EP2931930B1 - Verfahren zur verarbeitung von titanlegierungen - Google Patents

Verfahren zur verarbeitung von titanlegierungen Download PDF

Info

Publication number
EP2931930B1
EP2931930B1 EP13812249.4A EP13812249A EP2931930B1 EP 2931930 B1 EP2931930 B1 EP 2931930B1 EP 13812249 A EP13812249 A EP 13812249A EP 2931930 B1 EP2931930 B1 EP 2931930B1
Authority
EP
European Patent Office
Prior art keywords
workpiece
forging
temperature
axis
beta
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
EP13812249.4A
Other languages
English (en)
French (fr)
Other versions
EP2931930A1 (de
Inventor
David J. Bryan
John V. Mantione
Jean-Philippe Thomas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ATI Properties LLC
Original Assignee
ATI Properties LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US13/714,465 external-priority patent/US9206497B2/en
Application filed by ATI Properties LLC filed Critical ATI Properties LLC
Priority to PL13812249T priority Critical patent/PL2931930T3/pl
Publication of EP2931930A1 publication Critical patent/EP2931930A1/de
Application granted granted Critical
Publication of EP2931930B1 publication Critical patent/EP2931930B1/de
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C14/00—Alloys based on titanium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • 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 disclosure relates to methods for processing titanium alloys.
  • Methods for producing titanium and titanium alloys having coarse grain (CG), fine grain (FG), very fine grain (VFG), or ultrafine grain (UFG) microstructure involve the use of multiple reheats and forging steps.
  • Forging steps may include one or more upset forging steps in addition to draw forging on an open die press.
  • the term "coarse grain” refers to alpha grain sizes of 400 ⁇ m down to greater than about 14 ⁇ m; the term “fine grain” refers to alpha grain sizes in the range of 14 ⁇ m down to greater than 10 ⁇ m; the term “very fine grain” refers to alpha grain sizes of 10 ⁇ m down to greater than 4.0 ⁇ m; and the term “ultrafine grain” refers to alpha grain sizes of 4.0 ⁇ m or less.
  • the key to grain refinement in the ultra-slow strain rate MAF process is the ability to continually operate in a regime of dynamic recrystallization that is a result of the ultra-slow strain rates used, i.e., 0.001 s -1 or slower.
  • dynamic recrystallization grains simultaneously nucleate, grow, and accumulate dislocations. The generation of dislocations within the newly nucleated grains continually reduces the driving force for grain growth, and grain nucleation is energetically favorable.
  • the ultra-slow strain rate MAF process uses dynamic recrystallization to continually recrystallize grains during the forging process.
  • Relatively uniform cubes of ultrafine grain Ti-6-4 alloy can be produced using the ultra-slow strain rate MAF process, but the cumulative time taken to perform the MAF steps can be excessive in a commercial setting.
  • conventional large scale, commercially available open die press forging equipment may not have the capability to achieve the ultra-slow strain rates required in such embodiments and, therefore, custom forging equipment may be required for carrying out production-scale ultra-slow strain rate MAF.
  • the invention provides a method of refining the grain size of a workpiece comprising a titanium alloy selected from Ti-6AI-2Sn-4Zr-6Mo alloy (UNS R56260), Ti-6AI-2Sn-4Zr-2Mo-0.08Si alloy (UNS R54620), Ti-4AI-2.5V alloy (UNS R54250), Ti-6AI-7Nb alloy (UNS R56700), and Ti-6AI-6V-2Sn alloy (UNS R56620), in accordance with claim 1 or claim 2 of the appended claims.
  • a titanium alloy selected from Ti-6AI-2Sn-4Zr-6Mo alloy (UNS R56260), Ti-6AI-2Sn-4Zr-2Mo-0.08Si alloy (UNS R54620), Ti-4AI-2.5V alloy (UNS R54250), Ti-6AI-7Nb alloy (UNS R56700), and Ti-6AI-6V-2Sn alloy (UNS R56620), in accordance with claim 1 or claim 2 of the appended claims.
  • a method of refining the grain size of a workpiece comprising a titanium alloy comprises beta annealing the workpiece. After beta annealing, the workpiece is cooled to a temperature below the beta transus temperature of the titanium alloy. The workpiece is then multi-axis forged.
  • Multi-axis forging comprises: press forging the workpiece at a workpiece forging temperature in a workpiece forging temperature range in the direction of a first orthogonal axis of the workpiece with a strain rate sufficient to adiabatically heat an internal region of the workpiece; press forging the workpiece at a workpiece forging temperature in the workpiece forging temperature range in the direction of a second orthogonal axis of the workpiece with a strain rate that is sufficient to adiabatically heat the internal region of the workpiece; and press forging the workpiece at a workpiece forging temperature in the workpiece forging temperature range in the direction of a third orthogonal axis of the workpiece with a strain rate that is sufficient to adiabatically heat the internal region of the workpiece.
  • the adiabatically heated internal region of the workpiece is allowed to cool to a temperature at or near the workpiece forging temperature in the workpiece forging temperature range, and an outer surface region of the workpiece is heated to a temperature at or near the workpiece forging temperature in the workpiece forging temperature range.
  • At least one of the press forging steps is repeated until a total strain of at least 1.0 up to less than 3.5 is achieved in at least a region of the workpiece.
  • a strain rate used during press forging is in the range of 0.2 s -1 to 0.8 s -1 .
  • the workpiece After beta annealing, the workpiece is cooled to a temperature below the beta transus temperature of the titanium alloy. The workpiece is then multi-axis forged using a sequence comprising the following forging steps.
  • the workpiece is press forged at a workpiece forging temperature in a workpiece forging temperature range in the direction of a first orthogonal A-axis of the workpiece to a major reduction spacer height with a strain rate that is sufficient to adiabatically heat an internal region of the workpiece.
  • a major reduction spacer height is a distance equivalent to the final forged dimension desired for each orthogonal axis of the workpiece.
  • the workpiece is press forged at the workpiece forging temperature in the workpiece forging temperature range in the direction of a second orthogonal B-axis of the workpiece in a first blocking reduction to a first blocking reduction spacer height.
  • the first blocking reduction is applied to bring the workpiece back to substantially the pre-forging shape of the workpiece. While the strain rate of the first blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the first blocking reduction may not occur because the total strain incurred in the first blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the first blocking reduction spacer height is larger than the major reduction spacer height.
  • the workpiece is press forged at the workpiece forging temperature in the workpiece forging temperature range in the direction of a third orthogonal C-axis of the workpiece in a second blocking reduction to a second blocking reduction spacer height.
  • the second blocking reduction is applied to bring the workpiece back to substantially the pre-forging shape of the workpiece. While the strain rate of the second blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the second blocking reduction may not occur because the total strain incurred in the second blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the second blocking reduction spacer height is greater than the major reduction spacer height.
  • the workpiece is press forged at a workpiece forging temperature in the workpiece forging temperature range in the direction of the second orthogonal B-axis of the workpiece to the major reduction spacer height with a strain rate that is sufficient to adiabatically heat an internal region of the workpiece.
  • the workpiece is press forged at the workpiece forging temperature in the workpiece forging temperature range in the direction of the third orthogonal C-axis of the workpiece in a first blocking reduction to the first blocking reduction spacer height.
  • the first blocking reduction is applied to bring the workpiece back to substantially the pre-forging shape of the workpiece. While the strain rate of the first blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the first blocking reduction may not occur because the total strain incurred in the first blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the first blocking reduction spacer height is larger than the major reduction spacer height.
  • the workpiece is press forged at the workpiece forging temperature in the workpiece forging temperature range in the direction of the first orthogonal A-axis of the workpiece in a second blocking reduction to the second blocking reduction spacer height.
  • the second blocking reduction is applied to bring the workpiece back to substantially the pre-forging shape of the workpiece. While the strain rate of the second blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the second blocking reduction may not occur because the total strain incurred in the second blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the second blocking reduction spacer height is larger than the major reduction spacer height.
  • the workpiece is press forged at the workpiece forging temperature in the workpiece forging temperature range in the direction of the third orthogonal C-axis of the workpiece in a major reduction to the major reduction spacer height with a strain rate that is sufficient to adiabatically heat an internal region of the workpiece.
  • the workpiece is press forged at the workpiece forging temperature in the workpiece forging temperature range in the direction of the first orthogonal A-axis of the workpiece in a first blocking reduction to the first blocking reduction spacer height.
  • the first blocking reduction is applied to bring the workpiece back to substantially the pre-forging shape of the workpiece. While the strain rate of the first blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the first blocking reduction may not occur because the total strain incurred in the first blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the first blocking reduction spacer height is larger than the major reduction spacer height.
  • the workpiece is press forged at the workpiece forging temperature in the workpiece forging temperature range in the direction of the second orthogonal B-axis of the workpiece in a second blocking reduction to the second blocking reduction spacer height.
  • the second blocking reduction is applied to bring the workpiece back to substantially the pre-forging shape of the workpiece. While the strain rate of the second blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the second blocking reduction may not occur because the total strain incurred in the second blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the second blocking reduction spacer height is larger than the major reduction spacer height.
  • the adiabatically heated internal region of the workpiece is allowed to cool to about the workpiece forging temperature in the workpiece forging temperature range, and the outer surface region of the workpiece is heated to about the workpiece forging temperature in the workpiece forging temperature range.
  • At least one of the press forging steps is repeated until a total strain of at least 1.0 and up to less than 3.5 is achieved in at least a region of the workpiece.
  • a strain rate used during press forging is in the range of 0.2 s -1 to 0.8 s -1 .
  • grammatical articles "one”, “a”, “an”, and “the”, as used herein, are intended to include “at least one” or “one or more”, unless otherwise indicated.
  • the articles are used herein to refer to one or more than one (i.e., to at least one) of the grammatical objects of the article.
  • a component means one or more components, and thus, possibly, more than one component is contemplated and may be employed or used in an implementation of the described embodiments.
  • An aspect of the present disclosure is directed to a multi-axis forging process for titanium alloys that includes the application of high strain rates during the forging steps to refine grain size.
  • These method embodiments are generally referred to in the present disclosure as “high strain rate multi-axis forging” or “high strain rate MAF”.
  • the terms “reduction” and “hit” interchangeably refer to an individual press forging step, wherein a workpiece is forged between die surfaces.
  • spacer height refers to the dimension or thickness of a workpiece measured along one orthogonal axis after a reduction along that axis.
  • the thickness of the press forged workpiece measured along that axis will be about 10.2cm (4.0 inches).
  • spacer heights are well known to those having ordinary skill in the field of press forging and need not be further discussed herein.
  • Methods according to the presentdisclosure involve the application of multi-axisforging and its derivatives, such as the multiple upset and draw (MUD) process disclosed in the '538 Application, to titanium alloys exhibiting slower effective alpha precipitation and growth kinetics than Ti-6-4 alloy.
  • MOD multiple upset and draw
  • Ti-6AI-2Sn-4Zr-2Mo-0.08Si alloy (UNS R54620), which also may be referred to as "Ti-6-2-4-2” alloy, has slower effective alpha kinetics than Ti-6-4 alloy as a result of additional grain pinning elements such as Si.
  • Ti-6AI-2Sn-4Zr-6Mo alloy (UNS R56260), which also may be referred to as "Ti-6-2-4-6" alloy, has slower effective alpha kinetics than T-6-4 alloy as a result of increased beta stabilizing content. It is recognized that in terms of alloying elements, the growth and precipitation of the alpha phase is a function of the diffusion rate of the alloying element in the titanium-base alloy. Molybdenum is known to have one of the slower diffusion rates of all titanium alloying additions. In addition, beta stabilizers, such as molybdenum, lower the beta transus temperature (T ⁇ ) of the alloy, wherein the lower T ⁇ results in general slower diffusion of atoms in the alloy at the processing temperature for the alloy.
  • T ⁇ beta transus temperature
  • a result of the relatively slow effective alpha precipitation and growth kinetics of the Ti-6-2-4-2 and Ti-6-2-4-6 alloys is that the beta heat treatment that is used prior to MAF according to embodiments of the present disclosure produces a fine and stable alpha lath size when compared to the effect of such processing on Ti-6-4 alloy.
  • the Ti-6-2-4-2 and Ti-6-2-4-6 alloys possess a fine beta grain structure that limits the kinetics of alpha grain growth.
  • the effective kinetics of alpha growth can be evaluated by identifying the slowest diffusing species at a temperature immediately below the beta transus. This approach has been theoretically outlined and experimentally verified in literature (see Semiatin et al., Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science 38 (4), 2007, pp. 910-921 ).
  • alloys such as Ti-6-2-4-6 alloy and Ti-6-2-4-2 alloy, which contain molybdenum, show the desirable, slow alpha kinetics required to achieve ultrafine grain microstructures at comparatively lower strain than Ti-6-4 alloy where the kinetics are controlled by the diffusion of aluminum. Based on periodic table group relationships, one could also reasonably postulate that tantalum and tungsten belong to the group of slow diffusers.
  • beta transus temperature in alloys controlled by aluminum diffusion will have a similar effect.
  • a beta transus temperature reduction of 100°C will reduce the diffusivity of aluminum in the beta phase by approximately an order of magnitude at the beta transus temperature.
  • the alpha kinetics in alloys such as ATI 425 ® alloy (Ti-4Al-2.5V; UNS 54250) and Ti-6-6-2 alloy (Ti-6Al-6V-2SN; UNS 56620) are likely controlled by aluminum diffusion; however, the lower beta transus temperatures of these alloys relative to Ti-6Al-4V alloy also result in the desirable, slower effective alpha kinetics.
  • Ti-6Al-7Nb alloy normally a biomedical version of Ti-6Al-4V alloy, may also exhibit slower effective alpha kinetics because of the niobium content.
  • alpha+beta alloys other than Ti-6-4 alloy could be processed under conditions similar to those disclosed in the '538 Application at temperatures that would result in similar volume fractions of the alpha phase.
  • PANDAT software a commercially available computational tool available from Computherm, LLC, Madison, Wisconsin, USA, it was predicted that Ti-6-4 alloy at 1500°F (815.6°C) should have approximately the same volume fraction of the alpha phase as both Ti-6-2-4-2 alloy at 1600°F (871.1°C) and Ti-6-2-4-6 alloy at 1200°F (648.9°C) See FIG. 1 .
  • Variations to the high strain rate MAF process including alpha/beta forging temperature(s), strain rate, strain per hit, hold time between hits, number and duration of reheats, and intermediate heat treatments can each affect the resultant microstructure and the presence and extent of cracking.
  • Lower total strains were initially attempted in order to inhibit cracking, without any expectation that ultrafine grain structures would result.
  • the samples processed using lower total strains showed significant promise for producing ultrafine grain structures. This result was entirely unanticipated.
