US20060105194A1 - Defect healing of deposited titanium alloys - Google Patents
Defect healing of deposited titanium alloys Download PDFInfo
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- US20060105194A1 US20060105194A1 US10/991,604 US99160404A US2006105194A1 US 20060105194 A1 US20060105194 A1 US 20060105194A1 US 99160404 A US99160404 A US 99160404A US 2006105194 A1 US2006105194 A1 US 2006105194A1
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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
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/14—Metallic material, boron or silicon
- C23C14/16—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/58—After-treatment
- C23C14/5806—Thermal treatment
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
- Y10T428/12771—Transition metal-base component
- Y10T428/12806—Refractory [Group IVB, VB, or VIB] metal-base component
Definitions
- the invention relates to deposition of Ti-based materials. More particularly, the invention relates to addressing deposition defects.
- EBPVD electron beam physical vapor deposition
- Such techniques may be used in the aerospace industry for the repair or remanufacture of damaged or worn parts such as gas turbine engine components (e.g., blades, vanes, seals, and the like).
- Deposition defects potentially compromise the condensate integrity.
- One group of such defects arises when a droplet of material is spattered onto the substrate or the accumulating condensate.
- the melt pool may contain additives not intended to vaporize and accumulate in the condensate.
- U.S. Pat. No. 5,474,809 discloses use of refractory elements in the melt pool.
- One aspect of the invention involves a method for treating a deposited titanium-base material from an initial condition to a treated condition.
- the material is heated from a first temperature to a second temperature.
- the first temperature is below an equilibrium ⁇ transus.
- the second temperature is above the equilibrium ⁇ transus.
- the heating includes a portion at a rate in excess of 5° C./s.
- the material is cooled from the second temperature to a third temperature below the equilibrium ⁇ transus.
- the heating may be to a peak at least 10° C. above a non-equilibrium ⁇ transus.
- the material may be above the equilibrium ⁇ transus for a brief period (e.g., no more than 2.0 seconds).
- the heating and cooling may have sufficient rates to maintain a characteristic grain size of at least a matrix of the material below 100 ⁇ m.
- the material may include a number of defects having trunks with microstructures distinct from a microstructure of a matrix of the material.
- the trunks' microstructures may be essentially integrated with the matrix microstructure.
- the heating may be to a peak 10-50° C. above a non-equilibrium ⁇ transus.
- the material may be above the equilibrium ⁇ transus for a very brief period (e.g., no more than 1.0 seconds).
- the heating may be to 1-30° C. above the equilibrium ⁇ transus for a somewhat longer period (e.g., 1.0-5.0 seconds).
- the cooling may be sufficiently rapid to limit ⁇ growth to a characteristic size smaller than 100 ⁇ m.
- One group of materials consist in largest weight parts of titanium, aluminum, and vanadium.
- An exemplary material thickness may be at least 2.0 mm (e.g., for relatively thick structural and repair material, contrasted with thinner coatings).
- FIG. 1 is an optical micrograph of a Ti-6Al-4V condensate atop a like substrate and showing defects.
- FIG. 2 is a view of a healed condensate.
- FIG. 3 is a temperature-time diagram showing healing processes.
- FIG. 1 shows a condensate 20 accumulated atop a surface 22 of a substrate 24 .
- Exemplary condensate thickness may be from less than 0.2 ⁇ mm (e.g., for thin coatings) to in excess of 2 mm (at least locally—e.g., for structural condensates such as certain repairs).
- the condensate has a first defect 26 triggered by a spattered molybdenum droplet 28 that landed atop the surface 22 .
- Exemplary droplet sizes are 30-500 ⁇ m (measured as a characteristic (mean/median/mode) transverse dimension).
- the defect comprises a trunk 30 extending from the droplet 28 toward the condensate surface (not shown).
- a second defect 32 is shown and may have been triggered by a droplet below the cut surface of the view.
- the exemplary deposition is of nominal Ti-6Al-4V condensate atop a like substrate.
- Alternate depositions may include Ti-6Al-2Sn-4Zr-2Mo and Ti-8Al-1Mo-1V.
