Effect of carbide dissolution on the corrosion performance of tungsten carbide reinforced Inconel 625 wire laser coating

In this work, clad layers of Spherotene (a mixed tungsten carbide)/Inconel 625 wire composite suitable for hardfacing in corrosive environments were deposited. Varying laser processing conditions were employed specifically to investigate carbide dissolution. The relative amount of Spherotene dissolution in each clad layer was analysed using a combination of methods including mass gain of clad layers, quantitative microscopic and microchemical analysis of microstructures using scanning electron microscopy (with energy dispersive X-ray analysis) and image processing software. The electrochemical corrosion performance of two typical composite clad layers formed at low and high Spherotene dissolution levels and Inconel 625 wire laser clad were investigated in de-aerated 3.5 wt.% NaCI solution. The results indicate that microstructural in-homogeneity, caused by the formation of secondary phases, increases as the Spherotene dissolution increases. The Spherotene dissolution increases as the energy per unit length of clad increases. The composite clad layers demonstrate decreasing resistance to corrosion as the Spherotene dissolution increases. Through careful control of process parameters, the corrosion performance of composite clad layers can be improved by reducing the amount of tungsten carbide dissolution. (C) 2016 Published by Elsevier B.V.