results showed that the nose of each C curve (i.e., intergranular, cellular, and transgranular Cr_2N) was around 1173K. Cr_2N precipitation occurred sequentially at grain boundaries, by cellular precipitation, and, finally, by transgranular precipitation within the matrix. The amount of intergranular and cellular Cr_2N precipitation increased with increasing holding time or decreasing cooling rate. High nitrogen containing Ni-free austenitic stainless steel exhibited excellent impact toughness at room temperature. At cryogenic temperatures, the value of absorbed energy was decreased markedly, and ductile-to-brittle (DBT) transition behavior associated with brittle transgranular fracture was observed. Intergranular and cellular Cr_2N precipitation reduced impact property of HAZ at room temperature. In addition, embrittlement occurred due to grain boundary separation and fracture through cellular precipitation regions, initiated by Cr_2N. However, regardless of intergranular and cellular Cr_2N precipitation, impact toughness values of HAZ were not observed at cryogenic temperatures.

Journal

  • Trans. JWRI

    Trans. JWRI 30 77-, 2001

    Osaka University

Citations (2)*help

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Details

  • CRID
    1573668927070022144
  • NII Article ID
    110006486105
  • NII Book ID
    AA00867058
  • ISSN
    03874508
  • Text Lang
    en
  • Data Source
    • CiNii Articles

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