- the deposition may be from a melted ingot at least partially through a pool containing one or more refractory or other elements which may be essentially non-consumed during deposition (e.g., a pool formed from a 30%Mo-70%Zr mixture). Accordingly, the droplets may tend to have composition similar to the surface layers of the pool. In the absence of the non-consumed pool additive, the droplet 28 might have a similar composition to the ingot yet still produce similar defects. Many droplets in systems using an Mo-containing pool would have Mo concentrations of at least 10% by weight; others at least 20%. This may be somewhat less than the Mo percentage of the non-expending pool material to reflect possible dilution by deposition material elements in the pool.
- the substrate 28 has an ⁇ - ⁇ microstructure of medium to coarse grains (e.g., 10-40 ⁇ m characteristic grain size (e.g., mean) or about ASTM 10.5-6.5).
- An exemplary 10-20% by weight of the substrate is ⁇ phase with the remainder essentially a phase.
- the condensate matrix (away from the defects) also has an ⁇ - ⁇ microstructure but of very fine grains (e.g., acicular ⁇ grains of 5-10 m in length and 2-5 ⁇ m in thickness, lengthwise oriented along the condensate growth/deposition direction).
- the trunk size will depend, in substantial part, upon the droplet size. Exemplary trunk diameters are from about 20 ⁇ m to about 50 ⁇ m. However, much larger trunks are possible.
- the trunks have a columnar ⁇ - ⁇ microstructure.
- This microstructure may have a characteristic grain size several times greater than that in the matrix and the grains may be elongated in the direction of accumulation (i.e., away from the substrate).
- the grain discontinuity at the trunk-matrix interface and the particular alignment of trunk grains may cause structural weaknesses affecting, inter alia, ductility, fracture toughness, fatigue resistance, fretting fatigue resistance, corrosion resistance, wear resistance, crack nucleation resistance, and the like.
- FIG. 2 shows a condensate 50 after healing.
- the substrate is not shown.
- the condensate surface 52 is, however, shown.
- a defect within the condensate had been caused by a droplet 54 .
- the resultant trunk had propagated all the way to the surface forming a bulge 56 .
- the healed condensate shows essentially no remaining artifacts of the defect other than the original droplet 54 and bulge 56 .
- the trunk has been microstructurally integrated with the condensate matrix as a fine ⁇ equiaxed microstructure (e.g., grain size of 10-100 ⁇ m ( ⁇ ASTM 10.5-3.5)).
- laminar variations in chemistry or microstructure may be diminished or eliminated, thereby increasing the isotropy of the condensate mechanical properties.
- the bulge 56 may be removed (e.g., during a subsequent surface machining).
- the healing permits the workpiece (e.g., a blade, vane, seal, or the like) to be operated at ambient temperature (e.g., 0-40° C.) and/or at elevated temperatures (e.g., above 250° C., such as in the range of 300-500° C.) essentially without increased chances of failure.
- the workpiece is initially at room temperature (condition/location 100 ) on the temperature against time plot of FIG. 3 .
- FIG. 3 further shows a line 102 representing the equilibrium ⁇ transus (T e ⁇ ) as well as curves 104 and 106 of non-equilibrium ⁇ transus temperatures for the condensate and substrate, respectively (specific to the microstructural and thermal history of this Example 1).
- the equilibrium ⁇ transus temperature is a function of chemistry only. Because the exemplary condensate and substrate have the same chemistry, they share the same equilibrium ⁇ transus temperature (e.g., 960-1010° C. for Ti-6Al-4V).
- the non-equilibrium ⁇ transus temperature is a function of composition, grain size/morphology, and heating rate. The smaller the grains, the lower the transus temperature. The more rapid the heating rate, the higher the transus temperature. At very slow heating rates, the equilibrium transus temperature equals the non-equilibrium transus temperature. Given very fine condensate grains, medium to coarse substrate grains, and a heating rate of approximately 100° C./sec, it is estimated that the difference between the non-equilibrium ⁇ transus of the two structures is about 100° C.
- the workpiece is heated 109 moderately above the condensate non-equilibrium ⁇ transus (condition/location 110 ).
- This heating may be under vacuum or in an inert atmosphere.
- This heating is advantageously rapid (e.g., occurring at a rate of 5-100° C./s or greater) so as to prevent excessive grain growth.
- Excessive grain growth e.g., above 150 ⁇ m ( ⁇ ASTM 2.5) or even 100 ⁇ m ( ⁇ ASTM 3.5), depending upon the application) is disadvantageous because it excessively reduces structural properties including one or more of ductility, fracture toughness, fatigue resistance, fretting fatigue resistance, corrosion resistance, wear resistance, crack nucleation resistance, and the like.
