Cracks susceptibility elimination in fiber laser cladding of Ni-based alloy with addition of tungsten carbides

"In plastic injection molding the most critical component in terms of wear and corrosion problem is represented bythe barrel-screw system. This is due to the friction of plastic on the inner part of the barrel and to contact between the screw and the inner walls of the barrel. Fiber laser cladding is a promising technique that, through deposition of powder onto a substrate increases wearproprieties and consequently lifetime of the component. In particular, cladding Ni-Cr alloy with WC is an extremely promising combination of elements for this purpose. Specifically, WC is able to increase the hardness of the deposit so that it becomes more suitable for severe wear application. On the other hand, high Cr amount contained in the Ni-based alloy, guaranties high corrosion resistance for harsh environments. Nevertheless, this combination of materials is highly susceptible to cracks. Through the optimization of process parameters and preheating temperature (250-350-450-550°C) defect free coatingsare obtained. This work presentsan investigation on fiber laser cladding of Ni based alloy (Ni40, Ni60) with addition of spherical tungsten carbides (-53+20 μm) on C60 steel substrate. Optimal conditions are evaluated through macro and a micro analysis. In the first case penetrantliquids are used to evaluate crack presence.For the second field, micro hardness was measured and microstructure if crosssectioned sampleswere investigated by optical microscopy."