Abstract: A 6-step room temperature equal channel extrusion (ECAP) test of equivalent strain to 1.02 was carried out on 316L austenitic stainless steel. The results show that the shear slip deformation, twinning deformation and grain fragmentation occur in the steel during ECAP extrusion, and equiaxed grains with average grain size of 80 nm and 61 nm are obtained respectively after 4 and 6 passes of extrusion. After 1 pass of ECAP extrusion, the tensile strength and the proof strength plastic extension of the steel increase from 674 MPa to 984 MPa and from 594 MPa to 922 MPa respectively, and the Vickers microhardness increases from 116.33 HV to 328.31 HV, but the plasticity decreases seriously, which can be improved by subsequent annealing at 600 ℃.

Key words: ECAP, 316L steel, nanoscale grain, mechanical properties