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

high-temperature tensile test, cracks were observed in characteristics of laser scanning morphology were retained
areas enriched with carbides along the grain boundaries on the fracture surface at HIP1100, accompanied by obvious
of all specimens. The average carbide size of the cracks, as shown in Figure 12A and A . The fracture surface
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HIP1100 specimen increased from 0.279 μm to 0.416 μm, of HIP1180 exhibited a pronounced massive pattern
as shown in Figure 10A -A . Moreover, the carbide morphology, which corresponded to the brittleness of the
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distribution along the grain boundaries transformed from grain boundaries, as shown in Figure 12B and B . Compared
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particle distribution to bulk distribution. However, the to the HIP1100 and HIP1180 specimens, this massive
average carbide size at both HIP1180 and HIP1210 showed feature was even more prominent in the HIP1210 specimen,
minimal changes compared to that of room temperature, demonstrating a typical characteristic of intergranular
as shown in Figure 10B -B and C -C . Furthermore, fracture, as presented in Figure 12C and C .
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carbides were observed within the grains in the HIP1180 1 2
and HIP1210 specimens. However, the carbides at the Based on the above analysis, the high-temperature
grain boundaries exhibited a chain-like distribution, with fracture mechanisms of the HIP specimens are presented
a higher concentration on grain boundaries compared to in Figure 13. During the 900°C tensile test, carbides
within the grains. continued to precipitate and coarsen in the HIP specimens.
Due to the enhanced diffusion capability of solute elements
Figure 11 illustrates the microstructural morphology in the high-temperature tensile test, these elements
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and the local magnified region of the deformation region exhibited a propensity to segregate into regions of high-
failed at the 900°C tensile test of HIP specimens. Long density dislocations and grain boundaries, promoting
cracks penetrating the tensile specimen were observed in carbide precipitation and coarsening in those areas.
the HIP1100 specimen, as shown in Figure 11A -A . In Therefore, the growth rate of carbides was higher at the
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the HIP1180 specimen, the wedge cracks were confined grain boundaries than within the grains. Due to the short
solely to a local region, as presented in Figure 11B -B . In duration of the high-temperature tensile test, variations in
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comparison with the HIP1100 and HIP1180 specimens, carbide morphology among the different HIP specimens
crack formation in the HIP1210 specimen was effectively were primarily governed by their morphology before
suppressed, with cracks appearing smaller, as depicted in deformation. In the HIP1100 specimen, the presence of
Figure 11C -C . In addition, most cracks occurred and numerous vacancies and the discontinuous distribution
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propagated along the grain boundaries due to its brittleness. of particle carbides along the grain boundaries before
Figure 12 illustrates the fracture surface of HIP tensile deformation proved conducive to the carbides during the
specimens at high-temperature deformation. Part of the tensile test, as shown in Figure 13A and A . Consequently,
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(A ) (A ) (A )
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(B ) (B ) (B )
1 2 3

(C ) (C ) (C )
1 2 3

Figure 11. Microstructural morphology of the deformation region failed at high tensile temperature. Results of (A -A ) HIP1100, (B -B ) HIP1180, and
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(C -C ) HIP1210 specimens. Scale bars: (A1-C1) 1 mm; (A2-C2, A3-C3) 100 μm, magnifications: (A -C ) ×100; (A -C , A -C ) ×500.
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Abbreviation: HIP: Hot isostatic pressing.
Volume 1 Issue 2 (2025) 10 doi: 10.36922/ESAM025240015