Influences of solution cooling on microstructures, mechanical properties and hot corrosion resistance of a nickel-based superalloy

The influences of solution cooling on the microstructures, mechanical properties and hot corrosion resistance of a nickel-based superalloy are researched. It is found that the mechanical properties and hot corrosion resistance are greatly influenced by the solution cooling methods including furnace-cooling (FC), water-cooling (WC) and air-cooling (AC). For the FC superalloy, large amount of coarse gamma '' (Ni3Nb) and gamma' (Ni3Al) phases precipitate from the matrix, and delta (Ni3Nb) phase preferentially precipitates on grain boundaries. Besides, compared with the WC and AC superalloys, the ultimate tensile strength, yield strength and micro-hardness of the FC superalloy are higher, but the elongation to fracture is lower. Additionally, the hot corrosion behavior can be well described by the sulfidation-oxidation model and the alkaline-base melting model. Furthermore, the FC superalloy has the best hot corrosion resistance among the three solution cooled superalloys,