Dual alloy rotor

A method of making a dual-alloy rotor member comprising the steps of:

• forming first material having a comparatively higher tensile strength into a disc-like annular first part defining a central bore, forming an axially disposed radially extending annular first interbonding surface upon said first part radially outwardly of said central bore, forming said first part to provide a boss extending axially from said first surface and circumscribing said bore, providing on said boss a radially outwardly disposed second interbonding surface, forming in said first interbonding surface of said first part a first recess;
• forming second material having a comparatively higher creep rupture strength at elevated temperatures into a disc-like annular second part defining a central through passage larger than said central bore, forming an axially disposed radially extending annular third interbonding surface upon said second part which is engageable with said first interbonding surface, forming within said central through passage a fourth radially inwardly disposed interbonding surface which is engageable with said second interbonding surface, forming in said third interbonding surface of said second part a second recess matching axially congruently with said first recess;
• providing a support member conforming with both said first recess and said second recess;
• uniting said first part and said second part to engage said first interbonding surface with said third interbonding surface and said second interbonding surface with said fourth interbonding surface and aligning said first recess with said second recess in matched axial congruence to cooperatively define a cavity;
• capturing said support member within said cavity with substantially no ullage space;
• subjecting said united first part, second part, and support member to hot isostatic pressure diffusion bonding (HIP);
• employing said HIP bonding to diffusion bond said engaged interbonding surfaces to unite said parts into a unitary body;
• and
• removing said support member from said cavity.

A dual-alloy centrifugal compressor rotor member of unitary construction having a plurality of closed cavities therein, said rotor member comprising:

• a disc-like annular first portion defining a central through bore, an axial inducer end and a first axially disposed radially extending annular bond interface spaced from said axial inducer end, a boss part of said first portion extending axially from said first bond interface and circumscribing said central through bore to define a second annular bond interface disposed radially outwardly and extending axially, a plurality of radially outwardly extending integral aerodynamic blade members spaced circumferentially apart and extending axially and circumferentially from proximate said axial inducer end to terminate in a radially outer discharge end thereof, said first portion comprising material having comparatively higher tensile strength;
• a disc-like annular second portion received upon and circumscribing said boss part of said first portion;
• said second portion defining an axially disposed radially extending third bond interface diffusion bonding with said first bond interface, a radially inwardly disposed axially extending fourth bond interface diffusion bonding with said second bond interface, said second portion comprising material having comparatively higher creep rupture strength at elevated temperatures;
• said first portion and said second portion cooperating to define a plurality of annularly arrayed circumferentially spaced apart, closed cavities spaced radially outwardly of said central through bore and within said rotor member, each one of said plurality of cavities being substantially similar and residing in part within said first portion and in part within said second portion so that said first bond interface and said second bond interface cooperatively define a transverse plane transecting each of said cavities, a respective plurality of passages extending axially outwardly each from a respective one of said plurality of cavities through said second portion to open outwardly upon said rotor member, each one of said plurality of passages being substantially similar and significantly smaller in axial cross section than said respective cavity;
• and
• means for closing each of said plurality of passages.