Effects of Specimen Size and Side-groove on the Results of J-R Fracture Toughness Test for LBB Evaluation

In this study, the effects of specimen size and side-groove on the results of the J-R test for leak-before-break (LBB) evaluation were investigated. A series of J-R tests were conducted at both RT and 316 degrees C, using three different sizes of compact tension (CT) specimens machined from SA508 Gr.1a piping material: 12.7 mm-thick 1T-CT, 25.4 mm-thick 1T-CT, and 25.4 mm-thick 2T-CT with and without side-groove. The results showed that side-grooving reduced the J-R curve for all specimens and the effect of side-grooving was more significant at 316 degrees C than at RT. As the thickness of the specimens decreased and the width of the specimens increased, the J-R curve slightly decreased at RT but it increased at 316 degrees C. However, the variation in the J-R curve of SA508 Gr.1a with the thickness and width of CT specimen was insignificant.