EP1378582B1 - A method of heat treating titanium aluminide - Google Patents
A method of heat treating titanium aluminide Download PDFInfo
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- EP1378582B1 EP1378582B1 EP03253539A EP03253539A EP1378582B1 EP 1378582 B1 EP1378582 B1 EP 1378582B1 EP 03253539 A EP03253539 A EP 03253539A EP 03253539 A EP03253539 A EP 03253539A EP 1378582 B1 EP1378582 B1 EP 1378582B1
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- titanium aluminide
- aluminide alloy
- temperature
- alpha
- titanium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
- C22F1/18—High-melting or refractory metals or alloys based thereon
- C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
Definitions
- the present invention relates to a method of heat-treating titanium aluminide and in particular to a method of heat-treating.
- first long term soak at a sub alpha transus temperature and a second short term soak at a temperature just above the alpha transus temperature followed by furnace or air cooling of a titanium aluminide alloy as disclosed by Yang J, Wang JN, Wang Y, Xia QF and Zhang B in Intermetallics 2001, 9, 369.
- first long term soaking temperature has to be as close to the alpha transus temperature as possible in order to minimise the soaking time.
- the original lamellar microstructure transforms into granular gamma and alpha with a high volume fraction of the alpha phase.
- the remaining gamma grains act as pinning points to prevent the rapid growth of alpha phase.
- the second short term soaking temperature has to be above the alpha transus temperature and as close as possible to the alpha transus temperature and the second short term soaking should be as short as possible.
- This heat treatment requires precision control and rapid heating to the second short term soaking temperature.
- the aim is to leave the titanium aluminide alloy in the alpha phase field for the shortest possible time to prevent excessive alpha grain growth but this is difficult to realise in a production environment.
- US-A-5 746 846 discloses a method to produced a fine grained gamma phase, nearly lamellar, microstructure by hot working the alloy in the range of 700°C to T alpha +20°C followed by annealing at T alpha -20°C to T alpha -1°C.
- the present invention seeks to provide a novel method of heat-treating titanium aluminide alloy which reduces, preferably overcomes, the above-mentioned problems.
- the present invention provides a method of heat-treating titanium aluminide alloy, the titanium aluminide alloy having a single alpha phase field and being capable of producing a massively transformed gamma microstructure, the method comprising the steps of
- the predetermined time period is up to 2 hours.
- the predetermined time period is up to 4 hours.
- step (d) comprises heating the titanium aluminide alloy to a temperature about 30°C to 60°C below the alpha transus temperature.
- step (a) comprises heating the titanium aluminide alloy to a temperature of about 20°C to 30°C above the alpha transus temperature.
- step (f) comprises air-cooling or furnace cooling.
- step (c) comprises air-cooling or oil cooling.
- the titanium aluminide alloy consists of at least 46at% aluminium.
- the titanium aluminide alloy may comprise 48at% aluminium, 2at% chromium, 2at% niobium and the balance titanium and incidental impurities.
- the alpha transus temperature is about 1360°C
- step (a) comprises heating to a temperature of 1380°C
- step (b) comprises maintaining the titanium aluminide alloy at a temperature of about 1380°C for about 1 hour
- step (c) comprises oil cooling the titanium aluminide alloy from a temperature of 1380°C to produce a massively transformed gamma microstructure
- steps (d) and (e) comprise heating the titanium aluminide alloy to a temperature of about 1320°C for about 2 hours to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced in the titanium aluminide alloy
- step (f) comprises air cooling the titanium aluminide alloy to ambient temperature.
- the titanium aluminide alloy may comprise 46at% aluminium, 8at% niobium, up to 0.07at% carbon and the balance titanium and incidental impurities.
- the alpha transus temperature is about 1335°C
- step (a) comprises heating to a temperature of 1360°C
- step (b) comprises maintaining the titanium aluminide alloy at a temperature of about 1360°C for about 1 hour
- step (c) comprises oil cooling, or air cooling, the titanium aluminide alloy from a temperature of 1360°C to produce a massively transformed gamma microstructure
- steps (d) and (e) comprise heating the titanium aluminide alloy to a temperature of about 1300°C for about 4 hours to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced in the titanium aluminide alloy
- step (f) comprises air cooling the titanium aluminide alloy to ambient temperature.
- the present invention is applicable to a gamma titanium aluminide alloy consisting of 45-46at% aluminium, 8at% niobium, up to 0.07at% carbon and the balance titanium and incidental impurities, for example 45.5at% aluminium, 8at% niobium and the balance titanium and incidental impurities.
