The influence of working distance on laser deposited WC–Co

Nanostructured WC–10 wt.% Co powder was used to make thick wall samples by the Laser Engineered Net Shaping (LENS®) process. During this process, a Nd:YAG laser was applied to create a molten pool on a stainless steel substrate and to deposit WC–Co into bulk cermets, the shape of which was controlled by a pre-programmed computer-aided design (CAD) model. Microstructure characteristics were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that working distance and relative location of the focal plane of the laser beam play an important role in controlling sample microstructures, in addition to other common process parameters such as laser power, traverse speed and powder feed rate. Thermal behavior leading to the observed microstructures that result from the variations in working distance was also investigated in this work.