Electron-Microscopic Study ofthe Structure ofthe Surface Layer In High-Nitrogen 05Kh22AG15N8M2F Steel after Face Turning

摘要

The structure ofthe surface layer in higli-nitrogen 05Kh22AG15N8M2F steel workpieces subjected to face turning is studied by electron microscopy. It is found that improved machinability by VK8 alloy cutting tools is achieved at a cutting depth of 0.25 mm and that the cutting-tool life decreases sharply when the cutting depth increases to 1 mm. A nanocrystalline structure with nanocrystal sizes from several to several tens of nanometers forms in the surface layer upon face turning in the as-cast, hot-rolled, and thermally deformed states. The structure ofthe surface layer is characterized by a high dislocation density and large aus-tenite fragments with broad subgrains and deformation twins.