Influence of buffer layer on surface and tribomechanical properties of laser cladded Stellite 6

Abstract

Wear resistance coatings of Stellite 6 were deposited on SS316 substrate by blending a buffer layer of Inconel 625 with varying Linear Heat Inputs (LHI). The mechanical and microstructural properties of Stellite 6 coatings are investigated to evaluate the effect of buffer layer. The surface flaws, microstructure, micro-hardness and wear resistance of Stellite 6 clads with buffer layer are studied and compared with direct deposited Stellite 6. The results show an increment in clad height by 30% and 9% at lower and higher LHIs, respectively as compared to pre-deposited Stellite 6 clads. The deposition pattern (with and without buffer) are free from surface and internal cracks. The dilution is reduced by 25% and 10% whereas the microhardness shown an improvement by 12% and 5% with addition of buffer layer. Further, a fine-grain microstructure is observed in buffer layer clads at the interface zone. Moreover, the studies on wear rate have shown improvement of 14% and 3%, respectively with low coefficient of friction (COF) in buffer layer deposition because of high microhardness and fine grain microstructure. Thus, laser cladding of Stellite 6 at lower LHI with buffer layer has shown excellent mechanical and microstructural properties.