CA2010147A1 - Tantalum-containing superalloys - Google Patents
Tantalum-containing superalloysInfo
- Publication number
- CA2010147A1 CA2010147A1 CA002010147A CA2010147A CA2010147A1 CA 2010147 A1 CA2010147 A1 CA 2010147A1 CA 002010147 A CA002010147 A CA 002010147A CA 2010147 A CA2010147 A CA 2010147A CA 2010147 A1 CA2010147 A1 CA 2010147A1
- Authority
- CA
- Canada
- Prior art keywords
- alloy
- tantalum
- nickel
- iron
- niobium
- 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.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
- C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
- C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
- C22C19/056—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 10% but less than 20%
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/10—Alloys containing non-metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
- C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
- C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
- C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
- C22C19/057—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being less 10%
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
- Forging (AREA)
- Powder Metallurgy (AREA)
- Manufacture Of Alloys Or Alloy Compounds (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Fats And Perfumes (AREA)
Abstract
Abstract of the Disclosure Nickel base superalloys which contain niobium (columbium) to promote gamma double prime strengthening are improved by replacing the niobium with tantalum on an atom-for-atom basis and then heat treating the new alloy at temperatures in excess of those conventionally used for superalloys which include niobium. The resultant tantalum-bearing alloys are found to exhibit increased strength and greater phase stability than corresponding niobium bearing alloys.
Description
Q~
TANTALUM-CONTAINING SUPERALLOYS
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to improved nickel base alloys which have a particularly high combination of strength properties and ductility over the temperature range e~tending from about room temperature to approximately 1500-F. The improvement is provided by incorporating a substantial amount of tantalum in the alloy, generally as an atom-for-atom replacement for niobium, and then heat treating the alloy at very high temperatures for extended periods.
DESCRIPTION OF THE PRIOR ART
Prior art nickel-base superalloys while steadily being improved, have disadvantages either from a standpoint of strength or ductility, particularly at elevated temperatures, i.e., above about 1200F.
These alloys are generally based upon nickel in combination with one or more of chromium, iron, and cobalt. In addition, they may contain a variety of elements in a large number of combinations to produce desired effects. Some of the elements which have been utilized in nickel-base superalloys to provide or improve one or more of the following properties are:
strength (Mo, Ta, W, Re), o~idation resistance (Cr, Al), phase stability (Ni) or increased volume fractions of favorable secondary precipitates (Co).
Other elements are added to form hardening precipitates such as gamma prime (Al, Ti) and gamma double prime (Cb). Minor elements (C, B) are added to form carbides and borides and others (Ce, Mg) are added for purposes of tramp element control. Some elements (B, Zr, Hf) also are added to promote favorable grain boundary effects. Many elements (e.g., Co, Mo, W, Cr), although added for their favorable alloying qualities, can participate, in some circumstances, in the formation of undesirable phases ~e.g., sigma, mu, Laves~.
Gamma double prime is generally considered to be a body centered tetragonal ordered Ni3Nb strengthening precipitate which is formed when niobium is present in nickel-base superalloys. A superalloy in which gamma double prime strengthening occurs is Inconel 718 which is within the scope of U.S. Patent No. 3,046,108 (Eiselstein). Eiselstein teaches that the alloy must contain about 4 to about 8 weight percent columbium and that the columbium in the alloy may be replaced in part with tantalum in an amount of up to 4% of the alloy. In partially replacing the columbium content of th2 alloy with tantalum, Eiselstein teaches that double the weight of tantalum should be used to obtain the same effect on properties. He also teaches that only tantalum-free alloys and/or alloys wherein not ~Q3~
more than 50% of the columbium is replaced by tantalum are notch-ductile at elevated temperatures.
Eiselstein thus teaches that tantalum and niobium act the same in nickel-based alloys provided that only a limited amount of tantalum is present.
The gamma double prime phase is not normally a stable phase since it can convert to gamma prime or to delta on e~tended e~posure to elevated temperatures.
Alloys hardened with gamma double prime achieve high tensile strength and very good creep rupture properties at lower temperatures, but the conversion of gamma double prime to gamma prime or delta above about 1250F causes a sharp reduction of strength.
(Donachie, M.J., ~Relationship of Properties to Microstructure in Superalloys" in Superalloys Source ~ook, American Society for Metals, 1984).
