STP856

    Experimental Observations of Ductile Crack Growth in Type 304 Stainless Steel

    Published: Jan 1985


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    Abstract

    J-integral fracture toughness tests were performed at room temperature on small compact tension (1/2TCT) specimens of stainless steel Type 304 (Unified Numbering System [UNS] S30400). The ductile crack growth resistance curve was measured with the multi-specimen heat tinting method and automatically recorded using the potential drop (PD) technique and an optical system. The first parts of the curves were different for each method, however, for larger Δa values the curves were nearly the same. Profile measurements of the stretch zone showed blunting to be best represented by the formula J = 3.5σfΔa. There was no distinct separation between the blunting and stable crack growth phenomena. A continuous process of alternating crack-tip stretching and ductile crack extension was observed from the very beginning up to final crack extension (about 3 mm). Ductile initiation (formation of first dimples) was measured at about 300 kJ · m−2 (Ji) and “onset of stable crack growth” was measured at about 750 kJ · m−2 (JQ).

    Keywords:

    crack initiation, stainless steels, temperature, J, -integral test, multi-specimen method, single-specimen test, optical crack extension recording, potential drop technique, crack-tip stretch, crack extension


    Author Information:

    de Vries, MI
    Research scientist and technician, Netherlands Energy Research Foundation ECN, Petten, ZG

    Schaap, B
    Research scientist and technician, Netherlands Energy Research Foundation ECN, Petten, ZG


    Paper ID: STP34525S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP34525S


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