Abstract
The combination of laser powder bed fusion (LPBF), known for its geometrical freedom and accuracy, and the nozzle-based laser metal deposition process (LMD), known for its high build-up rates, has great potential to reduce the additive manufacturing times for large metallic parts. For the industrial application of the LPBF-LMD hybrid process chain, it is necessary to investigate the influence of the LMD process on the LPBF substrate. In addition, the build plate material also has a significant impact on the occurrence of distortion along the additive manufacturing process chain. In the literature, steel build plates are often used in laser-based additive manufacturing processes of Inconel 718, since a good metallurgical bonding can be assured whilst reducing costs in the production and restoration of the build plates. This paper examines the distortion caused by LMD material deposition and the influence of the build plate material along the hybrid additive manufacturing process chain. Twin cantilevers are manufactured by LPBF and an additional layer is subsequently deposited with LMD. The distortion is measured in the as-built condition as well as after heat treatment. The effect of different LMD hatch strategies on the distortion is determined. The experiments are conducted using the nickel-base alloy Inconel 718. The results show a significant influence of LMD path strategies on distortion, with shorter tool paths leading to less distortion. The remaining distortion after heat treatment is considerably dependent on the material of the build plate.
Highlights
Additive manufacturing processes have become very popular in recent years
Progress in Additive Manufacturing (2021) 6:385–394 structure and cooling channels was produced by laser powder bed fusion (LPBF) and the massive fir-tree root was added in a subsequent laser metal deposition process (LMD) process
The results of the curvature measurements before and after wire electrical discharge machining (WEDM) of the cantilever arms are pictured in Fig. 4 for each LMD strategy in the as-built condition
Summary
The new geometrical freedom of design has a great potential to overcome the limitations posed by conventional manufacturing processes, and it becomes possible to focus on the component function. The great potential and the continuous improvement of the processes led to an increased usage in the industrial environment, as indicated in the annual Wohlers Report [1]. Progress in Additive Manufacturing (2021) 6:385–394 structure and cooling channels was produced by LPBF and the massive fir-tree root was added in a subsequent LMD process. Besides the time-saving aspect, it was demonstrated that this approach can be used to repair LPBF components with LMD [7].
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