SEDL / STP / STP514-EB / STP38824S

Relationship Between Charpy V and Fracture Mechanics K^Ic Assessments of A533-B Class 2 Pressure Vessel Steel

Hawthorne, JR
Naval Research Laboratory, Washington, D.C.

Mager, TR
Nuclear Energy Systems, Westinghouse Electric Corp., Pittsburgh, Pa.

Pages: 13    Published: Jan 1972

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Abstract

A cooperative program between the Naval Research Laboratory and the Westinghouse Nuclear Energy Systems Division was established to explore possible relationships between postirradiation Charpy-V and fracture mechanics (K^Ic) data. Initial efforts centered on a 6 ⅜-in. AS33 grade B Class 2 steel plate for which the preirradiation condition had been well characterized by Charpy-V (C^v), tension, dynamic tear, and fracture mechanics tests. Low (<250 F, 121 C) temperature-high fluence exposure conditions were utilized to obtain large C^v, tensile and plane strain fracture toughness (K^Ic) property changes over the preirradiation condition.

The simultaneous exposure of C^v and 1-in.-thick compact tension (CT) specimens produced comparable increases in C^v 30 ft ∙ lb transition temperature and K^Ic 65,000 psi √in. temperature. The C^v shelf energy was reduced from 74 to 46 ft ∙ lb. The postirradiation 75 F (24 C) yield strength was 127.3 ksi compared to a preirradiation value of 74.2 ksi; however, postirradiation yield strength decreased markedly with increasing temperature.

The test capacity of the 1-in. CT specimen was found insufficient for ASTM valid K^Ic determinations at the C^v shelf level temperature for pre- or postirradiation conditions. The estimate of postirradiation K^Ic at C^v shelf temperatures would require a CT specimen thickness of at least 5 in. The data suggest that, if power reactor surveillance programs restrict test specimen size to a maximum of 1-in. thickness, and if the measuring capacity of CT specimens is the function of thickness described by ASTM, an empirical or correlation-projection approach would be required to utilize fracture mechanics specimens in such programs.