Abstract
A novel heat treatment strategy, termed solution-double aging treatment (SDAT), is proposed to enhance the tensile properties and creep resistance at high-temperature of Inconel 617 Ni-based superalloy. This method aims to achieve a microstructure that maintains excellent thermal stability at elevated temperature up to 760 °C. The results suggest that the improved tensile properties of SDAT-treated alloys are attributable to orderly precipitation and synergistic interaction of M23C6 carbides and γ′ phases. Under identical creep conditions, SDAT alloys significantly enhance creep strength and extend creep rupture life in comparison to solution-treated (ST) alloys. Specifically, under creep conditions of 760 °C/170 MPa, SDAT alloys exhibit a 37.25 % longer creep rupture life than ST alloys, particularly under low-stress conditions. The enhanced creep properties of SDAT alloys are due to the unique microstructure produced by the SDAT treatment: the high-density and small-size of γ′ phases effectively impede dislocation movement, thereby reducing the minimum creep rate; the evolution of cylindrical coarse M23C6 carbides predominantly occurs near grain boundaries or within grains, reducing the formation of creep cracks; the high proportion of grain boundary M23C6 carbides mitigates creep damage caused by carbide evolution, inhibiting the initiation and extension of grain boundary cracks. The SDAT heat treatment process provides a novel approach to improving the creep life of Ni-based superalloys by controlling the synergistic evolution mechanisms of carbides and γ′ phases.
Published Version
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