CO2 and Nd:YAG laser cladding using Stellite 6

Cladding of an austenitic stainless steel with the cobalt-based alloy Stellite 6, a trademark of Deloro Co, has been investigated by using both CO2 and Nd:YAG laser beams. This material is used for hardfacing in a number of industries, notably power generation and heavy engineering. Alloy powder was fed into the laser beam by using argon as a carrier gas. Clads were produced with a range of processing parameters, and sectioned for metallographic examination. Hardness values measured in the clads increased to a maximum with an increase in powder feed rate. This correlated with a decrease in the dendrite arm spacing observed in the micrographs. Abrasive wear testing also indicated that a finer microstructure resulted in improved properties. The Nd:YAG laser beam was found to be more efficient for melting the powder because it is absorbed to a greater extent than the CO2 laser beam. Cladding procedures were developed for both types of laser, and it is shown that in order to maximize in-service performance, the energy input of the process should be minimized.