  • the flow chart in FIG. 2 and the schematic representation in FIG. 3 illustrate aspects of a non-limiting embodiment according to the present disclosure of a method (16) of using a high strain rate multi-axis forging (MAF) to refine grain size of titanium alloys.
  • a titanium alloy workpiece 24 Prior to multi-axis forging (26), a titanium alloy workpiece 24 is beta annealed (18) and cooled (20). Air cooling is possible with smaller workpieces, such as, for example, 4 inch cubes; however, water or liquid cooling also can be used. Faster cooling rates result in finer lath and alpha grain sizes.
  • Beta annealing (18) comprises heating the workpiece 24 above the beta transus temperature of the titanium alloy of the workpiece 24 and holding for a time sufficient to form all beta phase in the workpiece 24.
  • Beta annealing (18) is a process well-known to a person of ordinary skill and, therefore, is not described in detail herein.
  • a non-limiting embodiment of beta annealing may include heating the workpiece 24 to a beta annealing temperature that is about 50°F (27.8°C) above the beta transus temperature of the titanium alloy and holding the workpiece 24 at the temperature for about 1 hour.
  • the workpiece 24 is cooled (20) to a temperature below the beta transus temperature of the titanium alloy of the workpiece 24.
  • the workpiece is cooled to ambient temperature.
  • ambient temperature refers to the temperature of the surroundings.
  • cooling (20) can include quenching. Quenching includes immersing the workpiece 24 in water, oil, or another suitable liquid and is a process understood by a person skilled in the metallurgical arts. In other non-limiting embodiments, particularly for smaller sized workpieces, cooling (20) may comprise air cooling.
  • cooling (20) comprises cooling directly to a workpiece forging temperature in the workpiece forging temperature range for subsequent high strain rate multi-axis forging.
  • High strain rate multi-axis forging includes heating (step 22 in FIG. 2 ) a workpiece 24 comprising a titanium alloy to a workpiece forging temperature in a workpiece forging temperature range that is within the alpha+beta phase field of the titanium alloy, followed by MAF (26) using a high strain rate.
  • the cooling step (20) comprises cooling to a temperature in the workpiece forging temperature range
  • the heating step (22) is not necessary.
  • a high strain rate is used in the high strain rate MAF to adiabatically heat an internal region of the workpiece.
  • the temperature of the internal region of the titanium alloy workpiece 24 should not exceed the beta transus temperature (T ⁇ ) of the titanium alloy workpiece. Therefore, in such non-limiting embodiments the workpiece forging temperature for at least the final cycle of A-B-C hits, or at least the last hit of the cycle, of high strain rate MAF should be chosen to ensure that during the high strain rate MAF the temperature of the internal region of the workpiece does not equal or exceed the beta transus temperature of the alloy.
  • the temperature of the internal region of the workpiece does not exceed 20°F (11.1°C) below the beta transus temperature of the alloy, i.e., T ⁇ - 20°F (T ⁇ -11.1°C), during at least the final high strain rate cycle of A-B-C hits in the MAF or during at least the last press forging hit when a total strain of at least 1.0, or in a range of at least 1.0 up to less than 3.5, is achieved in at least a region of the workpiece.
  • a workpiece forging temperature comprises a temperature within a workpiece forging temperature range.
  • the workpiece forging temperature range is 100°F (55.6°C) below the beta transus temperature (T ⁇ ) of the titanium alloy of the workpiece to 700°F (388.9°C) below the beta transus temperature of the titanium alloy.
  • the workpiece forging temperature range is 300°F (166.7°C) below the beta transus temperature of the titanium alloy to 625°F (347°C) below the beta transus temperature of the titanium alloy.
  • the low end of a workpiece forging temperature range is a temperature in the alpha+beta phase field wherein damage, such as, for example, crack formation and gouging, does not occur to the surface of the workpiece during the forging hit.
  • the workpiece forging temperature range may be from 1120°F (604.4°C) to 1720°F (937.8°C), or in another embodiment may be from 1195°F (646.1 °C) to 1520°F (826.7°C).
  • T ⁇ beta transus temperature
  • the workpiece forging temperature range may be from 1020°F (548.9°C) to 1620°F (882.2°C), or in another embodiment may be from 1095°F (590.6°C) to 1420°F (771.1°C).
  • T ⁇ beta transus temperature
  • the workpiece forging temperature range may be from 1080°F (582.2°C) to 1680°F (915.6°C), or in another embodiment may be from 1155°F (623.9°C) to 1480°F (804.4°C).
  • T ⁇ beta transus temperature
  • Ti-6AI-6V-2Sn alloy which also may be referred to as "Ti-6-6-2" alloy, and which has a beta transus temperature (T ⁇ ) of about 1735°F (946.1°C)
  • the workpiece forging temperature range may be from 1035°F (527.2°C) to 1635°F (890.6°C), or in another embodiment may be from 1115°F (601.7°C) to 1435°F (779.4°C).
  • the present disclosure involves the application of high strain rate multi-axis forging and its derivatives, such as the MUD method disclosed in the '538 Application, to titanium alloys that posses slower effective alpha precipitation and growth kinetics than Ti-6-4 alloy.
  • MAF (26) comprises press forging (step 28, shown in FIG. 3(a) ) the workpiece 24 at the workpiece forging temperature in the direction (A) of a first orthogonal axis 30 of the workpiece using a strain rate that is sufficient to adiabatically heat the workpiece, or at least adiabatically heat an internal region of the workpiece, and plastically deform the workpiece 24.
  • High strain rates and fast ram speeds are used to adiabatically heat the internal region of the workpiece in non-limiting embodiments of high strain rate MAF according to the present disclosure.
  • the term “high strain rate” refers to a strain rate in the range of about 0.2 s -1 to about 0.8 s -1 .
  • the term “high strain rate” refers to a strain rate in the range of about 0.2 s -1 to about 0.4 s -1 .
  • an internal region of the titanium alloy workpiece may be adiabatically heated to about 200°F (111.1°C) above the workpiece forging temperature.
  • an internal region is adiabatically heated to a temperature in the range of about 100°F (55.6°C) to about 300°F (166.7°C) above the workpiece forging temperature.
  • an internal region is adiabatically heated to a temperature in the range of about 150°F (83.3°C) to about 250°F (138.9°C) above the workpiece forging temperature.
  • no portion of the workpiece should be heated above the beta transus temperature of the titanium alloy during the last cycle of high strain rate A-B-C MAF hits, or during the last hit on an orthogonal axis.
  • the workpiece 24 is plastically deformed to a reduction in height or another dimension that is in the range of 20% to 50%, i.e ., the dimension is reduced by a percentage within that range.
  • the workpiece 24 is plastically deformed to a reduction in height or another dimension in the range of 30% to 40%.
  • a known ultra-slow strain rate (0.001 s -1 or slower) multi-axis forging process is depicted schematically in FIG. 4 .
  • an aspect of multi-axis forging is that after every three-stroke, (i.e ., "three-hit") cycle by the forging apparatus (which may be, for example, an open die forge), the shape and size of the workpiece approaches that of the workpiece just prior to the first hit of that three-hit cycle.
  • a 5-inch sided cube-shaped workpiece is initially forged with a first "hit” in the direction of the "a" axis, rotated 90° and forged with a second hit in the direction of the orthogonal "b” axis, and then rotated 90° and forged with a third hit in the direction of the orthogonal "c" axis, the workpiece will resemble the starting cube and include approximately 5-inch sides.
  • the overall result of the three forging deformations is to return the cube to approximately its original shape and size.
  • a first press forging step (28), shown in FIG. 2(a) , also referred to herein as the "first hit”, may include press forging the workpiece on a top face down to a predetermined spacer height while the workpiece is at a temperature in the workpiece forging temperature range
  • spacer height refers to the dimension of the workpiece on the completion of a particular press forging reduction. For example, for a spacer height of 12.7cm (5 inches), the workpiece is forged to a dimension of 12.7cm (5 inches).
  • a spacer height is, for example, 12.7cm (5 inches).
  • a spacer height is 8.3cm (3.25inches).
  • Other spacer heights such as, for example, less than 12.7cm (5 inches), about 10.2cm (4 inches), about 7.6cm (3 inches), greater than 12.7cm (5inches), or 12.7cm (5inches) up to 76.2cm (30inches) are within the scope of embodiments herein, but should not be considered as limiting the scope of the present disclosure.
  • Spacer heights are only limited by the capabilities of the forge and optionally, as will be seen herein, the capabilities of the thermal management system according to non-limiting embodiments of the present disclosure to maintain the workpiece at the workpiece forging temperature.
  • Spacer heights of less than 7.6cm (3 inches) are also within the scope of embodiments disclosed herein, and such relatively small spacer heights are only limited by the desired characteristics of a finished product.
  • the use of spacer heights of about 76.2cm (30 inches), for example, in methods according to the present disclosure allows for the production of billet-sized (e.g.,76.2cm (30-inch) sided) cube-shaped titanium alloy forms having fine grain size, very fine grain size, or ultrafine grain size.
  • Billet-sized cube-shaped forms of conventional alloys have been employed as workpieces that are forged into disk, ring, and case parts for aeronautical or land-based turbines, for example.
  • the predetermined spacer heights that should be employed in various non-limiting embodiments of methods according to the present disclosure may be determined by a person having ordinary skill in the art without undue experimentation on considering the present disclosure.
  • Specific spacer heights may be determined by a person having ordinary skill without undue experimentation.
  • Specific spacer heights are dependent upon a specific alloy's susceptibility to cracking during forging. Alloys that have a higher susceptibility to cracking will require larger spacer heights, i.e ., less deformation per hit to prevent cracking.
  • the adiabatic heating limit must also be considered when choosing a spacer height because, at least in the last cycle of hits, the workpiece temperature should not surpass the T ⁇ of the alloy.
  • the forging press capability limit needs to be considered when selecting a spacer height.
  • the cross-sectional area increases during the pressing step.
  • the load cannot increase beyond the capabilities of the forging press.
  • the workpiece geometry needs to be considered when selecting spacer heights. Large deformations may result in bulging of the workpiece. Too great a reduction could result in a relative flattening of the workpiece, so that the next forging hit in the direction of a different orthogonal axis could result in bending of the workpiece.
  • the spacer heights used for each orthogonal axis hit are equivalent. In certain other non-limiting embodiments, the spacer heights used for each orthogonal axis hits are not equivalent.
  • Non-limiting embodiments of high strain rate MAF using non-equivalent spacer heights for each orthogonal axis are presented below.
  • a non-limiting embodiment of a method according to the present disclosure optionally further comprises a step of allowing (step 32) the temperature of the adiabatically heated internal region (not shown) of the workpiece to cool to a temperature at or near the workpiece forging temperature in the workpiece forging temperature range, which is shown in FIG.
  • internal region cooling times, or “waiting" times may range, for example, from 5 seconds to 120 seconds, from 10 seconds to 60 seconds, or from 5 seconds to 5 minutes,
  • an "adiabatically heated internal region" of a workpiece refers to a region extending outwardly from a center of the workpiece and having a volume of at least about 50%, or at least about 60%, or at least about 70%, or at least about 80% of the workpiece.
  • an aspect of a thermal management system 33 optionally comprises heating (step 34) an outer surface region 36 of the workpiece 24 to a temperature at or near the workpiece forging temperature.
  • the temperature of the workpiece 24 is in a uniform or near uniform and substantially isothermal condition at or near the workpiece forging temperature prior to each high strain rate MAF hit.
  • the outer surface of the workpiece optionally is heated (34) after each cycle of A-B-C hits.
  • the outer surface region optionally is be heated after any hit or cycle of hits, as long as the overall temperature of the workpiece is maintained within the workpiece forging temperature range during the forging process.
  • the times that a workpiece should be heated to maintain a temperature of the workpiece 24 in a uniform or near uniform and substantially isothermal condition at or near the workpiece forging temperature prior to each high strain rate MAF hit may depend on the size of the workpiece, and this may be determined by a person having ordinary skill without undue experimentation.
  • an "outer surface region" of a workpiece refers to a region extending inwardly from an outer surface of the workpiece and having a volume of at least about 50%, or at least about 60%, or at least about 70%, or at least about 80% of the workpiece.
  • heating (34) an outer surface region 36 of the workpiece 24 may be accomplished using one or more surface heating mechanisms 38 of the thermal management system 33. Examples of possible surface heating mechanisms successive press forging steps, the entire workpiece may be placed in a furnace or otherwise heated to a temperature with the workpiece forging temperature range.
  • the thermal management system 33 is used to heat the outer surface region 36 of the workpiece, and the adiabatically heated internal region is allowed to cool for an internal region cooling time so as to return the temperature of the workpiece to a substantially uniform temperature at or near the selected workpiece forging temperature.
  • the thermal management system 33 is used to heat the outer surface region 36 of the workpiece, and the adiabatically heated internal region is allowed to cool for an internal region cooling time so that the temperature of the workpiece returns to a substantially uniform temperature within the workpiece forging temperature range.
  • Non-limiting embodiments of a method according to the present disclosure utilizing both (1) a thermal management system 33 to heat the outer surface region of the workpiece to a temperature within the workpiece forging temperature range and (2) a period during which the adiabatically heated internal region cools to a temperature within the workpiece forging temperature range may be referred to herein as "thermally managed, high strain rate multi-axis forging”.38 include, but are not limited to, flame heaters adapted for flame heating; induction heaters adapted for induction heating; and radiant heaters adapted for radiant heating of the outer surface of the workpiece 24.
  • Other mechanisms and techniques for heating an outer surface region of the workpiece will be apparent to those having ordinary skill upon considering the present disclosure, and such mechanisms and techniques are within the scope of the present disclosure.
  • a non-limiting embodiment of an outer surface region heating mechanism 38 may comprise a box furnace (not shown).
  • a box furnace may be configured with various heating mechanisms to heat the outer surface region of the workpiece using one or more of flame heating mechanisms, radiant heating mechanisms, induction heating mechanisms, and any other suitable heating mechanism known now or hereafter to a person having ordinary skill in the art.
  • the temperature of the outer surface region 36 of the workpiece 24 optionally is heated (34) and maintained at or near the workpiece forging temperature and within the workpiece forging temperature range using one or more die heaters 40 of a thermal management system 33.
  • Die heaters 40 may be used to maintain the dies 42 or the die press forging surfaces 44 of the dies at or near the workpiece forging temperature or at temperatures within the workpiece forging temperature range.
  • the dies 42 of the thermal management system are heated to a temperature within a range that includes the workpiece forging temperature down to 100°F (55.6°C) below the workpiece forging temperature.
  • Die heaters 40 may heat the dies 42 or the die press forging surface 44 by any suitable heating mechanism known now or hereafter by a person skilled in the art, including, but not limited to, flame heating mechanisms, radiant heating mechanisms, conduction heating mechanisms, and/or induction heating mechanisms.
  • a die heater 40 may be a component of a box furnace (not shown). While the thermal management system 33 is shown in place and being used during the cooling steps (32),(52),(60) of the multi-axis forging process (26) shown in FIGS. 2(b), (d), and (f) , it will be recognized that the thermal management system 33 may or may not be in place during the press forging steps (28),(46),(56) depicted in FIGS. 2(a), (c), and (e) .
