Potential resistance to transgranular fatigue crack growth of Fe–C alloy with a supersaturated carbon clarified through FIB micro-notching technique

The threshold stress intensity factor range (ΔKth) of water-quenched Fe–0.017C (wt.%) fully ferritic steel was determined using room-temperature fatigue tests on micro-notched specimens. The experimentally determined ΔKth was approximately 40.5% higher than conventionally predicted results. This extraordinary resistance to transgranluar fatigue crack propagation likely results from the strain–age hardening.