Annealing Effect on Wear Resistance of Nanostructured 316L Stainless Steel Subjected to Dynamic Plastic Deformation

Abstract

Bulk nanostructured 316L austenitic stainless steel (55) samples with nano-scale twin bundles embedded in nano-sized grains were synthesized by using dynamic plastic deformation (DPD). Subsequent thermal annealing of the as-DPD sample leads to a single austenitic structure with static recrystallized (SRX) grains in nanostructured matrix. Oil-lubricated sliding tests of ball-on-disc type were carried out for the as-DPD and the as-annealed DPD steel samples in comparison with coarse grained (CG) steel samples. Experimental results show that the as-DPD 316L steel exhibits a little enhanced wear resistance under a load of 10 N, and nearly identical wear resistance under a load of 30 N relative to that of the CG sample. After annealing, the wear resistance roughly follows the Archard equation under a load of 10 N. However, the wear resistance increases with increasing hardness, and decreases with a further increase in hardness under a load of 30 N. The highest wear resistance can be found in the DPD sample annealed at 750 degrees C for about 20 min, which is more than 46% higher than that of the CG steel sample. This phenomenon is originated from the microstructure with an optimized combination of strength and ductility as a result of moderate plastic deformation in SRX grained regions.