Very early stage rolling contact fatigue crack growth in pearlitic rail steels

▶ Very early stage RCF crack growth in rail steels is very microstructurally influenced. ▶ Initially cracks grow along favourably aligned, strained prior-austenite (PA) grain boundaries. ▶ RCF crack initiation favoured at PA boundaries with pro-eutectoid (PE) ferrite. ▶ Very short RCF crack growth is restricted/halted at PA boundaries when un-favourably aligned. ▶ 3D early RCF crack growth and deformed PA grain shapes are linked to ratcheting flakes.