MICROSTRUCTURAL AND MECHANICAL STUDY OF INCONEL 625-TUNGSTEN CARBIDE COMPOSITE COATINGS OBTAINED BY POWDER LASER CLADDING

This study focuses on the investigation of fine (similar to 0.54 mu m) tungsten carbide particles effect on structural and mechanical properties of laser cladded Inconel 625-WC composite. Three powder mixtures with different Inconel 625 - WC weight ratio ( 10, 20 and 30 weight % of WC) were prepared. Coatings were made using following process parameters: laser beam diameter empty set approximate to 500 mu m, powder feeder rotation speed - 7 m/min, scanning velocity - 10 m/min, laser power - 220 W changed to 320 W, distance between tracks - 1 mm changed to 0.8 mm. Microstructure and hardness were investigated. Coatings produced by laser cladding were crack and pore free, chemically and structurally homogenous. High cooling rate during cladding process resulted in fine microstructure of material. Hardness improved with addition of WC from 396.3 +/- 10.5 HV for pure Inconel 625, to 469.9 +/- 24.9 HV for 30 weight % of WC. Tungsten carbide dissolved in Inconel 625 which allowed formation of intergranular eutectic that contains TCP phases.