STP1248

    Low Cost Lower Bound Toughness Measurements

    Published: Jan 1995


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    Abstract

    A method is proposed for determining the lower bound toughness of engineering steels based on impact loading of a modified Charpy specimen in a standard Charpy machine. The modified Charpy specimen employed here is nearly the same as the over-sized specimen studied previously by Bonenberger et al. The primary difference is that a sharp notch is employed to initiate the crack instead of pre-compression. A master curve is developed to relate the stress intensity developed at the tip of the notch to the time of crack initiation. An instrumented tup is then employed to give a force-time trace that can be interpreted to estimate the crack initiation time. Results are presented for the lower bound toughness of ASTM A 533, Type B, Class 1 steel over the temperature range from 0 to 40°C. These results are higher than the results reported by Bonenberger et al. for the same steel. The differences are attributed to the different techniques used to develop the starter crack in the modified Charpy specimen.

    Keywords:

    Charpy V-Notch, Instrumented Impact Test, Lower bound toughness


    Author Information:

    McCowan, CN
    NIST, Boulder Laboratories, Boulder, CO

    Dally, JW
    University of Maryland, College Park, MD

    Vigliotti, DP
    NIST, Boulder Laboratories, Boulder, CO

    Lee, OS
    University of Inchon, Inchon,


    Paper ID: STP14668S

    Committee/Subcommittee: E28.07

    DOI: 10.1520/STP14668S


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