Laser cladding for wear‐resistant cobalt base alloy and tungsten carbide composite coatings

Abstract

Stellite12 cobalt base alloys with different WC contents were deposited on SK3‐carbon tool steel by laser cladding. The behavior of WC particulates, including dissolution and distribution, and the microstructure of WC‐Co‐Cr‐C composite coatings with rapid solidification were investigated. Several significantly different solidified microstructures were characterized by dendrites, eutectics, faceted dendrites and the retained WC particles in the laser cladding WC + Stellite12 coatings, under different laser energy densities. When WC was melted and dissolved into the Stellite12 melt pool, the basic structure of solidification, characterized by the matrix and faceted dendrites in various shapes, and the contents of the faceted dendrites remained nearly identical. The faceted dendrites contained the majority of W as well as some Cr, Co while more Cr and Co were located in the matrix. The X‐ray diffraction analyses indicated the existence of σ‐Co, M₂₃C₆, M₆C and M₇C₃ (M = W, Cr, Co) in the Stellite12 with different WC contents when deposited on substrates by laser cladding. The faceted dendrites provided the coatings with excellent resistance during dry sliding wear test. A higher content of WC gave higher volume fractions of faceted dendrites that imparted excellent wear resistance to the coating.

Key words:

• Stellite12
• WC
• laser cladding
• faceted dendrites

Notes

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