Microstructure evolution of laser clad layers of W-C-Co alloy powders

Clad layers using high power carbon dioxide laser and various powder compos itions of W, C, Co and WC on carbon steel substrate have been investigated. Microstructures of the clad layers are greatly affected by the processing parameters: powder size; powder type; shielding gas; degree of dilution; an d geometry of the clad layer. Clad layers with large WC particles in a eute ctic matrix and a high hardness, or with a mostly eutectic structure and lo w hardness, can be made for applications of cutting tools or wear resistant surfaces, respectively. Microstructure such as: (1) WC, Co,W,C, and a bina ry eutectic mixture of Co3W3C and alpha-(Fe,Co); (2) Co3W3C and a binary eu tectic mixture of Co3W3C and alpha'-(Fe,Co); (3) a binary eutectic mixture of Co3W3C and alpha'-(Fe,Co) have been produced in the clad layer. (C) 2000 Elsevier Science S.A. All rights reserved.