Free-form fabrication of steel parts by multi-layer laser cladding

Laser Cladding (LC) is actually one of the most attractive techniques in the group of Material Accretion Manufacturing (MAM) processes. As a surface coating technique, laser cladding has been developed for improving wear, corrosion and fatigue properties of mechanical components. Multilayer laser cladding (MLC) can be used also for high performance part repair and as a rapid manufacturing process. Thus, the application of laser cladding technology is nowadays widely extended in several industrial sectors due to its advantages for high added value parts direct manufacturing and repairing. Multilayer laser cladding (MLC) combines powder metallurgy, solidification metallurgy, laser, CAD/CAM, CNC, rapid prototyping and sensors technologies. This process allows to produce metal components ready to use, in a single step, without the need for molds or tools and using a wide variety of metals, including those very difficult to work with conventional techniques. The aim of this work was to manufacture MLC steel parts using a CO2 laser with a maximum power of 3kW. The effect of the main process parameters (laser power, travel speed, powder flow rate, degree of overlapping) on the properties of built parts was investigated. A Taguchi experimental plane was used to reduce the number of experiments and a mathematical model was applied in order to obtain an optimized degree of overlapping between adjacent layers and between tracks. Performance of the MLC samples were analyzed in terms of density, macro structure, adhesion to the substrate and microhardness. The powder material chosen for experiments had a composition close to a maraging steel (grade 300). Experimental results showed that high density parts could be produced with a limited number of tests.