Page 56 - MSAM-1-3

Materials Science in Additive Manufacturing Characterization of TPMS structures

Table 2. The geometric parameters and processing 2.4. Material characterization and mechanical
parameters of the Schwarz‑P structures properties
No. Lattice size Shape factor Theoretical relative density The macrostructure of the Schwarz-P structures (A0-E0.8)
A0 1 0 0.2262 was analyzed using optical microscopy (OM; HiROX
A0.2 1 0.2 0.2244 RH-2000, Japan) and scanning electron microscopy
(SEM). Electron backscatter diffraction (EBSD) was
A0.4 1 0.4 0.2201 used to further analyze the grain structure and phase
A0.6 1 0.6 0.2124 distribution of the remaining four samples (F1 – F4). The
A0.8 1 0.8 0.2003 Schwarz-P samples for EBSD were mechanically polished
B0 2 0 0.1130 and then argon ion-polished for 5 h at 4 kV voltage and
B0.2 2 0.2 0.1122 2 angles. The mass of each structure was measured using
B0.4 2 0.4 0.1101 an analytical balance (BSS224S, Hengda, China), and the
B0.6 2 0.6 0.1062 relative density d was calculated as follows:
mr
B0.8 2 0.8 0.1001 m p
C0 3 0 0.0712 d mr V s (III)
C0.2 3 0.2 0.0719
Where m is the mass of the Schwarz-P structure, V is
C0.4 3 0.4 0.0725 the volume of the Schwarz-P structure, and ρ = 4.43g/cm
p
3
C0.6 3 0.6 0.0735 is the density of the dense Ti6Al4V alloy. s
C0.8 3 0.8 0.0710
Static uniaxial compression experiments were
D0 4 0 0.0565 performed using a cmt5305 machine based on the ISO
D0.2 4 0.2 0.0561 13314:2011 standard . Compression tests were conducted
[22]
D0.4 4 0.4 0.0550 at room temperature at a constant rate of 2 mm/min. Three
D0.6 4 0.6 0.0531 identical samples were tested for each Schwarz-P structure.
D0.8 4 0.8 0.0501 After the test, the fracture surface morphology of each
E0 5 0 0.0452 sample was examined using SEM.
E0.2 5 0.2 0.0449 According to the Gibson-Ashby model, mechanical
E0.4 5 0.4 0.0440 properties are related to the relative density of open-cell
[23]
E0.6 5 0.6 0.0425 porous structures . Equation IV gives the relationship
E0.8 5 0.8 0.0401 between the elastic modulus and relative density.
F1-F4 1 0 0.2262 E n 1
p C p (IV)
when the processing parameters remained the same. We E s 1 s
also considered the cross-sectional shape of the melt track
to be a rectangle and neglected the overlap in the corner. Where E is the elastic modulus of the porous structure,
P
Under this assumption, the theoretical relative density of E is the elastic modulus of the bulk material, and for
S
the Schwarz-P structure with no hatched toolpath was Ti6Al4V alloy, E = 110 GPa. ρ and ρ are the porous
s
p
S
calculated as follows: and dense material density, respectively. C and n are the
1
1
coefficients and can be calculated by fitting the test results
wh len into Equation IV. Normally, C is in the range of 0.1 to 4,
1
d p V i (II) and n equals to 2. It must be pointed out that, compared
1
tr
with the real measured relative density, we thought that the
s
theoretically calculated value is more suitable for Equation
Where d is the theoretical relative density of the IV. The reason is detailed in section 3.1.
tr
Schwarz-P structure, w is the width of the melt track, h
is the layer thickness, len is the length of the ith toolpath, 3. Results and discussion
i
and V is the volume of the hull model of the Schwarz-P
structure. In this study, the layer thickness h is 0.03mm, 3.1. Macrostructural analysis
and the melt track width w is 0.12 mm when laser power, Figures 6A–E present the manufacturing samples of
scanning speed and laser spot diameter are 90 W, 1100 Schwarz-P structures with different geometric parameters.
mm/s and 50 μm, respectively. Figures 6F–H show enlarged images of regions A1,
Volume 1 Issue 3 (2022) 5 http://doi.org/10.18063/msam.v1i3.17