  • an aspect of a non-limiting embodiment of a multi-axis forging method (26) comprises press forging (step 46) the workpiece 24 at a workpiece forging temperature in the workpiece forging temperature range in the direction (B) of a second orthogonal axis 48 of the workpiece 24 using a strain rate that is sufficient to adiabatically heat the workpiece 24, or at least an internal region of the workpiece 24, and plastically deform the workpiece 24.
  • the workpiece 24 is deformed to a plastic deformation of a 20% to 50% reduction in height or another dimension.
  • the workpiece 24 is plastically deformed to a plastic deformation of a 30% to 40% reduction in height or another dimension.
  • the workpiece 24 may be press forged (46) in the direction of the second orthogonal axis 48 to the same spacer height used in the first press forging step (28).
  • the workpiece 24 may be press forged in the direction of the second orthogonal axis 48 to a different spacer height than is used in the first press forging step (28).
  • the internal region (not shown) of the workpiece 24 is adiabatically heated during the press forging step (46) to the same temperature as in the first press forging step (28).
  • the high strain rates used for press forging (46) are in the same strain rate ranges as disclosed for the first press forging step (28).
  • the workpiece 24 may be rotated (50) between successive press forging steps (e.g., (28),(46),(56)) to present a different orthogonal axis to the forging surfaces.
  • This rotation may be referred to as "A-B-C" rotation.
  • it may be possible to rotate the ram on the forge instead of rotating the workpiece 24, or a forge may be equipped with multi-axis rams so that rotation of neither the workpiece nor the forge is required.
  • the important aspect is the relative change in position of the workpiece and the ram being used, and rotating (50) the workpiece 24 may be unnecessary or optional. In most current industrial equipment set-ups, however, rotating (50) the workpiece to a different orthogonal axis in between press forging steps will be required to complete the multi-axis forging process (26).
  • the workpiece 24 may be rotated manually by a forge operator or by an automatic rotation system (not shown) to provide A-B-C rotation (50).
  • An automatic A-B-C rotation system may include, but is not limited to including, free-swinging clamp-style manipulator tooling or the like to enable a non-limiting thermally managed high strain rate multi-axis forging embodiment disclosed herein.
  • process (20) optionally further comprises allowing (step 52) an adiabatically heated internal region (not shown) of the workpiece to cool to a temperature at or near the workpiece forging temperature, which is shown in FIG. 3(d) .
  • internal region cooling times, or waiting times may range, for example, from 5 seconds to 120 seconds, or from 10 seconds to 60 seconds, or from 5 seconds up to 5 minutes. It will be recognized by an ordinarily skilled person that the minimum cooling times are dependent upon the size, shape, and composition of the workpiece 24, as well as the characteristics of the environment surrounding the workpiece.
  • an optional aspect of a thermal management system 33 comprises heating (step 54) an outer surface region 36 of the workpiece 24 to a temperature in the workpiece forging temperature range at or near the workpiece forging temperature. In this manner, the temperature of the workpiece 24 is maintained in a uniform or near uniform and substantially isothermal condition at or near the workpiece forging temperature prior to each high strain rate MAF hit.
  • the thermal management system 33 when using the thermal management system 33 to heat the outer surface region 36, together with allowing the adiabatically heated internal region to cool for a specified internal region cooling time, the temperature of the workpiece returns to a substantially uniform temperature at or near the workpiece forging temperature between each A-B-C forging hit.
  • the temperature of the workpiece when using the thermal management system 33 to heat the outer surface region 36, together with allowing the adiabatically heated internal region to cool for a specified internal region cooling time, the temperature of the workpiece returns to a substantially uniform temperature within the workpiece forging temperature range prior to each high strain rate MAF hit.
  • heating (54) an outer surface region 36 of the workpiece 24 may be accomplished using one or more outer surface heating mechanisms 38 of the thermal management system 33.
  • Examples of possible heating mechanisms 38 may include, but are not limited to, flame heaters adapted for flame heating; induction heaters adapted for induction heating; and/or radiant heaters adapted for radiant heating of the workpiece 24.
  • a non-limiting embodiment of a surface heating mechanism 38 may comprise a box furnace (not shown).
  • Other mechanisms and techniques for heating an outer surface of the workpiece will be apparent to those having ordinary skill upon considering the present disclosure, and such mechanisms and techniques are within the scope of the present disclosure.
  • a box furnace may be configured with various heating mechanisms to heat the outer surface of the workpiece, and such heating mechanisms may comprise one or more of flame heating mechanisms, radiant heating mechanisms, induction heating mechanisms, and/or any other heating mechanism known now or hereafter to a person having ordinary skill in the art.
  • the temperature of the outer surface region 36 of the workpiece 24 may be heated (54) and maintained at or near the workpiece forging temperature and within the workpiece forging temperature range using one or more die heaters 40 of a thermal management system 33.
  • Die heaters 40 may be used to maintain the dies 42 or the die press forging surfaces 44 of the dies at or near the workpiece forging temperature or at temperatures within the workpiece forging temperature range.
  • Die heaters 40 may heat the dies 42 or the die press forging surfaces 44 by any suitable heating mechanism known now or hereafter by a person skilled in the art, including, but not limited to, flame heating mechanisms, radiant heating mechanisms, conduction heating mechanisms, and/or induction heating mechanisms.
  • a die heater 40 may be a component of a box furnace (not shown). While the thermal management system 33 is shown in place and being used during the equilibration and cooling steps (32),(52),(60) of the multi-axis forging process (26) shown in FIGS, 2(b), (d), and (f) , it is recognized that the thermal management system 33 may or may not be in place during the press forging steps (28),(46),(56) depicted in FIGS. 2(a), (c), and (e) .
  • an aspect of an embodiment of multi-axis forging (26) comprises press forging (step 56) the workpiece 24 at a workpiece forging temperature in the workpiece forging temperature range in the direction (C) of a third orthogonal axis 58 of the workpiece 24 using a ram speed and strain rate that are sufficient to adiabatically heat the workpiece 24, or at least adiabatically heat an internal region of the workpiece, and plastically deform the workpiece 24.
  • the workpiece 24 is deformed during press forging (56) to a plastic deformation of a 20% to 50% reduction in height or another dimension.
  • the workpiece during press forging (56) the workpiece is plastically deformed to a plastic deformation of a 30% to 40% reduction in height or another dimension.
  • the workpiece 24 may be press forged (56) in the direction of the third orthogonal axis 58 to the same spacer height used in the first press forging step (28) and/or the second forging step (46).
  • the workpiece 24 may be press forged in the direction of the third orthogonal axis 58 to a different spacer height than used in the first press forging step (28).
  • the internal region (not shown) of the workpiece 24 is adiabatically heated during the press forging step (56) to the same temperature as in the first press forging step (28).
  • the high strain rates used for press forging (56) are in the same strain rate ranges as disclosed for the first press forging step (28).
  • the workpiece 24 may be rotated (50) to a different orthogonal axis between successive press forging steps (e.g., 46,56). As discussed above, this rotation may be referred to as A-B-C rotation. It is understood that by using different forge configurations, it may be possible to rotate the ram on the forge instead of rotating the workpiece 24, or a forge may be equipped with multi-axis rams so that rotation of neither the workpiece nor the forge is required. Therefore, rotating 50 the workpiece 24 may be unnecessary or an optional step. In most current industrial set-ups, however, rotating 50 the workpiece to a different orthogonal axis between press forging steps will be required to complete the multi-axis forging process (26).
  • process 20 optionally further comprises allowing (step 60) an adiabatically heated internal region (not shown) of the workpiece to cool to a temperature at or near the workpiece forging temperature, which is indicated in FIG. 3(f) .
  • Internal region cooling times may range, for example, from 5 seconds to 120 seconds, from 10 seconds to 60 seconds, or from 5 seconds up to 5 minutes, and it is recognized by a person skilled in the art that the cooling times are dependent upon the size, shape, and composition of the workpiece 24, as well as on the characteristics of the environment surrounding the workpiece.
  • an optional aspect of a thermal management system 33 comprises heating (step 62) an outer surface region 36 of the workpiece 24 to a temperature at or near the workpiece forging temperature. In this manner, the temperature of the workpiece 24 is maintained in a uniform or near uniform and substantially isothermal condition at or near the workpiece forging temperature prior to each high strain rate MAF hit.
  • the thermal management system 33 by using the thermal management system 33 to heat the outer surface region 36, together with allowing the adiabatically heated internal region to cool for a specified internal region cooling time, the temperature of the workpiece returns to a substantially uniform temperature at or near the workpiece forging temperature between each A-B-C forging hit.
  • the thermal management system 33 by using the thermal management system 33 to heat the outer surface region 36, together with allowing the adiabatically heated internal region to cool for a specified internal region cooling time, the temperature of the workpiece returns to a substantially isothermal condition within the workpiece forging temperature range between successive A-B-C forging hits.
  • heating (62) an outer surface region 36 of the workpiece 24 may be accomplished using one or more outer surface heating mechanisms 38 of the thermal management system 33.
  • Examples of possible heating mechanisms 38 may include, but are not limited to, flame heaters for flame heating; induction heaters for induction heating; and/or radiant heaters for radiant heating of the workpiece 24.
  • Other mechanisms and techniques for heating an outer surface of the workpiece will be apparent to those having ordinary skill upon considering the present disclosure, and such mechanisms and techniques are within the scope of the present disclosure.
  • a non-limiting embodiment of a surface heating mechanism 38 may comprise a box furnace (not shown).
  • a box furnace may be configured with various heating mechanisms to heat the outer surface of the workpiece using one or more of flame heating mechanisms, radiant heating mechanisms, induction heating mechanisms, and/or any other suitable heating mechanism known now or hereafter to a person having ordinary skill in the art.
  • the temperature of the outer surface region 36 of the workpiece 24 may be heated (62) and maintained at or near the workpiece forging temperature and within the workpiece forging temperature range using one or more die heaters 40 of a thermal management system 33.
  • Die heaters 40 may be used to maintain the dies 42 or the die press forging surfaces 44 of the dies at or near the workpiece forging temperature or at temperatures within the temperature forging range.
  • the dies 42 of the thermal management system are heated to a temperature within a range that includes the workpiece forging temperature to 100°F (55.6°C) below the workpiece forging temperature.
  • Die heaters 40 may heat the dies 42 or the die press forging surface 44 by any suitable heating mechanism known now or hereafter by a person skilled in the art, including, but not limited to, flame heating mechanisms, radiant heating mechanisms, conduction heating mechanisms, and/or induction heating mechanisms.
  • a die heater 40 may be a component of a box furnace (not shown). While the thermal management system 33 is shown in place and being used during the equilibration steps (32),(52),(60) of the multi-axis forging process show in FIGS. 2(b), (d), and (f) , it will be recognized that the thermal management system 33 may or may not be in place during the press forging steps 28,46,56 depicted in FIGS. 2(a), (c), and (e) .
  • An aspect of the present disclosure includes a non-limiting embodiment wherein one or more of the press forging steps along the three orthogonal axes of a workpiece are repeated until a total strain of at least 1.0 is achieved in the workpiece.
  • the total strain is the total true strain.
  • the phrase "true strain” is also known to a person skilled in the art as “logarithmic strain” or "effective strain”. Referring to FIG. 2 , this is exemplified by step (g), i.e ., repeating (step 64) one or more of press forging steps (28),(46),(56) until a total strain in the range of at least 1.0 up to less than 3.5 is achieved in the workpiece.
  • the workpiece can simply be cooled to ambient temperature, in a non-limiting embodiment, by quenching in a liquid, or in another non-limiting embodiment, by air cooling or any faster rate of cooling.
  • the total strain is the total strain in the entire workpiece after multi-axis forging, as disclosed herein.
  • the total strain may comprise equal strains on each orthogonal axis, or the total strain may comprise different strains on one or more orthogonal axes.
  • a workpiece may be multi-axis forged at two different temperatures in the alpha-beta phase field.
  • repeating step (64) of FIG. 2 may include repeating one of more of steps (a)-(optional b), (c)-(optional d), and (e)-(optional f) at a first temperature in the alpha-beta phase field until a certain strain is achieved, and then repeating one or more of steps (a)-(optional b), (c)-(optional d), and (e)-(optional f) at a second temperature in the alpha-beta phase field until after a final press forging step (a), (b), or (c) ( i.e ., (28),(46), (56)) a total strain of at least 1.0, or in the range of at least 1.0 up to less than 3.5, is achieved in the workpiece.
  • the second temperature in the alpha-beta phase field is lower than first temperature in the alpha-beta phase field. It is recognized that conducting the method so as to repeat one or more of steps (a)-(optional b), (c)-(optional d), and (e)-(optionalf) at more than two MAF press forging temperatures is within the scope of the present disclosure as long as the temperatures are within the forging temperature range. It is also recognized that, in a non-limiting embodiment, the second temperature in the alpha-beta phase field is higher than the first temperature in the alpha-beta phase field.
  • different reductions are used for the A-axis hit, B-axis hit, and C-axis hit to provide equalized strain in all directions.
  • Applying high strain rate MAF to introduce equalized strain in all directions results in less cracking of, and a more equiaxed alpha grain structure for, the workpiece.
  • non-equalized strain may be introduced into a cubic workpiece by starting with a 10.2 cm (4-inch) cube that is high strain rate forged on the A-axis to a height of 7.6 cm (3.0 inches). This reduction on the A-axis causes the workpiece to swell along the B-axis and the C-axis.
  • Equation 1 A general equation for calculating reduction on each orthogonal axis of a cubic workpiece during high strain rate MAF is provided in Equation 1.
  • a process (70) for the production of ultra-fine grain titanium alloy includes: beta annealing (71) a titanium alloy workpiece; cooling (72) the beta annealed workpiece 24 to a temperature below the beta transus temperature of the titanium alloy of the workpiece; heating (73) the workpiece 24 to a workpiece forging temperature within a workpiece forging temperature range that is within an alpha+beta phase field of the titanium alloy of the workpiece; and high strain rate MAF (74) the workpiece, wherein high strain rate MAF (74) includes press forging reductions to the orthogonal axes of the workpiece to different spacer heights.
  • the workpiece 24 is press forged (75) on the first orthogonal axis (A-axis) to a major reduction spacer height.
  • press forged ... to major reduction spacer height refers to press forging the workpiece along an orthogonal axis to the desired final dimension of the workpiece along the specific orthogonal axis. Therefore, the term "major reduction spacer height" is defined as the spacer height used to attain the final dimension of the workpiece along each orthogonal axis. All press forging steps to major reduction spacer heights should occur using a strain rate sufficient to adiabatically heat an internal region of the workpiece.