- the present invention is also applicable to a gamma titanium aluminide alloy consisting of 45-46at% aluminium, 2-6at% niobium, 2-6at% hafnium and the balance titanium and incidental impurities, for example 46at% aluminium, 4at% niobium, 4at% hafnium and the balance titanium and incidental impurities.
- the titanium aluminide alloy may be a cast titanium aluminide component.
- the method may comprise hot isostatic pressing of the cast titanium aluminide alloy component.
- the hot isostatic pressing of the cast titanium aluminide alloy component is concurrent with step (e) .
- the hot isostatic pressing comprises applying a pressure of about 150Mpa for about 4 hours.
- the titanium aluminide alloy may be a compressor blade or a compressor vane.
- a method of heat-treating a titanium aluminide alloy according to the present invention is described with reference to figure 1.
- the present invention is concerned with heat-treating gamma titanium aluminide alloys with at least 46at% aluminium and a single alpha phase field.
- the heat treatment process comprises heating the gamma titanium aluminide to a temperature T 1 above the alpha transus temperature T ⁇ .
- the gamma titanium aluminide alloy is then maintained at a temperature T 1 above the alpha transus temperature T ⁇ in the single alpha phase field for a predetermined time period t 1 .
- the gamma titanium aluminide is quenched, for example air cooled, or oil cooled, from the single alpha phase field at temperature T 1 to produce a massively transformed gamma microstructure.
- the gamma titanium aluminide alloy is then heated to a temperature T 2 below the alpha transus temperature T ⁇ .
- the gamma titanium aluminide alloy is maintained at the temperature T 2 in the alpha and gamma phase field for a predetermined time period t 2 to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced in the titanium aluminide alloy.
- the gamma titanium aluminide is cooled, for example air cooled, or furnace cooled, to ambient temperature.
- Figure 2 illustrates a very fine duplex microstructure of a gamma titanium aluminide alloy treated according to the present invention.
- differently orientated alpha plates precipitated in a massive gamma phase matrix effectively reduce the grain size of the gamma titanium aluminide alloy and these are produced by the massive gamma to alpha + gamma phase transformation.
- FIG 4 illustrates a coarse lamellar microstructure of a gamma titanium aluminide alloy treated according to a prior art method.
- the coarse lamellar microstructure is produced by the alpha to alpha + gamma phase transformation.
- the gamma titanium aluminide is heated to a temperature T 1 about 20°C to 30°C above the alpha transus temperature T ⁇ .
- the gamma titanium aluminide alloy is maintained at the temperature T 1 for up to 2 hours.
- the gamma titanium aluminide alloy is then quenched, for example air cooled, or oil cooled, at a rate sufficient to induce a massively transformed gamma microstructure.
- the gamma titanium alloy is heated to a temperature T 2 about 30°C to 60°C below the alpha transus temperature T ⁇ .
- the gamma titanium aluminide alloy is maintained at the temperature T 2 for up to 4 hours to precipitate fine alpha plates with different orientations in the massively transformed gamma microstructure due to the massive gamma to alpha + gamma phase transformation. This gives rise to a very fine duplex microstructure.
- the differently orientated alpha plates precipitated in the massive gamma phase matrix effectively reduce the grain size of the gamma titanium aluminide.
- the gamma titanium aluminide alloy is then cooled, for example air cooled, or furnace cooled, to ambient temperature.
- the holding at temperature T 1 for a time period t 1 also acts a homogenisation process for cast titanium aluminide alloys.
- a gamma titanium aluminide alloy consisting of 48at% aluminium, 2at% chromium, 2at% niobium and the balance titanium plus incidental impurities was heat treated according to the present invention.
- the gamma titanium aluminide alloy was oil cool quenched.
- the gamma titanium aluminide alloy was air cooled to ambient temperature.
- the microstructure of the gamma titanium aluminide alloy is shown in figure 3.
- a gamma titanium aluminide alloy consisting of 46at% aluminium, 8at% niobium, up to 0.07at% carbon and the balance titanium plus incidental impurities was heat treated according to the present invention.
- the gamma titanium aluminide alloy was oil quenched.
- the gamma titanium aluminide alloy was air cooled to ambient temperature.
- the present invention is applicable to a gamma titanium aluminide alloy consisting of 46at% aluminium, 5at% niobium, 0.3at% boron, 0.2at% carbon and the balance titanium plus incidental impurities.
