Cracking Behavior of Directionally Solidified CM247LC Nickel-based Superalloy

LIU Manping; ZONG Zhouyingyi; MA Hui; CHEN Yulin; LI Haohao; ZHAO Guoping; SUN Shaochun

doi:10.3969/j.issn.1674-6457.2026.02.025

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (2) : 266-274. DOI: 10.3969/j.issn.1674-6457.2026.02.025

Superalloy Forming

Cracking Behavior of Directionally Solidified CM247LC Nickel-based Superalloy

LIU Manping^1,*, ZONG Zhouyingyi¹, MA Hui¹, CHEN Yulin^2,*, LI Haohao¹, ZHAO Guoping¹, SUN Shaochun¹

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Abstract

To investigate the causes of crack formation of nickel-based superalloys during use, the work aims to analyze the grain boundary cracks in directionally solidified CM247LC alloy, and study the effect of microsegregation of alloy elements and carbides on cracking behavior. The microstructure of CM247LC alloy in as cast and heat-treated states was observed with a light microscope. The distribution of fine γ/γ' eutectic precipitates and MC carbides inside the alloy was analyzed by scanning electron microscopy, and the segregation of elements in different regions was obtained. The cross-sectional microstructure of directionally solidified cast CM247LC alloy was dendritic, with obvious MC carbides and γ/γ' eutectic structures between dendrites. The alloy exhibited severe segregation in the as cast state. Compared with the heat-treated state, the grain boundary cracks in the as cast state were wider, and the microstructure and morphology of the grain boundary cracks were clearer. The location of the grain boundary cracks was still in the interdendritic region. Owing to the mismatch in elastic and thermophysical properties between MC carbides and the matrix, stress concentration is prone to occur at their interface regions, which may induce microcracks. When MC carbides become enriched in local areas, the stress concentration effect is further intensified. Once the local stress exceeds the fracture strength of the material, cracks initiate and propagate, ultimately leading to alloy cracking.

Key words

directional solidification / CM247LC nickel-based superalloy / cracking behavior / segregation / microstructure

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LIU Manping, ZONG Zhouyingyi, MA Hui, CHEN Yulin, LI Haohao, ZHAO Guoping, SUN Shaochun. Cracking Behavior of Directionally Solidified CM247LC Nickel-based Superalloy[J]. Journal of Netshape Forming Engineering. 2026, 18(2): 266-274 https://doi.org/10.3969/j.issn.1674-6457.2026.02.025

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