Page 36 - MSAM-2-2

Materials Science in Additive Manufacturing Tensile and fatigue properties of Ti6Al4V SLM parts

2. Materials and methods Table 1. Nominal composition of Ti‑6Al‑4V (% by weight)

2.1. Powder preparation Ti Al V Fe C N O H Others
Balance 5.50 – 6.50 3.50 – 4.50 0.25 0.08 0.03 0.13 0.013 0.5
Plasma-atomized Ti6Al4V titanium powder with
particle size distribution of 20 – 63 μm from SLM
Solutions Group AG (Germany) was used. The chemical
composition of the Ti6Al4V titanium alloy powder is
listed in Table 1.

2.2. SLM
Ti6Al4V titanium alloy specimens in the project were
fabricated using SLM 280 2.0 Twin 700 W AM machine
(SLM Solutions Group AG), as shown in Figure 1.
The energy density E (J/mm ) of the SLM process can
3
be obtained by using the following formula:
P
E = (1)
V d h
Where P represents the laser power (W), V represents
the scanning velocity (mm/s), d represents the hatch Figure 1. Tensile samples being produced inside the chamber of the SLM
spacing (mm), and h represents the layer thickness 280 AM machine.
(mm) . In this research, the scanning strategy used
[27]
for fabricating 30 μm layer thickness is as follows: Laser
power is 280 W, scanning velocity is 1475 mm/s, and
hatch spacing is 0.12 mm with strip scanning pattern.
The scanning strategy used for fabricating 130 μm layer
thickness is as follows: laser power is 550 W, scanning
velocity is 1000 mm/s, and hatch spacing is 0.15 mm with
strip scanning pattern. Post-processing was performed
after printing. First, the specimens had to be removed from
the substrate plate. Second, since the horizontal specimens
were printed with supports underneath the arch of the dog
bone, supports were removed. Support removal was done
by manual grinding and polishing tools. Sandblasting was
also done manually by SLM Solution Singapore office’s
in-house technician to control the same results on the final
surface quality of sandblasted parts. The process is shown
in Figures 2 and 3. Figure 2. Specimens on substrate plate taken out from SLM280 machine.
2.3. Tensile property measurements and post-processing of sandblasting. Table 2 lists the
Ti6Al4V specimens were printed using SLM280. Tensile 10 specimens and their parameters.
testing was carried out according to ASTM E8 standard For the layer height, 30 μm versus 130 μm was
[28]
with Instron 5569 Universal Test Machine. For the first compared. It was expected that a smaller layer height
series of tests, Ti6Al4V tensile properties with regard to has a finer microstructure, which gives better bonding
various printing process parameters were tested. First, and fusion. This results in lesser porosity and thus better
we designed a dog bone-shaped specimen in accordance tensile strength. For build orientation, we compared the
with E8 standard (L = 115 mm, B = 19 mm, b = 6 mm, three orthogonal orientations: Flat, horizontal, and vertical
L0 = 55 mm, and thickness = 3.2 mm). orientations .
[29]
We designed the experiment with 10 specimens of Tensile tests were conducted according to ASTM E8/
different parameter configurations. The three focus E8M testing standard to characterize the mechanical
parameters were layer thickness, build orientation, properties of the SLM-fabricated Ti6Al4V. The dimensions

Volume 2 Issue 2 (2023) 3 https://doi.org/10.36922/msam.0912