US3366513A - Heat treatment of niobium alloys - Google Patents
Heat treatment of niobium alloys Download PDFInfo
- Publication number
- US3366513A US3366513A US432891A US43289165A US3366513A US 3366513 A US3366513 A US 3366513A US 432891 A US432891 A US 432891A US 43289165 A US43289165 A US 43289165A US 3366513 A US3366513 A US 3366513A
- Authority
- US
- United States
- Prior art keywords
- carbide
- alloy
- heat
- treatment
- ductility
- 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 - Lifetime
Links
- 238000010438 heat treatment Methods 0.000 title description 31
- 229910001257 Nb alloy Inorganic materials 0.000 title description 3
- 229910045601 alloy Inorganic materials 0.000 description 33
- 239000000956 alloy Substances 0.000 description 33
- 239000000463 material Substances 0.000 description 13
- 238000000034 method Methods 0.000 description 11
- 229910052735 hafnium Inorganic materials 0.000 description 9
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical group [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 9
- 239000006185 dispersion Substances 0.000 description 8
- 239000002244 precipitate Substances 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 229910052750 molybdenum Inorganic materials 0.000 description 5
- 239000011733 molybdenum Substances 0.000 description 5
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 5
- 229910052721 tungsten Inorganic materials 0.000 description 5
- 239000010937 tungsten Substances 0.000 description 5
- 238000001816 cooling Methods 0.000 description 4
- 238000003466 welding Methods 0.000 description 4
- 238000010894 electron beam technology Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 229910052758 niobium Inorganic materials 0.000 description 3
- 239000010955 niobium Substances 0.000 description 3
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005242 forging Methods 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- WHJFNYXPKGDKBB-UHFFFAOYSA-N hafnium;methane Chemical compound C.[Hf] WHJFNYXPKGDKBB-UHFFFAOYSA-N 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 229910000846 In alloy Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000001226 reprecipitation Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
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
- This invention relates to the heat-treatment of niobiumbase alloys containing a hafnium-bearing carbide. Examples of such alloys are described in our co-pending application for Letters Patent No. 335,029.
- the said alloys contain 0-25 wt. percent tungsten, 0-10 wt. percent molybdenum and up to 8 wt. percent hafnium with sufficient carbon to form a dispersion of carbide.
- the carbide contains hafnium and carbon but may not be of a simple formula corresponding to hafnium carbide since it may also contain niobium or other elements forming a complex mixed carbide.
- the present invention provides a method of heattreating niobium-base alloys containing a dispersion of hafnium-bearing carbide comprising first heating the alloy at a temperature above 1550 C. and secondly heating the alloy at a temperature between 1000 C. and 1350 C.
- the first heat-treatment is preferably between 1600 C. and 1900 C. and the second between 1100 C. and 1250 C.
- the heattreatment may be applied to the alloys in two ways. Firstly, the alloys, for example, in the form of forgings, may be treated at the temperatures given above as separate reheating steps, and secondly, a melting operation or a fusion welding operation may be utilised as the first heating step, since in such operations, as in the first, separate reheating step, a coarse form of carbide is produced.
- the times of heat-treatment are not critical and will depend upon the temperature. Suflicient time should be allowed for the structure of the alloy to approach equilibrium.
- the first heat-treatment at elevated temperature should preferably not exceed two hours in order to avoid excessive grain growth and in practice a range of times between minutes and 2 hours is suitable.
- For the second heat-treatment at the lower end of the temperature range about 3 hours are required, but the upper limit is indeterminate since a stable structure is obtained.
- the temperature range for the second heat-treatment is, therefore, in practice Within the range 5 minutes to an indeterminate maximum time but it will depend upon the temperature.
- the improvement in properties after heat-treatment is due to the carbide being fine and uniformly dispersed.
- the carbide is a coarse plate-like form and the ductility of the alloy is reduced.
- low temperatures e.g. 1200 C.
- a fine carbide structure is obtained and the alloy possesses high ductility without sacrifice of strength.