- the heating reaches a peak of ⁇ T 1 above the condensate non-equilibrium ⁇ transus of approximately 10-50° C.
- the heating substantially converts the condensate microstructure to ⁇ .
- the upper limit on ⁇ T 1 will reflect the microstructural/thermal history and is advantageously sufficiently low to avoid excessive ⁇ grain growth (in view of time considerations discussed below).
- the lower limit is advantageously high enough to provide essentially complete transition to the ⁇ phase ( ⁇ + ⁇ to ⁇ ).
- the substrate may be essentially unaffected.
- the workpiece is rapidly cooled 111 back to room temperature (condition/location 112 ).
- This heating may be under the same vacuum or atmosphere as the first stage.
- metastable martensite may accumulate in the condensate and the substrate.
- the cooling is advantageously sufficiently rapid to further limit ⁇ (grain growth.
- the rapid heating and cooling maintain the condensate above its equilibrium ⁇ transus for a time interval sufficiently brief to avoid the excessive ⁇ grain growth noted above while providing the ⁇ phase transition.
- An exemplary time interval above the equilibrium ⁇ transus is 1.0 seconds or less.
- This microstructure is characterized by preservation of the boundaries of the prior ⁇ grains with a (e.g., in needle- or platelet-like form) in a ⁇ matrix within such boundaries.
- the rapid heating and cooling may provide a sufficiently short time at elevated temperature (in view of the magnitude of such temperature) to greatly limit oxidation even if the procedure is performed in an ambient atmosphere rather than under vacuum or an inert atmosphere.
- elevated temperature in view of the magnitude of such temperature
- An optional third stage involves annealing/aging by heating the workpiece to an annealing temperature (e.g., in the vicinity of 500-600° C. for the exemplary Ti alloy).
- the exemplary annealing/aging is for a period of 1-24 hours and is effective to eliminate the martensite but without producing ⁇ grain growth. This may leave the condensate as essentially fine grain ⁇ (e.g., broadly smaller than 150 ⁇ m, more narrowly smaller than 100 ⁇ m, and preferably smaller than 50 ⁇ m ( ⁇ ASTM 2.5, 3.5, and 5.5, respectively)) plus the droplets and leaves the substrate as essentially medium to coarse grain ⁇ - ⁇ .
- the cooling of the second stage may be sufficiently slow to avoid martensite formation, in which case it is particularly appropriate to omit the aging/annealing.
- the initial heating stage 119 is similarly rapid but to a temperature above the equilibrium ⁇ transus but below the condensate non-equilibrium ⁇ transus.
- the resulting condition/location 120 may be at a temperature of ⁇ T 2 above the equilibrium ⁇ transus (e.g., by 10-30° C.).
- the upper limit on this range is advantageously effective to avoid excessive ⁇ grain growth.
- the lower limit on this range is advantageously high enough to provide essentially complete transition to the ⁇ phase ( ⁇ + ⁇ to ⁇ ).
- the substrate may be essentially unaffected.
- the workpiece is maintained 121 at such a temperature for a moderate time interval (e.g., of about two seconds, more broadly 1.5-4.0 seconds or 1.0-5.0 seconds) to achieve a condition/location 122 . It is during this time interval that the condensate microstructure changes to fine ⁇ as in condition/location 110 . Thereafter, a rapid cooling 123 may transition the workpiece to a condition/location 124 similar to 112 and may, in turn, be followed by a similar annealing/aging if appropriate or desired.
- a moderate time interval e.g., of about two seconds, more broadly 1.5-4.0 seconds or 1.0-5.0 seconds
- the heating and cooling may be performed by a variety of techniques.
- One family of rapid heating techniques provides highly local heating (exemplary such techniques include induction heating, laser heating, electron beam heating, and the like). Such heating facilitates heating of the condensate with less substantial heating of the substrate, thereby minimizing any structural effects on the substrate.
- the desired heating depth may be controlled in view of the coating thickness by means including frequency control of induction heating, beam intensity of laser or electron beam heating, and the like. With some implementations of such heating, the heating may progress across the condensate (e.g., by moving or reorienting the workpiece relative to the heating source). Direct electrical resistance heating may be used to more generally heat the workpiece.
