EFFECT OF LASER SCANNING SPEED ON PHASE CONSTITUTION AND WEAR RESISTANCE OF LASER CLADDING HARD FACING ALLOY STELLITE 12

Effect of laser scanning speed on phase constitution,microstructure,microhardness and wearresistance of laser-cladding hard facing alloy Stellite 12 has been investigated by means of across-flow-type COlaser of 1.5 kW.The laser-cladding layer on the alloy consists of ma-trix phase of suppersaturated solid solution γ(Co,Cr)and complex hexagonal carbideMC.Under certain condition,at higher laser scanning speed,the suppersaturated solubilityof elements increases in γ(Co,Cr),and the precipitation of the complex carbtde MCde-creases,so the microhardness increases and the wear resistance decreases.But at slower laserscanning speed,more complex carbide MCmay precipitate,and the wear resistance may beimproved.Therefore,it is believed that the principal factor in improving wear resistance is theprecipitation of carbide MC,while increment of microhardness is the suppersaturated solu-bility of elements in matrix phase γ(Co,Cr).