The effect of pulse frequency on the microstructure and surface mechanical properties of composite coatings on the surface of AISI304

Abstract

This study investigated the in-situ formation of TiC–Al ₂O ₃ and TiB ₂–TiC–Al ₂O ₃ composite coatings on the surface of austenitic 304 stainless steel by the use of 3TiO ₂-4Al-3C and 3TiO ₂-4Al-B ₄C powder and argon arc cladding technology. The effects of pulse frequency 0–200 Hz on microstructure and mechanical properties of coating are studied. Microstructural study of coatings showed that the high cladding temperature triggered the self-propagating high-temperature synthesis of reinforcement phases TiC, Al ₂O ₃, and TiB ₂ at the surface of 304 stainless steel. The use of pulsed current instead of direct current reduced the hardness of the coating by increasing the dilution. Also, in both groups of coatings, no significant difference was found between the hardness distribution over the coating layer in the specimens coated with pulsed currents at frequencies of 10 and 200 Hz.