  • the process (70) optionally further comprises allowing (step 76, indicated in FIG. 3(b) ) an adiabatically heated internal region (not shown) of the workpiece to cool to a temperature at or near the workpiece forging temperature.
  • Internal region cooling times may range, for example, from 5 seconds to 120 seconds, from 10 seconds to 60 seconds, or from 5 seconds up to 5 minutes, and a person having ordinary skill will recognize that required cooling times will be dependent upon the size, shape, and composition of the workpiece, as well as the characteristics of the environment surrounding the workpiece.
  • an aspect of a thermal management system 33 may comprise heating (step 77) an outer surface region 36 of the workpiece 24 to a temperature at or near the workpiece forging temperature.
  • the temperature of the workpiece 24 is maintained in a uniform or near uniform and substantially isothermal condition at or near the workpiece forging temperature prior to each high strain rate MAF hit.
  • using the thermal management system 33 to heat the outer surface region 36, together with allowing the adiabatically heated internal region to cool for a specified internal region cooling time the temperature of the workpiece returns to a substantially uniform temperature at or near the workpiece forging temperature intermediate each of the A, B, and C forging hits.
  • the temperature of the workpiece returns to a substantially uniform temperature within the workpiece forging temperature range intermediate each of the A, B, and C forging hits.
  • heating (77) an outer surface region 36 of the workpiece 24 may be accomplished using one or more outer surface heating mechanisms 38 of the thermal management system 33.
  • outer surface heating mechanisms 38 include, but are not limited to, flame heaters adapted for flame heating; induction heaters adapted for induction heating; and radiant heaters adapted for radiant heating of the workpiece 24.
  • flame heaters adapted for flame heating adapted for flame heating
  • induction heaters adapted for induction heating adapted for induction heating
  • radiant heaters adapted for radiant heating of the workpiece 24.
  • Other mechanisms and techniques for heating an outer surface region of the workpiece will be apparent to those having ordinary skill upon considering the present disclosure, and such mechanisms and techniques are within the scope of the present disclosure.
  • a non-limiting embodiment of an outer surface region heating mechanism 38 may comprise a box furnace (not shown).
  • a box furnace may be configured with various heating mechanisms to heat the outer surface region of the workpiece using, for example, one or more of flame heating mechanisms, radiant heating mechanisms, induction heating mechanisms, and/or any other suitable heating mechanism known now or hereafter to a person having ordinary skill in the art.
  • the temperature of the outer surface region 36 of the workpiece 24 may be heated (34) and maintained at or near the workpiece forging temperature and within the workpiece forging temperature range using one or more die heaters 40 of a thermal management system 33.
  • Die heaters 40 may be used to maintain the dies 42 or the die press forging surfaces 44 of the dies at or near the workpiece forging temperature or at temperatures within the workpiece forging temperature range.
  • the dies 42 of the thermal management system are heated to a temperature within a range that includes the workpiece forging temperature down to 100°F (55.6°C) below the workpiece forging temperature.
  • Die heaters 40 may heat the dies 42 or the die press forging surface 44 by any suitable heating mechanism known now or hereafter by a person skilled in the art, including, but not limited to, flame heating mechanisms, radiant heating mechanisms, conduction heating mechanisms, and/or induction heating mechanisms.
  • a die heater 40 may be a component of a box furnace (not shown). While the thermal management system 33 is shown in place and being used during the cooling steps of the multi-axis forging process, it is recognized that the thermal management system 33 may or may not be in place during the press forging steps.
  • blocking reduction spacer height otherwise referred to herein as press forging to a first blocking reduction spacer height ((78),(87),(96)) and press forging to a second blocking reduction spacer ((81),(90),(99))
  • press forging step that is used to reduce or "square-up" the bulging that occurs near the center of any face after press forging to major reduction spacer height. Bulging at or near the center of any face results in a triaxial stress state being introduced into the faces, which could result in cracking of the workpiece.
  • the steps of press forging to a first reduction spacer height and press forging to a second blocking reduction spacer height are employed to deform the bulged faces, so that the faces of the workpiece are flat or substantially flat before the next press forging to a major reduction spacer height along an orthogonal axis.
  • the blocking reductions involve press forging to a spacer height that is greater than the spacer height used in each step of press forging to a major reduction spacer height.
  • the strain rate of all of the first and second blocking reductions disclosed herein may be sufficient to adiabatically heat an internal region of the workpiece
  • adiabatic heating during the first blocking and second blocking reductions may not occur because the total strain incurred in the first and second blocking reductions may not be sufficient to significantly adiabatically heat the workpiece.
  • the blocking reductions are performed to spacer heights that are greater than those used in press forging to a major reduction spacer height, the strain added to the workpiece in a blocking reduction may not be enough to adiabatically heat an internal region of the workpiece.
  • incorporation of the first and second blocking reductions in a high strain rate MAF process results in a forging sequence of at least one cycle consisting of: A -B-C- B -C-A- C , wherein A , B , and C comprise press forging to the major reduction spacer height, and wherein B, C, C, and A comprise press forging to first or second blocking reduction spacer heights; or in another non-limiting embodiment at least one cycle consisting of: A -B-C- B -C-A- C -A-B, wherein A , B , and C comprise press forging to the major reduction spacer height, and wherein B, C, C, A, A, and B comprise press forging to first or second blocking reduction spacer heights.
  • the workpiece is press forged (78) on the B-axis to a first blocking reduction spacer height.
  • the strain rate of the first blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the first blocking reduction may not occur because the strain incurred in the first blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the adiabatically heated internal region of the workpiece is allowed (79) to cool to a temperature at or near the workpiece forging temperature, while the outer surface region of the workpiece is heated (80) to a temperature at or near the workpiece forging temperature.
  • All cooling times and heating methods for the A reduction (75) disclosed hereinabove and in other embodiments of the present disclosure are applicable for steps (79) and (80) and to all optional subsequent steps of allowing the internal region of the workpiece to cool and heating the outer surface region of the workpiece.
  • the workpiece is next press forged (81) on the C-axis to a second blocking reduction spacer height that is greater than the major reduction spacer height.
  • the first and second blocking reductions are applied to bring the workpiece back to substantially the pre-forging shape of the workpiece.
  • the strain rate of the second blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the second blocking reduction may not occur because the strain incurred in the second blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the adiabatically heated internal region of the workpiece is allowed (82) to cool to a temperature at or near the workpiece forging temperature, while the outer surface region of the workpiece is heated (83) to a temperature at or near the workpiece forging temperature.
  • the workpiece is next pressed forged to a major reduction spacer height (84) in the direction of the second orthogonal axis, or B-axis. Press forging to a major reduction spacer height on the B-axis (84) is referred to herein as a B reduction.
  • the adiabatically heated internal region of the workpiece is allowed (85) to cool to a temperature at or near the workpiece forging temperature, while the outer surface region of the workpiece is heated (86) to a temperature at or near the workpiece forging temperature.
  • the workpiece is next press forged (87) on the C-axis to a first blocking reduction spacer height that is greater than the major reduction spacer height. While the strain rate of the first blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the first blocking reduction may not occur because the strain incurred in the first blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the adiabatically heated internal region of the workpiece is allowed (88) to cool to a temperature at or near the workpiece forging temperature, while the outer surface region of the workpiece is heated (89) to a temperature at or near the workpiece forging temperature.
  • the workpiece is next press forged (90) on the A-axis to a second blocking reduction spacer height that is greater than the major reduction spacer height.
  • the first and second blocking reductions are applied to bring the workpiece back to substantially the pre-forging shape of the workpiece.
  • the strain rate of the second blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the second blocking reduction may not occur because the strain incurred in the second blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the adiabatically heated internal region of the workpiece is allowed (91) to cool to a temperature at or near the workpiece forging temperature, while the outer surface region of the workpiece is heated (92) to a temperature at or near the workpiece forging temperature.
  • the workpiece is next press forged to a major reduction spacer height (93) in the direction of the third orthogonal axis, or C-axis. Press forging to the major reduction spacer height on the C-axis (93) is referred to herein as a C reduction.
  • the adiabatically heated internal region of the workpiece is allowed (94) to cool to a temperature at or near the workpiece forging temperature, while the outer surface region of the workpiece is heated (95) to a temperature at or near the workpiece forging temperature.
  • the workpiece is next press forged (96) on the A-axis to a first blocking reduction spacer height that is greater than the major reduction spacer height. While the strain rate of the first blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the first blocking reduction may not occur because the strain incurred in the first blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the adiabatically heated internal region of the workpiece is allowed (97) to cool to a temperature at or near the workpiece forging temperature, while the outer surface region of the workpiece is heated (98) to a temperature at or near the workpiece forging temperature.
  • the workpiece is next press forged (99) on the B-axis to a second blocking reduction spacer height that is greater than the major reduction spacer height.
  • the first and second blocking reductions are applied to bring the workpiece back to substantially the pre-forging shape of the workpiece.
  • the strain rate of the second blocking reduction may be sufficient to adiabatically heat an internal region of the workpiece, in a non-limiting embodiment, adiabatic heating during the second blocking reduction may not occur because the strain incurred in the second blocking reduction may not be sufficient to significantly adiabatically heat the workpiece.
  • the adiabatically heated internal region of the workpiece is allowed (100) to cool to a temperature at or near the workpiece forging temperature, while the outer surface region of the workpiece is heated (101) to a temperature at or near the workpiece forging temperature.
  • one or more of press forging steps (75), (78), (81), (84), (87), (90), (93), (96), and (99) are repeated (102) until a total strain of at least 1.0 is achieved the titanium alloy workpiece.
  • one or more of press forging steps (75), (78), (81), (84), (87), (90), (93), (96), and (99) are repeated (102) until a total strain in a range of at least 1.0 up to less than 3.5 is achieved in the titanium alloy workpiece.
  • cooling comprise liquid quenching, such as, for example, water quenching.
  • cooling comprises cooling with a cooling rate of air cooling or faster.
  • a forging sequence that represents one total MAF cycle as disclosed in the above-described non-limiting embodiment may be represented as A -B-C- B -C-A- C -A-B, wherein the reductions (hits) that are in bold and underlined are press forgings to a major reduction spacer height, and the reductions that are not in bold or underlined are first or second blocking reductions.
  • press forging reductions including press forging to major reduction spacer heights and the first and second blocking reductions, of the MAF process according to the present disclosure are conducted with a high strain rate that is sufficient to adiabatically heat the internal region of the workpiece, e.g ., and without limitation, a strain rate in the range of 0.2 s -1 to 0.8 s -1 , or in the range of 0.2 s -1 to 0.4 s -1 . It will also be understood that adiabatic heating may not substantially occur during the first and second blocking reductions due to the lower degree of deformation in these reductions, as compared to the major reductions.
  • the use of blocking reductions intermediate each press forging to a major reduction spacer height reduces the tendency for crack formation in the workpiece.
  • the first blocking reduction spacer height for a first blocking reduction may be to a spacer height that is 40-60% larger than the major reduction spacer height.
  • the second blocking reduction spacer height for the second blocking reduction may be to a spacer height that is 15-30% larger than the major reduction spacer height.
  • the first blocking reduction spacer height may be substantially equivalent to the second blocking reduction spacer height.
  • the workpiece comprises an average alpha particle grain size of 4 ⁇ m or less, which is considered to be an ultra-fine grain (UFG) size.
  • UFG ultra-fine grain
  • the workpiece-press die interface is lubricated with lubricants known to those of ordinary skill, such as, but not limited to, graphite, glasses, and/or other known solid lubricants.
  • a titanium alloy processed by the method according to the present disclosure comprises effective alpha phase precipitation and growth kinetics that are slower than those of Ti-6-4 alloy (UNS R56400), and such kinetics may be referred to herein as "slower alpha kinetics".
  • slower alpha kinetics is achieved when the diffusivity of the slowest diffusing alloying species in the titanium alloy is slower than the diffusivity of aluminum in Ti-6-4 alloy at the beta transus temperature (T ⁇ ).
  • T ⁇ beta transus temperature
  • Ti-6-2-4-2 alloy exhibits slower alpha kinetics than Ti-6-4 alloy as a result of the presence of additional grain pinning elements, such as silicon, in the Ti-6-2-4-2 alloy.
  • Ti-6-2-4-6 alloy has slower alpha kinetics than Ti-6-4 alloy as a result of the presence of additional beta stabilizing alloy additions, such as higher molybdenum content than T-6-4 alloy.
  • the result of slower alpha kinetics in these alloys is that beta annealing the Ti-6-2-4-6 and Ti-6-2-4-2 alloys prior to high strain rate MAF produces a relatively fine and stable alpha lath size and a fine beta-phase structure as compared with Ti-6-4 alloy and certain other titanium alloys exhibiting faster alpha phase precipitation and growth kinetics than Ti-6-2-4-6 and Ti-6-2-4-2 alloys.
  • the phrase "slower alpha kinetics" is discussed in further detail earlier in the present disclosure.
  • Titanium alloys that may be processed according to the present disclosure are selected from Ti-6-2-4-2 alloy, Ti-6-2-4-6 alloy, ATI 425®alloy (Ti-4Al-2.5V alloy), Ti-6-6-2 alloy, and Ti-6AI-7Nb alloy.
  • beta annealing comprises: heating the workpiece to a beta annealing temperature; holding the workpiece at the beta annealing temperature for an annealing time sufficient to form a 100% titanium beta phase microstructure in the workpiece; and cooling the workpiece directly to a temperature at or near the workpiece forging temperature.
  • the beta annealing temperature is in a temperature range of the beta transus temperature of the titanium alloy up to 300°F (166.7°C) above the beta transus temperature of the titanium alloy.
  • Non-limiting embodiments include a beta annealing time from 5 minutes to 24 hours.
  • beta annealing temperatures and beta annealing times are within the scope of embodiments of the present disclosure and that, for example, relatively large workpieces may require relatively higher beta annealing temperatures and/or longer beta annealing times to form a 100% beta phase titanium microstructure.