SUMMARY OF THE INVENTION
It has now been discovered that tantalum does not act the same as niobium in nickel base superalloys.
Rather, tantalum has been found to produce an alloy which has greater phase stability and different phase relationships than the corresponding niobium containing alloy. This difference in phase stability makes the Ta containing alloys much stronger to much higher temperatures than Nb containing alloys. In addition, the gamma double prime in the alloys of the invention does not readily convert to delta phase as occurs in niobium-bearing counterpart alloys.
The present invention particularly contemplates a nickel base alloy which comprises at least about 30 weight percent nickel, about 8 to about 16 weight percent tantalum and which is substantially niobium-free. Additional elements contained in the alloy are primarily selected from the group consisting of chromium, iron, cobalt, molybdenum, titanium, zirconium, tungsten, hafnium, aluminum, boron, and carbon and combinations thereof. In addition, other elements such as manganese, silicon, phosphorus, sulfur, lead, bismuth, tellurium, selenium, niobium and silver may also be present as incidental impurities.
The invention further extends broadly to the method for improving the high temperature strength properties of niobium-bearing nickel base superalloys by replacing substantially all of the niobium contained therein with tantalum on an atom-for-atom basis.
The invention also comprehends a method for improving the high temperature strength properties of th~ tantalu~-bearing nickel base superalloys of the invention by heat treatments at higher temperatures and for longer duration than those used for their niobium-bearing counterparts.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The alloys of the present invention contain at least about 30% nickel (all perc~nts expressed herein and in the claims are by weight unless otherwise specified~ and about 8 to about 16% tantalum. The balance of the alloy will consist of other elements which are conventionally alloyed with nickel to form superalloys such as elements selected from the group consisting of chromium, iron, cobalt, molybdenum, titanium, zirconium, tungsten, hafnium, aluminum, 5160L 13DV~9629 boron, carbon and combinations thereof. Further, other elements such as manganese, silicon, phosphorus, sulfur, lead, bismuth, tellurium, selenium, and silver may also be found in the alloy as incidental impurities. These alloys will be substantially niobium-free, i.e., they will contain less than about 1%, preferably less than 0.5%, and most preferably less than about 0.1~ Nb.
Generally, the alloy will contain, in addition to nickel and tantalum, up to about 25% chromium, up to about 40% iron, up to about 25% cobalt, up to about 8%
molybdenum, up to about 3~ titanium, up to about 2%
aluminum, up to about 7% tungsten about 30 to about 150 ppm boron, and up to about 0.1% carbon. Other elements, such as those other a:Lloying elements specified above, may be present in amounts up to about 1% each with a total maximum of up to about 5~.
One preferred alloy consist's essentially of about 8 to about 16% tantalum, about 17 to about 22%
chromium, up to about 25% iron, up to about 16~
cobalt, but not less than 12% total Fe plus Co, about 2 to about 6~ molybdenum, about 1 to about 5%
titanium, about 0.1 to about 5% aluminum, about 30 to about 150 ppm boron, about 0.01 to about 0.1% carbon, the balance nickel (including incidental impurities), wherein the total amount of iron plus cobalt is about 8 to about 25%.
A second preferred alloy consists essentially of about 8.5 to about 10% tantalum, about 18 to about 20%
chromium, about 17 to about 19% iron, about 2.5 to about 4% molybdenum, about 0.75 to about 2.5%
titanium, about 0.25 to about 0.75% aluminum, about 3C
to about 60 ppm boron, if the alloy is to be cast, or about 80 to about lS0 ppm boron if the alloy is to be wrought, about 0.03 to about 0.05% carbon, the balance nickel. A most preferred version of this alloy consists essentially of about 9% tantalum, about 19%
chromium, about 18~ iron, about 3% molybdenum, about l~ titanium, about 0.5% aluminum, about 30 to about 60 ppm boron, if the alloy is to be cast, or about 80 to about lO0 ppm boron if the alloy is to ~e wrought, about 0.05% carbon, the balance nickel.
