Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
  • C22C27/02—Alloys based on vanadium, niobium, or tantalum

Definitions

• Columbiumbase alloys are known for their high-temperature strength and for their high-temperature oxidation resistance.
• the present invention is concerned with the discovery that if a small but critical amount of carbon is present in columbium-base alloys, it has the effect of significantly raising the embrittlement temperature of such alloys; i.e., for any given period of time, the alloys of this invention are able to withstand considerably higher temperatures without becoming embrittled.
• the use of carbon in the amounts herein specified in columbian-base alloys it is possible to work and weld these alloys more readily and to utilize them at much higher temperatures than was previously possible.
• the columbium-base alloys in which carbon can be used to raise the embrittlement temperature are those containing titanium and either molybdenum or tungsten, or mixtures of molybdenum and tungsten.
• the amount of carbon required is 0.02%-0.2% by weight of the alloy, with a range of 0.05 %-0.15 being preferred.
• Preferred alloy compositions possessing good hightemperature strength and oxidation resistance which are improved by the addition of 0.02%0.2% of carbon are those containing 7-13% titanium, 718% molybdenum, the balance being essentially columbium. In these compositions, all or a portion of the molybdenum may be replaced on an atom-for-atom basis by the element tungsten.
• the alloys of this invention comprise 0.02%0.2% carbon, 713% titanium, and one of the group consisting of 1) 7-18% molybdenum, (2.) 10'- 34% tungsten, and (3) 734% of a mixture of molybdenum and tungsten in which the molybdenum content is not greater than 18% of the total alloy composition, the balance being essentially columbium in an amount of at least 50%.
• the alloys of this invention comprise 0.02%-0.2% carbon, 713% titanium, 7- 18% molybdenum, the balance being essentially columbium.
• the alloys comprise 0.02%- 0.2% carbon, 7-13% titanium, 27% molybdenum, 15- 30% tungsten, the sum of the molybdenum and tungsten being 7-34% of the total and the balance being essentially columbium.
• the alloy comprises 0.022% carbon, 7-13% titanium, 15-30% tungsten, the balance being essentially columbium.
• the alloys which are herein described can be prepared by conventional procedures, such as by powdered metallur-gy or by melting and casting techniques.
• the individual metals can be melt-cast together and the melt [allowed to cool and solidify into a desired shape.
• the required amount of carbon may be added in any convenient form, as for example lampbl-ack, or graphite; or it may be added in combination with one of the metals used, as for example columbium carbide, titanium carbide, molybdenum carbide, or tungsten carbide.
• arc melting operation can be carried out in an arc melting furnace provided with consumable or nonconsumable electrodes, or by subjecting the charge to induction heating in a skull or specially designed crucible type of container.
• arc melting furnace comprises that having an integral, water-cooled copper crucible in which the charge can be melted, and solidified, such as that described by W. Kroll in Transactions of the Electrochemical Society, vol. 78, pages 35-47, 1940.
• a compressed, consumable arc electrode type melting furnace can be employed, such as described in U.S. 2,640,860 to S. A. Herres, as can the combination of a nonconsumable and consumable electrode type of double melting furnace described in U.S. 2,541,764 to S. A.
• a continuous-feed type of furnace can also be used, such as described in U.S.P.B. Report 111,083. Whatever the type of furnacing means employed, care should be exercised in the melting and casting operation to protect the molten metal from normal atmospheric contamination through contact with oxygen, nitrogen, etc. Contamination can be prevented by conducting the operation under a vacuum or an atmosphere of an inert gas, such as argon, helium, etc.
• an inert gas such as argon, helium, etc.
• the individual metals charged to the melting furnace can be in any desired form, e.g. powder, grains, shot, wire, or sponge, and should be of commercially acceptable purity to insure production of a satisfactorily pure alloy product. Although preferably metals exhibiting relatively high purity are utilized herein, some variance in purity properties can be tolerated. Residual amounts of carbon are usually found in one or more of the metals used to prepare the alloy compositions. Therefore, it is pointed out that this residual carbon content of the alloy should be taken into consideration in adjusting the amount of carbon to 0.02%0.2%.
• the alloys of the examples and those tested were prepared from commercially available columbium, titanium, and molybdenum. The carbon was added in some cases as commercially available columbium carbide, and in some cases as commercially available graphite.
