Investigation on Dendritic Evolution Mechanism during Solidification of Laser-cladded IN718 Coatings

CAI Zhaoyuan; LIAN Guofu; FENG Meiyan; CHEN Changrong

doi:10.3969/j.issn.1674-6457.2026.05.004

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (5) : 34-48. DOI: 10.3969/j.issn.1674-6457.2026.05.004

Additive Manufacturing

Investigation on Dendritic Evolution Mechanism during Solidification of Laser-cladded IN718 Coatings

CAI Zhaoyuan, LIAN Guofu^*, FENG Meiyan, CHEN Changrong

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Abstract

The work aims to investigate the solidification behavior of the molten pool and the evolution of the microstructure during the laser cladding process, and elucidate the correlation mechanism between microstructural characteristics and coating performance, thereby achieving optimal coating properties. Numerical simulation and experimental approaches were integrated to explore the microstructural evolution mechanism during the solidification process of the molten pool. Based on numerical models, the heat transfer behavior of the molten pool was analyzed, as well as the relationship between molten pool size and the increase in laser power, with the molten pool length increasing from 5.13 μm at 2 000 W to 7.21 μm at 3 000 W. By extracting parameters such as the temperature gradient (G) and solidification rate (R), a columnar-to-equiaxed transformation (CET) diagram was established, which clearly elucidated the delayed mechanism of the CET behavior of IN718 coatings under high laser power conditions. The study revealed the relationship between solidification parameters and microstructure during the solidification process and further elucidated the mechanism of grain growth during the solidification of the molten pool. The grain size was controlled by the G×R composite factor, with an increase in laser power leading to an expansion of the equiaxed grain area from 19.91 μm² to 35.98 μm², and the width of the columnar grains from 6.45 μm to 11.33 μm when the laser power increased from 2 000 W to 3 000 W. In addition, the correlation between grain size and microhardness as well as wear resistance was also investigated. At a laser power of 2 000 W, the tissue strengthening caused by grain refinement resulted in an average microhardness of 408.6HV0.2 for the coating, which is a 1.22-fold increase. At a laser power of 2 500 W, the optimal proportion of grain types was achieved, with the coating’s coefficient of friction reaching a minimum of 0.596. By regulating the laser power, the distribution and evolution of the coating’s microstructure can be influenced to a certain extent, thereby enhancing its mechanical properties. The research findings provide a theoretical foundation for the fabrication of coatings with optimized microstructures and properties.

Key words

laser cladding / dendrite transformation / solidification parameters / numerical model / mechanical properties

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CAI Zhaoyuan, LIAN Guofu, FENG Meiyan, CHEN Changrong. Investigation on Dendritic Evolution Mechanism during Solidification of Laser-cladded IN718 Coatings[J]. Journal of Netshape Forming Engineering. 2026, 18(5): 34-48 https://doi.org/10.3969/j.issn.1674-6457.2026.05.004

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