PSI - Issue 65

Boris Voloskov et al. / Procedia Structural Integrity 65 (2024) 302–309 Voloskov et al./ Structural Integrity Procedia 00 (2024) 000–000

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3. Results

3.1. XCT analysis

The specimens of two different scanning strategies as described in section 2 were examined by XCT analysis to estimate the porosity. The XCT results for the specimens printed using the NP strategy are shown in Fig. 3a. It can be clearly seen that the sample with the lowest hatch distance has a high number of large defects, which is assumed to be a lack of fusion due to its irregular shape. In addition, round gas pores are observed near the surface. The sample with the largest hatch distance of 110 µm has a large number of uniformly distributed small gas pores. The pores are lined up in clearly visible stripes along the printing direction. A ring of small pores was also observed near the surface. The average hatch distance, which is 80 µm, showed the lowest porosity. However, some lack of fusion defects was observed.

Fig. 3. 3D rendering of porosity (red) projected to XY (top row) and XZ (bottom) planes of the specimens printed using (a) NP scanning strategy; (b) chess scanning strategy.

The results on volume fraction of pores are summarized in Table 2.

Table 2. Volume fraction of pores as a function of hatch distance for NP and chessboard strategies. Scanning strategy Hatch distance (  m) Volume fraction of pores (%)

50 80

0.110 0.028 0.110 0.051 0.010 0.245

Chessboard

110

50 80

NP

110

3.2. Tensile testing results The tensile tests were carried out for each specific combination of hatch distance and scanning strategy. The results of tensile tests are demonstrated in Fig. 4a,b. The photos of broken specimens are shown in Fig. 4c. The results of mechanical characteristics showed that highest ultimate tensile strength (UTS) and yield strength was obtained on specimens with hatch distance of 80  m for both scanning strategies chessboard and NP. In addition, the specimens of chessboard strategy with 110  m hatch distance demonstrated similar results. The sample