• EXAMPLE 1 An alloy of 10% Ti, 10% Mo, 0.025% C, balance Nb was prepared by melting together in an atmosphere of helium in a water-cooled, copper crucible of an arc-melting furnace 395.6 parts of columbium, 50.0 parts of titanium, 50.0 parts of molybdenum, 4.37 parts of columbium carbide. When the metals had become completely molten, the furnace was turned 01f and the melt was allowed to solidify and cool in the helium atmosphere. The alloy was then remelted and resolidified six additional times in order to insure thorough mixing of the ingredient metals. The casting was ultimately recovered in the form of the water-cooled copper crucible. The casting was machined to a round bar of approximately /2" diameter x 5".
• Table 1 material 1350 C. at an extrusion ratio of approximate- INFLUENCE or CARBON ADDITIONS ON WORKABILITY f 6 to Part of thls extruslon was maQhmed diameter and swaged at 1000 C. to approximately 70% Composition (percent) Reduction in cross-sectional area reductlon In Press Sectlonal area: Speclmens of thl s wit o c a (p swaged material were heat treated in vacuum at the various temperatures specified in Table III and tested at room Nb T1 Mo 0 S ed a Swaged at Swaeed at temperature. The results of these tests are given in Table 1,000 0. 1,400 0. 000 C. In
• T bl H NOTE.10% Ti, 10% Mo, bal. Nb: 1 hr. at 1,400 O.-En1brittled.
• the specimens were bent around a mandrel, with the 0.2% Ultimate Percent Percent mandrel directly beneath the weld bead, to determine the f iil gg ggg g minimum temperature at which a bend could be section obtained without fracture; A transition from ductile (90 bend) to brittle (less than 40 bend) occurs at 1381.
• Nb 10% Ti, 10% M0, 75 C.
• EXAMPLE I'II EXAMPLE 1 AH l y of 10% Ti, 10% Carbon, PalanCe An alloy sample of 10% Ti, 10% Mo, 0.05% C, bal columbium was prepared by consumable arc-melting. A ance columbium was prepared for welding as given in 3" billet of this composition was extruded at approxi- Example V. The sheet in this case was rolled to 0.040"
• EXAMPLE VII Part of the extruded stock from Example III was forged into a plate to approximately 0.100 thick. The surfaces of the plate were cleaned and the sample was heat treated in vacuum at 1400 C. The heat-treated sample was cold rolled to 0.04" strip. One piece of the rolled strip was heat treated in vacuum for one hour at 1400 C., and another piece Was heated for one hour at 1500 C. Both specimens showed 23% elongation (in /1" gauge length) in room temperature tensile tests.
• the alloys of this invention will be found particularly valuable in applications where a highly fabricable, ductile, strong, and oxidation-resistant material is required. Particularly, the alloys will be found useful where equipment is to be used at high temperatures, and in which it is especially desirable to retain such properties as strength and ductility at low temperatures after high-temperature service.
• the alloys herein described are exceptionally useful in applications requiring sheet and in which cupping, forming, and welding are necessary.
• the alloys of this invention have been found particularly suitable for use in high-temperature equipment, such as turbine vanes, flame holders, high-speed aircraft skin, after-burner liners, and chemical reactors and their accessories.
• a columbium-base alloy consisting essentially of, by weight, 0.02%-0.2% carbon, 7-13% titanium, and one of the group consisting of 1) 7-l8% molybdenum, (2) 1034% tungsten, and (3) 7-34% of a mixture of molybdenum and tungsten in which the molybdenum content is not greater than 18% of the total alloy composition, the balance of this alloy composition being essentially colurnbium, the amount of said columbium being at least 50% of the total alloy.
• a colurnbiumbase alloy consisting essentially of, by Weight, 0.02%0.2% carbon, 713% titanium, 7l8% molybdenum, the balance being essentially columbium.
• a columbium-base alloy consisting essentially of, by weight, 0.02%-0.2% carbon, 713% titanium, 27% molybdenum, 15-30% tungsten, the sum of the molybdenum and tungsten being 17-34% of the total, the balance being essentially columbium.
• a columbium-base alloy consisting essentially of, by weight, 0.02%-0.2% carbon, 7-13% titanium, 1530% tungsten, the balance being essentially columbi'um.
• a columbium-base alloy consisting essentially of, by weight, 0.02%-0.2% carbon, about 10% titanium, about 10% molybdenum, the balance being essentially columbium.
• a columbium-base alloy consisting essentially of, by weight, 0.02%0.2% carbon, about 10% titanium, about 6% molybdenum, about 20% tungsten, the balance being essentially columbium.

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• Chemical & Material Sciences (AREA)
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• Organic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Powder Metallurgy (AREA)

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• 1960
  • 1960-08-30 US US52768A patent/US3086859A/en not_active Expired - Lifetime
• 1961
  • 1961-08-29 DE DEP27788A patent/DE1242375B/de active Pending
  • 1961-08-29 GB GB31137/61A patent/GB923225A/en not_active Expired
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