pISSN : 1598-706X / eISSN : 2288-8381
한국주조공학회지 (37권1호 21-29)
Effect of Tungsten Contents and Heat Treatment on the Microstructures and Mechanical Properties of Hastelloy C-276 Alloy Investment Castings
정밀주조 Hastelloy C-276 합금의 미세조직과 기계적 성질에 미치는 W 함량과 열처리의 영향
Byung-Ki Yoo, Heung-Il Park*, Cha-Hurn Bae, Sung-Gyoo Kim* and Hae-Yong Jeong**†
Modern Casting & Metals Co., Ltd, *Dept. of Materials System Engineering, Pukyong National University,**Dept. of Materials Science and Engineering, Pukyong National University,
The effects of W content and heat treatment on the microstructure and mechanical properties of Hastelloy C-276 alloy investment castings were discussed. As the W c content was increased, dendritic microstructure was refined and network type p precipitate formed during solidification was distributed on the dendritic grain b boundaries. Cr, Fe and Mn were highly segregated in the Nibased dendrite matrix, and M Mo, W, C and Si were in the precipitates. Due to the heat treatment, fine granular and f flake precipitates were newly formed in the matrix, and unresolved network type p precipitates remained on the grain boundary. The network type precipitates and the granular and flake precipitates formed by heat treatment were confirmed to be μ phase intermetallic compounds with similar compositions. Due to the increase of t the W content and the heat treatment, hardness and tensile strength were significantly increased. However, tensile strength after aging treatment was decreased with the W content. These results can be explained in that brittle fracturing by the unresolved n network type precipitates dispersed in the grain boundary was predominant over ductile fracturing by the dimple ruptures originating from the fine granular precipitates in the matrix.
Investment casting, Hastelloy C-276 alloy, Tungsten contents, Solution and aging, Microstructures and mechanical properties
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