- the exemplary rapid cooling may be performed by forced cooling with an inert gas (especially when the heating is performed under vacuum), forced air cooling, liquid quench (e.g., in oil or water), and the like.
Abstract
Description
- The invention relates to deposition of Ti-based materials. More particularly, the invention relates to addressing deposition defects.
- A growing art exists regarding the deposition of Ti-based materials. For example, electron beam physical vapor deposition (EBPVD) may be used to build a coating or structural condensate of a Ti alloy atop a substrate of like or dissimilar nominal composition. Such techniques may be used in the aerospace industry for the repair or remanufacture of damaged or worn parts such as gas turbine engine components (e.g., blades, vanes, seals, and the like).
- Deposition defects, however, potentially compromise the condensate integrity. One group of such defects arises when a droplet of material is spattered onto the substrate or the accumulating condensate. The melt pool may contain additives not intended to vaporize and accumulate in the condensate. For example, U.S. Pat. No. 5,474,809 discloses use of refractory elements in the melt pool. Once the droplet lands on the surface (of the substrate or the accumulating condensate) further deposition builds atop the droplet and the adjacent surface. Along the sides of the droplet, there may be microstructural discontinuities in the accumulating material due to the relative orientation of the sides of the droplet. As further material accumulates, these discontinuities may continue to build all the way to the final condensate surface.
- One aspect of the invention involves a method for treating a deposited titanium-base material from an initial condition to a treated condition. The material is heated from a first temperature to a second temperature. The first temperature is below an equilibrium β transus. The second temperature is above the equilibrium β transus. The heating includes a portion at a rate in excess of 5° C./s. The material is cooled from the second temperature to a third temperature below the equilibrium β transus.
- In various implementations, the heating may be to a peak at least 10° C. above a non-equilibrium β transus. The material may be above the equilibrium β transus for a brief period (e.g., no more than 2.0 seconds). The heating and cooling may have sufficient rates to maintain a characteristic grain size of at least a matrix of the material below 100 μm. In the initial condition, the material may include a number of defects having trunks with microstructures distinct from a microstructure of a matrix of the material. In the treated condition, the trunks' microstructures may be essentially integrated with the matrix microstructure.
- In one group of implementations, the heating may be to a peak 10-50° C. above a non-equilibrium β transus. The material may be above the equilibrium β transus for a very brief period (e.g., no more than 1.0 seconds). In another group of potentially overlapping implementations, the heating may be to 1-30° C. above the equilibrium β transus for a somewhat longer period (e.g., 1.0-5.0 seconds). The cooling may be sufficiently rapid to limit β growth to a characteristic size smaller than 100 μm. One group of materials consist in largest weight parts of titanium, aluminum, and vanadium. An exemplary material thickness may be at least 2.0 mm (e.g., for relatively thick structural and repair material, contrasted with thinner coatings).
- The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
-
FIG. 1 is an optical micrograph of a Ti-6Al-4V condensate atop a like substrate and showing defects. -
FIG. 2 is a view of a healed condensate. -
FIG. 3 is a temperature-time diagram showing healing processes. - Like reference numbers and designations in the various drawings indicate like elements.