- the present invention is applicable to a gamma titanium aluminide alloy consisting of 47at% aluminium, 2at% niobium, 1at% tungsten, 1at% chromium, 1at% boron, 0.2at% silicon and the balance titanium plus incidental impurities.
- the present invention is applicable to gamma titanium aluminide alloy consisting of 47at% aluminium, 2at% tantalum, 1at% chromium, 1at% manganese, 1at% boron, 0.2at% silicon and the balance titanium plus incidental impurities.
- the present invention is also applicable to gamma titanium aluminide alloy consisting of 46at% aluminium, 5at% niobium, 1at% tungsten and the balance titanium plus incidental impurities.
- the present invention is applicable to a gamma titanium aluminide alloy consisting of 45-46at% aluminium, 8at% niobium, up to 0.07at% carbon and the balance titanium and incidental impurities, for example 45.5at% aluminium, 8at% niobium and the balance titanium and incidental impurities.
- the present invention is also applicable to a gamma titanium aluminide alloy consisting of 45-46at% aluminium, 2-6at% niobium, 2-6at% hafnium and the balance titanium and incidental impurities, for example 46at% aluminium, 4at% niobium, 4at% hafnium and the balance titanium and incidental impurities.
- the present invention may be used to refine the microstructure of titanium aluminide alloys without the need for hot working.
- the present invention has the advantage of simplicity and practicality over the prior art previously discussed.
- the heat treatment at temperature T 1 for time t 1 in the single alpha phase field and does not have a rigid holding time and this allows the process to be carried out in conventional heat treatment facilities.
- the gamma titanium aluminide alloys must be capable of producing massively transformed gamma microstructures.
- the cooling rate during the quenching is not excessive and most gamma titanium aluminide alloys with at least 46at% aluminium and with at least 4at% refractory alloying elements may be quenched in air or oil depending on the size of the gamma titanium aluminide alloy component.
- the temperature range for heat treatment at temperature T 2 for time t 2 is relatively wide and is not close to the alpha transus temperature T ⁇ , which reduces the technical requirement of the heat treatment facilities and makes the heat treatment process easier.
- the present invention is particularly useful for gamma titanium aluminide alloy castings in which hot working is not possible.
- the present invention refines the microstructure of gamma titanium aluminide alloy castings and reduces the scatter in mechanical properties and improves the room temperature ductility.
- the cast gamma titanium aluminide alloy component may be hot isostatically pressed (HIP) to remove the porosity.
- the hot isostatic pressing preferably occurs at the same time as the heat treatment temperature T 2 and for the time period of about 4 hours at a pressure of about 150Mpa and this is beneficial because this dispenses with the requirement for a separate hot isostatic pressing step.
- the present invention is particularly suitable for gamma titanium aluminide gas turbine engine compressor blades as illustrated in figure 5.
- the compressor blade 10 comprises a root 12, a shank 14, a platform 16 and an aerofoil 18.
- the present invention is also suitable for gamma titanium aluminide gas turbine engine compressor vanes or other gamma titanium aluminide gas turbine engine components.
- the present invention may also be suitable for gamma titanium aluminide components for other engine, machines or applications.
Description
- The present invention relates to a method of heat-treating titanium aluminide and in particular to a method of heat-treating.
- There is a requirement to refine the microstructure of a titanium aluminide alloy, in particular cast titanium aluminide alloy, which does not involve hot working of the titanium aluminide alloy.
- It is known to use six to eight rapid heating and rapid cooling cycles of a titanium aluminide alloy to obtain satisfactory fineness of the microstructure, as disclosed by Wang JN, Xia K in Intermetallics 2000, 8, 545. But this is only practical on a laboratory scale. The rapid heating and rapid cooling is beyond the ability of conventional heat treatment facilities. In order to achieve rapid heating and rapid cooling of a titanium aluminide component, the size of the titanium aluminide component is limited and cracks may be produced in an irregular shaped titanium aluminide component.
- It is also known to use a first long term soak at a sub alpha transus temperature and a second short term soak at a temperature just above the alpha transus temperature followed by furnace or air cooling of a titanium aluminide alloy, as disclosed by Yang J, Wang JN, Wang Y, Xia QF and Zhang B in Intermetallics 2001, 9, 369. However, the first long term soaking temperature has to be as close to the alpha transus temperature as possible in order to minimise the soaking time. During the first long term soaking the original lamellar microstructure transforms into granular gamma and alpha with a high volume fraction of the alpha phase. The remaining gamma grains act as pinning points to prevent the rapid growth of alpha phase. The second short term soaking temperature has to be above the alpha transus temperature and as close as possible to the alpha transus temperature and the second short term soaking should be as short as possible. This heat treatment requires precision control and rapid heating to the second short term soaking temperature. The aim is to leave the titanium aluminide alloy in the alpha phase field for the shortest possible time to prevent excessive alpha grain growth but this is difficult to realise in a production environment.
