Page 110 - ESAM-1-2

Engineering Science in
Additive Manufacturing HIP temperature effects on LPBF Hastelloy X

and HIP1210 specimens demonstrated hardness values improved, reaching a maximum value of 45% at HIP1210,
of 244.24 HV, 214.42 HV, and 211.44 HV, representing a while the yield strength and tensile strength declined.
decline of 8.9%, 20.0%, and 21.1%, respectively. This could The HIP specimen, HIP1100, achieved the highest yield
be attributed to the progressed recrystallization process strength of 569 MPa and the highest tensile strength of
with the elevated HIP temperature. The substructures 774 MPa, which was associated with the synergistic effect
gradually vanished, accompanied by a reduction in the of the dislocation slip, grain size, and carbide distribution.
number of low-angle grain boundaries, as depicted in On one hand, dislocation slip was effectively hindered at
Figure 3. Therefore, the hindrance for substructures to HIP1100 due to a higher proportion of low-angle grain
dislocation slip is reduced, leading to a decline in hardness. boundaries compared to HIP1180 and HIP1210. On
the other hand, the presence of fine grains and small,
Tensile tests of all specimens at room temperature were
conducted, and the results are presented in Figure 7B. dispersed particle carbides contributed to grain refinement
Compared to the as-built specimen, the tensile strength and strengthening and dispersion strengthening, respectively.
elongation of the HIP specimens improved, while the yield Figure 8 presents the fracture surfaces of the as-built,
strength decreased. The improvement of tensile strength HIP1100, HIP1180, and HIP1210 tensile specimens
of HIP specimens was achieved due to the reduction of tested at room temperature. Cracks were observed on the
porosity through the HIP treatment. In addition, as the fracture surfaces of the HIP1180 and HIP1210 specimens.
HIP temperature increased, the elongation gradually This cracking is attributed to the precipitation and

A B

Figure 7. Mechanical properties obtained at room temperature of as-built, HIP1100, HIP1180, and HIP1210 specimens. (A) Microhardness and (B) Yield
strength, tensile strength, and elongation.
Abbreviation: HIP: Hot isostatic pressing.

(A ) (B ) (C ) (D )
1 1 1 1

(A ) (B ) (C ) (D )
2 2 2 2

Figure 8. Fracture surfaces of Hastelloy X tensile specimens failed at room temperature. Results of (A and A ) as-built, (B and B ) HIP1100,
1
2
1
2
(C and C ) HIP1180, and (D and D ) HIP 1210 specimens. Scale bars: (A -D ) 100 μm; (A -D ) 10 μm, magnifications: (A -D ) ×500; (A -D ) ×5,000.
2
1
1
2
1
2
1
2
1
2
2
1
Abbreviation: HIP: Hot isostatic pressing.
Volume 1 Issue 2 (2025) 8 doi: 10.36922/ESAM025240015