-
FIG. 1 shows acondensate 20 accumulated atop asurface 22 of asubstrate 24. Exemplary condensate thickness may be from less than 0.2 μmm (e.g., for thin coatings) to in excess of 2 mm (at least locally—e.g., for structural condensates such as certain repairs). The condensate has afirst defect 26 triggered by aspattered molybdenum droplet 28 that landed atop thesurface 22. Exemplary droplet sizes are 30-500 μm (measured as a characteristic (mean/median/mode) transverse dimension). The defect comprises atrunk 30 extending from thedroplet 28 toward the condensate surface (not shown). Asecond defect 32 is shown and may have been triggered by a droplet below the cut surface of the view. - The exemplary deposition is of nominal Ti-6Al-4V condensate atop a like substrate. Alternate depositions may include Ti-6Al-2Sn-4Zr-2Mo and Ti-8Al-1Mo-1V. The deposition may be from a melted ingot at least partially through a pool containing one or more refractory or other elements which may be essentially non-consumed during deposition (e.g., a pool formed from a 30%Mo-70%Zr mixture). Accordingly, the droplets may tend to have composition similar to the surface layers of the pool. In the absence of the non-consumed pool additive, the
droplet 28 might have a similar composition to the ingot yet still produce similar defects. Many droplets in systems using an Mo-containing pool would have Mo concentrations of at least 10% by weight; others at least 20%. This may be somewhat less than the Mo percentage of the non-expending pool material to reflect possible dilution by deposition material elements in the pool. - In the exemplary implementation, the
substrate 28 has an α-β microstructure of medium to coarse grains (e.g., 10-40 μm characteristic grain size (e.g., mean) or about ASTM 10.5-6.5). An exemplary 10-20% by weight of the substrate is β phase with the remainder essentially a phase. The condensate matrix (away from the defects) also has an α-β microstructure but of very fine grains (e.g., acicular α grains of 5-10 m in length and 2-5 μm in thickness, lengthwise oriented along the condensate growth/deposition direction). The trunk size will depend, in substantial part, upon the droplet size. Exemplary trunk diameters are from about 20 μm to about 50 μm. However, much larger trunks are possible. The trunks have a columnar α-β microstructure. This microstructure may have a characteristic grain size several times greater than that in the matrix and the grains may be elongated in the direction of accumulation (i.e., away from the substrate). Particularly in the case of very large diameter trunks (e.g., in excess of 100 μm in diameter), there may be porosity around the trunk. The grain discontinuity at the trunk-matrix interface and the particular alignment of trunk grains may cause structural weaknesses affecting, inter alia, ductility, fracture toughness, fatigue resistance, fretting fatigue resistance, corrosion resistance, wear resistance, crack nucleation resistance, and the like. - We have, accordingly, developed heat treatment regimes for healing workpieces having such defects.
FIG. 2 shows acondensate 50 after healing. In this view, the substrate is not shown. Thecondensate surface 52 is, however, shown. A defect within the condensate had been caused by adroplet 54. The resultant trunk had propagated all the way to the surface forming abulge 56. The healed condensate, however, shows essentially no remaining artifacts of the defect other than theoriginal droplet 54 andbulge 56. The trunk has been microstructurally integrated with the condensate matrix as a fine β equiaxed microstructure (e.g., grain size of 10-100 μm (˜ASTM 10.5-3.5)). Additionally, laminar variations in chemistry or microstructure may be diminished or eliminated, thereby increasing the isotropy of the condensate mechanical properties. Thebulge 56 may be removed (e.g., during a subsequent surface machining). The healing permits the workpiece (e.g., a blade, vane, seal, or the like) to be operated at ambient temperature (e.g., 0-40° C.) and/or at elevated temperatures (e.g., above 250° C., such as in the range of 300-500° C.) essentially without increased chances of failure. - In a first exemplary healing method, the workpiece is initially at room temperature (condition/location 100) on the temperature against time plot of
FIG. 3 .FIG. 3 further shows aline 102 representing the equilibrium β transus (Te β) as well ascurves - In a first stage, the workpiece is heated 109 moderately above the condensate non-equilibrium β transus (condition/location 110). This heating may be under vacuum or in an inert atmosphere. This heating is advantageously rapid (e.g., occurring at a rate of 5-100° C./s or greater) so as to prevent excessive grain growth. Excessive grain growth (e.g., above 150 μm (˜ASTM 2.5) or even 100 μm (˜ASTM 3.5), depending upon the application) is disadvantageous because it excessively reduces structural properties including one or more of ductility, fracture toughness, fatigue resistance, fretting fatigue resistance, corrosion resistance, wear resistance, crack nucleation resistance, and the like. The heating reaches a peak of ΔT1 above the condensate non-equilibrium β transus of approximately 10-50° C. The heating substantially converts the condensate microstructure to β. The upper limit on ΔT1 will reflect the microstructural/thermal history and is advantageously sufficiently low to avoid excessive β grain growth (in view of time considerations discussed below). The lower limit is advantageously high enough to provide essentially complete transition to the β phase (α+β to β). The substrate may be essentially unaffected.
