Investigation of Specimen Geometry Effects and Material Inhomogeneity Effects in A533B Steel

摘要

The Master Curve method and the associated reference temperature, as defined in the new test standard ASTM E1921, is rapidly moving from the research laboratory to applications in the U.S. commercial nuclear power industry. The T_o reference temperature is very robust, and it has rapidly become a tool to investigate material inhomogeneity effects and constraint effects because it is capable of measuring differences imperceptible using earlier methods that have been used to define the ductile-to-brittle transition in structural ferritic steels. Previous work by the present authors has shown that T_o is sensitive to the specimen geometry used in its evaluation. While this geometry sensitivity is expected if shallow crack specimens are compared with deep crack specimens, a significant difference also appears to exist between deep crack C(T) and SE(B) geometries. This difference causes concern in the application of ASTM E1921 to regulatory decisions facing the US Nuclear Regulatory Commission. In this work a study is made to separate the effects of material inhomogeneity and specimen geometry for the same A533B pressure vessel material studied extensively in the previous work. The results show that the T_o differences due to material inhomogeneity can be separated from that due to specimen geometry, at least if the data set utilized is extensive enough.