STP755

    A 2¼Cr-1Mo Pressure Vessel Steel with Improved Creep Rupture Strength

    Published: Jan 1982


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    Abstract

    In the ASME Boiler and Pressure Vessel Code, Sec. VIII, Div. 1, design allowable stress-intensity values are influenced by the creep rupture strength at temperatures higher than 450°C. Pressure vessels for such high-temperature service inevitably tend to be thickwalled unless a steel with high creep strength is used. In the case of a coal liquefaction reactor, for instance, a possible wall thickness would be approximately 300 mm or even greater with the use of conventional 2¼Cr-1Mo steel (SA336 F22).

    The objective of the present work was to develop a heavy-section 2¼Cr-1Mo steel with better creep strength by conducting a set of experiments with regard to the effect of microalloying elements. The best composition to obtain improved creep-rupture properties was found to be low Si-0.10C-2¼Cr-1Mo-¼V-Ti-B. With this composition, remarkable reduction in temper embrittlement susceptibility was also achieved. Other properties, such as weldability, low temperature toughness, and hydrogen embrittlement resistance, were similar to those of conventional 2¼Cr-1Mo steel.

    Keywords:

    creep rupture strength, microalloying, hardenability, microstructure, temper embrittlement, hydrogen assisted cracking, design stress intensity value, weld heat affected zone, base metal


    Author Information:

    Ishiguro, T
    Material Research Laboratory, The Japan Steel Works, Ltd., Muroran,

    Murakami, Y
    Research Laboratory, Muroran Plant, The Japan Steel Works, Ltd., Muroran,

    Ohnishi, K
    Material Research Laboratory, The Japan Steel Works, Ltd., Muroran,

    Watanabe, J
    Material Research Laboratory, The Japan Steel Works, Ltd., Muroran,


    Paper ID: STP28413S

    Committee/Subcommittee: A01.22

    DOI: 10.1520/STP28413S


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