- Furthermore it is known to provide rapid heating at a rate of about 1500°Cs-1 to a temperature above the alpha transus temperature, a short holding of about 5 minutes at this temperature and normal cooling to produce a fully lamellar refined microstructure in a titanium aluminide alloy, as disclosed by Salishnov GA, Imayev RM, Kuznetsov AV, Shagiev MR, Imayev VM, Shenkov ON, Froes FH, In Kim Y-W, Dumiduk DM, Loretto MH, editors of Gamma Titanium Aluminides 1999, Warendale, PA:TMS, 1999, p291. However, the rapid heating rate required is difficult to achieve using a conventional furnace and the very short holding time is difficult to control. Additionally prolonged holding at a temperature above the alpha transus temperature results in rapid growth of alpha grains, which limits the use of this technique in industrial applications. US-A-5 746 846 discloses a method to produced a fine grained gamma phase, nearly lamellar, microstructure by hot working the alloy in the range of 700°C to Talpha +20°C followed by annealing at Talpha -20°C to Talpha -1°C.
- Accordingly the present invention seeks to provide a novel method of heat-treating titanium aluminide alloy which reduces, preferably overcomes, the above-mentioned problems.
- Accordingly the present invention provides a method of heat-treating titanium aluminide alloy, the titanium aluminide alloy having a single alpha phase field and being capable of producing a massively transformed gamma microstructure, the method comprising the steps of
- (a) heating a titanium aluminide alloy to a temperature above the alpha transus temperature,
- (b) maintaining the titanium aluminide alloy at a temperature above the alpha transus temperature in the sinqle alpha phase field for a predetermined time period,
- (c) cooling the titanium aluminide alloy from the single alpha phase field to produce a massively transformed gamma microstructure,
- (d) heating the titanium aluminide alloy to a temperature below the alpha transus temperature in the alpha and gamma phase field,
- (e) maintaining the titanium aluminide alloy at the temperature below the alpha transus temperature for a predetermined time period to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced in the titanium aluminide alloy,
- (f) cooling the titanium aluminide alloy to ambient temperature.
-
- Preferably in step (b) the predetermined time period is up to 2 hours.
- Preferably in step (e) the predetermined time period is up to 4 hours.
- Preferably step (d) comprises heating the titanium aluminide alloy to a temperature about 30°C to 60°C below the alpha transus temperature.
- Preferably step (a) comprises heating the titanium aluminide alloy to a temperature of about 20°C to 30°C above the alpha transus temperature.
- Preferably step (f) comprises air-cooling or furnace cooling.
- Preferably step (c) comprises air-cooling or oil cooling.
- Preferably the titanium aluminide alloy consists of at least 46at% aluminium. The titanium aluminide alloy may comprise 48at% aluminium, 2at% chromium, 2at% niobium and the balance titanium and incidental impurities.
- The alpha transus temperature is about 1360°C, step (a) comprises heating to a temperature of 1380°C, step (b) comprises maintaining the titanium aluminide alloy at a temperature of about 1380°C for about 1 hour, step (c) comprises oil cooling the titanium aluminide alloy from a temperature of 1380°C to produce a massively transformed gamma microstructure, steps (d) and (e) comprise heating the titanium aluminide alloy to a temperature of about 1320°C for about 2 hours to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced in the titanium aluminide alloy, and step (f) comprises air cooling the titanium aluminide alloy to ambient temperature.
- The titanium aluminide alloy may comprise 46at% aluminium, 8at% niobium, up to 0.07at% carbon and the balance titanium and incidental impurities.
- The alpha transus temperature is about 1335°C, step (a) comprises heating to a temperature of 1360°C, step (b) comprises maintaining the titanium aluminide alloy at a temperature of about 1360°C for about 1 hour, step (c) comprises oil cooling, or air cooling, the titanium aluminide alloy from a temperature of 1360°C to produce a massively transformed gamma microstructure, steps (d) and (e) comprise heating the titanium aluminide alloy to a temperature of about 1300°C for about 4 hours to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced in the titanium aluminide alloy, and step (f) comprises air cooling the titanium aluminide alloy to ambient temperature.
