In direct laser deposition (DLD), metallic powder is injected into the melt pool in order to join different metals to develop fully dense and near net shape part. The cost of powder wasted in commercial DLD machines has been a major concern to the industries. More than 60% of the powder is wasted and is being disposed off which make the system economically and environmentally expensive. Recycling of powder is not feasible in many sectors, because of the fear of drop in the quality of the product. The objective of this study is to enhance the deposition efficiency of the DLD process, so that to minimize the amount of powder wasted. In present study, flow of powder is achieved by vibration of the powder delivery nozzle at sonic frequencies. Experimental studies are performed to analyze the deposition of powder by varying laser intensities, powder flow rate and laser scanning speed. The mass flow during certain time is weighed and the actual clad weight that is formed during the same period is weighted. The difference of the two is used to calculate the powder efficiency. Different set of experiments are performed. Powder mass flow rates are increased subsequently and Taguchi matrix are prepared for each set of experiment. Mass flow rate in initial experiments is from 0.044 grams/sec to 0.244 g/s and increases up to 0.86 g/s in the final set of experiments. Laser power during these experiments varies between 1KW to 2 KW, while laser scanning speeds varies from 100 mm/min to 350 mm/min. Maximum deposition efficiency is achieved in initial set of experiments and is up to 70%, which is significant improvement in the form of deposition efficiencies available in literature.
Microstructure evolution, wear behavior, and corrosion performance of alloy steel gradient material fabricated by direct laser deposition
