Low carbon steel with nanostructured surface layer induced by high-energy shot peening

Nanostructured surface layer can be successively obtained in a low carbon steel plate by means of the high-energy shot peening (HESP) technique. The average grain size in the top surface layer can be as small as a few nanometers, and gradually increases with the distance from the surface. The thickness of the nanostructured surface layer is not less than 20 μm. The yield strength was found to be significantly enhanced without considerable degradation of ductility and toughness. The strengthening of material after the HESP treatment can be attributed to work-hardening and formation of surface nanostructure.