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Mechanisms of Microstructural and Defect Evolution in Laser Powder Bed Fusion-Fabricated In625 Induced by Heat
Qing Chen1,2,3,4, Yi Liu1,2,3, Xuxing Duan1,2,3
1National Key Laboratory of Nuclear Reactor Technology, Nuclear Power Institute of China, Chengdu 610213, China.
Materials (Basel, Switzerland)
|May 13, 2026
Summary
Solution heat treatment optimizes Inconel 625 (In625) fabricated via laser powder bed fusion (L-PBF). Optimal treatment at 1090°C reduces porosity and refines microstructure, enhancing mechanical properties.
Area of Science:
- Materials Science
- Metallurgy
- Additive Manufacturing
Background:
- Laser powder bed fusion (L-PBF) is a key additive manufacturing technique for producing Inconel 625 (In625).
- Heat treatment is critical for optimizing the microstructure and properties of L-PBF-fabricated In625.
- Understanding the influence of heat treatment parameters on defects and microstructure is essential for engineering applications.
Purpose of the Study:
- To systematically investigate the effects of different solution heat treatments on L-PBF-fabricated In625.
- To characterize the evolution of internal defects and microstructure under varying heat treatment conditions.
- To evaluate the impact of heat treatment on the mechanical properties and anisotropy of L-PBF In625.
Main Methods:
- Industrial computed tomography (CT) for internal defect characterization.
- Optical microscopy, Electron Backscatter Diffraction (EBSD), Transmission Electron Microscopy (TEM), and Energy Dispersive Spectroscopy (EDS) for microstructural analysis.
- Room-temperature tensile testing for mechanical property evaluation.
Main Results:
- Heat treatment at 1090°C reduced porosity from 0.33% to 0.25%, while 1150°C increased it to 0.45% due to competing pore closure and coarsening mechanisms.
- Complete grain equiaxiality (<100 μm) was achieved at 1090°C and above, with coarsening at higher temperatures.
- Samples treated at 1150°C showed reduced mechanical anisotropy, with tensile strength >919 MPa and elongation up to 60%.
Conclusions:
- Solution heat treatment significantly influences porosity, microstructure, and mechanical anisotropy in L-PBF In625.
- A non-monotonic relationship exists between heat treatment temperature and porosity, driven by complex pore evolution mechanisms.
- Optimized heat treatment parameters, such as at 1090°C or 1150°C, can tailor the microstructure-defect-property relationships for improved engineering performance of L-PBF In625.
