Hastelloy X 주조재의 열간 노출에 따른 미세조직 및 인장 특성 변화

• Published in: 한국주조공학회지 Vol. 37; no. 5; pp. 139 - 147
• Main Authors: 최백규, Baig Gyu Choi, 김인수, In Soo Kim, 도정현, Jeonghyeon Do, 정중은, Joong Eun Jung, 정인용, In Yong Jung, 홍현욱, Hyun Uk Hong, 조창용, Chang Yong Jo
• Format: Journal Article
• Language: Korean
• Published: 한국주조공학회 31.10.2017
• Subjects: Carbide; Hastelloy X; Microstructure; Tensile properties; Thermal exposure; 금속공학; Carbide; Thermal exposure; Microstructure; Hastelloy X; Tensile properties
• ISSN: 1598-706X; 2288-8381
• DOI: 10.7777/jkfs.2017.37.5.139

Microstructural evolution of cast Hastelloy X during thermal exposure has been investigated. OM, SEM, and TEM microscopy were carried out on the as-cast, the standard heat treated, and the thermally exposed conditions. Tensile tests were also conducted to understand the effect of microstructural evolution on the degradation of tensile properties. Coarse M 6 C and fine M 23 C 6 carbides were found in as-cast Hastelloy X with fine carbides on sub-boundary. Some of M 23 C 6 carbide dissolved into the matrix during solution heat treatment and dislocation network formed at the interface between the carbide and the matrix due to the misfit strain. There was no significant microstructural difference between the exposed specimens at 400℃ and the solution heat treated specimen. A large amount of M 23 C 6 carbides precipitated along and near grain boundaries and sub-boundaries after exposure at 650℃. Expo-sure at 870℃ of the alloy caused precipitation of M 6 C and μ. The strength increased and the elongation decreased by thermal expo-sure at 650℃ and 870℃ because carbides interfere with the movement of the dislocation. It was found that the precipitation of carbide gave significant effects on the tensile properties of Hastelloy X.