STP995V2

    Elastic-Plastic Fracture Mechanics Evaluations of Stainless Steel Tungsten/Inert-Gas Welds

    Published: Jan 1988


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    Abstract

    A combined experimental and analytical study of ductile crack growth in a high-toughness austenitic stainless steel weld was performed. The substantially greater yield strength of the weld metal relative to the base metal favored plastic deformation in the base metal adjacent to the weld. Accordingly, the analytical studies focused on the stress/strain interaction between the crack tip and the weld/base-metal interface.

    Experimental work included development of J-resistance curves from both compact (tension) specimen tests and pipe bend tests. To provide several ratios of weld size to specimen size, the compact specimens were of three planform sizes (0.5T, 1.5T, and 3T) machined from a tungsten/inert-gas (TIG) weldment, also known as a gas/tungsten-arc (GTA) weldment, in Type 304 stainless steel plate. A TIG-welded pipe test conducted by the David Taylor Naval Ship Research and Development Center was also analyzed.

    A clear dependence of the crack initiation toughness on the weld size relative to the specimen size was found.

    Elastic-plastic finite-element methods were used to model the tests. Because of stress/strain nonproportionality associated with local unloading due to crack growth, attention was focused on crack-tip integral parameters, such as Tp* and , that remain path independent under these conditions. However, an engineering J-estimation scheme also was employed in attempting to predict the load-carrying capacity of the welded pipe with a circumferential through-wall crack under bending.

    Keywords:

    experimental-analytical fracture mechanics, tungsten/inert-gas welds, submerged-arc welds, finite-element method, J, -integral, virtual crack extension , J, crack-tip opening angle, fracture mechanics, nonlinear fracture mechanics


    Author Information:

    M, Nakagaki
    Professor, Kyushu,

    CW, Marschall
    Senior research scientists and principal research scientist, Battelle Columbus Division, Columbus, OH

    FW, Brust
    Senior research scientists and principal research scientist, Battelle Columbus Division, Columbus, OH


    Paper ID: STP27710S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP27710S


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