  • the workpiece may also be plastically deformed at a plastic deformation temperature in the beta phase field of the titanium alloy prior to cooling the workpiece to a temperature at or near the workpiece forging temperature or to ambient temperature.
  • Plastic deformation of the workpiece may comprise at least one of drawing, upset forging, and high strain rate multi-axis forging the workpiece.
  • plastic deformation in the beta phase region comprises upset forging the workpiece to a beta-upset strain in the range of 0.1 to 0.5.
  • the plastic deformation temperature is in a temperature range including the beta transus temperature of the titanium alloy up to 300°F (166.7°C) above the beta transus temperature of the titanium alloy.
  • FIG. 6 is a temperature-time thermomechanical process chart for a non-limiting method of plastically deforming the workpiece above the beta transus temperature and directly cooling to the workpiece forging temperature.
  • a non-limiting method 200 comprises heating 202 a workpiece comprising a titanium alloy having alpha precipitation and growth kinetics that are slower than those of Ti-6-4 alloy, for example, to a beta annealing temperature 204 above the beta transus temperature 206 of the titanium alloy, and holding or "soaking" 208 the workpiece at the beta annealing temperature 204 to form an all beta titanium phase microstructure in the workpiece.
  • the workpiece may be plastically deformed 210.
  • plastic deformation 210 comprises upset forging. In a non-limiting embodiment, plastic deformation 210 comprises upset forging to a true strain of 0.3. In a non-limiting embodiment, plastically deforming 210 comprises thermally managed high strain rate multi-axis forging (not shown in FIG. 6 ) at a beta annealing temperature.
  • cooling 212 comprises air cooling or cooling at a rate faster than achieved through air cooling.
  • cooling comprises liquid quenching, such as, but not limited to, water quenching.
  • the workpiece is hit or press forged 12 times, i.e., the three orthogonal axes of the workpiece are non-sequentially press forged a total of 4 times each.
  • the cycle including steps (a)-(optional b), (c)-(optional d), and (e)-(optional f) is performed 4 times.
  • the total strain is in the range of at least 1.0 up to less than 3.5.
  • the workpiece is cooled 216 to ambient temperature.
  • cooling 216 comprises air cooling or cooling at a rate faster than achieved through air cooling, but other forms of cooling, such as, but not limited to, fluid or liquid quenching are within the scope of embodiments disclosed herein.
  • FIG. 7 is a temperature-time thermomechanical process chart for a non-limiting method according to the present disclosure that comprises multi-axis forging the titanium alloy workpiece at a first workpiece forging temperature; optionally utilizing a non-limiting embodiment of the thermal management feature disclosed hereinabove; cooling to a second workpiece forging temperature in the alpha+beta phase; multi-axis forging the titanium alloy workpiece at the second workpiece forging temperature; and optionally utilizing a non-limiting embodiment of the thermal management feature disclosed herein.
  • a non-limiting method 230 comprises heating 232 the workpiece to a beta annealing temperature 234 above the beta transus temperature 236 of the alloy and holding or soaking 238 the workpiece at the beta annealing temperature 234 to form an all beta phase microstructure in the titanium alloy workpiece.
  • the workpiece may be plastically deformed 240.
  • plastic deformation 240 comprises upset forging.
  • plastic deformation 240 comprises upset forging to a strain of 0.3.
  • plastically deforming 240 the workpiece comprises high strain multi-axis forging (not shown in FIG. 7 ) at a beta annealing temperature.
  • the workpiece is cooled 242 to a first workpiece forging temperature 244 in the alpha+beta phase field of the titanium alloy.
  • cooling 242 comprises one of air cooling and liquid quenching.
  • the workpiece is high strain rate multi-axis forged 246 at the first workpiece forging temperature, and optionally a thermal management system according to non-limiting embodiments disclosed herein is employed.
  • the workpiece is hit or press forged at the first workpiece forging temperature 12 times with 90° rotation between each hit, i.e., the three orthogonal axes of the workpiece are press forged 4 times each.
  • the cycle including steps (a)-(optional b), (c)-(optional d), and (e)-(optional f) is performed 4 times.
  • the titanium alloy workpiece is cooled 248 to a second workpiece forging temperature 250 in the alpha+beta phase field.
  • the workpiece is high strain rate multi-axis forged 250 at the second workpiece forging temperature, and optionally a thermal management system according to non-limiting embodiments disclosed herein is employed.
  • a thermal management system according to non-limiting embodiments disclosed herein is employed.
  • the workpiece is hit or press forged at the second workpiece forging temperature a total of 12 times. It is recognized that the number of hits applied to the titanium alloy workpiece at the first and second workpiece forging temperatures can vary depending upon the desired true strain and desired final grain size, and that the number of hits that is appropriate can be determined without undue experimentation upon considering the present disclosure.
  • the workpiece is cooled 252 to ambient temperature.
  • cooling 252 comprises one of air cooling and liquid quenching to ambient temperature.
  • the first workpiece forging temperature is in a first workpiece forging temperature range of more than 100°F (55.6°C) below the beta transus temperature of the titanium alloy to 500°F (277.8°C) below the beta transus temperature of the titanium alloy, i.e ., the first workpiece forging temperature T 1 is in the range of T ⁇ - 100°F > T 1 ⁇ T ⁇ - 500°F.
  • the second workpiece forging temperature is in a second workpiece forging temperature range of more than 200°F (277.8°C) below the beta transus temperature of the titanium alloy to 700°F (388.9°C) below the beta transus temperature, i.e., the second workpiece forging temperature T 2 is in the range of T ⁇ - 200°F > T 2 ⁇ T ⁇ - 700°F.
  • the titanium alloy workpiece comprises Ti-6-2-4-2 alloy; the first workpiece temperature is 1650°F (898.9°C); and the second workpiece forging temperature is 1500°F (815.6°C).
  • FIG. 8 is a temperature-time thermomechanical process chart of a non-limiting method embodiment according to the present disclosure for plastically deforming a workpiece comprising a titanium alloy above the beta transus temperature and cooling the workpiece to the workpiece forging temperature, while simultaneously employing thermally managed high strain rate multi-axis forging on the workpiece according to non-limiting embodiments herein.
  • a non-limiting method 260 of using thermally managed high strain rate multi-axis forging for grain refining of a titanium alloy comprises heating 262 the workpiece to a beta annealing temperature 264 above the beta transus temperature 266 of the titanium alloy and holding or soaking 268 the workpiece at the beta annealing temperature 264 to form an all beta phase microstructure in the workpiece.
  • plastic deformation 270 may comprise thermally managed high strain rate multi-axis forging.
  • the workpiece is repetitively high strain rate multi-axis forged 272 using the optional thermal management system as disclosed herein as the workpiece cools through the beta transus temperature.
  • FIG. 8 shows three intermediate high strain rate multi-axis forging 272 steps, but it will be understood that there can be more or fewer intermediate high strain rate multi-axis forging 272 steps, as desired.
  • the intermediate high strain rate multi-axis forging 272 steps are intermediate to the initial high strain rate multi-axis forging step 270 at the soaking temperature and the final high strain rate multi-axis forging step in the alpha+beta phase field 274 of the titanium alloy. While FIG. 8 shows one final high strain rate multi-axis forging step wherein the temperature of the workpiece remains entirely in the alpha+beta phase field, it will be understood on reading the present description that more than one multi-axis forging step could be performed in the alpha+beta phase field for further grain refinement. According to non-limiting embodiments of the present disclosure, at least one final high strain rate multi-axis forging step takes place entirely at temperatures in the alpha+beta phase field of the titanium alloy workpiece.
  • the thermal management system (33 of FIG. 3 ) is used in through beta transus multi-axis forging to maintain the temperature of the workpiece at a uniform or substantially uniform temperature prior to each hit at each through beta transus forging temperature and, optionally, to slow the cooling rate,
  • the workpiece is cooled 276 to ambient temperature.
  • cooling 276 comprises air cooling.
  • Non-limiting embodiments of multi-axis forging using a thermal management system can be used to process titanium alloy workpieces having cross-sections greater than 25.8 sq. cm (4 square inches) using conventional forging press equipment, and the size of cube-shaped workpieces can be scaled to match the capabilities of an individual press. It has been determined that alpha lamellae or laths from the ⁇ -annealed structure break down easily to fine uniform alpha grains at workpiece forging temperatures disclosed in non-limiting embodiments herein. It has also been determined that decreasing the workpiece forging temperature decreases the alpha particle size (grain size).
  • grain refinement that occurs in non-limiting embodiments of thermally managed, high strain rate multi-axis forging according to the present disclosure occurs via meta-dynamic recrystallization.
  • dynamic recrystallization occurs instantaneously during the application of strain to the material.
  • meta-dynamic recrystallization occurs at the end of each deformation or forging hit, while at least the internal region of the workpiece is hot from adiabatic heating. Residual adiabatic heat, internal region cooling times, and external surface region heating influence the extent of grain refinement in non-limiting methods of thermally managed, high strain rate multi-axis forging according to the present disclosure.
  • the present inventors have further developed alternate methods according to the present disclosure providing certain advantages relative to a process as described above including multi-axis forging and using a thermal management system and a cube-shaped workpiece comprising a titanium alloy. It is believed that one or more of (1) the cubical workpiece geometry used in certain embodiments of thermally managed multi-axis forging disclosed herein, (2) die chill ( i.e ., allowing the temperature of the dies to dip significantly below the workpiece forging temperature), and (3) use of high strain rates may disadvantageously concentrate strain within a core region of the workpiece.
  • the alternate methods according to the present disclosure can achieve generally uniform fine grain, very fine grain, or ultrafine grain size throughout a billet size titanium alloy workpiece.
  • a workpiece processed by such alternate methods may include the desired grain size, such as an ultrafine grain microstructure, throughout the workpiece, and not only in a central region of the workpiece
  • Non-limiting embodiments of such alternate methods comprise "multiple upset and draw” steps performed on billets having cross-sections greater than 25.8 sq. cm (4 square inches).
  • the multiple upset and draw steps are intended to impart uniform fine grain, very fine grain, or ultrafine grain microstructure throughout the workpiece, while preserving substantially the original dimensions of the workpiece. Because these alternate methods include Multiple Upset and Draw steps, they are referred to herein as embodiments of the "MUD" method.
  • the MUD method includes severe plastic deformation and can produce uniform ultrafine grains in billet-size (e.g ., 30 inch (76.2 cm) in length) titanium alloy workpieces.
  • strain rates used for the upset forging and draw forging steps are in the range of 0001 s -1 to 0.002 s -1 .
  • strain rates typically used for conventional open die upset and draw forging are in the range of 0001 s -1 to 0.002 s -1 .
  • the strain rate for MUD is slow enough to prevent adiabatic heating in the workpiece in order to keep the forging temperature in control, yet the strain rate is acceptable for commercial practices.
  • a non-limiting method 300 for refining grains in a workpiece comprising a titanium alloy using multiple upset and draw forging steps comprises heating an elongate titanium alloy workpiece 302 to a workpiece forging temperature in the alpha+beta phase field of the titanium alloy.
  • the shape of the elongate workpiece is a cylinder or a cylinder-like shape.
  • the shape of the workpiece is an octagonal cylinder or a right octagon.
  • the elongate workpiece has a starting cross-sectional dimension.
  • the starting cross-sectional dimension is the diameter of the cylinder.
  • the starting cross-sectional dimension is the diameter of the circumscribed circle of the octagonal cross-section, i.e ., the diameter of the circle that passes through all the vertices of the octagonal cross-section.
  • the workpiece When the elongate workpiece is at the workpiece forging temperature, the workpiece is upset forged 304. After upset forging 304, in a non-limiting embodiment, the workpiece is rotated 90 degrees to the orientation 306 and then is subjected to multiple pass draw forging 312. Actual rotation of the workpiece is optional, and the objective of the step is to dispose the workpiece into the correct orientation (refer to FIG. 9 ) relative to a forging device for subsequent multiple pass draw forging 312 steps.
  • Multiple pass draw forging comprises incrementally rotating (depicted by arrow 310) the workpiece in a rotational direction (indicated by the direction of arrow 310), followed by draw forging 312 the workpiece after each increment of rotation.
  • incrementally rotating 310 and draw forging 312 is repeated until the workpiece comprises the starting cross-sectional dimension. Heating, upset forging, and multiple pass draw forging steps is repeated until a total strain in the range of at least 1.0 up to less than 3.5 is achieved in the workpiece.
  • An aspect of the present disclosure is to employ a strain rate during the upset and multiple pass drawing steps that is sufficient to result in severe plastic deformation of the titanium alloy workpiece, which, in non-limiting embodiments, further results in ultrafine grain size.
  • a strain rate used in upset forging is in the range of 0.001 s -1 to 0.003 s -1 .
  • a strain rate used in the multiple pass draw forging steps is the range of 0.01 s -1 to 0.02 s -1 . It was disclosed in the '538 Application that strain rates in these ranges do not result in adiabatic heating of the workpiece, which enables workpiece temperature control, and were found sufficient for an economically acceptable commercial practice.
  • the workpiece after completion of the MUD method, has substantially the original dimensions of the starting elongate article, such as, for example, cylinder 314 or octagonal cylinder 316.
  • the workpiece after completion of the MUD method, has substantially the same cross-section as the starting workpiece.
  • a single upset requires numerous draw hits and intermediate rotations to return the workpiece to a shape including the starting cross-section of the workpiece.
  • incrementally rotating and draw forging further comprises multiple steps of rotating the cylindrical workpiece in 15° increments and subsequently draw forging, until the cylindrical workpiece is rotated through 360° and is draw forged at each increment.
  • twenty-four draw forging steps with intermediate incremental rotation between successive draw forging steps are employed to bring the workpiece to substantially its starting cross-sectional dimension.
  • incrementally rotating and draw forging further comprises multiple steps of rotating the cylindrical workpiece in 45° increments and subsequently draw forging, until the cylindrical workpiece is rotated through 360° and is draw forged at each increment.
  • MUD method wherein the workpiece is in the shape of an octagonal cylinder
  • eight forging steps separated by incremental rotation of the workpiece are employed to bring the workpiece substantially to its starting cross-sectional dimension. It was observed in non-limiting embodiments of the MUD method that manipulation of an octagonal cylinder by handling equipment was more precise than manipulation of a cylinder by handling equipment.
  • a workpiece forging temperature comprises a temperature within a workpiece forging temperature range.
  • the workpiece forging temperature is in a workpiece forging temperature range of 100°F (55.6°C) below the beta transus temperature (T ⁇ ) of the titanium alloy to 700°F (388.9°C) below the beta transus temperature of the titanium alloy.
  • the workpiece forging temperature is in a temperature range of 300°F (166.7°C) below the beta transus temperature of the titanium alloy to 625°F (347°C) below the beta transus temperature of the titanium alloy.