A third preferred alloy consists essentially of about 30 to about 40% nickel, about 30 to about 40%
iron, abollt 15 to about 23% cobalt, about 8 to about 16~ tantalum, and about 30 to about 150 ppm boron. A
more preferred version of this alloy consists essentially of about 35 to about 38% nickel, about 35 to about 38% iron, about 17 to about 20% cobalt, about 8 to about 10% tantalum, and about 30 to about 60 ppm boron, if the alloy is to be cast, or about 80 to about lOOppm boron if the alloy is to be wrought. A
most preferred version of this alloy consists essentially of about 36 to about 37~ nickel, about 36 to about ~7% iron, about 17 to about 19% cobalt, about 8.5 to about 9.5% tantalum, and about 30 to about 60 ppm boron, if the alloy is to be cast, or about 80 to about 100 ppm ~oron if the alloy is to be wrought.
The alloys of this invention may be cast or wrought and may be produced by conventional methods.
For the alloys of the invention to develop their improved high temperature properties, they need to be heat treated The heat treatment is conducted at a higher temperature for a substantially longer period than is conventionally used for similar niobium containing alloys.
'7 The presently preferred heat treatment cycle for the second preferred alloy entails heating at about 2000F for about 1 hour, followed by hot isostatic pressing at about 2050F, at a pressure of about 12 to about 15 ksi, for about 3 to about 5 hours, followed by heating at about 1925F for about 4 hours, and followed by heating at about 1600F for about 2 hours. An additional heating (aging) at about 1350F
for about 8 hours may be helpful to produce optimal properties with some alloys. The conventional heat treatment for this alloy in its niobium containing version would not include the 1600F step and would include a lower temperature aging step at about 1150F
for about 4 to 8 hours.
By the use of tantalum in the substantial absence of niobium in combination with the higher heat treatment conditions, alloys are produced which make greater use of gamma doub`le prime strengthening than in conventional niobium-containing alloys. The alloys of the invention are age-hardenable, malleable, and are characterized by a high combination of strength and ductility, particularly at elevated temperatures.
In addition, it is believed that the amount of aluminum plus titanium, if included in the alloy, can be increased above that conventionally found in niobium containing alloys without inducing strain age cracking of weldments. Another benefit of using tantalum inst~ad of niobium in the alloys is improved weldability. This is due to an increased resistance to heat affected zone microcracXing due to the higher Ta-Ni eutectic temperature compared to that of the Nb-Ni eutectic.
The following non-limiting e~amples are provided to demonstrate the preparation of alloys of the present invention and their improved properties, especially at high temperatures.
EXAMPLE I
A tantalum-containing alloy like 718 was produced by melting a composition of 48.6% nickel, 19.2%
chromium, 18.0% iron, 0.02% niobium, 9.1% tantalum, 3.0% molybdenum, 1.04% titanium, 0.47% aluminum, 0.0043% boron, 0.044% carbon, and 0.02% silicon, in a vacuum induction furnace. The melted alloy was cast into ceramic molds to form 2~ ~ 4~ ~ 1/4A slabs.
Specimens from the slabs were subjected to heat treatment as follows: 2000F for 1 hour, 2050F hot isostatic pressing at 14.7 KSI for 3 hours, 1925F for 4 hours, 1600F for 2 hours, ancl then 1350F for 8 hours.
A conventional 718 alloy of the same composition containing essentially no tantalum, but about 4.6%
niobium, was produced in the sarne manner as above and heat treated to conventional 713 practice (as noted in footnote 1 to Table I below).
The microstructure of the tantalum-bearing alloy is found to have equal or less stable Laves phase on solidification as the conventional 718 alloy. In addition, the tantalum-bearing alloy does not produce the delta phase after ezposure in the 1600DF to 1800F
range; a heat treatment which is used to determine element segregation in 718 alloys (delta dump3. The microstructure of the tantalum-bearing alloy has an e~cellent distribution of gamma prime and gamma double prime of a size which produces a reasonable strengthening effect. The gamma prime and gamma double prime precipitate in the tantalum-bearing alloy is much more uniformly distributed throughout the dendrite cores and interstices than in conventional cast 718.
Specimens of the two alloys were evaluated to determine their mechanical properties at both room temperature (RT) and at elevated temperature. The results are:
TABLE I
Cast Ta 7181~3 Cast Nb 7181 Cast Ta 7182~4 UTS 155.3 130 122 151 117 178.2 147.7 133.3 0.2% 118.1 114 106.5 133 104 142.5 117.8 112.6 ~El 19 11.5 9 15 11 12 11 6 %RA 29.1 22.5 21.5 29 29 18 8 6 12000F/1 hr; 2050 hip/14.7ksi/3 hr; 1925/1 hr; 1350/8 hr;
1150/8 hr.