- The present invention is applicable to a gamma titanium aluminide alloy consisting of 45-46at% aluminium, 8at% niobium, up to 0.07at% carbon and the balance titanium and incidental impurities, for example 45.5at% aluminium, 8at% niobium and the balance titanium and incidental impurities. The present invention is also applicable to a gamma titanium aluminide alloy consisting of 45-46at% aluminium, 2-6at% niobium, 2-6at% hafnium and the balance titanium and incidental impurities, for example 46at% aluminium, 4at% niobium, 4at% hafnium and the balance titanium and incidental impurities.
- The titanium aluminide alloy may be a cast titanium aluminide component.
- The method may comprise hot isostatic pressing of the cast titanium aluminide alloy component.
- Preferably the hot isostatic pressing of the cast titanium aluminide alloy component is concurrent with step (e) .
- Preferably the hot isostatic pressing comprises applying a pressure of about 150Mpa for about 4 hours.
- The titanium aluminide alloy may be a compressor blade or a compressor vane.
- The present invention will be more fully described by way of example with reference to the accompanying drawings in which:-
- Figure 1 is graph of temperature versus time illustrating the method of heat-treating a titanium aluminide alloy according to the present invention.
- Figure 2 is a schematic view of the microstructure of a titanium aluminide alloy heat treated according to the present invention.
- Figure 3 is a view of the microstructure of a titanium aluminide alloy heat treated according to the present invention.
- Figure 4 is a schematic view of the microstructure of a titanium aluminide alloy heat treated according to the prior art.
- Figure 5 is a gamma titanium aluminide alloy gas turbine engine compressor blade heat treated according to the present invention.
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- A method of heat-treating a titanium aluminide alloy according to the present invention is described with reference to figure 1. The present invention is concerned with heat-treating gamma titanium aluminide alloys with at least 46at% aluminium and a single alpha phase field.
- The heat treatment process comprises heating the gamma titanium aluminide to a temperature T1 above the alpha transus temperature Tα. The gamma titanium aluminide alloy is then maintained at a temperature T1 above the alpha transus temperature Tα in the single alpha phase field for a predetermined time period t1. The gamma titanium aluminide is quenched, for example air cooled, or oil cooled, from the single alpha phase field at temperature T1 to produce a massively transformed gamma microstructure. The gamma titanium aluminide alloy is then heated to a temperature T2 below the alpha transus temperature Tα. The gamma titanium aluminide alloy is maintained at the temperature T2 in the alpha and gamma phase field for a predetermined time period t2 to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced in the titanium aluminide alloy. The gamma titanium aluminide is cooled, for example air cooled, or furnace cooled, to ambient temperature.
- Figure 2 illustrates a very fine duplex microstructure of a gamma titanium aluminide alloy treated according to the present invention. In the present invention differently orientated alpha plates precipitated in a massive gamma phase matrix effectively reduce the grain size of the gamma titanium aluminide alloy and these are produced by the massive gamma to alpha + gamma phase transformation.
- For comparison Figure 4 illustrates a coarse lamellar microstructure of a gamma titanium aluminide alloy treated according to a prior art method. In the prior art the coarse lamellar microstructure is produced by the alpha to alpha + gamma phase transformation.
- In particular, the gamma titanium aluminide is heated to a temperature T1 about 20°C to 30°C above the alpha transus temperature Tα. The gamma titanium aluminide alloy is maintained at the temperature T1 for up to 2 hours. The gamma titanium aluminide alloy is then quenched, for example air cooled, or oil cooled, at a rate sufficient to induce a massively transformed gamma microstructure. The gamma titanium alloy is heated to a temperature T2 about 30°C to 60°C below the alpha transus temperature Tα. The gamma titanium aluminide alloy is maintained at the temperature T2 for up to 4 hours to precipitate fine alpha plates with different orientations in the massively transformed gamma microstructure due to the massive gamma to alpha + gamma phase transformation. This gives rise to a very fine duplex microstructure. The differently orientated alpha plates precipitated in the massive gamma phase matrix effectively reduce the grain size of the gamma titanium aluminide. The gamma titanium aluminide alloy is then cooled, for example air cooled, or furnace cooled, to ambient temperature.
- The holding at temperature T1 for a time period t1 also acts a homogenisation process for cast titanium aluminide alloys.
