HEAT TREATMENT METHOD

Abstract

The present disclosure relates to a method of heat treating a component (e.g. a combustor tile) which may be formed of a first material e.g. a nickel superalloy. The component may be formed using an ALM method. The method comprises enclosing at least part of the component in a foil envelope which may be formed of a second material wherein the second material (e.g. stainless steel) is more susceptible to reactive oxidation than the first material. Next the envelope is purged with an inert gas (e.g. argon) and the envelope is sealed. The component is then heated e.g. using hot isostatic pressing.

Claims

1. A method of heat treating a component, the method comprising: enclosing at least part of the component in a foil envelope; purging the envelope with an inert gas; sealing the envelope; and heating the component.

2. A method according to claim 1 further comprising manufacturing the component using an ALM method prior to enclosing at least part of the component in the foil envelope.

3. A method according to claim 2 comprising manufacturing the component from a nickel superalloy using an ALM method.

4. A method according to claim 3 comprising manufacturing the component from a high gamma prime nickel superalloy using an ALM method.

5. A method according to claim 1 further comprising forming the component of a nickel superalloy prior to enclosing at least part of the component in the foil envelope.

6. A method according to claim 5 comprising forming the component of a high gamma prime nickel superalloy.

7. A method according to claim 1 wherein the method further comprises grit blasting, surface finished or peening the surface of the component prior to enclosing it in the foil envelope.

8. A method according to claim 1 wherein the component is formed of a first material and the foil envelope if formed of a second material which is more susceptible to reactive oxidation that the first material.

9. A method according to claim 8 wherein the second material comprises an alloy having iron, aluminium, titanium, zirconium, or hafnium as a major component.

10. A method according to claim 9 wherein the second material for forming the foil envelope is stainless steel.

11. A method according to claim 1 comprising forming a spacing structure surrounding the component/component part prior to enclosing it in the foil envelope.

12. A method according to claim 1 comprising purging the foil envelope with an inert gas comprising argon.

13. A method according to claim 1 comprising enclosing the component/component part within the foil envelope whilst providing an inert gas inlet opening at an uppermost edge of the foil envelope and an inert gas outlet opening at a lowermost edge of the foil envelope with an inert gas flow path extending therebetween.

14. A method according to claim 1 wherein the component is heated under increased pressure.

15. A method according to claim 14 comprising heating the component using hot isostatic pressing.

16. A method according to claim 1 comprising providing one or more vents in the envelope during or after sealing of the envelope.

17. A method according to claim 1 wherein the component is a combustor tile for a gas turbine engine.

18. A method of manufacturing a combustor tile for a gas turbine engine comprising a heat treating method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Embodiments will now be described by way of example with reference to the accompanying drawings in which:

[0039] FIG. 1 shows a schematic representation of a first embodiment of the first aspect; and

[0040] FIG. 2 is a sectional view of a gas turbine engine.

DETAILED DESCRIPTION

[0041] In step 1, a combustor tile is formed of a high gamma prime nickel superalloy CM247LC using an additive layer manufacturing method.

[0042] In step 2, the surface of the combustor file is grit-blasted to remove any surface irregularities.

[0043] In step 3, a spacing structure is formed to surround the combustor tile. The spacing structure comprises a plurality of struts which project from the combustor tile.

[0044] In step 4, the combustor tile is enclosed in a foil envelope formed of 0.05 mm thick 321 stainless steel foil. The foil is wrapped around the spacing structure such that the plurality of struts maintains a small spacing between the foil envelope and the combustor tile i.e. so that the foil envelope does not touch the combustor tile at any point. The foil envelope has an inlet opening at an uppermost edge and an outlet opening at a lowermost edge.

[0045] In step 5, the foil envelope is purged with argon by flowing argon into the inlet opening such that it passes through the foil envelope and out of the outlet opening. The argon purges the foil envelope of atmospheric air.

[0046] In step 6, the outlet opening is sealed followed by sealing of the inlet opening. A series of small perforations are provided at the uppermost edge of the foil envelope to allow for venting of the foil envelope under pressure.

[0047] In step 7, the combustor tile and foil envelope are placed within a heat treatment vessel and the heat treatment vessel is purged with argon.

[0048] Finally, in step 8, the combustor tile is subjected to hot isostatic pressing.

[0049] The resulting combustor tile has been found to have a reduced susceptibility to cracking, even at locations which are highly stressed owing to their geometry.

[0050] The foil envelope encloses the combustor tile within a reduced volume (compared to the heat treatment vessel) which can be more effectively purged with inert gas thus reducing the exposure of the highly stressed location to residual oxygen contained within the heat treatment vessel. Furthermore, the foil envelope is also sacrificed to improve the purity of the inert gas surrounding the envelope and which may gain access to the combustor tile e.g. through the venting perforations.

[0051] With reference to FIG. 2, a gas turbine engine is generally indicated at 10, having a principal and rotational axis 11. The engine 10 comprises, in axial flow series, an air intake 12, a propulsive fan 13, an intermediate pressure compressor 14, a high-pressure compressor 15, combustion equipment 16 comprising a plurality of combustor tiles manufactured as described above, a high-pressure turbine 17, an intermediate pressure turbine 18, a low-pressure turbine 19 and an exhaust nozzle 20. A nacelle 21 generally surrounds the engine 10 and defines both the intake 12 and the exhaust nozzle 20.

[0052] The gas turbine engine 10 works in the conventional manner so that air entering the intake 12 is accelerated by the fan 13 to produce two air flows: a first air flow into the intermediate pressure compressor 14 and a second air flow which passes through a bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 14 compresses the air flow directed into it before delivering that air to the high pressure compressor 15 where further compression takes place.

[0053] The compressed air exhausted from the high-pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture combusted. The combustion equipment 16 typically comprises an annular combustion chamber which is lined with the plurality of combustor tiles which can be manufactured according to the method described herein.

[0054] The resultant hot combustion products generated within the combustion equipment 16 then expand through, and thereby drive the high, intermediate and low-pressure turbines 17, 18, 19 before being exhausted through the nozzle 20 to provide additional propulsive thrust. The high 17, intermediate 18 and low 19 pressure turbines drive respectively the high pressure compressor 15, intermediate pressure compressor 14 and fan 13, each by suitable interconnecting shaft.

[0055] Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. By way of example such engines may have an alternative number of interconnecting shafts (e.g. two) and/or an alternative number of compressors and/or turbines. Further the engine may comprise a gearbox provided in the drive train from a turbine to a compressor and/or fan.

[0056] It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.