The influence of process parameters on structure and abrasive wear resistance of laser clad WC-NiCrBSi coatings

Abstract

In laser cladding, the final structure of coatings and thus their functional properties are dependent on process parameters used and the initial powder composition. This study focuses on laser cladding of WC-NiCrBSi coatings. As the powder used is a blend of 60% tungsten carbide spherical particles and 40% NiCrBSi matrix, the carbides’ morphology and distribution in the final coating would be dependent on laser cladding parameters. Coatings were cladded using a solid state laser and by varying key process parameters: process speed, powder feed rate and laser power. Cladded coatings are evaluated in terms of their microstructure, hardness and abrasive wear resistance tested by dry sand rubber wheel test ASTM G-65. It was found that the amount of dissolved WC carbides increases with increasing heat input and both Fe dilution and carbide dissolution affect the coatings´ properties. This shows that the selection of process parameters is crucial, as they significantly affect the final coatings´ wear resistance. In the overlay regions, the non-homogeneity of the coating’s microstructure was responsible for significant selective abrasive wear behavior.