Abstract
Bound Metal Deposition (BMD) is an alternative to the most common additive manufacturing (AM) technology for metal parts, Powder Bed Fusion (PBF), since the equipment used is more affordable and there are no risks due to exposure to loose powder and lasers or beams. However, the mechanical properties of parts manufactured by BMD are generally lower than those of PBF, making it necessary to study the process parameters to improve their performance. The aim of this work was to analyse the effect of different process parameters on the mechanical properties of 316L parts manufactured by BMD based on a set of specially designed experiments. The methodology followed in this research was thus based on the manufacturing of a series of samples with variations of the build orientation, infill pattern and chamber temperature followed by subsequent characterization and analysis. The microstructural analysis showed that voids were formed as a consequence of the air gaps generated between rasters during printing. It was observed that the characteristics of these macropores had a significant effect on the mechanical properties. The location, distribution and shape of these macropores depended on the alignment of rasters in each of the conditions, which varied with build orientation and infill pattern. Regarding the build orientation, horizontal parts exhibited lower porosity and considerably higher ultimate tensile strengths (UTS), approximately 160 MPa higher, than vertical samples. With respect to the infill pattern, horizontal parts with a concentric infill pattern showed triangular voids and a total porosity higher than 5%. However, samples with line infill patterns presented elongated macropores and a total porosity lower than 5%, properties that resulted in an improvement in UTS of 20 MPa, approximately. Overall, the results presented here offer a better comprehension of the effect of the BMD process parameters on mechanical properties and serve as a guideline for future work.
Highlights
In recent years, additive manufacturing technologies have received more attention because they allow complex, light and economical parts to be manufactured with short lead times
The aim of this work is to study the process parameters that may have a greater effect on the formation of defects in order to establish a relationship between process parameters and mechanical properties in Bound Metal Deposition (BMD)
Several 316L sintered specimens were successfully obtained by BMD using the Desktop Metal Studio System
Summary
Additive manufacturing technologies have received more attention because they allow complex, light and economical parts to be manufactured with short lead times. These technologies produce three-dimensional parts by successively adding layers of materials such as polymers, ceramics, metals or alloys [1]. The most commercially used MAM processes are those based on PBF, where the powder is spread on a build platform and selectively fused by a high-energy beam. These methods are widely employed mainly due to the high density (usually >99%) and the good mechanical properties of the manufactured parts [1,7]. A careful machining step is usually required for support removal [8,9,10]
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