Study of process window development for high deposition-rate laser material deposition by using mixed processing parameters

For several years, the interest in additive manufacturing is continuously expanding, owing to the paradigm shift that new production processes, such as laser material deposition (LMD), provide over conventional manufacturing technologies. With LMD, three-dimensional, complex components out of a wide range of materials can be manufactured consecutively layer-by-layer. However, aiming for the production of large components with LMD, the currently achieved deposition-rates of approximately 0.5 kg/h remain a major concern in regards to processing time and economic feasibility. In this respect, an experimental setup for high-deposition rate LMD is built up in the current work. Furthermore, an approach for developing a process window for resource efficient, high-deposition rate LMD is investigated in this paper. For the production of sound layers with LMD, the processing parameters need to be considered in an appropriate relation. Thus, by setting the main processing parameters: powder mass flow, traversal speed, laser power, and laser spot diameter into proportion, the mixed processing parameters: energy mass density and energy area density can be defined. Based on the metallographic investigation of laser deposited Inconel 718 single tracks regarding dilution, aspect ratio of track (ratio of track width to track height) and level of porosity, upper and lower limits for these two parameters can be set which represent process window boundaries. With this approach, a processing parameter field can be defined, to deposit sound Inconel 718 single tracks with a deposition-rate of approximately 5 kg/h and powder capture efficiency higher than 90%.