FRACTURE CHARACTERISTICS OF STRUCTURAL METALS.
Quarterly progress rept. no. 1, 22 Jan-22 Apr 64,
TRW INC CLEVELAND OHIO
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This report was divided into two parts. The first consists of the results of a literature survey being conducted to assemble K sub IC data for possible use in handbook form. In addition, selected tests have been initiated to determine the influence of specimen geometry and processing conditions on the toughness parameter. The second section summarizes results obtained from a study to determine the effect of test conditions on the measurement of accurate K sub IC values from sheet specimens. The data presented in this section indicate that the initiation of slow crack growth can be categorized into three distinct types which correlate with the macroscopic fracture mode of the specimens. In the temperature region where no shear failure occurred, the initiation of slow crack growth was coincident with complete specimen failure. In the transition region, where the fracture mode contained both flat and shear areas, the onset of slow cracking was characterized by a discontinuity in the measurement of crack propagation pop in, while at temperatures where the fracture mode was completely shear, the initiation of slow crack propagation occurred with no obvious discontinuity.