Microstructure characterization of recycled IN718 powder and resulting laser clad material

Abstract

The possibility to reuse the metal powder wasted in Laser Material Deposition (LMD) process has been evaluatedand a simple procedure developed. LMD uses metal powder which is fed through a nozzle into the focal point of alaser, where it melts the powder and the substrate material. During the process, a high ratio of particles hitsagainst an unmelted area and directly bounces off the deposited area. The efficiency ratio of deposition can dropto 40% depending on the configuration and spot size. This work deals with the design of a procedure to recollectand reuse the wasted powder of a nickel based superalloy IN718. After usage, powder is recollected, undesiredfractions are magnetically segregated and aggregates are removed by sieving. The particles are mixed again andready for reuse. In order to study the effectiveness of the process, no new powder has been added to the recoveredfraction, and this procedure has been repeated five times. Experimental tests show that depositedmaterial present similar properties than those obtained with new powder grains. But, after 3 reuses, the porositycontent increases consequently and the rupture strain decreases strongly. The implementation of this processallows the improvement of the final efficiency, reducing costs and decreasing the hazardous powder amount.