Quantitative characterization of short fatigue crack and grain boundary interaction behavior in zirconium

Abstract

Short fatigue crack growth behavior of zirconium was quantitatively investigated through post-mortem electron backscattering diffraction analyses. Results show that the short fatigue crack growth was mainly transgranular, sensitive to crystallographic orientation which determined the slip systems within grains and often deflected at grain boundaries. The cracks propagated preferentially on prismatic slip planes and pyramidal slip planes due to higher Schmid factor for each grain. A set of crack deflection at grain boundaries was quantitatively analyzed. A combination of the geometrical compatibility factor, m', and twist angle, α, as well as the Schmid factor, m, were proposed to evaluate short fatigue crack growth across grain boundaries. It was found the short fatigue crack could cross grain boundaries on the conditions of m > 0.3, α < 40°, and m' > 0.3.