22000F/1 hr; 2050 hip/14.7ksi/3 hr; 1925/1 hr; 1600/2 hr;
1350/8 hr.
3average of 2 specimens 4One specimen As may be noted from Table I, the tantalum-bearing 718 type superalloy showed improved elevated temperature strength properties over its niobium-bearing counterpart and these properties were even further improved by the use of the preferred heat treatment Ex~MpLE ~I
The proc~dure of E~ample I was repeated with an alloy whose composition was 36.6% nickel, 36.6~ iron, 17.7% cobalt, 9.1~ tantalum, and 45 ppm boron. The corresponding conventional alloy in which the tantalum is replaced with niobium on an atom for atom basis, i.e. the niobium content is 4.5%, was also prepared for comparison purposes. The alloys are evaluated for mechanical properties as in Example I. The results are:
TABLE II
~as~ Ta Alloy C~st Nb Alloy ~1~ 1200F R,T.1200F
Ultimate tensile 182.5 141.8 135 108 strength (K~I) 0.2% Yield strength (KSI~ 159.4 128.6120 89 % Elongation 4.5 3.0 4.0 7.0 Reduction in area 6.5 6.5 7.013.0 As is evident, the tantalum-bearing alloy of the present invention e~hibits substantially increased ultimate tensile and yiPld strengths, reduced reduction in area, and similar elongation as compared to the same alloy containing niobium.
Evaluations of the various alloys again demonstrate the superiority of the tantalum-beariny alloy of this invention as compared to the comparable niobium-bearing alloy.
EXAMPLE III
Although the conven~ional 713 alloy of E~ample I
is highly resistant to strain-age cracking during weld stress relief, the alloy can be susceptible to both liquation cracking in the weld heat-affected-zone (HAZ) and, under conditions of high restraint, solidification cracking in the weld fusion zone. To evaluate the effect of the tantalum for niobium substitution of the present invention, the alloy forma~ion steps of E~ample I are repeated to produce cast-to-size weldability test specimens 5 mm in thickness. Prior to weldability testing all specimens were heat treated in vacuum at 2000F for one hour and cooled to 1200F in twenty minutes. Spot Varestraint and Mini Varestraint weldability tests were utilized to evaluate HAZ liquidation ancl fusion zone solidification cracking susceptibilities. In the Spot Varestraint test, strain is ap~lied to a gas-tungsten-arc spot weld immeaiately after e~tinguishing the arc, thereby restricting cracking to the weld HAZ. During Mini Varestraint testing, straining occurs during the generation of a continuous gas tun~sten-arc weld, wi~h cracks forming primarily in the previously solidified fusion zone. Total crack length is utilized as the quantitative measure of cracking susceptibility.
As shown in Table III, the tantalum-bearing alloy e~hibits the lowest susceptibility to weld HAZ
cracking over the entire range of strain levels tested, i.e. 0.25 to 3% augmented strain, by the Spot Varestraint test.
TABLE III
Strain Cas~ Alloy 718 Cast Ta 718 Cra~ks TCL MCL Cracks TCL MCL
0.29% 24.422 .03~ 12 .21~ .025 .29% 26.4~3 .033 12 .240 .028 1.16% 33.671 .040 19 .391 .03 1.16% 35.775 .040 20 o462 .03 2.9% 421.008 .055 30 .664 .03~
2.9% 481.108 .053 30 .669 .045 Cracks: number of cracks per weld TCL: Total Crack Length MCL. Ma~imum Crack Length Altho~gh the present invention has been described in connection with specific e~amples and embodiments, it will be understood by those skilled in the arts involved that the present invention is capable of modification without departing from its spirit and scope as represented by the appended claims.
TANTALUM-CONTAINING SUPERALLOYS
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to improved nickel base alloys which have a particularly high combination of strength properties and ductility over the temperature range e~tending from about room temperature to approximately 1500-F. The improvement is provided by incorporating a substantial amount of tantalum in the alloy, generally as an atom-for-atom replacement for niobium, and then heat treating the alloy at very high temperatures for extended periods.
DESCRIPTION OF THE PRIOR ART
Prior art nickel-base superalloys while steadily being improved, have disadvantages either from a standpoint of strength or ductility, particularly at elevated temperatures, i.e., above about 1200F.