- A gamma titanium aluminide alloy consisting of 48at% aluminium, 2at% chromium, 2at% niobium and the balance titanium plus incidental impurities was heat treated according to the present invention. This gamma titanium aluminide alloy has an alpha transus temperature Tα = 1360°C. The gamma titanium aluminide alloy was heated to a temperature T1 = 1380°C and was held at T1 = 1380°C for 1 hour. The gamma titanium aluminide alloy was oil cool quenched. The gamma titanium aluminide alloy was heated to a temperature T2 = 1320°C and was held at T2 = 1320°C for 2 hours. The gamma titanium aluminide alloy was air cooled to ambient temperature. The microstructure of the gamma titanium aluminide alloy is shown in figure 3.
- A gamma titanium aluminide alloy consisting of 46at% aluminium, 8at% niobium, up to 0.07at% carbon and the balance titanium plus incidental impurities was heat treated according to the present invention. This gamma titanium aluminide alloy has an alpha transus temperature Tα = 1335°C. The gamma titanium aluminide alloy was heated to a temperature T1 = 1360°C and was held at T1 = 1360°C for 1 hour. The gamma titanium aluminide alloy was oil quenched. The gamma titanium aluminide alloy was heated to a temperature T2 = 1300°C and was held at T2 = 1300°C for 4 hours. The gamma titanium aluminide alloy was air cooled to ambient temperature.
- The present invention is applicable to a gamma titanium aluminide alloy consisting of 46at% aluminium, 5at% niobium, 0.3at% boron, 0.2at% carbon and the balance titanium plus incidental impurities. The present invention is applicable to a gamma titanium aluminide alloy consisting of 47at% aluminium, 2at% niobium, 1at% tungsten, 1at% chromium, 1at% boron, 0.2at% silicon and the balance titanium plus incidental impurities. The present invention is applicable to gamma titanium aluminide alloy consisting of 47at% aluminium, 2at% tantalum, 1at% chromium, 1at% manganese, 1at% boron, 0.2at% silicon and the balance titanium plus incidental impurities. The present invention is also applicable to gamma titanium aluminide alloy consisting of 46at% aluminium, 5at% niobium, 1at% tungsten and the balance titanium plus incidental impurities.
- The present invention is applicable to a gamma titanium aluminide alloy consisting of 45-46at% aluminium, 8at% niobium, up to 0.07at% carbon and the balance titanium and incidental impurities, for example 45.5at% aluminium, 8at% niobium and the balance titanium and incidental impurities. The present invention is also applicable to a gamma titanium aluminide alloy consisting of 45-46at% aluminium, 2-6at% niobium, 2-6at% hafnium and the balance titanium and incidental impurities, for example 46at% aluminium, 4at% niobium, 4at% hafnium and the balance titanium and incidental impurities.
- The present invention may be used to refine the microstructure of titanium aluminide alloys without the need for hot working. The present invention has the advantage of simplicity and practicality over the prior art previously discussed. The heat treatment at temperature T1 for time t1 in the single alpha phase field and does not have a rigid holding time and this allows the process to be carried out in conventional heat treatment facilities. The gamma titanium aluminide alloys must be capable of producing massively transformed gamma microstructures. The cooling rate during the quenching is not excessive and most gamma titanium aluminide alloys with at least 46at% aluminium and with at least 4at% refractory alloying elements may be quenched in air or oil depending on the size of the gamma titanium aluminide alloy component. This significantly reduces the possibility of cracking of the gamma titanium aluminide alloy component during quenching. The temperature range for heat treatment at temperature T2 for time t2 is relatively wide and is not close to the alpha transus temperature Tα, which reduces the technical requirement of the heat treatment facilities and makes the heat treatment process easier. The present invention is particularly useful for gamma titanium aluminide alloy castings in which hot working is not possible. The present invention refines the microstructure of gamma titanium aluminide alloy castings and reduces the scatter in mechanical properties and improves the room temperature ductility.
- In the case of cast gamma titanium aluminide alloy components it may be necessary to remove porosity from the cast gamma titanium aluminide alloy component. In this case the cast gamma titanium aluminide alloy component may be hot isostatically pressed (HIP) to remove the porosity. The hot isostatic pressing preferably occurs at the same time as the heat treatment temperature T2 and for the time period of about 4 hours at a pressure of about 150Mpa and this is beneficial because this dispenses with the requirement for a separate hot isostatic pressing step.
- The present invention is particularly suitable for gamma titanium aluminide gas turbine engine compressor blades as illustrated in figure 5. The
compressor blade 10 comprises aroot 12, ashank 14, aplatform 16 and anaerofoil 18. The present invention is also suitable for gamma titanium aluminide gas turbine engine compressor vanes or other gamma titanium aluminide gas turbine engine components. The present invention may also be suitable for gamma titanium aluminide components for other engine, machines or applications.
