Patent ID: 7156932

Claim:
A method of heat treating a 718-type nickel-base alloy comprising: pre-solution treating the nickel-base alloy wherein an amount of at least one grain boundary precipitate selected from the group consisting of δ-phase precipitates and n-phase precipitates is formed within the nickel-base alloy, the at least one grain boundary precipitate having a short, generally rod-shaped morphology; solution treating the nickel-base alloy wherein substantially all γ′-phase precipitates and γ″-phase precipitates in the nickel-base alloy are dissolved while at least a portion of the amount of the at least one grain boundary precipitate is retained; cooling the nickel-base alloy after solution treating the nickel-base alloy at a first cooling rate sufficient to suppress formation of γ′-phase and γ″-phase precipitates in the nickel-base alloy; aging the nickel-base alloy in a first aging treatment wherein primary precipitates of γ′-phase and γ″-phase are formed in the nickel-base alloy; and aging the nickel-base alloy in a second aging treatment wherein secondary precipitates of γ′-phase and γ″-phase are formed in the nickel-base alloy, the secondary precipitates being finer than the primary precipitates; and wherein after heat treating the nickel-base alloy, the γ′-phase precipitates are predominant strengthening precipitates in the nickel-base alloy and a majority of the grain boundaries of the nickel-base alloy are pinned by at least one grain boundary precipitate.