Patent ID: 7115175
Filing Date: 2006-10-03
Classification: C22C,C22F

Abstract:
1. A process for forming an improved nickel base superalloy comprising the steps of: casting an object formed from a single crystal nickel base superalloy having a microstructure; closing any as-cast microporosity and partially solutioning eutectic γ–γ′ phase islands in the microstructure of said single crystal nickel base superalloy; fully solutioning any eutectic γ–γ′ phase and precipitating a uniform distribution of large γ′ particles in the microstructure; forming fine γ′ particles in the microstructure to improve the strength of the nickel base superalloy; said closing and partially solutioning step comprising subjecting said cast object to hot isostatic processing at a final temperature in the range of from 2145° F. to 2625° F. for a time period in the range of from 3.5 to 4.5 hours at a final pressure in the range of from 13 ksi to 16.5 ksi; and wherein said hot isostatic processing step further comprises bringing the cast object from room temperature to a first temperature in the range of from 2075° F. to 2550° F. at a rate of from about 5.4 to 6.6° F./min, from the first temperature to a second temperature in the range of from 2125° F. to 2595° F. at a rate of from 0.4 to 0.6° F./min, and from the second temperature to the final temperature at a rate of 0.05° F./min to 0.15° F./min.