These alloys are generally based upon nickel in combination with one or more of chromium, iron, and cobalt. In addition, they may contain a variety of elements in a large number of combinations to produce desired effects. Some of the elements which have been utilized in nickel-base superalloys to provide or improve one or more of the following properties are:
strength (Mo, Ta, W, Re), o~idation resistance (Cr, Al), phase stability (Ni) or increased volume fractions of favorable secondary precipitates (Co).
Other elements are added to form hardening precipitates such as gamma prime (Al, Ti) and gamma double prime (Cb). Minor elements (C, B) are added to form carbides and borides and others (Ce, Mg) are added for purposes of tramp element control. Some elements (B, Zr, Hf) also are added to promote favorable grain boundary effects. Many elements (e.g., Co, Mo, W, Cr), although added for their favorable alloying qualities, can participate, in some circumstances, in the formation of undesirable phases ~e.g., sigma, mu, Laves~.
Gamma double prime is generally considered to be a body centered tetragonal ordered Ni3Nb strengthening precipitate which is formed when niobium is present in nickel-base superalloys. A superalloy in which gamma double prime strengthening occurs is Inconel 718 which is within the scope of U.S. Patent No. 3,046,108 (Eiselstein). Eiselstein teaches that the alloy must contain about 4 to about 8 weight percent columbium and that the columbium in the alloy may be replaced in part with tantalum in an amount of up to 4% of the alloy. In partially replacing the columbium content of th2 alloy with tantalum, Eiselstein teaches that double the weight of tantalum should be used to obtain the same effect on properties. He also teaches that only tantalum-free alloys and/or alloys wherein not ~Q3~
more than 50% of the columbium is replaced by tantalum are notch-ductile at elevated temperatures.
Eiselstein thus teaches that tantalum and niobium act the same in nickel-based alloys provided that only a limited amount of tantalum is present.
The gamma double prime phase is not normally a stable phase since it can convert to gamma prime or to delta on e~tended e~posure to elevated temperatures.
Alloys hardened with gamma double prime achieve high tensile strength and very good creep rupture properties at lower temperatures, but the conversion of gamma double prime to gamma prime or delta above about 1250F causes a sharp reduction of strength.
(Donachie, M.J., ~Relationship of Properties to Microstructure in Superalloys" in Superalloys Source ~ook, American Society for Metals, 1984).
SUMMARY OF THE INVENTION
It has now been discovered that tantalum does not act the same as niobium in nickel base superalloys.
Rather, tantalum has been found to produce an alloy which has greater phase stability and different phase relationships than the corresponding niobium containing alloy. This difference in phase stability makes the Ta containing alloys much stronger to much higher temperatures than Nb containing alloys. In addition, the gamma double prime in the alloys of the invention does not readily convert to delta phase as occurs in niobium-bearing counterpart alloys.
The present invention particularly contemplates a nickel base alloy which comprises at least about 30 weight percent nickel, about 8 to about 16 weight percent tantalum and which is substantially niobium-free. Additional elements contained in the alloy are primarily selected from the group consisting of chromium, iron, cobalt, molybdenum, titanium, zirconium, tungsten, hafnium, aluminum, boron, and carbon and combinations thereof. In addition, other elements such as manganese, silicon, phosphorus, sulfur, lead, bismuth, tellurium, selenium, niobium and silver may also be present as incidental impurities.
The invention further extends broadly to the method for improving the high temperature strength properties of niobium-bearing nickel base superalloys by replacing substantially all of the niobium contained therein with tantalum on an atom-for-atom basis.
The invention also comprehends a method for improving the high temperature strength properties of th~ tantalu~-bearing nickel base superalloys of the invention by heat treatments at higher temperatures and for longer duration than those used for their niobium-bearing counterparts.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The alloys of the present invention contain at least about 30% nickel (all perc~nts expressed herein and in the claims are by weight unless otherwise specified~ and about 8 to about 16% tantalum. The balance of the alloy will consist of other elements which are conventionally alloyed with nickel to form superalloys such as elements selected from the group consisting of chromium, iron, cobalt, molybdenum, titanium, zirconium, tungsten, hafnium, aluminum, 5160L 13DV~9629 boron, carbon and combinations thereof. Further, other elements such as manganese, silicon, phosphorus, sulfur, lead, bismuth, tellurium, selenium, and silver may also be found in the alloy as incidental impurities. These alloys will be substantially niobium-free, i.e., they will contain less than about 1%, preferably less than 0.5%, and most preferably less than about 0.1~ Nb.
