Microstructure Analysis of Inconel 625 Alloy Fabricated by CMT-AAM based on Phase Field Simulation

SHI Ruixu; YANG Quantao; LI Bing; GU Xiaoyan; LIN Xiaopeng

doi:10.3969/j.issn.1674-6457.2026.09.013

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (9) : 124-134. DOI: 10.3969/j.issn.1674-6457.2026.09.013

Additive Manufacturing

Microstructure Analysis of Inconel 625 Alloy Fabricated by CMT-AAM based on Phase Field Simulation

SHI Ruixu, YANG Quantao^*, LI Bing, GU Xiaoyan, LIN Xiaopeng

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Abstract

The work aims to explore the microstructural evolution and element segregation behavior during the CMT arc wire additive manufacturing process of Inconel 625 alloy, to provide theoretical guidance for optimizing processing parameters and enhancing component performance. The finite element method was employed to calculate the temperature field distribution during the arc wire additive manufacturing process. Temperature gradients and cooling rates at different deposition layers were extracted and integrated into a phase-field model to simulate the microstructural evolution and element segregation behavior. The accuracy of the simulation results was confirmed through experimental observations. As the number of deposition layers increased, the effects of thermal accumulation became more pronounced. The maximum molten pool temperature escalated from 2 595.15 K (Layer 1) to 2 877.15 K (Layer 7), while the temperature gradient and the cooling rate decreased from 307.9 K/mm to 101.1 K/mm and from 537.5 K/s to 176.4 K/s, respectively. Dendrite growth was observed in four stages: planar crystal, interfacial instability, competitive growth, and stable growth. As the temperature gradient and cooling rate decreased, dendritic structures progressively coarsened. The primary dendrite arm spacing expanded from 28.0 μm to 38.9 μm, with an increase in secondary dendrite development. The simulation results aligned well with the experimental data. Nb elements, enriched between dendrites, formed blocky or chain-like Laves phases distributed within the γ-phase matrix. Experimental measurements indicated an Nb content of approximately 2.64 wt% in the γ matrix and 22.0 wt% in Laves phases, while simulations predicted 1.95 wt% in the γ matrix and 24.38 wt% in Laves phases, thereby validating the precision of the simulation model. In conclusion, during the CMT arc wire additive manufacturing of Inconel 625 alloy, thermal accumulation reduces temperature gradients and cooling rates, resulting in dendritic coarsening and element segregation.

Key words

phase-field simulation / CMT arc wire additive manufacturing / dendritic spacing / microstructural evolution / elemental segregation

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SHI Ruixu, YANG Quantao, LI Bing, GU Xiaoyan, LIN Xiaopeng. Microstructure Analysis of Inconel 625 Alloy Fabricated by CMT-AAM based on Phase Field Simulation[J]. Journal of Netshape Forming Engineering. 2026, 18(9): 124-134 https://doi.org/10.3969/j.issn.1674-6457.2026.09.013

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Funding

The National Natural Science Foundation of China (51705218); The Guiding Project of the Scientific Research Program of Hubei Provincial Department of Education (B2024073); Doctoral Research Start-up Fund (BK202303); Hubei Province Science and Technology Talent Service Enterprise Project (2025DJB012); 2018 Project of the Hubei Province Higher Education Institutions Outstanding Young and Middle-Aged Science and Technology Innovation Team Program: "Research on Key Preparation Technologies and Application of High-Performance Automotive Powder Metallurgy Parts" (T201811)