Effect of pulse current on microstructure and wear resistance of Stellite6/tungsten carbide claddings produced by tungsten inert gas process

In this paper, the tungsten inert gas (TIG) surfacing process was carried out in two, pulse and constant current modes to produce Stellite/WC composite claddings. To evaluate the coating, phase composition, microstructure, hardness and wear behavior of the clad layers were investigated. The results showed that the microstructure of the cladding was composed of a hypoeutectic structure (gamma + (gamma + WC)). The added WC was completely melted into the weld pool and the resolidified structure contained alpha-Co, sigma-CoCr and some types of carbides. It was indicated that the use of pulsed current leads to a decrease in dilution and formation of a finer microstructure having higher hardness. Several significantly different solidified microstructures were characterized by dendrites, eutectics and faceted dendrites in the claddings. The faceted dendrites contained the majority of W as well as Cr and Co while the matrix had higher Cr and Co content. The presence of faceted dendrites caused improvement in wear behavior of claddings, with more WC content introduced, more faceted dendrites was obtained. (C) 2011 Elsevier B.V. All rights reserved.