STP743: An Experimental Investigation of Creep Crack Growth in IN100

    Donath, RC
    Materials research engineer, AFWAL Materials Laboratory, Wright-Patterson Air Force Base, Ohio

    Nicholas, T
    Materials research engineer, AFWAL Materials Laboratory, Wright-Patterson Air Force Base, Ohio

    Fu, LS
    Ohio State University, Columbus, Ohio

    Pages: 21    Published: Jan 1981


    Abstract

    Sustained load crack growth in IN100 at 732°C (1350°F) is studied using two specimen geometries, a standard compact tension specimen, and a radially crack ring loaded in tension. The effects of specimen thickness on the growth rate are investigated covering a range from 5.6 mm to 18.3 mm (0.22 to 0.72 in.) in thickness. Only the thinnest specimens show a crack growth rate which is lower than that obtained from all of the other thickness specimens. Stress-intensity factor, net section stress, and the C*-integral were investigated as possible crack growth rate correlating parameters. The concept of an “effective” crack length determined from specimen compliance measurements is introduced as a measure of crack length for severely tunneled crack front geometries. Neither net section stress nor C* is found to be acceptable as a crack growth parameter based on data from both test geometries. Although K provides fair correlation, the phenomenology of creep crack growth prevents its description adequately with only a single parameter. In particular, the crack growth rate is observed to decrease from an initially higher value to a “steady state” rate for constant values for any of the correlating parameters investigated.

    Keywords:

    creep crack growth, crack propagation, compliance testing, linear elastic fracture mechanics, C*-integral, nickel-based alloy, temperature


    Paper ID: STP28797S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP28797S


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