ScholarWorks@경상국립대학교

초록

Although Inconel 939 (IN939) is a popular γ′ precipitate-hardened Ni-based superalloy known for its outstanding creep, corrosion, and oxidation resistance at high temperatures, surface cracks and wear are inevitable during long-term service under extreme conditions. To address this issue, laser-based directed energy deposition (DED) offers an effective solution for developing efficient and precise repair techniques. Several research groups have reported the basic mechanical properties and the effects of post-heat treatment on DED IN939 alloy; however, the optimization of processing parameters under various conditions remains insufficiently explored. In this study, DED processing parameters for IN939 alloy were optimized by combining a database from coupon specimens with response surface methodology (RSM). The estimated relative density and deposition accuracy from quadratic polynomial models correlated with experimental results within deviations of 5% and 3%, respectively. Based on these models, the optimized DED processing parameters for IN939 alloy were determined to be 300 W laser power, 800 mm/min scan speed, and 2 g/min feed rate. These results demonstrate that the RSM-based optimization approach is effective for obtaining optimal processing parameters when the optimized values lie within the database range.

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