  • the low end of a workpiece forging temperature range is a temperature in the alpha+beta phase field at which substantial damage does not occur to the surface of the workpiece during the forging hit, as may be determined without undue experimentation by a person having ordinary skill in the art.
  • the workpiece forging temperature range for a Ti-6-2-4-2 alloy which has a beta transus temperature (T ⁇ ) of about 1820°F (993.3°C)
  • T ⁇ beta transus temperature
  • the workpiece forging temperature range for a Ti-6-2-4-2 alloy which has a beta transus temperature (T ⁇ ) of about 1820°F (993.3°C)
  • Non-limiting embodiments of the MUD method comprise multiple reheating steps.
  • the titanium alloy workpiece is heated to the workpiece forging temperature after upset forging the titanium alloy workpiece.
  • the titanium alloy workpiece is heated to the workpiece forging temperature prior to a draw forging step of the multiple pass draw forging.
  • the workpiece is heated as needed to bring the actual workpiece temperature back to or near the workpiece forging temperature after an upset or draw forging step.
  • embodiments of the MUD method impart redundant work or extreme deformation, also referred to as severe plastic deformation, which is aimed at creating ultrafine grains in a workpiece comprising a titanium alloy.
  • severe plastic deformation which is aimed at creating ultrafine grains in a workpiece comprising a titanium alloy.
  • the temperature of the workpiece may be cooled 416 to a second workpiece forging temperature.
  • the workpiece is upset forged at the second workpiece forging temperature 418.
  • the workpiece is rotated 420 or otherwise oriented relative to the forging press for subsequent draw forging steps.
  • the workpiece is multiple-step draw forged at the second workpiece forging temperature 422.
  • Multiple-step draw forging at the second workpiece forging temperature 422 comprises incrementally rotating 424 the workpiece in a rotational direction (refer to FIG. 9 ) and draw forging at the second workpiece forging temperature 426 after each increment of rotation.
  • the steps of upset, incrementally rotating 424, and draw forging are repeated 426 until the workpiece comprises the starting cross-sectional dimension.
  • the steps of upset forging at the second workpiece temperature 418, rotating 420, and multiple step draw forging 422 are repeated until a total strain in the range of 1.0 up to less than 3.5 is achieved in the workpiece. It is recognized that the MUD method can be continued until any desired total strain is imparted to the titanium alloy workpiece.
  • the workpiece forging temperature or a first workpiece forging temperature
  • the second workpiece forging temperature is about 1500°F (815.6°C).
  • Subsequent workpiece forging temperatures that are lower than the first and second workpiece forging temperatures such as a third workpiece forging temperature, a fourth workpiece forging temperature, and so forth, are within the scope of non-limiting embodiments of the present disclosure.
  • a total strain in a range of at least 1.0 up to less than 3.5 results in a uniform equiaxed alpha ultrafine grain microstructure in titanium alloy workpieces.
  • An aspect of the present disclosure includes the possibility that after processing a workpiece by the MUD method, subsequent deformation steps are performed without coarsening the refined grain size, as long as the temperature of the workpiece is not subsequently heated above the beta transus temperature of the titanium alloy.
  • a subsequent deformation practice after the MUD method may include draw forging, multiple draw forging, upset forging, or any combination of two or more of these forging techniques at temperatures in the alpha+beta phase field of the titanium alloy.
  • subsequent deformation or forging steps include a combination of multiple pass draw forging, upset forging, and draw forging to reduce the starting cross-sectional dimension of the cylinder-like or other elongate workpiece to a fraction of the cross-sectional dimension, such as, for example, but not limited to, one-half of the cross-sectional dimension, one-quarter of the cross-sectional dimension, and so forth, while still maintaining a uniform fine grain, very fine grain, or ultrafine grain structure in the titanium alloy workpiece.
  • the workpiece is a titanium alloy selected from a Ti-6-2-4-2 alloy, a Ti-6-2-4-6 alloy, ATI 425®titanium alloy (Ti-4Al-2.5V), and a Ti-6-6-2 alloy.
  • the workpiece Prior to heating the workpiece to the workpiece forging temperature in the alpha+beta phase field according to MUD embodiments of the present disclosure, in a non-limiting embodiment the workpiece may be heated to a beta annealing temperature, held at the beta annealing temperature for a beta annealing time sufficient to form a 100% beta phase titanium microstructure in the workpiece, and cooled to ambient temperature.
  • the beta annealing temperature is in a beta annealing temperature range that includes the beta transus temperature of the titanium alloy up to 300°F (166.7°C) above the beta transus temperature of the titanium alloy.
  • the beta annealing time is from 5 minutes to 24 hours.
  • the workpiece is a billet that is coated on all or certain surfaces with a lubricating coating that reduces friction between the workpiece and the forging dies.
  • the lubricating coating is a solid lubricant such as, but not limited to, one of graphite and a glass lubricant.
  • Other lubricating coatings known now or hereafter to a person having ordinary skill in the art are within the scope of the present disclosure.
  • the contact area between the workpiece and the forging dies is small relative to the contact area in multi-axis forging of a cube-shaped workpiece.
  • the workpiece Prior to heating the workpiece comprising a titanium alloy to the workpiece forging temperature in the alpha+beta phase field according to MUD embodiments of the present disclosure, in a non-limiting embodiment the workpiece is plastically deformed at a plastic deformation temperature in the beta phase field of the titanium alloy after being held at a beta annealing time sufficient to form 100% beta phase in the titanium alloy and prior to cooling the alloy to ambient temperature,
  • the plastic deformation temperature is equivalent to the beta annealing temperature
  • the plastic deformation temperature is in a plastic deformation temperature range that includes the beta transus temperature of the titanium alloy up to 300°F (166.7°C) above the beta transus temperature of the titanium alloy.
  • plastically deforming the workpiece in the beta phase field of the titanium alloy comprises at least one of drawing, upset forging, and high strain rate multi-axis forging the titanium alloy workpiece.
  • plastically deforming the workpiece in the beta phase field of the titanium alloy comprises multiple upset and draw forging according to non-limiting embodiments of the present disclosure, and wherein cooling the workpiece to a temperature at or near the workpiece forging temperature comprises air cooling.
  • plastically deforming the workpiece in the beta phase field of the titanium alloy comprises upset forging the workpiece to a 30-35% reduction in height or another dimension, such as length.
  • Another aspect of the MUD method of the present disclosure may include heating the forging dies during forging.
  • a non-limiting embodiment comprises heating dies of a forge used to forge the workpiece to temperature in a temperature range bounded by the workpiece forging temperature down to 100°F (55.6°C) below the workpiece forging temperature.
  • a bar of Ti-6-2-4-2 alloy was processed according to a commercial forging process, identified in the industry by specification number AMS 4976, which is typically used to process Ti-6-2-4-2 alloy.
  • AMS 4976 specification number
  • those having ordinary skill understand the specifics of the process to achieve the mechanical properties and microstructure set out in that the specification.
  • the alloy was metallographically prepared and the microstructure was evaluated microscopically. As shown in the micrograph of the prepared alloy included as FIG. 11 (a) , the microstructure includes alpha grains (the lighter colored regions in the image) that are on the order of 20 ⁇ m or larger.
  • a 10.2 cm (4.0 inch) cube-shaped workpiece of Ti-6-2-4-2 alloy was beta annealed at 1950°F (1066°C) for 1 hour and then air cooled to ambient temperature. After cooling, the beta annealed cube-shaped workpiece was heated to a workpiece forging temperature of 1600°F (871.1 °C) and forged using four hits of high strain rate MAF. The hits were to the following orthogonal axes, in the following sequence: A-B-C-A. The hits were to a spacer height of 8.3 cm (3.25 inches), and the ram speed was 2.5 cm (1 inch) per second.
  • a bar of Ti-6-2-4-6 alloy was processed according to a commercial forging process typically used for T-6-2-4-6 alloy, i.e., according to specification AMS 4981.
  • AMS 4981 specification, those having ordinary skill understand the specifics of the process to achieve the mechanical properties and microstructure set out in that the specification.
  • the alloy was metallographically prepared and the microstructure was evaluated microscopically. As shown in the micrograph of the prepared alloy shown in FIG. 12(a) , the microstructure exhibits alpha grains (the lighter colored regions) that are on the order of 10 ⁇ m or larger.
  • a 10.2 cm (4.0 inch) cube-shaped workpiece of Ti-6-2-4-6 alloy was beta annealed at 1870°F (1066°C) for 1 hour and then air cooled. After cooling, the beta annealed cube-shaped workpiece was heated to a workpiece forging temperature of 1500°F (815.6°C) and forged using four hits of high strain rate MAF. The hits were to the following orthogonal axes and followed the following sequence: A-B-C-A. The hits were to a spacer height of 8.3 cm (3.25 inches), and the ram speed was 2.5 cm (1 inch) per second.
  • a 10.2 cm (4.0 inch) cube-shaped workpiece of Ti-6-2-4-6 alloy was beta annealed at 1870°F (1066°C) for 1 hour and then air cooled. After cooling, the beta annealed cube-shaped workpiece was heated to a workpiece forging temperature of 1500°F (815.6°C) and forged using three hits of high strain rate MAF, one each on the A, the B, and the C axes (i.e., the hits were to the following orthogonal axes and in the following sequence: A-B-C). The hits were to a spacer height of 8.3 cm (3.25 inches), and the ram speed was 2.5 cm (1 inch) per second.
  • the workpiece was reheated to 1500°F (815.6°C) for 30 minutes.
  • the cube was then high strain rate MAF with one hit at each of the A, the B, and the C axes, i.e., an A-B-C sequence.
  • the hits were to the same spacer heights and used the same ram speed and time in between hits as in the first sequence of A-B-C hits.
  • This embodiment of a high strain rate multi-axis forging process imparted a strain of 3.46.
  • the microstructure of the alloy processed in this manner is depicted in the micrograph of FIG.13 . It is seen that the majority of alpha particles (lighter colored areas) are on the order of 4 ⁇ m or less. It is believed likely that the alpha particles are comprised of individual alpha grains and that each of the alpha grains has a grain size of 4 ⁇ m or less and is equiaxed in shape.
  • a 10.2 cm (4.0 inch) cube-shaped workpiece of Ti-6-2-4-2 alloy was beta annealed at 1950°F (1066°C) for 1 hour and then air cooled. After cooling, the beta annealed cube-shaped workpiece was heated to a workpiece forging temperature of 1700°F (926.7°C) and held for 1 hour, Two high strain rate MAF cycles (2 sequences of three A-B-C hits, for a total of 6 hits) were employed at 1700°F (926.7°C). The time between successive hits was about 15 seconds.
  • the forging sequence was: an A hit to a 7.6 cm (3 inch) stop; a B hit to an 8.9 cm (3.5 inch) stop; and a C hit to a 10.2 cm (4.0 inch) stop.
  • This forging sequence provides an equal strain to all three orthogonal axes every three-hit MAF sequence.
  • the ram speed was 2.5 cm (1 inch) per second. There was no strain rate control on the press, but for the 10.2 cm (4.0 inch) cubes, this ram speed results in a minimum strain rate during pressing of 0.25 s -1 .
  • the total strain per cycle is less than forging to an 8.3 cm (3.25 inch) reduction in each direction as in previous examples.
  • the workpiece was heated to 1650°F (898.9°C) and subjected to high strength MAF for three additional hits (i.e., one additional A-B-C high strain rate MAF cycle).
  • the forging sequence was: an A hit to a 7.6 cm (3 inch) stop; a B hit to an 8.9 cm (3.5 inch) stop; and a C hit to a 10.2 cm (4.0 inch) stop. After forging, the total strain imparted to the workpiecewas 2.59.
  • the microstructure of the forged workpiece of Example 4 is depicted in the micrograph of FIG. 14 . It is seen that the majority of alpha particles (lighter colored regions) are in a networked structure, It is believed likely that the alpha particles are comprised of individual alpha grains and that each of the alpha grains has a grain size of 4 ⁇ m or less and is equiaxed in shape.
  • a 10.2 cm (4.0 inch) cube-shaped workpiece of Ti-6-2-4-2 alloy was beta annealed at 1950°F (1066°C) for 1 hour and then air cooled. After cooling, the beta annealed, cube-shaped workpiece was heated to a workpiece forging temperature of 1700°F (926. 7°C) and held for 1 hour.
  • MAF according to the present disclosure was employed to apply 6 press forgings to a major reduction spacer height (A, B, C, A, B, C) to the cube-shaped workpiece.
  • first and second blocking reductions were conducted on the other axes to "square up" the workpiece.
  • the overall forging sequence used is as follows, wherein the bold and underlined hits are press forgings to the major reduction spacer height: A -B-C- B -C-A- C -A-B- A -B-C- B -C-A- C .
  • the forging sequence including major, first blocking, and second blocking spacer heights (in cm and inches) that were utilized are outlined in the table below.
  • the ram speed was 2.5 cm (1 inch) per second. There was no strain rate control on the press, but for the 10.2 cm (4.0 inch) cubes this ram speed results in a minimum strain rate during pressing of 0.25 s -1 .
  • the time elapsed between hits was about 15 seconds.
  • the total strain after thermally managed MAF according to this non-limiting embodiment was 2.37.
  • the microstructure of the workpiece forged by the process described in this Example 5 is depicted in the micrograph of FIG. 15 . It is seen that the majority of alpha particles (lighter colored regions) are elongated. It is believed likely that the alpha particles are comprised of individual alpha grains and that each of the alpha grains has a grain size of 4 ⁇ m or less and is equiaxed in shape.
  • a 10.2 cm (4.0 inch) cube-shaped workpiece of Ti-6-2-4-2 alloy was beta annealed at 1950°F (1066°C) for 1 hour and then air cooled.
  • Thermally managed high strain rate MAF according to embodiments of the present disclosure, was performed on the workpiece, including 6 hits (2 A-B-C MAF cycles) at 1900°C, with 30 second holds between each hit.
  • the ram speed was 2.5 cm (1 inch) per second. There was no strain rate control on the press, but for the 10.2 cm (4.0 inch) cubes, this ram speed results in a minimum strain rate during pressing of 0.25 s -1 .
  • the sequence of 6 hits with intermediate holds was designed to heat the surface of the piece through the beta transus temperature during MAF, and this may therefore be referred to as a through transus high strain rate MAF.
  • the process results in refining the surface structures and minimizing cracking during subsequent forging.
  • the workpiece was then heated at 1650°F (898.9°C), i.e., below the beta transus temperature for 1 hour.
  • MAF according to embodiments of the present disclosure was applied to the workpiece, including 6 hits (two A-B-C MAF cycles) with about 15 seconds between hits.
  • the first three hits were performed with an 8.9 cm (3.5 inch) spacer height
  • the second 3 hits were performed with an 8.3 cm (3.25 inch) spacer height
  • the workpiece was heated to 1650°F (898.9°C) and held for 30 minutes between the hits with the 8.9 cm (3.5 inch) spacer and the hits with the 8.3 cm (3.25 inch) spacer.
  • the smaller reduction i.e., larger spacer height
  • the workpiece was reheated to 1500°F (815.6°C) for 1 hour.
  • MAF MAF according to embodiments of the present disclosure was then applied using 3 A-B-C hits (one MAF cycle) to 8.3 cm (3.25 inch) reductions with 15 seconds in between each hit. This sequence of heavier reductions is designed to put additional work into the non-boundary structures.
  • the ram speed for all hits described in Example 6 was 2.5 cm (1 inch) per second.
  • FIG. 16(a) A representative micrograph from the center of the thermally managed MAF workpiece of Example 6 is shown in FIG. 16(a) .
  • FIG. 16(b) A representative micrograph of the surface of the thermally managed MAF workpiece of Example 6 is presented in FIG.16(b) .
  • the surface microstructure ( FIG. 16(b) ) is substantially refined and the majority of the particles and/or grains have a size of about 4 ⁇ m or less, which is an ultrafine grain microstructure.
  • the center microstructure shown in FIG. 16(a) shows highly refined grains, and it is believed likely that the alpha particles are comprised of individual alpha grains and each of the alpha grains has a grain size of 4 ⁇ m or less and is equiaxed in shape.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Forging (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Claims (19)

