Effect of High-temperature Short-term Annealing on Microstructure and Mechanical Properties of Inconel 625 Alloy Fabricated by Selective Laser Melting

YANG Min; JIA Zhi; WANG Yanjiang; LI Yinming; ZHANG Chi; LIANG Chengwei; MA Lin

doi:10.3969/j.issn.1674-6457.2026.01.007

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (1) : 64-75. DOI: 10.3969/j.issn.1674-6457.2026.01.007

Additive Manufacturing

Effect of High-temperature Short-term Annealing on Microstructure and Mechanical Properties of Inconel 625 Alloy Fabricated by Selective Laser Melting

YANG Min^a,b, JIA Zhi^a,b,*, WANG Yanjiang^a,b, LI Yinming^a,b, ZHANG Chi^a,b, LIANG Chengwei^a,b, MA Lin^a

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Abstract

The work aims to clarify the microstructure evolution and recrystallization mechanism of Inconel 625 alloy fabricated by selective laser melting (SLM) during high-temperature short-term annealing, and to explore their relationship with mechanical properties, thereby providing a theoretical basis for the engineering application of additively manufactured nickel-based superalloys. The high residual stress generated during SLM processing was used as the stored activation energy of Inconel 625 alloy interface control. The effects of high-temperature short-term annealing (1 000-1 200 ℃) on the microstructure, grain boundary characteristics, recrystallization behavior, and mechanical properties of the samples were studied by means of optical microscopy (OM), electron backscatter diffraction (EBSD), and other characterization methods. The results showed that the rapid cooling process in SLM processing made the sample form a unique multi-scale microstructure, and the initial surface of the sample presented a chessboard-shaped molten pool distribution, which was related to the scanning strategy with 67° inter-layer rotation during SLM processing. As the annealing temperature increased, the molten pool morphology gradually disappeared, accompanied by grain coarsening and a reduction in dislocation density. When the annealing temperature reached 1 150 ℃, the samples initiated significant static recrystallization. Following annealing at 1 200 ℃, recrystallization was nearly complete, yielding the most homogeneous internal stress distribution within the alloy. The recrystallization process was dominated by discontinuous static recrystallization nucleation, supplemented by continuous static recrystallization nucleation. In summary, high-temperature annealing releases the stored energy of the alloy through thermal activation, which effectively promotes the recrystallization process and the formation of annealing twins. With the increase of annealing temperature, the strength and hardness of the alloy gradually decrease, while the elongation increases significantly.

Key words

Inconel 625 alloy / selective laser melting / high-temperature short-term annealing / interface control / mechanical properties

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YANG Min, JIA Zhi, WANG Yanjiang, LI Yinming, ZHANG Chi, LIANG Chengwei, MA Lin. Effect of High-temperature Short-term Annealing on Microstructure and Mechanical Properties of Inconel 625 Alloy Fabricated by Selective Laser Melting[J]. Journal of Netshape Forming Engineering. 2026, 18(1): 64-75 https://doi.org/10.3969/j.issn.1674-6457.2026.01.007

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Funding

The National Nature Science Foundation of China (52265049); The Gansu Province Joint Research Fund Project (24JRRA833); The Key Research and Development Plan Project of Gansu Province-industrial Projects (23YFGA0054); The Industrial Support Program for Colleges and Universities in Gansu Province (2022CYZC-26); The Gansu Provincial Talent Project in 2024 (2024QNTD44); The Lanzhou University of Technology Support plan for Distinguished Young Scholars (HLJQ2402); The Natural Science Foundation of Gansu Province (23JRRA922)