- In a second stage, the workpiece is rapidly cooled 111 back to room temperature (condition/location 112). This heating may be under the same vacuum or atmosphere as the first stage. During this cooling, metastable martensite may accumulate in the condensate and the substrate. The cooling is advantageously sufficiently rapid to further limit β (grain growth. The rapid heating and cooling maintain the condensate above its equilibrium β transus for a time interval sufficiently brief to avoid the excessive β grain growth noted above while providing the β phase transition. An exemplary time interval above the equilibrium β transus is 1.0 seconds or less. Once below the β transus, the β will transform to α+β in a β-transformed (also known as transformed β) microstructure. This microstructure is characterized by preservation of the boundaries of the prior β grains with a (e.g., in needle- or platelet-like form) in a β matrix within such boundaries. The rapid heating and cooling may provide a sufficiently short time at elevated temperature (in view of the magnitude of such temperature) to greatly limit oxidation even if the procedure is performed in an ambient atmosphere rather than under vacuum or an inert atmosphere. Thus, especially for workpieces to be exposed to relatively low thermal and mechanical stresses (e.g., some non-rotating turbine engine parts), there may be greater environmental flexibility during the heating and/or cooling.
- An optional third stage (not shown in
FIG. 3 ) involves annealing/aging by heating the workpiece to an annealing temperature (e.g., in the vicinity of 500-600° C. for the exemplary Ti alloy). The exemplary annealing/aging is for a period of 1-24 hours and is effective to eliminate the martensite but without producing β grain growth. This may leave the condensate as essentially fine grain β (e.g., broadly smaller than 150 μm, more narrowly smaller than 100 μm, and preferably smaller than 50 μm (˜ASTM 2.5, 3.5, and 5.5, respectively)) plus the droplets and leaves the substrate as essentially medium to coarse grain β-β. However, the cooling of the second stage may be sufficiently slow to avoid martensite formation, in which case it is particularly appropriate to omit the aging/annealing. - In a second exemplary healing method, the
initial heating stage 119 is similarly rapid but to a temperature above the equilibrium β transus but below the condensate non-equilibrium β transus. The resulting condition/location 120 may be at a temperature of ΔT2 above the equilibrium β transus (e.g., by 10-30° C.). The upper limit on this range is advantageously effective to avoid excessive β grain growth. The lower limit on this range is advantageously high enough to provide essentially complete transition to the β phase (α+β to β). The substrate may be essentially unaffected. - Rather than being immediately followed by rapid cooling, the workpiece is maintained 121 at such a temperature for a moderate time interval (e.g., of about two seconds, more broadly 1.5-4.0 seconds or 1.0-5.0 seconds) to achieve a condition/
location 122. It is during this time interval that the condensate microstructure changes to fine β as in condition/location 110. Thereafter, arapid cooling 123 may transition the workpiece to a condition/location 124 similar to 112 and may, in turn, be followed by a similar annealing/aging if appropriate or desired. - The heating and cooling may be performed by a variety of techniques. One family of rapid heating techniques provides highly local heating (exemplary such techniques include induction heating, laser heating, electron beam heating, and the like). Such heating facilitates heating of the condensate with less substantial heating of the substrate, thereby minimizing any structural effects on the substrate. The desired heating depth may be controlled in view of the coating thickness by means including frequency control of induction heating, beam intensity of laser or electron beam heating, and the like. With some implementations of such heating, the heating may progress across the condensate (e.g., by moving or reorienting the workpiece relative to the heating source). Direct electrical resistance heating may be used to more generally heat the workpiece. The exemplary rapid cooling may be performed by forced cooling with an inert gas (especially when the heating is performed under vacuum), forced air cooling, liquid quench (e.g., in oil or water), and the like.
- One or more embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, details of the chemical composition of the particular substrate and condensate and of the physical configuration of the substrate and thickness of the condensate may influence details of any particular implementation. Accordingly, other embodiments are within the scope of the following claims.
