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Vol.62, No.6, 445 ~ 455, 2024
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| Title |
| Microstructure and Tensile Properties of Ni-Base Superalloy IN738LC according to Solidification Rate and Heat Treatment |
| 김병훈 Byung-hoon Kim , 공병욱 Byeong-ook Kong , 주윤곤 Yun-kon Joo , 주영규 Young-kyu Ju , 홍현욱 Hyun-uk Hong , 이재현 Je-hyun Lee |
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| Abstract |
| The strength of Ni-base superalloys mainly depends on theγ' precipitates that improve the strength of the materials at high temperatures. The presence ofγ' particles within the matrix restricts dislocation movement, and optimized heat treatments can tailor the size, shape, and volume fraction ofγ'. In this study the effects of solidification rate and solution temperature on the tensile properties of IN738LC superalloy were investigated. The secondary dendritic arm spacing of casting materials with different diameters was measured and the solidification rate of the casting materials was derived by comparing the results of the solidification microstructure obtained from a directional solidification experiment. The D17 material, which had a faster solidification rate, showed higher values of tensile strength and yield strength than the D60 material, which had a slower solidification rate. The study also concluded that the monomodalγ' precipitates in the S80 material have higher tensile strength and yield strength at room temperature and 760℃ than the bimodalγ' precipitates in the S20 material. As for the deformation behavior at 760℃, an isolated stacking fault was observed in the S20 material only within the largeγ’ precipitates. In the S80 material, the high dislocation density increased the yield strength due to the strong interaction between dislocations and fineγ’ precipitates.
(Received 2 January, 2024; Accepted 8 March, 2024) |
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| Key Words |
| IN738LC, Solidification rate, Tensile property, Stacking fault |
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