STP995V2: Effect of Prestrain on the J-Resistance Curve of HY-100 Steel

    I, Bar-On
    Assistant professor and associate professor, Worcester Polytechnic,

    FR, Tuler
    Assistant professor and associate professor, Worcester Polytechnic,

    WM, Howerton
    Senior engineer, Failure Analysis Associates, Newton, MA

    Pages: 15    Published: Jan 1988


    Abstract

    Metal forming and welding operations can introduce residual stresses into structural components. In this study the effect of prestrain on the J-resistance (J-R) curve of subthickness specimens of HY-100 steel was investigated. Prior to testing, the specimen blanks were subjected to four levels of tensile strain up to 10% prestrain. J-resistance curves were determined for unstrained material using multiple-specimen and single-specimen techniques and for the prestrain material using the single-specimen technique. In all cases a half-thickness, full-width, three-point bend specimen geometry was used. Irregularities in the J-resistance curves were correlated with distinct features on the fracture surfaces. In particular, discontinuities in the J-R curve were correlated with the location of ridges along the crack front. The J-R curves obtained after considering the effect of these discontinuities showed a definite influence of the prestraining: the fracture toughness JIc and tearing modulus T decrease with increasing levels of prestrain, with T being more sensitive to the prestrain level than JIc.

    Keywords:

    HY-100 steel, fracture toughness, J, -resistance curve, prestrain, crack deflection, crack branching, nonlinear fracture mechanics, fracture mechanics


    Paper ID: STP27711S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP27711S


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