Claims (20)
- A method of heat-treating a titanium aluminide alloy, the titanium aluminide alloy having a single alpha phase field and being capable of producing a massively transformed gamma microstructure the method comprising the steps of(a) heating a titanium aluminide alloy to a temperature above the alpha transus temperature,(b) maintaining the titanium aluminide alloy at the temperature above the alpha transus temperature in the single alpha phase field for a predetermined time period,(c) cooling the titanium aluminide alloy from the single alpha phase field to produce a massively transformed gamma microstructure,(d) heating the titanium aluminide alloy to a temperature below the alpha transus temperature in the alpha and gamma phase field,(e) maintaining the titanium aluminide alloy at the temperature below the alpha transus temperature for a predetermined time period to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced in the titanium aluminide alloy,(f) cooling the titanium aluminide alloy to ambient temperature.
- A method as claimed in claim 1 wherein in step (b) the predetermined time period is up to 2 hours.
- A method as claimed in claim 1 or claim 2 wherein in step (e) the predetermined time period is up to 4 hours.
- A method as claimed in claim 1, claim 2 or claim 3 wherein step (d) comprises heating the titanium aluminide alloy to a temperature about 30°C to 60°C below the alpha transus temperature.
- A method as claimed in any of claims 1 to 4 wherein step (a) comprises heating the titanium aluminide alloy to a temperature of about 20°C to 30°C above the alpha transus temperature.
- A method as claimed in any of claims 1 to 5 wherein step (f) comprises air-cooling or furnace cooling.
- A method as claimed in any of claims 1 to 6 wherein step (c) comprises air-cooling or oil cooling.
- A method as claimed in any of claims 1 to 7 wherein the titanium aluminide alloy consists of at least 46at% aluminium.
- A method as claimed in any of claims 1 to 8 wherein the titanium aluminide alloy comprises 48at% aluminium, 2at% chromium, 2at% niobium and the balance titanium and incidental impurities.
- A method as claimed in claim 9 wherein the alpha transus temperature is about 1360°C, step (a) comprises heating to a temperature of 1380°C, step (b) comprises maintaining the titanium aluminide alloy at a temperature of about 1380°C for about 1 hour, step (c) comprises oil cooling the titanium aluminide alloy from a temperature of 1380°C to produce a massively transformed gamma microstructure, steps (d) and (e) comprise heating the titanium aluminide alloy to a temperature of about 1320°C for about 2 hours to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced in the titanium aluminide alloy, and step (f) comprises air cooling the titanium aluminide alloy to ambient temperature.
- A method as claimed in any of claims 1 to 8 wherein the titanium aluminide alloy comprises 46at% aluminium, 8at% niobium, up to 0.07at% carbon and the balance titanium and incidental impurities.
- A method as claimed in claim 11 wherein the alpha transus temperature is about 1335°C, step (a) comprises heating to a temperature of 1360°C, step (b) comprises maintaining the titanium aluminide alloy at a temperature of about 1360°C for about 1 hour, step (c) comprises oil cooling, or air cooling, the titanium aluminide alloy from a temperature of 1360°C to produce a massively transformed gamma microstructure, steps (d) and (e) comprise heating the titanium aluminide alloy to a temperature of about 1300°C for about 4 hours to precipitate alpha plates in the massively transformed gamma microstructure such that a refined microstructure is produced in the titanium aluminide alloy, and step (f) comprises air cooling the titanium aluminide alloy to ambient temperature.
- A method as claimed in any of claims 1 to 7 wherein the titanium aluminide alloy consists of 45-46at% aluminium, 8at% niobium, up to 0.07at% carbon and the balance titanium and incidental impurities.
- A method as claimed in any of claims 1 to 7 wherein the titanium aluminide alloy consists of 45-46at% aluminium, 2-6at% niobium, 2-6at% hafnium and the balance titanium and incidental impurities.
- A method as claimed in claim 14 wherein the titanium aluminide alloy consists of 46at% aluminium, 4at% niobium, 4at% hafnium and the balance titanium and incidental impurities.
- A method as claimed in any of claims 1 to 15 wherein the titanium aluminide alloy is a cast titanium aluminide alloy component.
- A method as claimed in claim 16 comprising hot isostatic pressing of the cast titanium aluminide alloy component.
