No abstract

No abstract

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%

The aim of this study is to characterize microstructures and tensile properties of Inconel 718 (IN718) formed by high deposition-rate laser metal deposition (LMD), and furthermore to verify that the properties of the material are equivalent to those obtained by conventional manufacturing processes, such as casting and forging, and therefore satisfy the specifications for industrial applications. Initially, the powdery additive was characterized in terms of chemical composition, morphology, and porosity. Afterward, blocks for producing tensile specimens were deposited by applying the newly developed high deposition-rate LMD process that has a deposition rate of approximately 2 kg/h. Finally, microstructures and tensile properties of directly deposited and heat-treated material were analyzed, respectively. From the results, precipitation of an irregular shaped phase, which is believed to be Laves phase, and segregation of Nb and Mo were found at interdendritic regions of the directly deposited material. The directly deposited material exhibited relative low tensile strength and 0.2% yield strength but high elongation. Moreover, due to recrystallization that occurred in heat treatment, columnar grains in the directly deposited material transformed to equiaxed grains. By heat treatment, Laves phase was dissolved, and three extra phases, which are believed to be δ phase, strength phases γ′ and γ″, were precipitated. After heat treatment, tensile strength and 0.2% yield strength of the material were significantly enhanced, whereas the plastic elongation decreased by approximately 38%. In comparison to conventional manufacturing technology, the heat-treated IN718 presented superior tensile strength, 0.2% yield strength, and plastic elongation to aerospace material specifications for casted and wrought IN718

No abstract