Estimation of fracture toughness of reactor pressure vessel steels using automated ball indentation test

The automated ball indentation (ABI) test was utilized to develop a semi-nondestructive method for estimating the fracture toughness (KJC) in the transition temperature range. The key concept of the method is that the indentation deformation energy to the load at which the mean ball-specimen contact pressure reaches the fracture stress is related to the fracture energy of the material. ABI tests were performed for the reactor pressure vessel (RPV) base and weld metals at the temperatures of -150 .deg. C ∼ 0 .deg. C and the fracture toughness (estimated KJC) was calculated from the indentation load-depth data. For all steels the temperature dependence of the estimated fracture toughness was almost the same as that of the ASTM KJC master curve. The reference temperature (To) of the steels were determined from the estimated KJC versus temperature curves. The reference temperature was well correlated with the index temperature of 41J Charpy impact energy (T41J)