SYMPOSIA PAPER Published: 01 January 1997

Estimation of Lower-Bound K on Pressure Vessel Steels from Invalid Data


Statistical methods are currently being introduced into the transition temperature characterization of ferritic steels. The objective is to replace imprecise correlations between empirical impact test methods and universal KIc or KIa lower-bound curves with direct use of material-specific fracture mechanics data. This paper will introduce a computational procedure that couples order statistics, weakest-link statistical theory, and a constraint model to arrive at estimates of lower-bound KJc values. All of the above concepts have been used before to meet various objectives. In the present case, the scheme is to make a best estimate of lower-bound fracture toughness when resource KJc data are too few to use conventional statistical analyses. The utility of the procedure is of greatest value in the middle-to-high toughness part of the transition range where specimen constraint loss and elevated lower-bound toughness interfere with the conventional statistical analysis methods.

Author Information

McCabe, DE
Oak Ridge National Laboratory, Oak Ridge, TN
Merkle, JG
Oak Ridge National Laboratory, Oak Ridge, TN
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Developed by Committee: E08
Pages: 198–213
DOI: 10.1520/STP12309S
ISBN-EB: 978-0-8031-5374-5
ISBN-13: 978-0-8031-2410-3