CHANGES IN MICROSTRUCTURE AND PROPERTIES OF AUSTENITIC STEEL AISI 316 DURING HIGH-PRESSURE TORSION.

The effect of high-pressure torsion process in a new die on the structure and mechanical properties of corrosionresistant steel AISI 316 was studied. Deformation was carried out at room temperature, the number of deformation cycles was 7. In the process of high-pressure torsion, the structure of samples is considerably refined to nanostructured, so steel AISI 316 with an average grain size of 30 µm after deformation is refined to 80 - 100 nm. The tensile strength and yield strength values increase in seven passes from 595 to 1590 MPa and from 320 to 870 MPa, respectively. Relative elongation changes from 55 to 25 %, but remains at a sufficient level for an application. The initial structure of nondeformed steel has good ductility and demonstrates typical signs of ductile fracture. But with increasing HPT cycles the fracture mechanism changes from ductile to brittle, indicating a decrease in ductility of stainless steel AISI 316. [ABSTRACT FROM AUTHOR]