Multilayered WC–Co coatings by Direct Energy Deposition-based cladding: Effect of laser remelting on interface defects

Abstract

Despite ongoing optimization of WC-Co Direct Energy Deposition-based cladding, the deposition of multilayer coating is currently challenging. Pores and cracks that extended along the deposit thickness have been always observed in medium-large multilayer coatings. The change of substrate from steel to hard metal in multilayer deposition, replaces all of the thermal characteristics and dilution modes. This study looks into ways to improve the deposition quality of WC-Co multilayers for metal cutting application by remelting between subsequent layers. In order to define the key process parameters and to identify the effects of remelting, the characteristics of coatings are first examined in a single-track and single-layer simplified condition. These initial tests demonstrate that remelting reduces porosity and identify a “white layer” microstructural modification. The multilayer configuration was then examined, and a thorough analysis of the microstructure revealed an enrichment in Fe-Co-C elements in the surface that was advantageous for the deposition of a second layer. Remelting's observed effects on porosity and microstructure have been discussed, and the method's advantages and drawbacks have been made clear for potential future application.