Referencing procedures and the PCVN test

New referencing procedures are under development which compute statistical bounds to fracture toughness predictions for three stress intensification rates, equivalent to static, dynamic, and dynamic bend testing. The predictions cover the full temperature range for ferritic steels, and they are based upon a set of standard Charpy (CVN) test data. A curve is fitted to the energy-temperature data (after a mathematical transformation), and the coefficients coupled with a set of tabulated constants define the fracture toughness-temperature relationship. The predictions have now been compared with measured fracture toughness values for a large number of heats of pressure vessel steel, of which a large proportion (about sixty heats) had not been included in the original data base from which the procedure was developed. The procedure has special interest in the context of PCVN testing. First, as a statistical procedure it is suspect since it strictly applies only to the population of data sampled in the current data base. If predictions were checked against a few PCVN tests, they would carry much greater weight. In turn, the referencing procedure would extend the PCVN data to cover the temperature range through the upper shelf, in which tests taken by standard procedures are not valid. It would also extend the results to include static and dynamic fracture toughness, and would show statistical bounds. Second, it supports the idea that PCVN test data can be given extended utility through correlation procedures, and in fact such procedures have been developed. The work highlighted the large variability in fracture toughness within plates