Deformation Reduction in Laser Cladding of Sheet Metals by Heat Recycling

A new technique was proposed to reduce the thermal distortion by heat recycling during laser cladding. The powder/gas mixture flew through a heat exchange channel mounted under the sheet substrate, and it was then heated by heat exchange. The temperature, deformation, microstructure, and the microhardness were investigated under the natural cooling, water forced cooling, and powder/gas mixture cooling conditions. The thermal power absorbed by the powder/gas mixture is 0.4% of the laser power and is much less than that of water (~ 36%), but the recycled laser energy preheated the powder and increased the thickness of the cladding layer. The deformation under the powder/gas mixture cooling condition lies between the natural cooling and the water cooling conditions. The results indicated that the cooling medium significantly affected the thermal history of thin plate substrate laser cladding and the property of cladding layer.