Surface modification of high carbon steel through microstructural engineering

Abstract

Surface modification of steel has been used for a decade to increase its hardness and impact resistance that withstand extreme operational condition. One of the successful approaches for this modification is using other materials as surface coating via physical or chemical bonding or diffusion of the element(s) into steel structure as an alloying element(s). Surface diffusion technique required the temperature to activate diffusion of elements into steel structure which may cause grain growth. In this study, we have demonstrated the success of using microstructural engineering for modifying the surface properties of high carbon steel. A controlled impact deformation was carried out via drop ball test to generate nano-grain martensitic structure through high deformation process combined with in situ recrystallizations which caused by generated heat through deformation. This newly formed structure on the surface of the steel exhibits high and uniform nano-structured (~40 nm) layer which has a smooth transition from the base material to the surface and has ultra-hardness of 14.29 GPa without compensating the fracture toughness. This new approach facilitates the surface modification of steel without adding any additional element or materials and is applicable for modifying the surface properties of high carbon steel which can be used in some industrial application.