Generally, the alloy will contain, in addition to nickel and tantalum, up to about 25% chromium, up to about 40% iron, up to about 25% cobalt, up to about 8%
molybdenum, up to about 3~ titanium, up to about 2%
aluminum, up to about 7% tungsten about 30 to about 150 ppm boron, and up to about 0.1% carbon. Other elements, such as those other a:Lloying elements specified above, may be present in amounts up to about 1% each with a total maximum of up to about 5~.
One preferred alloy consist's essentially of about 8 to about 16% tantalum, about 17 to about 22%
chromium, up to about 25% iron, up to about 16~
cobalt, but not less than 12% total Fe plus Co, about 2 to about 6~ molybdenum, about 1 to about 5%
titanium, about 0.1 to about 5% aluminum, about 30 to about 150 ppm boron, about 0.01 to about 0.1% carbon, the balance nickel (including incidental impurities), wherein the total amount of iron plus cobalt is about 8 to about 25%.
A second preferred alloy consists essentially of about 8.5 to about 10% tantalum, about 18 to about 20%
chromium, about 17 to about 19% iron, about 2.5 to about 4% molybdenum, about 0.75 to about 2.5%
titanium, about 0.25 to about 0.75% aluminum, about 3C
to about 60 ppm boron, if the alloy is to be cast, or about 80 to about lS0 ppm boron if the alloy is to be wrought, about 0.03 to about 0.05% carbon, the balance nickel. A most preferred version of this alloy consists essentially of about 9% tantalum, about 19%
chromium, about 18~ iron, about 3% molybdenum, about l~ titanium, about 0.5% aluminum, about 30 to about 60 ppm boron, if the alloy is to be cast, or about 80 to about lO0 ppm boron if the alloy is to ~e wrought, about 0.05% carbon, the balance nickel.
A third preferred alloy consists essentially of about 30 to about 40% nickel, about 30 to about 40%
iron, abollt 15 to about 23% cobalt, about 8 to about 16~ tantalum, and about 30 to about 150 ppm boron. A
more preferred version of this alloy consists essentially of about 35 to about 38% nickel, about 35 to about 38% iron, about 17 to about 20% cobalt, about 8 to about 10% tantalum, and about 30 to about 60 ppm boron, if the alloy is to be cast, or about 80 to about lOOppm boron if the alloy is to be wrought. A
most preferred version of this alloy consists essentially of about 36 to about 37~ nickel, about 36 to about ~7% iron, about 17 to about 19% cobalt, about 8.5 to about 9.5% tantalum, and about 30 to about 60 ppm boron, if the alloy is to be cast, or about 80 to about 100 ppm ~oron if the alloy is to be wrought.
The alloys of this invention may be cast or wrought and may be produced by conventional methods.
For the alloys of the invention to develop their improved high temperature properties, they need to be heat treated The heat treatment is conducted at a higher temperature for a substantially longer period than is conventionally used for similar niobium containing alloys.
'7 The presently preferred heat treatment cycle for the second preferred alloy entails heating at about 2000F for about 1 hour, followed by hot isostatic pressing at about 2050F, at a pressure of about 12 to about 15 ksi, for about 3 to about 5 hours, followed by heating at about 1925F for about 4 hours, and followed by heating at about 1600F for about 2 hours. An additional heating (aging) at about 1350F
for about 8 hours may be helpful to produce optimal properties with some alloys. The conventional heat treatment for this alloy in its niobium containing version would not include the 1600F step and would include a lower temperature aging step at about 1150F
for about 4 to 8 hours.
By the use of tantalum in the substantial absence of niobium in combination with the higher heat treatment conditions, alloys are produced which make greater use of gamma doub`le prime strengthening than in conventional niobium-containing alloys. The alloys of the invention are age-hardenable, malleable, and are characterized by a high combination of strength and ductility, particularly at elevated temperatures.
In addition, it is believed that the amount of aluminum plus titanium, if included in the alloy, can be increased above that conventionally found in niobium containing alloys without inducing strain age cracking of weldments. Another benefit of using tantalum inst~ad of niobium in the alloys is improved weldability. This is due to an increased resistance to heat affected zone microcracXing due to the higher Ta-Ni eutectic temperature compared to that of the Nb-Ni eutectic.
