LASER SURFACE ALLOYING OF 304 STAINLESS STEEL WITH TUNGSTEN POWDER

Abstract

Laser surface alloying was employed to enhance the wear resistance of 304 stainless steel with pure tungsten powder. The effect of laser fluence on phase constituents, microstructure, hardness and corrosion properties was investigated. It is found that the laser fluence has a direct correlation with the phases present in the coatings. Intermetallic Fe7W6 phase was found in the composite coating due to the metallurgical reaction of W with the Fe, Cr and Ni elements in the melting pool. Coatings with composite microstructure in nature were obtained resulting from the dilution of substrate and the laser-induced rapid cooling process. Intermetallic phase of Fe7W6 with solid solution of Ni and Cr shows dendrite or hallo structure depending on the laser fluence. Sintering and/or consolidation of W particles is observed for samples processed with lower laser fluences. It has been found that hardness of the coatings was improved significantly compared with the 304 stainless steel substrate. Coating processed with laser fluence of [Formula: see text] J/m2 shows the best corrosion resistance.