- A method as claimed in claim 17 wherein the hot isostatic pressing of the cast titanium aluminide alloy component is concurrent with step (e).
- A method as claimed in claim 17 or claim 18 wherein the hot isostatic pressing comprises applying a pressure of about 150MPa for about 4 hours.
- A method as claimed in any of claims 1 to 19 wherein the titanium aluminide alloy is a compressor blade or a compressor vane.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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GB0215563 | 2002-07-05 | ||
GBGB0215563.8A GB0215563D0 (en) | 2002-07-05 | 2002-07-05 | A method of heat treating titanium aluminide |
Publications (2)
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EP1378582A1 EP1378582A1 (en) | 2004-01-07 |
EP1378582B1 true EP1378582B1 (en) | 2004-10-20 |
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EP03253539A Expired - Fee Related EP1378582B1 (en) | 2002-07-05 | 2003-06-04 | A method of heat treating titanium aluminide |
Country Status (4)
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US (1) | US20040003877A1 (en) |
EP (1) | EP1378582B1 (en) |
DE (1) | DE60300101T2 (en) |
GB (1) | GB0215563D0 (en) |
Families Citing this family (8)
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GB0319061D0 (en) * | 2003-08-14 | 2003-09-17 | Rolls Royce Plc | A method of heat treating titanium aluminide |
GB0601662D0 (en) * | 2006-01-27 | 2006-03-08 | Rolls Royce Plc | A method for heat treating titanium aluminide |
GB0616566D0 (en) * | 2006-08-19 | 2006-09-27 | Rolls Royce Plc | An alloy and method of treating titanium aluminide |
CA2696778A1 (en) * | 2010-03-17 | 2011-09-17 | Ignis Innovation Inc. | Lifetime, uniformity, parameter extraction methods |
US8953165B2 (en) | 2010-10-21 | 2015-02-10 | Spectrasensors, Inc. | Validation and correction of spectrometer performance using a validation cell |
US10006113B2 (en) * | 2012-08-21 | 2018-06-26 | United Technologies Corporation | Gamma titanium dual property heat treat system and method |
CN104480347B (en) * | 2014-12-17 | 2017-03-29 | 南京理工大学 | A kind of TiAl-base alloy and its Technology for Heating Processing |
CN114150242B (en) * | 2021-11-25 | 2023-07-18 | 南京理工大学 | Method for inhibiting coarsening of light high-strength TiAl alloy sheet |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
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US5076858A (en) * | 1989-05-22 | 1991-12-31 | General Electric Company | Method of processing titanium aluminum alloys modified by chromium and niobium |
JP2903102B2 (en) * | 1994-03-02 | 1999-06-07 | 科学技術庁金属材料技術研究所長 | High temperature high strength TiAl based alloy |
US5442847A (en) * | 1994-05-31 | 1995-08-22 | Rockwell International Corporation | Method for thermomechanical processing of ingot metallurgy near gamma titanium aluminides to refine grain size and optimize mechanical properties |
US5417781A (en) * | 1994-06-14 | 1995-05-23 | The United States Of America As Represented By The Secretary Of The Air Force | Method to produce gamma titanium aluminide articles having improved properties |
US6231699B1 (en) * | 1994-06-20 | 2001-05-15 | General Electric Company | Heat treatment of gamma titanium aluminide alloys |
US5558729A (en) * | 1995-01-27 | 1996-09-24 | The United States Of America As Represented By The Secretary Of The Air Force | Method to produce gamma titanium aluminide articles having improved properties |
USH1659H (en) * | 1995-05-08 | 1997-07-01 | The United States Of America As Represented By The Secretary Of The Air Force | Method for heat treating titanium aluminide alloys |
US5653828A (en) * | 1995-10-26 | 1997-08-05 | National Research Council Of Canada | Method to procuce fine-grained lamellar microstructures in gamma titanium aluminides |
-
2002
- 2002-07-05 GB GBGB0215563.8A patent/GB0215563D0/en not_active Ceased
-
2003
- 2003-06-04 EP EP03253539A patent/EP1378582B1/en not_active Expired - Fee Related
- 2003-06-04 DE DE60300101T patent/DE60300101T2/en not_active Expired - Lifetime
- 2003-06-06 US US10/455,613 patent/US20040003877A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
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US20040003877A1 (en) | 2004-01-08 |
EP1378582A1 (en) | 2004-01-07 |
DE60300101D1 (en) | 2004-11-25 |
DE60300101T2 (en) | 2005-03-03 |
GB0215563D0 (en) | 2002-08-14 |
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