The following non-limiting e~amples are provided to demonstrate the preparation of alloys of the present invention and their improved properties, especially at high temperatures.
EXAMPLE I
A tantalum-containing alloy like 718 was produced by melting a composition of 48.6% nickel, 19.2%
chromium, 18.0% iron, 0.02% niobium, 9.1% tantalum, 3.0% molybdenum, 1.04% titanium, 0.47% aluminum, 0.0043% boron, 0.044% carbon, and 0.02% silicon, in a vacuum induction furnace. The melted alloy was cast into ceramic molds to form 2~ ~ 4~ ~ 1/4A slabs.
Specimens from the slabs were subjected to heat treatment as follows: 2000F for 1 hour, 2050F hot isostatic pressing at 14.7 KSI for 3 hours, 1925F for 4 hours, 1600F for 2 hours, ancl then 1350F for 8 hours.
A conventional 718 alloy of the same composition containing essentially no tantalum, but about 4.6%
niobium, was produced in the sarne manner as above and heat treated to conventional 713 practice (as noted in footnote 1 to Table I below).
The microstructure of the tantalum-bearing alloy is found to have equal or less stable Laves phase on solidification as the conventional 718 alloy. In addition, the tantalum-bearing alloy does not produce the delta phase after ezposure in the 1600DF to 1800F
range; a heat treatment which is used to determine element segregation in 718 alloys (delta dump3. The microstructure of the tantalum-bearing alloy has an e~cellent distribution of gamma prime and gamma double prime of a size which produces a reasonable strengthening effect. The gamma prime and gamma double prime precipitate in the tantalum-bearing alloy is much more uniformly distributed throughout the dendrite cores and interstices than in conventional cast 718.
Specimens of the two alloys were evaluated to determine their mechanical properties at both room temperature (RT) and at elevated temperature. The results are:
TABLE I
Cast Ta 7181~3 Cast Nb 7181 Cast Ta 7182~4 UTS 155.3 130 122 151 117 178.2 147.7 133.3 0.2% 118.1 114 106.5 133 104 142.5 117.8 112.6 ~El 19 11.5 9 15 11 12 11 6 %RA 29.1 22.5 21.5 29 29 18 8 6 12000F/1 hr; 2050 hip/14.7ksi/3 hr; 1925/1 hr; 1350/8 hr;
1150/8 hr.
22000F/1 hr; 2050 hip/14.7ksi/3 hr; 1925/1 hr; 1600/2 hr;
1350/8 hr.
3average of 2 specimens 4One specimen As may be noted from Table I, the tantalum-bearing 718 type superalloy showed improved elevated temperature strength properties over its niobium-bearing counterpart and these properties were even further improved by the use of the preferred heat treatment Ex~MpLE ~I
The proc~dure of E~ample I was repeated with an alloy whose composition was 36.6% nickel, 36.6~ iron, 17.7% cobalt, 9.1~ tantalum, and 45 ppm boron. The corresponding conventional alloy in which the tantalum is replaced with niobium on an atom for atom basis, i.e. the niobium content is 4.5%, was also prepared for comparison purposes. The alloys are evaluated for mechanical properties as in Example I. The results are:
TABLE II
~as~ Ta Alloy C~st Nb Alloy ~1~ 1200F R,T.1200F
Ultimate tensile 182.5 141.8 135 108 strength (K~I) 0.2% Yield strength (KSI~ 159.4 128.6120 89 % Elongation 4.5 3.0 4.0 7.0 Reduction in area 6.5 6.5 7.013.0 As is evident, the tantalum-bearing alloy of the present invention e~hibits substantially increased ultimate tensile and yiPld strengths, reduced reduction in area, and similar elongation as compared to the same alloy containing niobium.
Evaluations of the various alloys again demonstrate the superiority of the tantalum-beariny alloy of this invention as compared to the comparable niobium-bearing alloy.
