Fiber Laser Cladding with High Content of WC-Co Based Powder

The paper deals with the laser cladding application to improve wear properties of cutting edges, making use a fiber laser source. This type of laser is chosen due to the small dimension of the clad cross section that has to be rebuilt. The paper is aimed at obtaining good cladding layers using high content of WC as reinforcement phase, which mainly means a clad free of cracks and pores. In order to obtain very high hardness values of the clad surface, the deposited material is constituted by an high percentage of tungsten carbides (over 85% in weight), while the matrix is a standard cobalt powder. A preliminary experimental campaign allowed to investigate the process parameters which mainly affect the clad quality in terms of pores and cracks absence. Then the role of the three most affecting parameters, i.e. laser speed, laser power and shielding gas, was highlighted in order to better investigate the overall clad attributes, such as micro-hardness, geometry, integrity (pores and cracks) and dilution with the substrate steel. As a result, improved work condition is found, which produces clad with no pores, no crack and high hardness.