  1. Verfahren zum Verfeinern der Korngröße eines Werkstücks, das eine Titanlegierung umfasst, ausgewählt aus der Legierung Ti-6Al-2Sn-4Zr-6Mo (UNS R56260), der Legierung Ti-6Al-2Sn-4Zr-2Mo-0,08Si (UNS R54620), der Legierung Ti-4Al,-2,5V (UNS R54250), der Legierung Ti-6Al-7Nb (UNS R56700) und der Legierung Ti-6Al-6V-2Sn (UNS R56620), wobei das Verfahren Folgendes umfasst:
    Beta-Glühen des Werkstücks;
    Abkühlen des beta-geglühten Werkstücks auf eine Temperatur unterhalb der Beta-Übergangstemperatur der Titanlegierung; und
    Mehrachsschmieden des Werkstücks, wobei das Mehrachsschmieden Folgendes umfasst:
    Druckschmieden des Werkstücks bei einer Werkstückschmiedetemperatur in einem Werkstückschmiedetemperaturbereich in der Richtung einer ersten senkrechten Achse des Werkstücks mit einer Dehngeschwindigkeit, ausreichend, um einen Innenbereich des Werkstücks adiabatisch zu erwärmen,
    Druckschmieden des Werkstücks bei einer Werkstückschmiedetemperatur im Werkstückschmiedetemperaturbereich in der Richtung einer zweiten senkrechten Achse des Werkstücks mit einer Dehngeschwindigkeit, die ausreicht, um den Innenbereich des Werkstücks adiabatisch zu erwärmen,
    Druckschmieden des Werkstücks bei einer Werkstückschmiedetemperatur im Werkstückschmiedetemperaturbereich in der Richtung einer dritten senkrechten Achse des Werkstücks mit einer Dehngeschwindigkeit, die ausreicht, um den Innenbereich des Werkstücks adiabatisch zu erwärmen, und
    Wiederholen wenigstens eines der Druckschmiedeschritte bis eine gesamte wahre Dehnung von wenigstens 1,0 bis zu weniger als 3,5 im Werkstück erzielt wird.
  2. Verfahren zum Verfeinern der Korngröße eines Werkstücks, das eine Titanlegierung umfasst, ausgewählt aus der Legierung Ti-6Al-2Sn-4Zr-6Mo (UNS R56260), der Legierung Ti-6Al-2Sn-4Zr-2Mo-0,08Si (UNS R54620), der Legierung Ti-4Al,-2,5V (UNS R54250), der Legierung Ti-6Al-7Nb (UNS R56700) und der Legierung Ti-6Al-6V-2Sn (UNS R56620), wobei das Verfahren Folgendes umfasst:
    Beta-Glühen des Werkstücks;
    Abkühlen des beta-geglühten Werkstücks auf eine Temperatur unterhalb der Beta-Übergangstemperatur der Titanlegierung; und
    Mehrachsschmieden des Werkstücks, wobei das Mehrachsschmieden Folgendes umfasst:
    Druckschmieden des Werkstücks bei einer Werkstückschmiedetemperatur in einem Werkstückschmiedetemperaturbereich in der Richtung einer ersten senkrechten A-Achse des Werkstücks auf eine große Reduzierungsabstandhalterhöhe mit einer Dehngeschwindigkeit, ausreichend, um einen Innenbereich des Werkstücks adiabatisch zu erwärmen,
    Druckschmieden des Werkstücks bei der Werkstückschmiedetemperatur in der Richtung einer zweiten senkrechten B-Achse des Werkstücks auf eine erste Vorschmiedereduzierungsabstandhalterhöhe,
    Druckschmieden des Werkstücks bei der Werkstückschmiedetemperatur in der Richtung einer dritten senkrechten C-Achse des Werkstücks auf eine zweite Vorschmiedereduzierungsabstandhalterhöhe,
    Druckschmieden des Werkstücks bei der Werkstückschmiedetemperatur in der Richtung der zweiten senkrechten B-Achse des Werkstücks auf die große Reduzierungsabstandhalterhöhe mit einer Dehngeschwindigkeit, ausreichend, um einen Innenbereich des Werkstücks adiabatisch zu erwärmen,
    Druckschmieden des Werkstücks bei der Werkstückschmiedetemperatur in der Richtung der dritten senkrechten C-Achse des Werkstücks auf die erste Vorschmiedereduzierungsabstandhalterhöhe,
    Druckschmieden des Werkstücks bei der Werkstückschmiedetemperatur in der Richtung der ersten senkrechten A-Achse des Werkstücks auf die zweite Vorschmiedereduzierungsabstandhalterhöhe,
    Druckschmieden des Werkstücks bei der Werkstückschmiedetemperatur in der Richtung der dritten senkrechten C-Achse des Werkstücks auf die große Reduzierungsabstandhalterhöhe mit einer Dehngeschwindigkeit, ausreichend, um einen Innenbereich des Werkstücks adiabatisch zu erwärmen,
    Druckschmieden des Werkstücks bei der Werkstückschmiedetemperatur in der Richtung der ersten senkrechten A-Achse des Werkstücks auf die erste Vorschmiedereduzierungsabstandhalterhöhe,
    Druckschmieden des Werkstücks bei der Werkstückschmiedetemperatur in der Richtung der zweiten senkrechten B-Achse des Werkstücks auf die zweite Vorschmiedereduzierungsabstandhalterhöhe, und
    Wiederholen wenigstens eines der vorhergehenden Druckschmiedeschritte bis eine gesamte wahre Dehnung von wenigstens 1,0 bis zu weniger als 3,5 im Werkstück erzielt wird.
  3. Verfahren nach Anspruch 1 oder 2, wobei eine während des Druckschmiedens verwendete Dehngeschwindigkeit im Bereich von 0,2 s-1 bis 0,8 s-1 liegt.
  4. Verfahren nach Anspruch 1 oder 2, wobei das Abkühlen des beta-geglühten Werkstücks das Abkühlen des Werkstücks auf Umgebungstemperatur umfasst.
  5. Verfahren nach Anspruch 1 oder 2, wobei das Abkühlen des beta-geglühten Werkstücks das Abkühlen des Werkstücks auf eine Temperatur bei oder nahe der Werkstückschmiedetemperatur umfasst.
  6. Verfahren nach Anspruch 1 oder 2, wobei das Beta-Glühen des Werkstücks das Erwärmen des Werkstücks bei einer Beta-Glühtemperatur in einem Bereich der Beta-Übergangstemperatur der Titanlegierung bis zu 166,7 °C (300 °F) über der Beta-Übergangstemperatur der Titanlegierung umfasst.
  7. Verfahren nach Anspruch 1 oder 2, wobei das Beta-Glühen des Werkstücks das Erwärmen des Werkstücks bei einer Beta-Glühtemperatur eine Zeit im Bereich von 5 Minuten bis 24 Stunden lang umfasst.
  8. Verfahren nach Anspruch 1 oder 2, ferner umfassend das plastische Verformen des Werkstücks bei einer Temperatur für plastisches Verformen im Beta-Phasenfeld der Titanlegierung vor dem Abkühlen des beta-geglühten Werkstücks.
  9. Verfahren nach Anspruch 8, wobei das plastische Verformen des Werkstücks bei einer Temperatur für plastisches Verformen im Beta-Phasenfeld der Titanlegierung Ziehen, Stauchschmieden und/oder Mehrachsschmieden des Werkstücks umfasst.
  10. Verfahren nach Anspruch 8, wobei die Temperatur für plastisches Verformen in einem Bereich der Beta-Übergangstemperatur der Titanlegierung bis zu 166,7 °C (300 °F) über der Beta-Übergangstemperatur der Titanlegierung liegt.
  11. Verfahren nach Anspruch 8, wobei plastisches Verformen des Werkstücks Mehrachsschmieden mit hoher Dehnungsrate umfasst und wobei das Abkühlen des Werkstücks Mehrachsschmieden des Werkstücks mit hoher Dehnungsrate umfasst, während das Werkstück sich auf die Werkstückschmiedetemperatur in dem Alpha+Beta-Phasenfeld der Titanlegierung abkühlt.
  12. Verfahren nach Anspruch 8, wobei das plastische Verformen des Werkstücks Stauchschmieden des Werkstücks auf eine Beta-Stauchdehnung im Bereich von 0,1 bis 0,5 umfasst.
  13. Verfahren nach Anspruch 1 oder 2, wobei die Werkstückschmiedetemperatur in einem Bereich von 55,6 °C (100 °F) unterhalb der Beta-Übergangstemperatur der Titanlegierung bis 388,9 °C (700 °F) unterhalb der Beta-Übergangstemperatur der Titanlegierung liegt.
  14. Verfahren nach Anspruch 1 oder 2, ferner umfassend aufeinanderfolgende Druckschmiedezwischenschritte, Zulassen, dass sich der adiabatisch erwärmte Innenbereich des Werkstücks auf eine Temperatur bei oder nahe der Werkstückschmiedetemperatur im Werkstückschmiedetemperaturbereich abkühlt, und das Erwärmen der Außenoberfläche des Werkstücks auf eine Temperatur auf oder nahe der Werkstückschmiedetemperatur im Werkstückschmiedetemperaturbereich.
  15. Verfahren nach Anspruch 14, wobei es dem adiabatisch erwärmten Innenbereich des Werkstücks ermöglicht wird, sich über einen Innenbereichs-Abkühlzeitraum im Bereich von 5 Sekunden bis einschließlich 120 Sekunden abzukühlen.
  16. Verfahren nach Anspruch 14, wobei das Erwärmen der Außenoberfläche des Werkstücks das Erwärmen unter Einsatz von Flammwärmen, Kammerofenerwärmen, Induktionserwärmen und/oder Strahlungserwärmen umfasst.
  17. Verfahren nach Anspruch 14, wobei die Gesenke einer Schmiede, die zum Druckschmieden des Werkstücks eingesetzt werden, auf eine Temperatur in einem Bereich von der Werkstückschmiedetemperatur bis 55,6 °C (100 °F) unterhalb der Werkstückschmiedetemperatur erwärmt werden.
  18. Verfahren nach Anspruch 1 oder 2, wobei, nachdem eine gesamte wahre Dehnung von wenigstens 1,0 bis zu weniger als 3,5 erreicht ist, das Werkstück eine durchschnittliche Alpha-Partikelkorngröße im Bereich von höchstens 4 µm umfasst.
  19. Verfahren nach Anspruch 1 oder 2, wobei das Wiederholen wenigstens eines der Druckschmiedeschritte, bis eine gesamte wahre Dehnung von wenigstens 1,0 bis zu weniger als 3,5 im Werkstück erzielt wird, Folgendes umfasst: Druckschmieden des Werkstücks bei einer zweiten Werkstückschmiedetemperatur, wobei die zweite Werkstückschmiedetemperatur innerhalb des Alpha+Beta-Phasenfelds der Titanlegierung des Werkstücks liegt, und wobei die zweite Werkstückschmiedetemperatur geringer als die Werkstückschmiedetemperatur ist.
EP13812249.4A 2012-12-14 2013-11-26 Verfahren zur verarbeitung von titanlegierungen Active EP2931930B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PL13812249T PL2931930T3 (pl) 2012-12-14 2013-11-26 Sposoby przetwarzania stopów tytanu

