Investigation Of Surface Nanocrystallization Of A 316L Stainless Steel Induced By Supersonic Fine Particles Bombarding

A nanostructured surface layer was fabricated on a 316L stainless steel by using supersonic fine particles bombarding (SFPB) technique .The micro structure and mechanics property of the surface layer of sample was characterized by means of X-ray diffraction,transmission electron microscope,scan electron microscope,microhardness testing machine and surface roughness testing machine. The development mechanism and mechanics property of the surface layer was essentially probed. Experimented evidence show that the micro structure of the surface layer of sample was refined into nanoscale after SFPB treatment .The grain size is a few nanometers at the top surface layer,and gradually increases with the depth .The grain size at the surface gradually decreases with bombarded time until a steady-state value is obtained,and finally the value is a little increased .The deformation of the nano structured surface layer can be attributed to severe plastic deformation induced by the collision between the particles and the sample surface .For the bombarded samples,the microhardness of the surface layer is significantly enhanced compared with that of original sample,which can be primarily attributed to the grain refinement.