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EP0304530B1 - Niob, Vanadium und Molybdän enthaltende Titan-Aluminiumlegierungen - Google Patents

Niob, Vanadium und Molybdän enthaltende Titan-Aluminiumlegierungen Download PDF

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Publication number
EP0304530B1
EP0304530B1 EP19870630153 EP87630153A EP0304530B1 EP 0304530 B1 EP0304530 B1 EP 0304530B1 EP 19870630153 EP19870630153 EP 19870630153 EP 87630153 A EP87630153 A EP 87630153A EP 0304530 B1 EP0304530 B1 EP 0304530B1
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EP
European Patent Office
Prior art keywords
molybdenum
alloy
alloys
vanadium
titanium
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.)
Expired
Application number
EP19870630153
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English (en)
French (fr)
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EP0304530A1 (de
Inventor
Martin John Blackburn
Michael Price Smith
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.)
RTX Corp
Original Assignee
United Technologies Corp
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Filing date
Publication date
Priority to US06/424,668 priority Critical patent/US4716020A/en
Application filed by United Technologies Corp filed Critical United Technologies Corp
Priority to DE8787630153T priority patent/DE3779314D1/de
Priority to EP19870630153 priority patent/EP0304530B1/de
Publication of EP0304530A1 publication Critical patent/EP0304530A1/de
Application granted granted Critical
Publication of EP0304530B1 publication Critical patent/EP0304530B1/de
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    • 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

