2018 Volume 58 Issue 2 Pages 359-363
Subsurface microcracks developed in the Ti–Fe–O cross-rolled material were characterized in order to clarify the subsurface fatigue crack initiation. A considerable amount of microcracks in β platelets were detected. The {0001} transgraular microcracks in α grains predominantly generated at the β grain boundary between recovered α grain and recrystallized α grain, and grew into the recrystallized α grain along the basal plane, although the microcracks at the twist boundary of α grains and at the α-β interface were occasionally detected. Stress concentration around the microcrack in β platelets may assist the microcrack initiation on basal plane (transgranular facet) in neighboring α grain due to a combination of the shear stress and tensile stress normal to the basal plane at α-β boundary. The {0001} transgraular microcracks growth and/or coalescence occurred with the assistance of shear stress on prismatic plane such as {1010} steps.
