Laser cladding process of Fe/WC metal matrix composite coatings on low carbon steel using Yb: YAG disk laser

Abstract

The paper presents the studies of selected properties of Fe/WC metal matrix composite coatings produced using different laser beam power values and different powder feeding rates. Coatings were produced using the Yb: YAG disk laser by laser cladding method. Laser beam powers equal to 600 W, 700 W and 800 W were used. Scanning speed of laser beam was the same for all the coatings and was equal to 600 mm/min. Laser beam spot diameter was 1.64 mm. Two powder feeding rates (6.25 g/min and 12.50 g/min) were applied. In this study macroscopic observation, microstructure and microhardness examination as well as XRD and EDS analysis were carried out. Corrosion resistance was also investigated. In Fe/WC coating produced using slower powder feeding rate dendritic carbides that nucleated on the primary tungsten carbide particles were observed. In the coatings produced using an increased powder feeding rate, a changed type of secondary carbide was observed, which was bar-shaped or plate-shaped. The results of the XRD and EDS analysis of the composite Fe/WC coatings showed the presence of WC, W2C phases as well as M23C6 and (Fe,W)3C complex phases. The mechanism of formation and growth of composite coatings was described on the basis of microstructures obtained. The highest microhardness and corrosion resistance were observed for coatings produced at a powder feeding rate of 12.50 g/min.