STP995V2: A Combined Statistical and Constraint Model for the Ductile-Brittle Transition Region

    Anderson, TL
    Assistant professor, Texas,

    Pages: 21    Published: Jan 1988


    Abstract

    A model is presented which uses weakest link statistics to predict the fracture toughness of ferritic steels in the ductile-brittle transition region. This model is different from previous analyses in that it considers large-scale yielding and specimen geometry effects.

    The model is used to predict median crack-tip opening displacement (CTOD) transition curves for American Bureau of Shipping (ABS) EH36 steel. The shape of the predicted curves agreed very well with the experimental data, but the absolute position of predicted and experimental curves differed by as much as 20C. The model was also used to predict CTOD distributions at constant temperatures, although direct comparison with experimental data was not possible. Analysis of the predicted toughness distributions indicated that a three-parameter Weibull fit of fracture toughness data may result in a nonconservative estimate of lower-bound toughness. An alternative procedure for estimating lower-bound toughness is described, together with a method for determining an upper-bound transition temperature.

    Keywords:

    cleavage fracture, constraint, crack-tip opening displacement, ductile-brittle transition, ferritic steels, weakest link statistics, nonlinear fracture mechanics, fracture mechanics


    Paper ID: STP27727S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP27727S


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