SEDL / STP / STP631-EB / STP35556S

Dynamic Fracture Toughness of SA533 Grade A Class 2 Base Plate and Weldments

Logsdon, WA
professor, Mechanics Department, Westinghouse Research LaboratoriesThe Ohio State University, PittsburghColumbus, Pa.Ohio

Begley, JA
professor, Mechanics Department, Westinghouse Research LaboratoriesThe Ohio State University, PittsburghColumbus, Pa.Ohio

Pages: 16    Published: Jan 1977

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Abstract

Dynamic fracture toughness tests were performed on four base plate heats and six weldments of SA533 Gr A Cl 2 pressure vessel steel. Linear elastic K^Id results were obtained at low temperatures while J-integral techniques were utilized to evaluate dynamic toughness over the transition and upper shelf temperature ranges. Loading rates in terms of ˙K were on the order of 2 to 4 × 10⁴ ksi in∕s(2.2to4.4×104MPam∕s). Charpy and drop weight nil-ductility transition (NDT) tests were performed to permit a comparison of toughness results with the American Society of Mechanical Engineers (ASME) code reference toughness K^IR curve. Dynamic instrumented precracked Charpy tests on base plate material were included for a comparison with compact toughness (CT) specimen results. All dynamic fracture-toughness values of SA533 Gr A Cl 2 base, weld, and heat affected zone (HAZ) material exceeded the ASME code reference toughness K^IR curve. Fracture-toughness values obtained via small specimen dynamic J^Id tests (1.0 in. (2.5 cm) thick CT specimens) compared well with previously developed large specimen K^Id values. Dynamic instrumented precracked Charpy toughness values were also comparable at low temperatures but failed to meet minimum J specimen size limitations midway into the transition-temperature range. At this point, Charpy toughness values increased dramatically compared to J^Id results meeting a 25 J^Id/σ^f size criterion and, thus, should not be considered a valid representation of fracture toughness. True upper shelf dynamic fracture-toughness results are also presented. The point of crack initiation (which provides the minimum measured value of J^Id) was identified rather than the typical maximum load point.