Laser Beam Cladding of Stellite on Cast Iron

Abstract

  CO₂ laser beam was applied to the cladding of stellite on cast iron by using beam scanner. The hardness and microstructure of clad layer were investigated by changing the laser power and number of clad layer. The average hardness of clad layer obtained was 480∼510 HV 0.1, when the conditions were laser power from 2200 W to 2600 W, clad number from one layer to four layers (thickness of clad layer ; 0.9∼4.7mm), cladding speed of 400mm/min, defocusing distance of 30mm, oscillated width of 7mm and argon as the shielding gas. The microstructure of clad layer was completely transformed into a fine dendritic structure (secondary dendrite arm spacing; 5.0μm) and eutectic carbide by the rapid solidification conditions. The remelted zone was produced on the surface of cast iron (base metal) and a primary dendrite and ledebulite could be observed. EPMA line analysis indicated that alloyed layer (thickness ; 150∼200 μm) existed between clad layer and base metal. These results show that CO₂ laser beam cladding serves as a new surface treatment process for cast iron in foundry industries.