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US13/714,465 US9206497B2 (en) 2010-09-15 2012-12-14 Methods for processing titanium alloys
PCT/US2013/071801 WO2014093009A1 (en) 2012-12-14 2013-11-26 Methods for processing titanium alloys

Publications (2)

Publication Number Publication Date
EP2931930A1 EP2931930A1 (de) 2015-10-21
EP2931930B1 true EP2931930B1 (de) 2019-01-09

Family

ID=49880954

Family Applications (1)

Application Number Title Priority Date Filing Date
EP13812249.4A Active EP2931930B1 (de) 2012-12-14 2013-11-26 Verfahren zur verarbeitung von titanlegierungen

Country Status (23)

Country Link
EP (1) EP2931930B1 (de)
JP (2) JP6366601B2 (de)
KR (1) KR102001279B1 (de)
CN (1) CN104797723B (de)
AU (2) AU2013360096B2 (de)
BR (1) BR112015010745A8 (de)
CA (1) CA2886994C (de)
DK (1) DK2931930T3 (de)
ES (1) ES2717651T3 (de)
HK (1) HK1212400A1 (de)
HU (1) HUE042474T2 (de)
IL (2) IL238169B (de)
IN (1) IN2015DN02904A (de)
MX (1) MX368287B (de)
NZ (1) NZ707000A (de)
PL (1) PL2931930T3 (de)
PT (1) PT2931930T (de)
RU (2) RU2688109C2 (de)
SG (2) SG10201704857RA (de)
TR (1) TR201904960T4 (de)
TW (1) TWI602930B (de)
UA (1) UA115157C2 (de)
WO (1) WO2014093009A1 (de)

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3024160B1 (fr) * 2014-07-23 2016-08-19 Messier Bugatti Dowty Procede d'elaboration d`une piece en alliage metallique
JP6655937B2 (ja) 2015-10-08 2020-03-04 日立金属株式会社 回転鍛造により鍛造物を製造する方法および装置
RU2647071C2 (ru) * 2016-07-14 2018-03-13 Федеральное государственное унитарное предприятие "Всероссийский научно-исследовательский институт авиационных материалов" (ФГУП "ВИАМ") Способ термомеханической обработки титановых сплавов
JP6823827B2 (ja) 2016-12-15 2021-02-03 大同特殊鋼株式会社 耐熱Ｔｉ合金及びその製造方法
RU2664346C1 (ru) * 2017-05-12 2018-08-16 Хермит Эдванст Технолоджиз ГмбХ Способ получения заготовки из титановых сплавов для изделий, испытывающих переменные механические нагрузки
RU2681033C2 (ru) * 2017-05-12 2019-03-01 Хермит Эдванст Технолоджиз ГмбХ Способ получения заготовки из титановых сплавов для изделий, испытывающих переменные механические нагрузки
CN108754371B (zh) * 2018-05-24 2020-07-17 太原理工大学 一种细化近α高温钛合金晶粒的制备方法
CN109554639B (zh) * 2018-12-14 2021-07-30 陕西科技大学 一种高铌TiAl合金片层结构细化的方法
CN109778009A (zh) * 2019-03-24 2019-05-21 杭州辰卓科技有限公司 一种包含耐钛火双相（α+β）和高阻尼性能的钛合金
EP4118251B1 (de) * 2020-03-11 2024-06-26 BAE SYSTEMS plc Verfahren zur verarbeitung eines vorprodukts einer ti-legierung zu einem artikel
CN112191785B (zh) * 2020-08-28 2021-12-10 中国科学院金属研究所 一种高品质钛合金大规格棒材的锻造工艺
CN118064702B (zh) * 2024-02-17 2024-08-23 宝鸡市创信金属材料有限公司 一种可热塑性形变Ti6242S高温钛合金线材的加工方法

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
RU2134308C1 (ru) * 1996-10-18 1999-08-10 Институт проблем сверхпластичности металлов РАН Способ обработки титановых сплавов
CN1159472C (zh) * 2001-09-04 2004-07-28 北京航空材料研究院 钛合金准β锻造工艺
US7008491B2 (en) * 2002-11-12 2006-03-07 General Electric Company Method for fabricating an article of an alpha-beta titanium alloy by forging
US20050145310A1 (en) * 2003-12-24 2005-07-07 General Electric Company Method for producing homogeneous fine grain titanium materials suitable for ultrasonic inspection
RU2364660C1 (ru) * 2007-11-26 2009-08-20 Владимир Валентинович Латыш Способ получения ультрамелкозернистых заготовок из титановых сплавов
RU2393936C1 (ru) * 2009-03-25 2010-07-10 Владимир Алексеевич Шундалов Способ получения ультрамелкозернистых заготовок из металлов и сплавов
US8613818B2 (en) 2010-09-15 2013-12-24 Ati Properties, Inc. Processing routes for titanium and titanium alloys

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Also Published As

Publication number Publication date
BR112015010745A8 (pt) 2017-10-03
CA2886994C (en) 2020-03-24
UA115157C2 (uk) 2017-09-25
ES2717651T3 (es) 2019-06-24
TW201439333A (zh) 2014-10-16
WO2014093009A1 (en) 2014-06-19
IL257905B (en) 2018-10-31
RU2015128288A (ru) 2017-01-25
SG10201704857RA (en) 2017-07-28
AU2017203311B2 (en) 2018-01-04
JP2019007080A (ja) 2019-01-17
AU2017203311A1 (en) 2017-06-08
KR102001279B1 (ko) 2019-07-17
PL2931930T3 (pl) 2019-07-31
KR20150095613A (ko) 2015-08-21
MX2015004870A (es) 2015-07-21
CN104797723A (zh) 2015-07-22
CA2886994A1 (en) 2014-06-19
HUE042474T2 (hu) 2019-07-29
SG11201503654RA (en) 2015-06-29
MX368287B (es) 2019-09-27
CN104797723B (zh) 2017-11-17
IL238169B (en) 2018-04-30
PT2931930T (pt) 2019-04-02
BR112015010745A2 (pt) 2017-07-11
AU2013360096B2 (en) 2017-04-06
JP6366601B2 (ja) 2018-08-01
JP6734890B2 (ja) 2020-08-05
AU2013360096A1 (en) 2015-05-07
RU2017140315A (ru) 2019-02-12
NZ707000A (en) 2019-09-27
TR201904960T4 (tr) 2019-05-21
IN2015DN02904A (de) 2015-09-11
RU2688109C2 (ru) 2019-05-17
EP2931930A1 (de) 2015-10-21
AU2017203311C1 (en) 2018-04-12
RU2637446C2 (ru) 2017-12-04
RU2017140315A3 (de) 2019-02-12
JP2016503126A (ja) 2016-02-01
DK2931930T3 (en) 2019-03-18
HK1212400A1 (en) 2016-06-10
TWI602930B (zh) 2017-10-21

Similar Documents

Publication Publication Date Title
US9624567B2 (en) Methods for processing titanium alloys
EP2931930B1 (de) Verfahren zur verarbeitung von titanlegierungen
EP2616563B1 (de) Verfahren für titan und titanlegierungen
JP2016503126A5 (de)

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20150430

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

RIN1 Information on inventor provided before grant (corrected)

Inventor name: MANTIONE, JOHN V.

Inventor name: BRYAN, DAVID J.

Inventor name: THOMAS, JEAN-PHILIPPE

DAX Request for extension of the european patent (deleted)
RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: ATI PROPERTIES LLC

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

17Q First examination report despatched

Effective date: 20171129

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

INTG Intention to grant announced

Effective date: 20180604

GRAJ Information related to disapproval of communication of intention to grant by the applicant or resumption of examination proceedings by the epo deleted

Free format text: ORIGINAL CODE: EPIDOSDIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

INTC Intention to grant announced (deleted)
GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

INTG Intention to grant announced

Effective date: 20180831

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE PATENT HAS BEEN GRANTED

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

Ref country code: AT

Ref legal event code: REF

Ref document number: 1087353

Country of ref document: AT

Kind code of ref document: T

Effective date: 20190115

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 602013049662

Country of ref document: DE

REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: CH

Ref legal event code: NV

Representative=s name: ISLER AND PEDRAZZINI AG, CH

REG Reference to a national code

Ref country code: RO

Ref legal event code: EPE

REG Reference to a national code

Ref country code: DK

Ref legal event code: T3

Effective date: 20190311

REG Reference to a national code

Ref country code: NL

Ref legal event code: FP

REG Reference to a national code

Ref country code: PT

Ref legal event code: SC4A

Ref document number: 2931930

Country of ref document: PT

Date of ref document: 20190402

Kind code of ref document: T

Free format text: AVAILABILITY OF NATIONAL TRANSLATION

Effective date: 20190325

REG Reference to a national code

Ref country code: SE

Ref legal event code: TRGR

REG Reference to a national code

Ref country code: LT

Ref legal event code: MG4D

Ref country code: NO

Ref legal event code: T2

Effective date: 20190109

REG Reference to a national code

Ref country code: GR

Ref legal event code: EP

Ref document number: 20190400905

Country of ref document: GR

Effective date: 20190524

REG Reference to a national code

Ref country code: ES

Ref legal event code: FG2A

Ref document number: 2717651

Country of ref document: ES

Kind code of ref document: T3

Effective date: 20190624

REG Reference to a national code

Ref country code: HU

Ref legal event code: AG4A

Ref document number: E042474

Country of ref document: HU

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LV

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

Ref country code: RS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

Ref country code: IS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190509

Ref country code: HR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

REG Reference to a national code

Ref country code: DE

Ref legal event code: R097

Ref document number: 602013049662

Country of ref document: DE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: EE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

Ref country code: AL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SM

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

26N No opposition filed

Effective date: 20191010

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20191126

Ref country code: MC

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

REG Reference to a national code

Ref country code: AT

Ref legal event code: UEP

Ref document number: 1087353

Country of ref document: AT

Kind code of ref document: T

Effective date: 20190109

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: CY

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20190109

P01 Opt-out of the competence of the unified patent court (upc) registered

Effective date: 20230524

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 20231126

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SK

Payment date: 20231031

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20231127

Year of fee payment: 11

Ref country code: GR

Payment date: 20231129

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: ES

Payment date: 20231201

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: TR

Payment date: 20231109

Year of fee payment: 11

Ref country code: SE

Payment date: 20231127

Year of fee payment: 11

Ref country code: RO

Payment date: 20231103

Year of fee payment: 11

Ref country code: PT

Payment date: 20231110

Year of fee payment: 11

Ref country code: NO

Payment date: 20231129

Year of fee payment: 11

Ref country code: IT

Payment date: 20231122

Year of fee payment: 11

Ref country code: IE

Payment date: 20231127

Year of fee payment: 11

Ref country code: HU

Payment date: 20231108

Year of fee payment: 11

Ref country code: FR

Payment date: 20231127

Year of fee payment: 11

Ref country code: FI

Payment date: 20231127

Year of fee payment: 11

Ref country code: DK

Payment date: 20231127

Year of fee payment: 11

Ref country code: DE

Payment date: 20231129

Year of fee payment: 11

Ref country code: CZ

Payment date: 20231108

Year of fee payment: 11

Ref country code: CH

Payment date: 20231201

Year of fee payment: 11

Ref country code: BG

Payment date: 20231121

Year of fee payment: 11

Ref country code: AT

Payment date: 20231102

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: PL

Payment date: 20231102

Year of fee payment: 11

Ref country code: BE

Payment date: 20231127

Year of fee payment: 11