STP706

    Application of High-Purity Ferritic Stainless Steel Plates to Welded Structures

    Published: Jan 1980


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    Abstract

    This investigation deals with the practical application of high-purity 18Cr-2Mo-Nb ferritic stainless steel plates 6, 12, and 25 mm thick to welded structures.

    In the V-notch Charpy test, the ductile-to-brittle transition temperature is about -30°C. The fracture toughness, Kc, determined by the deep-notch test is 350 kgf/mm2 · √mm for 12-mm-thick plate at -100°C. In the ESSO test, which has a temperature gradient, the Kc -value obtained is more than 400 kgf/mm2 · √mm at 0°C.

    The toughness of the gas tungsten-arc welded joints using 316 L (C < 0.02 percent) wire deteriorated to some extent, compared with that of the base metal. In the deepnotch test (notch position: fusion boundary, heat-affected zone), however, the Kc-value is more than 200 kgy/mm2 · √mm at 0°C.

    It is generally recognized that the safety of a weldable structural steel can be secured if its weld zone has resistance to brittle fracture initiation and the base metal has brittle fracture arresting properties. It can be concluded, therefore, that in thicknesses up to 12 mm this material can be used for welded structures at service temperature above 0°C because of its excellent fracture toughness.

    Since the toughness of 18Cr-2Mo-Nb deteriorates with aging above 300°C or in cold-working in excess of 10 percent, and even further deteriorates in strain-aging, these effects must be taken into account in its fabrication.

    Keywords:

    ferritic stainless steels, deep-notch test, ESSO test with temperature gradient, fracture toughness, welded joint, cold-work, aging, precipitation treatment


    Author Information:

    Nakazawa, T
    Assistant to manager, engineering metallurgist, manager, and research supervisor, Yawata Works, Nippon Steel Corp., Kitakyushu,

    Suzuki, S
    Assistant to manager, engineering metallurgist, manager, and research supervisor, Yawata Works, Nippon Steel Corp., Kitakyushu,

    Sunami, T
    Assistant to manager, engineering metallurgist, manager, and research supervisor, Yawata Works, Nippon Steel Corp., Kitakyushu,

    Sogō, Y
    Assistant to manager, engineering metallurgist, manager, and research supervisor, Yawata Works, Nippon Steel Corp., Kitakyushu,


    Paper ID: STP38204S

    Committee/Subcommittee: A01.30

    DOI: 10.1520/STP38204S


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