The test of 8 pass cold extrusion of equal channel angular pressing (ECAP) with ratio of extrusion reduction 1.02 of each pass for 00Crl8Nil2 austenite stainless steel has been carried out. The results showed that the strength and hardness of steel increased obviously after two pass extrusion
then increased minor after third pass; due to interaction of slipping bands
with extrusion pass increasing
at 6th pass the slipping bands were separated into sub-grains which finally transformed into 300 nm new grain with large angular boundaries and at 8th pass 150 nm new grains occurred.