Determination of J-R Curves for Dissimilar Metal Welds Using Normalization Method and Compact Tension Specimens

Abstract

Normalization method is adopted in this paper to determine fracture resistance curves, i.e. J-R curves for dissimilar metal (DM) welds involved in nuclear reactor pressure vessels. Due to the restriction of material availability, three compact tension (CT) specimens containing a DM weld with a crack were utilized and tested under the guideline of ASTM fracture toughness test standard E1820 [1]. The test data of load versus load-line displacement were recorded during the tests, and directly applied to estimate crack extension using the normalization procedures. The J-R curves are then developed without the need of online crack extension measurement. Three J-R curves of DM welds were obtained using the standard 1T CT specimens and the normalization method. These resistance curves were evaluated through comparison with those obtained from small sized ½T CT specimens via ASTM E1820 standard procedures and those obtained from the electrical potential drop method. The results showed that the normalization method, ASTM E1820 standard procedures, and the electrical potential drop method can determine similar fracture resistance curves for DM welds in a good agreement. Among the three methods, the normalization method is of most attractive because it is the only one that does not need crack extension measurements, and thus test costs are saved.