Application of a Cleavage Fracture Stress Model for Estimating the ASTM E-1921 Reference Temperature of Ferritic Steels from Instrumented Impact Test of CVN Specimens without Precracking

AbstractA recently proposed semi-empirical cleavage fracture stress (CFS) model by the author based on the microscopic cleavage fracture stress, σf, for estimating the ASTM E-1921 reference temperature, T0, of ferritic steels from instrumented impact test (IIT) of Charpy V-notch (CVN) specimens without precracking has been demonstrated for steels with room temperature yield strength in the range 400-750MPa, including irradiated steels. The estimate of T0, based on the CFS model, TQcfs lies within a ± 20°C band, being conservative for most of the steels, but less conservative than TQIGC based on the IGC-procedure. CFS model enhances the validity and utility of the CVN IIT by enabling estimation of design-relevant master curve from unprecracked CVN specimens. In this paper, the method is further applied to some steels (both unirradiated and irradiated) reported in the literature most of which have only IIT data and static tensile data available. The method has also been applied to some IIT test results obtained at IGCAR for 9Cr-1Mo steel in various simulated weld-heat affected zone conditions. The results are compared with TQIGC or other estimates like TQBT or T0, if available