- intermediate temperatures a mixture of the two forms is obtained and such a structure is typical of alloys which have not been heat-treated.
- Such material is low in ductility both because of the presence of the coarse plate-like carbide and because the distribution of neither form of carbide is uniform.
- the upper limit of the temperature range in the first heat-treatment is not very precise but at temperatures above about 2000 C. the carbide is taken into solution causing embrittlement of the lattice and reprecipitation at grain boundaries on cooling. Below about 1600 C. the carbide is not uniformly distributed.
- the upper limit of the temperature range in the second heat-treatment is set by the tendency for the coarse platelike carbide to be formed at elevated temperatures and by the tendency for the fine dispersion to coalesce.
- the lower limit is not very precise but it should be high enough for an approach to equilibrium to be obtained in reasonable time.
- the carbide In alloys produced by some processes, for example, electron beam melting with a slow cooling rate, the carbide is predominantly of the coarse plate-like form in the ascast condition and because of the low ductility associated with this structure, subsequent processing is diflicult.
- a single heat-treatment in the range 1000 C. to 1350 C. will convert this carbide into a fine form and the material can then be processed into wrought forms, such as sheet.
- weld material can be improved in some cases by a single heat-treatment at a temperature in the range 1000 C.1350 C. A more uniform structure is obtained however by the two-stage heat-treatment -already described. Examples of the invention will now be particularly described.
- Example I An alloy consisting of 11 Wt. percent tungsten, 3 wt. percent molybdenum, 2 wt. percent hafnium and 0.08 wt. percent carbon was arc-melted.
- the as-cast structure contained a precipitate of carbide in plate-like form and also some fine dispersion; these phases being formed during cooling of the ingot.
- the alloy was extruded at 1450 C. and subsequently forged and rolled to sheet 0.040 inch thick.
- the sheet was then recrystallised by heating to 1600 C. for 1 hour in vacuo, after which the carbide was in the form of uniformly dispersed coarse plates. This material was very notch sensitive at room temperature and a failure rate of 50% was experienced in bend tests at 4T. After a second heat-treatment at 1200 C. for 3 hours in vacuo the carbide was transformed into a fine uniformly dispersed structure. All material passed the 4T bend test and sheet could be hammered flat on itself without cracking.
- Example II A second sample of the alloy was electron beam melted and cast and processed into sheet by a method similar to that described in Example I.
- the as-cast material con- Z3 tained areasonably uniformly dispersed carbide predominantly of coarse plate-like structure.
- the material was of low ductility and it was necessary to. pre-extrude it before forging and rolling.
- the sheet produced was of a limited ductility and the ductility was substantially increased by heating for 3 hours at 1200 C. in vacuo.
- a second sample of cast material was heat-treated for 3 hours at 1200 C. in vacuo before processing so as to transform the carbide into a fine uniformly dispersed structure. Ductility was increased and the material could be processed into sheet without pre-extrusion.
- Example 111 Samples of the alloy sheet produced by the method described in Example I were argon arc-welded in air at a speed of 20 inches/minute.
- the weld material contained carbide which was predominantly of a coarse plate-like form and was of low ductility.
- one sample ofthe weld material was heated for 3 hours at 1200 C. in vacuo and a substantial improvement in ductility was obtained, the material passing a bend test of 6T at room temperature.
- a second sample was heated in vacuo for 2 hours at 1700 C. followed by 3 hours at 1200 C. and a further increase in' ductility of the weld material was obtained.
- a method of heat-treating niobium-base alloys containing hafnium-bearing carbide comprising heating the said alloy to melt at least a portion thereof, slowly cooling said alloy to eifect solidification thereof and precipi Cir claimed in claim 1 in which the heating step which melts at least a portion of the alloy is a fusion welding process.
- a method of processing an as-cast alloy consisting of 11% by weight of tungsten, 3% by weight of molybdenum, 2% by weight of hafnium and 0.08% by weight of carbon, balance niobium apart from impurities, said alloy being characterized by the presence of a precipitate of carbide in coarse plate-like condition, said method comprising heating the as-cast alloy at a temperature of 1200" C. for 3 hours in vacuo to transform the said coarse platelike precipitate into a fine uniformly dispersed carbide structure.
