Effect of annealing temperature on microstructure and properties of stainless steel rings after high-pressure torsion

The effect of annealing temperature on the change in microstructure and properties of stainless steel rings after deformation by high-pressure torsion is studied. Analysis of specimen microstructure after deformation by high-pressure torsion at room and cryogenic temperatures shows that eight deformation cycles lead to a homogeneous nanostructure at both temperatures, but a finer-grained structure is obtained using cryogenic cooling. With deformation and cryogenic cooling a martensitic structure is obtained with a grain size of 0.2 μm, while at room temperature a microstructure of 0.5 μm consisting of a mixture of austenite and α‑martensite is obtained. Ductility properties obtained after such treatment are insufficient for further use. In order to increase the ductility properties and to check the possibility of preserving the microstructure when heated specimens after deformation specimens are annealed at 300–650 °C and exposure time of 15 min. The ultrafine grain structure formed in steel during deformation remains stable up to 600 °C.