Inhomogeneity Screening Criterion for the ASTM E1921 T0 Estimate Based on the SINTAP Lower-Tail Methodology

The master curve brittle fracture toughness estimation method described in the ASTM E1921-11 test standard is based on a theoretical scatter and size effect assumption and makes use of a maximum likelihood estimation method to determine the fracture toughness transition temperature T0. The estimation method in E1921-11 is valid only for macroscopically homogeneous steels. If the steel is inhomogeneous, the maximum likelihood method applied in E1921-11 becomes unreliable. Here, a simple screening criterion, based on the SINTAP lower-tail estimation method, is proposed, and the efficiency and limitations of the criterion are shown for a variety of different types of inhomogeneity