J-Integral Tearing Instability Analysis for 8-Inch Diameter ASTM A106 Steel Pipe.

An experimental investigation was performed to evaluate the applicability of using J-Integral tearing instability analysis to describe the fracture behavior of 8-inch diameter, nuclear grade, ASTM A106 steel pipe. J-Integral tests were performed on 1/2 T, 1 T, and 2 T plan compact specimens and compared to pipe bend tests. Two different J-Integral analyses were used to describe fracture behavior. In one analysis, the material was modelled by assuming elastic-perfectly plastic behavior, while a second analysis utilized measurements of mechanical response of the loaded structure including hardening of the steel. A series of nine fracture tests were performed on the 8-inch diameter pipes with computerized data acquisition of load, deflection and crack length. Crack lengths were measured using elastic compliance, and direct current potential drop techniques simultaneously. Evaluation of the J-Integral tearing instability analysis was performed using J versus T plots of each test. Results indicate that compact specimen J/sub I/-R curve test results agree with the J/sub I/-R curves from full size pipe bend tests. Further, J-Integral tearing instability analysis can accurately describe the ductile tearing behavior of 8-inch ASTM A106 steel pipe provided the actual load, displacement, crack length and hardening behavior is available. Such an analysis withmore » assumed elastic fully plastic behavior appears to produce conservative results.« less