- a method of processing a niobium-base alloy containing a dispersion of hafnium-bearing carbide comprising melting the alloy in an electron beam, cooling the alloy slowly to effect solidification thereof and precipitation of the carbide in coarse plate-like condition, heating the alloy to a temperature in the range 1000 C.13S0" C. to transform the said coarse plate-like precipitate into a fine uniformly dispersed carbide structure, and subsequently processing the alloy into a wrought form.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Alloys Or Alloy Compounds (AREA)
- Carbon And Carbon Compounds (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB7161/64A GB1043826A (en) | 1964-02-20 | 1964-02-20 | Heat-treatment of niobium alloys |
Publications (1)
Publication Number | Publication Date |
---|---|
US3366513A true US3366513A (en) | 1968-01-30 |
Family
ID=9827788
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US432891A Expired - Lifetime US3366513A (en) | 1964-02-20 | 1965-02-15 | Heat treatment of niobium alloys |
Country Status (5)
Country | Link |
---|---|
US (1) | US3366513A (id) |
AT (1) | AT279913B (id) |
BE (1) | BE659804A (id) |
GB (1) | GB1043826A (id) |
NL (1) | NL6502137A (id) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11198927B1 (en) | 2019-09-26 | 2021-12-14 | United States Of America As Represented By The Secretary Of The Air Force | Niobium alloys for high temperature, structural applications |
US11846008B1 (en) | 2019-09-26 | 2023-12-19 | United States Of America As Represented By Secretary Of The Air Force | Niobium alloys for high temperature, structural applications |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2973261A (en) * | 1959-06-11 | 1961-02-28 | Gen Electric | Columbium base alloys |
US3034934A (en) * | 1960-03-31 | 1962-05-15 | Gen Electric | Method for processing of refractory metals |
US3113863A (en) * | 1960-05-31 | 1963-12-10 | Gen Electric | Columbium base alloy |
US3194697A (en) * | 1962-09-28 | 1965-07-13 | Gen Electric | Heat treatment of refractory metals |
US3230119A (en) * | 1963-09-17 | 1966-01-18 | Du Pont | Method of treating columbium-base alloy |
-
0
- BE BE659804D patent/BE659804A/xx unknown
-
1964
- 1964-02-20 GB GB7161/64A patent/GB1043826A/en not_active Expired
-
1965
- 1965-02-15 US US432891A patent/US3366513A/en not_active Expired - Lifetime
- 1965-02-19 NL NL6502137A patent/NL6502137A/xx unknown
- 1965-02-19 AT AT151865A patent/AT279913B/de not_active IP Right Cessation
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2973261A (en) * | 1959-06-11 | 1961-02-28 | Gen Electric | Columbium base alloys |
US3034934A (en) * | 1960-03-31 | 1962-05-15 | Gen Electric | Method for processing of refractory metals |
US3113863A (en) * | 1960-05-31 | 1963-12-10 | Gen Electric | Columbium base alloy |
US3194697A (en) * | 1962-09-28 | 1965-07-13 | Gen Electric | Heat treatment of refractory metals |
US3230119A (en) * | 1963-09-17 | 1966-01-18 | Du Pont | Method of treating columbium-base alloy |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11198927B1 (en) | 2019-09-26 | 2021-12-14 | United States Of America As Represented By The Secretary Of The Air Force | Niobium alloys for high temperature, structural applications |
US11846008B1 (en) | 2019-09-26 | 2023-12-19 | United States Of America As Represented By Secretary Of The Air Force | Niobium alloys for high temperature, structural applications |
Also Published As
Publication number | Publication date |
---|---|
GB1043826A (en) | 1966-09-28 |
NL6502137A (id) | 1965-08-23 |
BE659804A (id) | |
AT279913B (de) | 1970-03-25 |
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