Effect of Surface Nano Crystallization on Tribological Properties of Stainless Steel
Résumé
A novel surface treatment has been developed in the present work to enhance the tribological properties of 316L Stainless Steel. This Technique involves the formation of a nanocrystalline layer ascribable to a grain refinement mechanism induced by repeated impact loadings supported by the surface. The resultant system has a layered structure, comprising nanometric grains (less than 100 nm) at the top and a strain hardened transition layer in the subsurface. Such a microstructural feature has the potential to significantlty enhance the surface hardness and to create a high compressive residual stress state. The tribological properties of the stainless steel are thus improved in terms of lower friction coefficient and increased wear resistance. Detailed studies on the response of the nanocrystalline surface layer to annealing at temperatures between 400°C and 600°C showed that an annealing at high temperature can offer much better tribological enhancement than low temperature annealings due to enhanced martensitic transformation.