Patent ID: 7841506

Claim:
A method for fabricating an impeller having a first region and and a second region, the first region having predetermined strength properties, and the second region having a predetermined creep resistance properties, the method comprising the steps of: providing a first titanium alloy formulated to be capable of having the predetermined strength properties imparted thereto; forming the first titanium alloy into a bore subelement having a first mating surface including a first conical shape; heat treating the bore subelement; providing a second titanium alloy formulated differently than the first titanium alloy and to be capable of having the predetermined creep resistance properties imparted thereto; forming the second titanium alloy into a body subelement, the body subelement including a hollow portion defined by a second mating surface including a second conical shape corresponding to the first conical shape of the first mating surface; heat treating the body subelement; inertia welding the first mating surface of the bore subelement to the second mating surface of the body subelement so as to form an intermediate structure; stress relieving the intermediate structure to optimize a microstructure of the intermediate structure, to impart the predetermined strength characteristic to the bore subelement, and to impart the predetermined elevated temperature performance characteristic to the body subelement; and machining away excess material from the intermediate structure to form the impeller.