Structure and Lattice Strains in the Surface Сr–Mn–N Steel Layer Formed by a Combination of Friction and Electron-Beam Treatments

Abstract

The effect of surface mechanical and heat treatment, which includes successive friction and electron-beam treatments, on the structure, mechanical properties, and the elastically deformed state of a 16.5 Cr–18.8 Mn–0.53 N–0.07 C steel has been studied in this work. The mechanical and heat treatment has been shown to refine the grain structure in the surface layer to a grain size of 2 μm, form a {100} 〈001〉 texture, and retain a deformation-hardened sublayer. A surface layer to 200 nm thick is enriched with oxygen, nitrogen, and carbon. X-ray diffraction has been used to study austenite lattice strains caused by residual stresses. The mechanical and heat treatment has been found to reduce the friction-induced elastic lattice contraction along the normal to the surface. The direction [100] is most sensitive to the effect of residual stresses and can serve as a marker when analyzing the nature of residual stresses in steels with structurally-changed plastically-undeformed surface layers.