PSI - Issue 21

E.F. Akbulut Irmak et al. / Procedia Structural Integrity 21 (2019) 190–197 E. F. Akbulut Irmak et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Table 1. Manufacturing parameters of SLM specimens

Speed (mm/s)

Power (W)

Focus (mm)

Hatch (mm)

Volume parameters Contour parameters

930 500 550

350 350 350

2 1 1

0.19

Contour-offset parameters

Support structures are required in the SLM manufacturing method in order to build geometries with overhangs. In this study, the support structures are formed on the specimen thickness surface in such a way that it creates as small contact areas as possible with the specimen surface. During the manufacturing process, environmental conditions are similar for each sample.

2.2. Specimen orientations

In order to gain deep insight into the orientation dependency of additively manufactured AlSi10Mg material, three different reference orientations were studied. All uniaxial and notched tensile specimens were produced with respect to an orientation angle. The key factor for the orientations is the angle between building plate and specimens. An illustration of the determination of the orientations can be seen in Figure 1. A short summarization of the number of produced specimen orientations is listed in Table 2.

Figure 1. Illustration of the orientations

Table 2. Number of specimens in all orientations

Orientation angle (θ)

0°

45°

90°

Uniaxial Tensile Notched Tensile

5 5

5 5

5 5

3. Experiments Experiments were carried out by the utilization of a universal tensile test machine to obtain the force-displacement data by the load cell integrated into the machine. To perform material characterization studies on additively manufactured AlSi10Mg, the specimens were clamped directly into the testing machine and tensile tests were carried out at room temperature under nearly 0.001 s -1 strain rate. During the tests, DIC measurement was carried out by a GOM Aramis 4M system. SLM manufacturing method has some disadvantages as well as the advantages of efficient, waste-free and productive production. In order to be able to evaluate the specimens produced by the SLM method under the same conditions and compare the results, all the samples used must be produced together. Considering the boundary of the platform surface required for production, it was decided that the samples to be used for this study are small in size. The geometries of the specimens with a thickness of 3 mm are given in Figure 2 and are based on the contributions by Basaran (2011) and Andrade et al. (2016). The specimens were produced by Direct Manufacturing Research Center (DMRC) in Paderborn University and thickness was determined considering the unpublished database. As known, the size effect has a significant influence on the geometric imperfection in additive manufacturing