Thermal Stability and Tensile Properties of GH984G Alloy for A-USC Power Plants

Abstract:

GH984G is a new Ni-Fe-based alloy which has been designed for use as superheater, reheater, and header materials for boilers in 700°C advanced ultra-supercritical (A-USC) coal-fired power plants. In this paper, the tensile properties and microstructure evolutions of GH984G were investigated during long-term thermal exposure at 700 and 750°C up to 15000h. The results show that the major precipitates were MC, M₂₃C₆ and γ ́, and no detrimental TCP or GCP phase appeared during long-term thermal exposure. The morphology of γ ́ was spherical and had no obvious change, but the size increases. After thermal exposure at 700°C for 15000h, the 700°C yield strength slightly increased, but the yield strength decreased after thermal exposure at 750°C for 15000h. The variation of strength is attributed to the coarsening of γ ́ precipitation. The deformation mechanism is the moving dislocations shear γ ́ precipitates and the stacking faults form in γ ́ precipitates at room temperature and 700°C. At 750°C, the deformation mechanism is characterized by the formation of dislocation loops and tangles.

• Periodical: Materials Science Forum (Volume 816)
• Pages: 534-539
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.816.534
• Online since: April 2015
• Authors: Mei Lin Tan*, Chang Shuai Wang, Yong An Guo, Gu Song Li, Jian Ting Guo, Lan Zhang Zhou
• Keywords: Mechanical Properties, Microstructural Stability, Ni-Fe-Based Superalloy, Thermal Exposure, γ Precipitates

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