Microstructure of nickel based nanometer WC/Co coating prepared by laser overlapping and scanning again cladding

CO2 laser was adopted to prepare nickel based nanometer WC/Co composite coating on the surface of 45 steel.Laser overlapping and scanning again was used to break the limitation of single channel laser cladding and the defect from the large difference of the carbides in shape and distribution after single overlapping.The results show that the hardness of laser overlapped and scanning again clad coating is not lowered and at the same time no new cracks and pores appear,it makes the practical application of broadened area of laser cladding possible.The composite coating in overlapping and scanning again has a considerable quantity of nanometer carbides particles visible with a granularity ≤100 nm,and its nanometer effect plays an important role in the anti-cracking function.