Claims (29)
Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/991,604 US20060105194A1 (en) | 2004-11-17 | 2004-11-17 | Defect healing of deposited titanium alloys |
AT05255509T ATE401429T1 (en) | 2004-11-17 | 2005-09-08 | METHOD FOR PRODUCING DEFECT-FREE COATED TITANIUM ALLOYS |
DE602005008169T DE602005008169D1 (en) | 2004-11-17 | 2005-09-08 | Process for the preparation of defect-free coated titanium alloys |
EP05255509A EP1662019B1 (en) | 2004-11-17 | 2005-09-08 | Method of producing defect free deposited titanium alloys |
UAA200509015A UA79864C2 (en) | 2004-11-17 | 2005-09-23 | Method for treatment of sprayed titanium-based material (variants) and component |
SG200508453A SG122960A1 (en) | 2004-11-17 | 2005-11-14 | Defect healing of deposited titanium alloys |
CN200510125479.2A CN1776000A (en) | 2004-11-17 | 2005-11-17 | Defect healing of deposited titanium alloys |
MXPA05012417A MXPA05012417A (en) | 2004-11-17 | 2005-11-17 | Defect healing of deposited titanium alloys. |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US10/991,604 US20060105194A1 (en) | 2004-11-17 | 2004-11-17 | Defect healing of deposited titanium alloys |
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US20060105194A1 true US20060105194A1 (en) | 2006-05-18 |
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US10/991,604 Abandoned US20060105194A1 (en) | 2004-11-17 | 2004-11-17 | Defect healing of deposited titanium alloys |
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US (1) | US20060105194A1 (en) |
EP (1) | EP1662019B1 (en) |
CN (1) | CN1776000A (en) |
AT (1) | ATE401429T1 (en) |
DE (1) | DE602005008169D1 (en) |
MX (1) | MXPA05012417A (en) |
SG (1) | SG122960A1 (en) |
UA (1) | UA79864C2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130319154A1 (en) * | 2011-03-31 | 2013-12-05 | Aisin Aw Co., Ltd. | Steel gear and manufacturing method for the same |
US9388476B2 (en) * | 2011-03-31 | 2016-07-12 | Aisin Aw Co., Ltd. | Steel gear and manufacturing method for the same |
Citations (4)
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US5474809A (en) * | 1994-12-27 | 1995-12-12 | General Electric Company | Evaporation method |
US5879760A (en) * | 1992-11-05 | 1999-03-09 | The United States Of America As Represented By The Secretary Of The Air Force | Titanium aluminide articles having improved high temperature resistance |
US6190473B1 (en) * | 1999-08-12 | 2001-02-20 | The Boenig Company | Titanium alloy having enhanced notch toughness and method of producing same |
US6626228B1 (en) * | 1998-08-24 | 2003-09-30 | General Electric Company | Turbine component repair system and method of using thereof |
-
2004
- 2004-11-17 US US10/991,604 patent/US20060105194A1/en not_active Abandoned
-
2005
- 2005-09-08 DE DE602005008169T patent/DE602005008169D1/en active Active
- 2005-09-08 EP EP05255509A patent/EP1662019B1/en not_active Not-in-force
- 2005-09-08 AT AT05255509T patent/ATE401429T1/en not_active IP Right Cessation
- 2005-09-23 UA UAA200509015A patent/UA79864C2/en unknown
- 2005-11-14 SG SG200508453A patent/SG122960A1/en unknown
- 2005-11-17 CN CN200510125479.2A patent/CN1776000A/en active Pending
- 2005-11-17 MX MXPA05012417A patent/MXPA05012417A/en not_active Application Discontinuation
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5879760A (en) * | 1992-11-05 | 1999-03-09 | The United States Of America As Represented By The Secretary Of The Air Force | Titanium aluminide articles having improved high temperature resistance |
US5474809A (en) * | 1994-12-27 | 1995-12-12 | General Electric Company | Evaporation method |
US6626228B1 (en) * | 1998-08-24 | 2003-09-30 | General Electric Company | Turbine component repair system and method of using thereof |
US6190473B1 (en) * | 1999-08-12 | 2001-02-20 | The Boenig Company | Titanium alloy having enhanced notch toughness and method of producing same |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130319154A1 (en) * | 2011-03-31 | 2013-12-05 | Aisin Aw Co., Ltd. | Steel gear and manufacturing method for the same |
US9388476B2 (en) * | 2011-03-31 | 2016-07-12 | Aisin Aw Co., Ltd. | Steel gear and manufacturing method for the same |
US9441723B2 (en) * | 2011-03-31 | 2016-09-13 | Aisin Aw Co., Ltd. | Steel gear and manufacturing method for the same |
Also Published As
Publication number | Publication date |
---|---|
UA79864C2 (en) | 2007-07-25 |
SG122960A1 (en) | 2006-06-29 |
CN1776000A (en) | 2006-05-24 |
EP1662019A1 (en) | 2006-05-31 |
ATE401429T1 (en) | 2008-08-15 |
EP1662019B1 (en) | 2008-07-16 |
DE602005008169D1 (en) | 2008-08-28 |
MXPA05012417A (en) | 2006-05-19 |
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