Additively Manufactured Blisk with Optimized Microstructure for Small Turbine Engines

Abstract

An integrally bladed rotor in which a hub and a web are formed from a fine grain microstructure using an investment casting process or from metal powder with a HIP process, and a plurality of rotor blades formed from a coarse grain microstructure using a metal additive manufacturing process, where the hub and the web and the rotor blades are formed as a single piece and from the same material.

Claims

We claim the following:

1. An integrally bladed rotor comprising: a hub; a web formed outward of the hub; a plurality of rotor blades extending outward from the web; the hub and the web and the plurality of rotor blades all formed as a single piece; the hub and the web being formed from a fine grain microstructure; and, the rotor blades being formed from a coarse grain microstructure.

2. The integrally bladed rotor of claim 1, and further comprising: an outer surface of the web being formed from a coarse grain microstructure the same as the plurality of rotor blades.

3. The integrally bladed rotor of claim 1, and further comprising: the hub and the web and the plurality of rotor blades are all made from the same material but with different properties resulting from different grain structures.

4. The integrally bladed rotor of claim 3, and further comprising: the material is a Low Solvus High Refractory material.

5. The integrally bladed rotor of claim 3, and further comprising: the material is IN100.

6. A method of forming an integrally bladed rotor, the integrally bladed rotor having a hub and a web and a plurality of rotor blades, the method comprising the steps of: forming the hub and the web using an investment casting process or from metal powder with a HIP process; and, forming an outer surface of the web and the rotor blades using a metal additive manufacturing process.

7. The method of forming an integrally bladed rotor of claim 6, and further comprising the step of: forming the hub and the web and the rotor blades from the same material.

8. The method of forming an integrally bladed rotor of claim 6, and further comprising the steps of: forming the hub and the web from a fine gain microstructure; and, forming the rotor blades with a coarse grain and radially directional microstructure for high temperature resistance.

9. The method of forming an integrally bladed rotor of claim 8, and further comprising the step of: forming an outer surface of the web with the coarse grain microstructure.

10. The method of forming an integrally bladed rotor of claim 7, and further comprising the step of: Forming the hub and the web and the rotor blades from a Low Solvus High Refractory material.

11. The method of forming an integrally bladed rotor of claim 7, and further comprising the step of: Forming the hub and the web and the rotor blades from IN100.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0009] FIG. 1 shows a section of a turbine rotor disk with rotor blades that are secured to a hub using a dovetail slot assembly of the prior art.

[0010] FIG. 2 shows a cross section side view of the prior art rotor disk of FIG. 1.

[0011] FIG. 3 shows a section of a blisk with a hub and web formed from a casting with the rotor blades and outer rim surface formed from an additive manufacturing process of the present invention.

[0012] FIG. 4 shows a cross section side view of the blisk of FIG. 3.

[0013] FIG. 5 shows a flow chart of the process of forming the blisk of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention is a blisk (IBR or Integrally Bladed Rotor) for a small gas turbine engine of the size to propel a UAV. The blisk is formed from the same material but with two different processes. The hub and web are formed by casting or metal power with HIP (High Isostatic Pressure) with a fine-grained microstructure in the hub and web regions (for high strength and fracture toughness) and a coarse-grained, radially directional microstructure (aligned parallel to the CF loading) in the outer rim and blades, where the temperatures are highest.

[0015] FIG. 3 shows a blisk of the present invention with a hub 21, a web 22, an outer surface 23 of the web, and rotor blades 24 extending from the web 22. The blisk is a one-piece rotor with the hub 21 and the web 22 and the web outer surface 23 and the rotor blades 24 all made from the same material but with different properties resulting from different grain structures. The hub 21 and the web 22 are cast or formed from a metal powder that is compressed using a HIP (High Isostatic Pressure) process which results in a fine grained micro structure that produces high strength and fracture toughness. These properties are required in the hub and web of the blisk. The outer surface 23 of the web 22 and the rotor blades 24 that are exposed to the hot gas stream are formed by an additive manufacturing (AM) process over the cast hub 21 and web 22. The outer surface 23 and the rotor blades 24 are thus printed onto the web 22 to form the IBR. The AM process produces a coarse grain and radially directional microstructure with give the rim and blades of the blisk excellent creep properties and thus a higher temperature capability.

[0016] The blisk can be formed from an advanced disk alloy developed by NASA Glenn Research Center (NASA GRC) termed LSHR, which stands for Low Solvus High Refractory. LSHR is a nickel based superalloy with properties similar to IN100 (a common second-generation aerospace disk alloy) but with improved creep resistance and also with the unique capability of being produced by additive manufacturing. In another embodiment, the blisk can be formed from IN100.

[0017] The process of forming the blisk of the present invention (shown in FIG. 5) is to form the hub and the web using an investment casting process or from metal powder with a HIP process to form the hub and the web with a fine grain microstructure for strength (step 31). Then, the outer surface of the web and the rotor blades are formed over the cast hub and web using an AM process (step 32) in order to produce blades with a coarse grain and radially directional microstructure for high temperature resistance.