PSI - Issue 49

Federico Fazzini et al. / Procedia Structural Integrity 49 (2023) 59–66 / Structural Integrity Procedia 00 (2023) 000 – 000

65

7

Fig. 2. (a) tensile stress-strain 112-B; (b) tensile stress-strain 211-O (c); tensile stress-strain 223-Z; (d) compression stress-strain 221-V.

It is worth noticing that none of the combinations exhibited values consistent with the specifications provided by BASF's technical datasheet for this material. Only configuration 211-O met the elongation at fracture requirement, but its values were notably lower compared to the other specifications. Similarly, it was possible to achieve values only lower than the typical values of parts made from 17-4PH through Metal Injection Molding, as defined by MPIF35. Upon examining the tensile fracture surfaces for the three different raster angle variations employed, represented in Figure 3, it is evident that there are notable differences in fracture mechanics among them. It is observed that specimens with exclusively longitudinal tracks relative to the applied load (0° raster angle) fracture in a flute-like manner. Conversely, specimens with a filament arrangement featuring a 0°-90° configurations exhibit a distinct and well-defined fracture surface: the load causes the detachment of filaments positioned at a 90° angle, resulting in a nearly flat fracture surface. Furthermore, the 0°-45°-90°-135° configuration demonstrates an intermediate behaviour between the other two infill strategies.

a

b

c

Fig. 3. (a) fracture surface for 0° raster angle; (b) fracture surface for 0°-90° raster angles (c); fracture surface for 0°-45°-90°-135° raster angles.

Table 3. Tensile and compression test results.

Name

Young Modulus [GPa] 140.63 ± 6.48 148.64 ± 2.35 142.17 ± 6.60 153.51 ± 4.53 168.69 ± 26.66 144.10 ± 3.57 146.77 ± 2.44 146.79 ± 12.57 142.99 ± 5.79 148.01 ± 4.07 140.65 ± 4.74 135.52 ± 5.81

Ultimate Tensile strength [MPa] 719.43 ± 63.82 721.76 ± 20.91 719.32 ± 1.42 752.97 ± 4.96 743.26 ± 7.64 741.20 ± 3.68 761.78 ± 9.33 727.47 ± 3.83 737.21 ± 6.27 753.20 ± 2.70 734.69 ± 1.66 731.96 ± 15.61

Tensile yield strength [MPa] 588.00 ± 16.31 574.38 ± 18.40 548.37 ± 14.37 577.50 ± 6.43 586.55 ± 13.17 562.00 ± 2.26 590.76 ± 12.13 553.17 ± 19.04 575.59 ± 14.28 575.25 ± 4.88 560.35 ± 8.97 563.35 ± 17.33

Elongation at break [%] 4.75 ± 2.76 1.68 ± 0.50 4.28 ± 1.42 3.69 ± 0.57 2.88 ± 0.80 3.97 ± 0.40 6.62 ± 1.67 3.24 ± 0.10 4.31 ± 0.37 4.39 ± 0.39 3.64 ± 0.51 4.25 ± 0.35

Compression yield strength [MPa]

111 - A 112 - B 113 - C 121 - E 122 - I 123 - N 211 - O 212 - P 213 - S 221 -V 222 - X 223 - Z

757.91 ± 51.61 713.06 ± 8.15 724.13 ± 18.21 741.42 ± 46.75 729.92 ± 15.56 730.93 ± 31.09 754.23 ± 1.10 748.49 ± 5.19 710.59 ± 43.11 767.99 ± 13.70 740.22 ± 17.49 743.17 ± 10.3

4. Conclusions In this study, 12 different combinations of parameters were employed to produce pieces using the metal FFF process by varying the extrusion temperature, deposition speed, and raster angle. From the conducted tensile tests, it was observed that the parameter variation with the greatest impact on the mechanical properties of the sintered piece is the raster angle. Specifically, layers with an alternating arrangement of 0°-90° exhibited maximum stiffness and minimum elongation at fracture. On the other hand, unidirectional layers with a 0° arrangement resulted in the highest values of ultimate tensile strength, yield tensile strength and elongation at fracture. The pieces with raster angles of 0°-45°-90°-135° displayed intermediate behaviour between the two aforementioned configurations. Further analyses are currently underway to develop a technological model that can accurately predict the mechanical, geometric, and dimensional properties of metal FFF artefacts based on the printing parameters and their correlation with the presence of micro voids within the artefacts.