IAEA Coordinated Research Project on Master Curve Approach to Monitor Fracture Toughness of RPV Steels: Effect of Loading Rate

The Master Curve (MC) approach procedure standardized in ASTM E1921 is defined for quasi-static loading conditions. However, the extension of the MC method to dynamic testing is still under discussion. The effect of loading rate can be broken down into two distinct aspects: 1) the effect of loading rate on Master Curve T_o values for loading rates within the loading rate range specified in ASTM E1921 for quasi-static loading, and 2) the effect of loading rate on Master Curve T_o values for higher loading rates. The IAEA CRP8 includes both aspects, but primarily focuses on the second element of loading rate effects, i.e. loading rate ranges above the upper limit of the E1921 standard and it comprises: - results of a round-robin exercise to validate the application of the Master Curve approach to precracked Charpy (PCC) specimens tested in the ductile-to-brittle transition region using an instrumented pendulum, - Master Curve data obtained at different loading rates on various RPV steels, in order to assess the loading rate dependence of T_o and compare it with an empirical model proposed by Wallin, and - the comparison of results from unloading compliance and monotonic loading in the quasi-static range.