Deposition of Stellite 6 on nickel superalloy and mild steel substrates with laser cladding

Stellite 6 was deposited by laser cladding of two different steel substrates (nickel superalloy and mild steel). The chemical compositions and microstructures of these coatings were characterized by atomic absorption spectroscopy, optical microscopy and scanning electron microscopy. The microhardness of the coatings was measured and the wear mechanism of the coatings was examined using a pin-on-plate (reciprocating) wear testing machine. The results showed less cracking and pore development for Stellite 6 coatings applied to the mild steel (MS) substrate. Further, the Stellite coating on mild steel was significantly harder than that deposited on the superalloy. The wear test results showed that the weight loss for the coating on mild steel was significantly lower than for the nickel superalloy substrate. It is concluded that the lower hardness of the coating on the nickel superalloy, together with the softer underlying substrate structure, markedly reduced the wear resistance of the Stellite 6 coating.