Abstract
The advantage of selective laser melting (SLM) is its high accuracy and geometrical flexibility. Because the maximum size of the components is limited by the process chamber, possibilities must be found to combine several parts manufactured by SLM. An application where this is necessary, is, for example, the components of gas turbines, such as burners or oil return pipes, and inserts, which can be joined by circumferential welds. However, only a few investigations to date have been carried out for the welding of components produced by SLM. The object of this paper is, therefore, to investigate the feasibility of laser beam welding for joining SLM tube connections made of nickel-based alloys. For this purpose, SLM-manufactured Inconel 625 and Inconel 718 tubes were welded with a Yb:YAG disk laser and subsequently examined for residual stresses and defects. The results showed that the welds had no significant influence on the residual stresses. A good weld quality could be achieved in the seam circumference. However, pores and pore nests were found in the final overlap area, which meant that no continuous good welding quality could be accomplished. Pore formation was presumably caused by capillary instabilities when the laser power was ramped out.
Highlights
The ongoing improvement in metal additive manufacturing (AM) processes allows a rapid and near-net-shape production of complex parts with good mechanical properties. When it comes to industrial applications, the selective laser melting (SLM) process is especially popular because its production of more detailed and accurate parts [1]
The results show that laser beam welding is feasible to join SLM parts with an acceptable weld quality
There were no differences in outer weld quality when comparing Inconel 625 (IN625) and Inconel 718 (IN718)
Summary
The ongoing improvement in metal additive manufacturing (AM) processes allows a rapid and near-net-shape production of complex parts with good mechanical properties. When it comes to industrial applications, the selective laser melting (SLM) process is especially popular because its production of more detailed and accurate parts [1]. To combine several parts to a bigger structure through welding would be a feasible strategy to improve the maximum size of SLM components. A large amount of research effort is needed to develop strategies and standards for that endeavor, as only few investigations on the joining of SLM parts can be currently found in the literature [4]
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