STP677: Variation of Fracture Toughness with Specimen Geometry and Loading Conditions in Welded Low Alloy Steels

    Penelon, A
    Graduate student, senior research scientist, and associate professor, Ecole Polytechnique, Montreal, Quebec,

    Bassim, MN
    Graduate student, senior research scientist, and associate professor, Ecole Polytechnique, Montreal, Quebec,

    Dorlot, JM
    Graduate student, senior research scientist, and associate professor, Ecole Polytechnique, Montreal, Quebec,

    Pages: 14    Published: Jan 1979


    Abstract

    There is an increasing demand for steels that have a good weldability and a high fracture toughness. An important example is that of the high strength low alloy (HSLA) steels used in pipeline construction in the Arctic regions. Presently, the fracture toughness of these materials is characterized primarily using Charpy impact tests which give empirical results and cannot be used in obtaining critical crack lengths at which catastrophic failure would occur.

    In this work, the J-integral was determined for the heat affected zone in welds of four low alloy steels containing various concentrations of niobium and molybdenum. Various procedures for evaluation of the J-integral were used such as the deep crack method on three-point bending specimens under controlled displacement, Charpy precracked specimens under static loading and three-point bending specimens under controlled loading. In the latter case, J was determined by the method of Lanteigne, Bassim, and Hay. Results obtained show a strong dependence of JIC on geometry. A model for the plastic zone size for three-point bending specimens which is an extension of the work of Lanteigne et al was used in the calculations.

    Keywords:

    fracture toughness, J-integral, heat affected zone, welded low alloy steels


    Paper ID: STP34928S

    Committee/Subcommittee: E08.04

    DOI: 10.1520/STP34928S


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