STP1072: Specimen Size Effects in Charpy Impact Testing

    Alexander, DJ
    Oak Ridge National Laboratory, Oak Ridge, Tennessee

    Klueh, RL
    Oak Ridge National Laboratory, Oak Ridge, Tennessee

    Pages: 13    Published: Jan 1990


    Abstract

    Full-size, half-size, and third-size specimens from several different steels have been tested as part of an ongoing alloy development program. The smaller specimens permit more specimens to be made from small trial heats and are much more efficient for irradiation experiments. The results of several comparisons between the different specimen sizes have shown that the smaller specimens show qualitatively similar behavior to large specimens, although the upper-shelf energy level and ductile-to-brittle transition temperature are reduced. The upper-shelf energy levels from different specimen sizes can be compared by using a simple volume normalization method. The effect of specimen size and geometry on the ductile-to-brittle transition temperature is more difficult to predict, although the available data suggest a simple shift in the transition temperature due to specimen size changes. The relatively shallower notch used in smaller specimens alters the deformation pattern, and permits yielding to spread back to the notched surface as well as through to the back. This reduces the constraint and the peak stresses, and thus the initiation of cleavage is more difficult. A better understanding of the stress and strain distributions is needed.

    Keywords:

    Charpy, fracture, size effects, constraint, cleavage, critical tensile stress, ductile-to-brittle transition temperature, upper-shelf energy, slip-line field theory, finite-element analysis


    Paper ID: STP24145S

    Committee/Subcommittee: E28.94

    DOI: 10.1520/STP24145S


    CrossRef ASTM International is a member of CrossRef.