Note on “Fracture Toughness Master Curve” Approach

Abstract

The validity of the fracture toughness master curve approach (FTMCA) was examined from discussion based on the Beremin model. It was shown that the transition curves of K_lc for various steels have similar temperature dependence irrespective of strength as proposed in FTMCA, due to cancelling between strength dependence of two exponents, i. e. the exponent of temperature dependence of the yield stress and the exponent of degree of scatter in local fracture stress. The similarity of the transition curves is lost depending on the degree of loss of the plain strain condition. The scatter of fracture toughness obeys the Weibull distribution of two parameters for high K_lc limitted with the lower boundary, which is expressed conveniently by that of three parameters in FTMCA.
In brief, FTMCA was rationalized and the principle for its refinement was shown.