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

(A ) (A ) (A )
1 2 3

(B )
(B ) (B ) 3
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2

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

Figure 3. Electron backscattered diffraction results of the as-built, HIP1100, HIP1180, and HIP1210 specimens. (A , B , C , and D ) Inverse pole figure
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maps, (A , B , C , and D ) grain boundary maps, and (A , B , C , and D ) pole figure map. Scale bar: 100 μm, magnification: ×500.
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Abbreviation: HIP: Hot isostatic pressing.
of substructure boundaries, accompanied by high-density processed, and the kernel average misorientation map
dislocations. Numerous low-angle grain boundaries were was employed to mark the recrystallized grains by
also observed at HIP1100, with the proportion decreasing setting a specific range for local strain, as shown in
to 49.7%, suggesting that the substructures remained, as Figure 4A , B , C , and D . The as-built specimen showed
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shown in Figure 3B . At HIP1180, the low-angle grain minimal recrystallization, while more recrystallization
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boundaries almost disappeared with a proportion of occurred in the HIP specimens. At HIP1100, the incomplete
4.3%, as displayed in Figure 3C . In addition, a large recrystallization of the Hastelloy X specimen was
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number of annealing twins appeared and were measured observed, with recrystallized grains accounting for 43% of
at approximately 31% (the ratio of twin boundary length the total. At HIP1180 and HIP1210, 98% and 100% of the
to the total grain boundary length), the low interface equiaxed grains underwent recrystallization, respectively,
energy of which was beneficial for alleviating the stress indicating that the recrystallization process was almost
concentration within the specimen. At HIP1210, the completed. The diagrams of grain size distribution were
low-angle grain boundaries were completely replaced by statistically analyzed in Figure 4A , B , C , and D . In
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the high-angle grain boundaries and twin boundaries, as the as-built specimen, the grain size was below 60 μm,
displayed in Figure 3D . with an average value of 16.4 μm. At HIP1100, a large
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To intuitively characterize the grain recrystallization number of microstructure characteristics in the as-built
under different HIP treatments, the EBSD data were specimen were retained with an average grain size of
Volume 1 Issue 2 (2025) 5 doi: 10.36922/ESAM025240015