Surface Nano-crystallization of AISI 304 Stainless Steel through Shot Peening Technique

Nano-crystalline materials had attracted the attention of scientific community in recent days as they showed extraordinary properties in comparison to bulk materials. An attempt is made to synthesize nano-crystalline surfaces in AISI 304 stainless steel through shot peening techniques. The formations of nano-crystals over the surface were investigated using SEM, EDX and x-ray diffraction techniques. The effect of surface nano-crystallization on mechanical properties: Y. S, UTS, and fracture toughness were explored in the present research work. The shot peened surface showed ultrafine austenite grains and martensitic transformation at severely deformed locations. The XRD analysis proved formation of 40 nm crystals at shot peened surface. The formation of martensite and grain refinement had enhanced the mechanical properties significantly. The tensile strength of AISI 304 stainless steel had risen from 657 MPa to 747 MPa and fracture toughness of the materials had raised about 17%. (C) 2015 Elsevier Ltd. All rights reserved.