Definitions

  • the present invention relates to a titanium aluminum alloy and relates more specifically to titanium base alloys of the Ti3Al (alpha-two) type which have both good elevated temperature properties and sufficient low temperature ductility to make them useful in an engineering sense.
  • the present invention is an improvement on the alloys described in US-A-4,292,077.
  • the new alloys are comprised of aluminum, niobium and titanium.
  • the compositional ranges for the patented alloys were quite narrow since changes in properties were discovered to be very sensitive to the precise composition Generally, the patented alloys contain titanium, 24-27 atomic percent aluminum and 11-16 atomic percent niobium.
  • the alloys have at least 1.5% tensile ductility at room temperature and good elevated temperature creep strength, thus permitting their potential substitution for certain nickel base alloys such as INCO 713C.
  • vanadium partially replaces niobium in atomic amounts of 1-4%. This substitution desirably lowers the density of the alloy but at the same time the favorable high temperature properties are retained.
  • An optimum atomic composition range for this embodiment is 24-26% aluminum, 10-12% niobium and 2-4% vanadium.
  • An object of the present invention is to provide Ti3Al type alloys which have a superior combination of creep rupture life and tensile strength at elevated temperatures in the 600°C range, but which alloys at the same time have sufficient ductility to enable their use at room temperature and their fabrication by conventional processes associated with titanium base alloys.
  • the titanium aluminum alloy of the present invention is defined as shown in the claims 1, 3 and 6.
  • new titanium base alloys contain by atomic percent 25-27 aluminum, 11-16 (niobium + molybdenum) and 0.5-4 molybdenum. Preferably they have 0.5-1.5 Mo.
  • An especially preferred embodiment of the invention is the lighter weight alloy containing vanadium in substitution for a portion of the niobium.
  • Such an alloy contains by atomic percent 25-27 Al, 11-16 (Nb + V + Mo), 1-4 (V + Mo), at least 0.5 Mo, balance titanium. More preferably, the light weight alloy contains 9-11 Nb, 1-3 V and 0.5-3 Mo, balance titanium.
  • molybdenum substantially increases high temperature ultimate tensile strength and creep rupture properties, compared to the essential alloys of our prior invention which did not contain molybdenum.
  • Figure 1 is a graph showing the comparative ultimate tensile strength-to-density ratio for various known alloys, compared to the invention.
  • Figure 2 is a bar chart showing comparative stress rupture properties on a density adjusted basis for the invention compared to various known alloys.
  • the alloys of the present invention are based essentially on the compositions which is disclosed in US-A-4,292,077. Those alloys contain a critical combination of Ti, Nb and Al. In the patent we showed that the essential invention could be enhanced by including substituting 4% V for Nb, thereby lowering density. In making and disclosing the present invention, the light weight vanadium containing version of our prior invention has been used. The work described herein shows that Mo is a particularly unique and valuable addition to the essential Ti-Nb-Al alloys of the prior patent.
  • alloys described herein were manufactured using conventional titanium base alloy technology, basically vacuum arc melting and isothermal forging which is quite familiar (albeit isothermal forging is a recent improvement). Alloys of the Ti3Al composition have been developed to the extent that large ingots, weighing up to 245 kg may be procured on a routine basis from commercial sources. In the invention, the alloys are cast, forged and heat treated. The procedures for manufacture and testing of forgings are the same as those described in US-A-4,292,077.
  • An exemplary alloy demonstrating the invention is Ti-25Al-10Nb-3V-1Mo. (All compositions hereinafter are in atomic percent unless otherwise stated.)
  • the alloy has a density of about 3% greater than that of Ti-25Al-10Nb-4V, which is 4.5 g/cc.
  • the alloy was isothermally beta forged (the cylindrical cast ingot pressed to a disk shape approximately 14% of the original ingot height) at a temperature of about 1120°C. This is about 40°C over the beta transus, estimated to be about 1080°C.
  • Tables 1 and 2 show respectively the tensile and creep rupture properties of the alloy. Table 1.
  • Figure 1 shows how the ultimate tensile strength to density ratio of the new alloy of the present invention compares with those of a similar alloy lacking molybdenum and two commercial alloys, alloy Ti-6-2-4-2 and nickel base alloy INCO 713C. It is seen that the new alloy provides a significant improvement.
  • Figure 2 shows how the density-adjusted stress for 300 hr rupture life at 650°C for the alloy containing molybdenum is substantially improved over the creep rupture life for a similar alloy lacking molybdenum.
  • the alloys of the present invention will be characterized in their optimally forged and heat treated condition by a tensile ductility at room temperature of at least 1.5%, typically about 2.5%; an ultimate tensile strength of 1000 MPa at 25°C; and a 650°C/372 MPa creep life of at least 150 hours, typically about 300 hours. They have stress-to-density ratios of the order of 2 kPa/m3, compared to less than 1.5 kPa/m3 for the alloys of our prior patent, and compared to even lower values for older alloys.
  • the new alloys of the present invention also have desirably increased dynamic elastic modulus compared to other alloys, as indicated in Table 3.
  • the Ti-25Al-10Nb-3V-1Mo 650°C modulus is almost 30% greater than the value for Ti-25Al-10Nb-4V, and a significant improvement over commercial alloys as well.
  • the modulus was measured by mechanically stimulating resonant vibration of a beam of known dimensions and measuring the frequency response thereof. Calculation is made from known dynamics relationships. Table 3.
  • the new alloys of the present invention will essentially consist of Ti, Al, Nb, Mo. They preferably will contain v. Tungsten may substitute in part or whole for Mo, as indicated below. Other intentional additions may be included in our essential alloys, such as less than 1% C or Si in replacement of Ti.
  • Table 4 shows the lightest and heaviest embodiments of the present invention in weight percent. This will be provided as a reference for the future. Table 4. Weight Percentages (w/o) for the Invention in Atomic Percentages (a/o) Alloy Element Al Mo Nb V Ti A a/o 25 4 12 -- 59 w/o 13.5 7.7 27.3 -- 56.5 B a/o 27 0.5 10.5 -- 62 w/o 15.4 1.0 20.6 -- 63 C a/o 25 1.5 14.5 -- 59 w/o 13.5 2.9 26.9 -- 56.7 D a/o 27 0.5 10.5 -- 62 w/o 15.4 1.0 20.6 -- 63.0 E a/o 25 3.5 12.0 0.5 59 w/o 13.6 6.7 22.4 0.5 56.8 F a/o 27.0 0.5 7.0 3.5 62 w/o 16.0 1.0 14.2 3.8 65.0 G a/o 25 3 11 1 60 w/o 13.7 5.9 20.8 1.0
  • tungsten Since tungsten is known to be metallurgically equivalent to molybdenum in titanium alloys, it will be substitutional for molybdenum in the present invention. However, the use of tungsten will result in an alloy with higher density and therefore, less desirable density-corrected properties than those which result from the use of molybdenum.
  • the desired microstructure will have an ASTM grain size of about 2-4 (0.15-0.20 mm nominal dimension).
  • the alloy made as described above is best used with limited time exposure at temperatures in the 565-675°C range. It has been noticed some instability, in that yield strength increased and ductility decreased after several hundreds of hours exposure. Further heat treatment development may avoid the instability.
  • the heat treatment which the alloys of the present invention should be given is similar to that disclosed previously in US-A 4,292,077.
  • Solutioning or forging should be conducted above the beta transus, followed by aging between 700-900°C for 2-24 hours.
  • the cooling rate from the solutioning or forging temperature should be that which produces a fine Widmanstatten structure characterized by acicular alpha two structures of about 50 x 5 x 10 ⁇ 6m dimension mixed with beta phase lathes, generally as shown in Figure 7(b) of the referenced patent.
  • the conditions necessary to achieve this will depend on the size of the article, but generally cooling in air or the equivalent will be suitable for most small articles.
  • An alternative heat treatment comprises solutioning above the beta transus followed by quenching in a molten salt bath maintained about 750°C, followed by air cooling.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
  • Catalysts (AREA)
  • Forging (AREA)

