Ductile inclusions in rail, subject to compressive rolling-sliding contact

▶ Ductile inclusions become 'pizza' shaped planes of weakness near-surface in rails. ▶ Ductile inclusions facilitate flake crack initiation and growth in dry contact. ▶ Ductile inclusions can initiate RCF cracking in water lubricated contact. ▶ Ductile inclusion number density and size vary significantly depending on rail steel source.