Evaluation of fracture toughness by the variation of crack length measurement method

The Direct Current Potential Drop(DCPD) method is the most commonly used method to evaluate the dynamic fracture resistance characteristics of a material. However, at using DCPD method in the dynamic fracture resistance test, there is a problem that the voltage drops sharply on the initiation of crack. For this reason mentioned above, the normalization method was suggested by ASTM E1820 which was revised recently, as a new method to evaluate the dynamic fracture resistance characteristic. The normalization method can be used to obtain a J-R curve directly from a load-load line displacement. In this study, we obtained two J-R curves from the dynamic fracture toughness test of two materials' weldment (SA508 Gr.1A, SA508 Gr.3A) for nuclear piping both by the DCPD and the normalization method