Claims (11)

  1. Titanaluminiumlegierung, bestehend aus (in Atomprozent) 25-27% Aluminium, 11-16% (Niob + Molybdän), 0,5-4% Molybdän, wahlweise weniger als 1% Kohlenstoff, weniger als 1% Silizium, und als Rest Titan plus unvermeidliche Verunreinigungen.
  2. Legierung nach Anspruch 1, mit 0,5-1,5% Molybdän.
  3. Titanaluminiumlegierung, bestehend aus (in Atomprozent) 25-27% Aluminium, 11-16% (Niob + Molybdän), 0,5-4% Molybdän, wobei 0,5-3,5% Vanadium anstelle von Niob vorgesehen sind und wobei die Legierung 1-4% (Molybdän + Vanadium), wahlweise weniger als 1% Kohlenstoff, weniger als 1% Silizium und als Rest Titan plus unvermeidliche Verunreinigungen enthält.
  4. Legierung nach Anspruch 3, mit 1-3% Vanadium und 0,5-3% Molybdän.
  5. Legierung nach Anspruch 3, mit 3% Vanadium und 1% Molybdän.
  6. Titanaluminiumlegierung, bestehend aus (in Atomprozent) 25-27% Aluminium, 11-16% (Niob + Molybdän) 0,5-4% Molybdän, wobei bis zu 4% Wolfram anstelle von Molybdän vorgesehen sind, wahlweise weniger als 1% Kohlenstoff, weniger als 1% Silizium und der Rest Titan plus unvermeidliche Verunreinigungen sind.
  7. Legierung nach Anspruch 1, die zuerst bei einer Temperatur oberhalb der Beta-Transus-Temperatur wärmebehandelt und dann mit kontrollierter Geschwindigkeit abgekühlt worden ist, und zwar ausreichend, um ein feines Widmanstätten-Gefüge zu erzeugen.
  8. Legierung nach Anspruch 1, die weiter wärmebehandelt worden ist durch Altern bei 700-900°C für 4-24 Stunden.
  9. Legierungen nach Anspruch 1, mit einer Zugduktilität bei Raumtemperatur von wenigsten 1,5%.
  10. Legierungen nach Anspruch 1, mit einem Verhältnis von Zeitstandfestigkeit zu Dichte bei 650°C von größer als 1,6 kPa pro kg pro m³.
  11. Legierung nach Anspruch 1, mit einem dynamischen Elastizitätsmodul bei 650°C von größer als 9 x 10⁷ kPa.
EP19870630153 1982-09-27 1987-08-27 Niob, Vanadium und Molybdän enthaltende Titan-Aluminiumlegierungen Expired EP0304530B1 (de)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US06/424,668 US4716020A (en) 1982-09-27 1982-09-27 Titanium aluminum alloys containing niobium, vanadium and molybdenum
DE8787630153T DE3779314D1 (de) 1987-08-27 1987-08-27 Niob, vanadium und molybdaen enthaltende titan-aluminiumlegierungen.
EP19870630153 EP0304530B1 (de) 1987-08-27 1987-08-27 Niob, Vanadium und Molybdän enthaltende Titan-Aluminiumlegierungen

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19870630153 EP0304530B1 (de) 1987-08-27 1987-08-27 Niob, Vanadium und Molybdän enthaltende Titan-Aluminiumlegierungen

Publications (2)

Publication Number Publication Date
EP0304530A1 EP0304530A1 (de) 1989-03-01
EP0304530B1 true EP0304530B1 (de) 1992-05-20

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8333923B2 (en) 2007-02-28 2012-12-18 Caterpillar Inc. High strength gray cast iron

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2760469B1 (fr) 1997-03-05 1999-10-22 Onera (Off Nat Aerospatiale) Aluminium de titane utilisable a temperature elevee
CN109371268B (zh) * 2018-09-30 2020-12-08 中国科学院金属研究所 一种高温、高热稳定性、高蠕变抗力钛合金棒材的制备方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2880087A (en) * 1957-01-18 1959-03-31 Crucible Steel Co America Titanium-aluminum alloys
DE1533180A1 (de) * 1966-05-27 1969-12-04 Winter Dr Heinrich Titanlegierung fuer Kolben von Verbrennungsmotoren
US4292077A (en) * 1979-07-25 1981-09-29 United Technologies Corporation Titanium alloys of the Ti3 Al type
US4716020A (en) * 1982-09-27 1987-12-29 United Technologies Corporation Titanium aluminum alloys containing niobium, vanadium and molybdenum

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8333923B2 (en) 2007-02-28 2012-12-18 Caterpillar Inc. High strength gray cast iron

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DE3779314D1 (de) 1992-06-25
EP0304530A1 (de) 1989-03-01

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