Fracture pattern of stainless Cr–Mn–N steel with nanostructured surface layers at cryogenic temperature

Effect of deformation treatment of the surface of stainless austenitic Cr–Mn–N steel on its structure, mechanical properties and fracture behavior at -196$^\circ$C has been studied. Structure refinement, decrease in the lattice parameter of austenite and strain aging with the formation of CrN and Fe$_2$N particles occurs during processing in the nearsurface layer. After processing, the steel has an increased yield strength and work hardening, but reduced ductility and toughness compared to the quenched state. Dimple fracture of near-surface layers is facilitated by a decrease in internal stresses associated with the release of nitrogen from interstitial positions and the formation of nitrides.