EXAMPLE III
Although the conven~ional 713 alloy of E~ample I
is highly resistant to strain-age cracking during weld stress relief, the alloy can be susceptible to both liquation cracking in the weld heat-affected-zone (HAZ) and, under conditions of high restraint, solidification cracking in the weld fusion zone. To evaluate the effect of the tantalum for niobium substitution of the present invention, the alloy forma~ion steps of E~ample I are repeated to produce cast-to-size weldability test specimens 5 mm in thickness. Prior to weldability testing all specimens were heat treated in vacuum at 2000F for one hour and cooled to 1200F in twenty minutes. Spot Varestraint and Mini Varestraint weldability tests were utilized to evaluate HAZ liquidation ancl fusion zone solidification cracking susceptibilities. In the Spot Varestraint test, strain is ap~lied to a gas-tungsten-arc spot weld immeaiately after e~tinguishing the arc, thereby restricting cracking to the weld HAZ. During Mini Varestraint testing, straining occurs during the generation of a continuous gas tun~sten-arc weld, wi~h cracks forming primarily in the previously solidified fusion zone. Total crack length is utilized as the quantitative measure of cracking susceptibility.
As shown in Table III, the tantalum-bearing alloy e~hibits the lowest susceptibility to weld HAZ
cracking over the entire range of strain levels tested, i.e. 0.25 to 3% augmented strain, by the Spot Varestraint test.
TABLE III
Strain Cas~ Alloy 718 Cast Ta 718 Cra~ks TCL MCL Cracks TCL MCL
0.29% 24.422 .03~ 12 .21~ .025 .29% 26.4~3 .033 12 .240 .028 1.16% 33.671 .040 19 .391 .03 1.16% 35.775 .040 20 o462 .03 2.9% 421.008 .055 30 .664 .03~
2.9% 481.108 .053 30 .669 .045 Cracks: number of cracks per weld TCL: Total Crack Length MCL. Ma~imum Crack Length Altho~gh the present invention has been described in connection with specific e~amples and embodiments, it will be understood by those skilled in the arts involved that the present invention is capable of modification without departing from its spirit and scope as represented by the appended claims.
Claims (16)
1. A nickel base alloy which comprises at least about 30 weight percent nickel, about 8 to about 16 weight percent tantalum, about 30 to about 150 ppm boron and which is substantially niobium-free.
2. The alloy of Claim 1 wherein the balance of the alloy comprises one or more elements selected from the group comprising of chromium, iron, cobalt, molybdenum, titanium, aluminum, tungsten and carbon.
3. The alloy of Claim 2 wherein the alloy further contains one or more elements selected from the group comprising zirconium and hafnium.
4. A nickel base superalloy which consists essentially of about 8 to about 16% tantalum, about 17 to about 22% chromium, up to about 25% iron, up to about 16% cobalt, about 2 to about 6% molybdenum, about 1 to about 5% titanium, about 0.1 to about 5%
aluminum, about 30 to about 150 ppm boron, about 0.01 to about 0.1% carbon, the balance nickel, and wherein the total amount of iron plus cobalt is not less than about 12%.
aluminum, about 30 to about 150 ppm boron, about 0.01 to about 0.1% carbon, the balance nickel, and wherein the total amount of iron plus cobalt is not less than about 12%.
5. A nickel base superalloy which consists essentially of about 8.5 to about 10% tantalum, about 18 to about 20% chromium, about 17 to about 19% iron, about 2.5 to about 4% molybdenum, about 0.75 to about 2.5% titanium, about 0.25 to about 0.75% aluminum, about 30 to about 60 ppm boron if the alloy is to be cast or about 80 to about 100 ppm boron if the alloy is to be wrought, and about 0.03 to about 0.05%
carbon, and the balance nickel.
carbon, and the balance nickel.
6. The alloy of Claim 5 wherein the alloy consists essentially of about 9% tantalum, about 19%
chromium, about 18% iron, about 3% molybdenum, about 1% titanium, about 0.5% aluminum, about 30 to about 60 ppm boron if the alloy is the be cast or about 80 to about 100 ppm boron if the alloy is to be wrought, and about 0.05% carbon, and the balance nickel.
chromium, about 18% iron, about 3% molybdenum, about 1% titanium, about 0.5% aluminum, about 30 to about 60 ppm boron if the alloy is the be cast or about 80 to about 100 ppm boron if the alloy is to be wrought, and about 0.05% carbon, and the balance nickel.
7. A nickel base superalloy which consists essentially of about 30 to about 40% nickel, about 30 to about 40% iron, about 15 to about 23% cobalt, about
8 to about 16% tantalum, and about 30 to about 150 ppm boron.
8. The alloy of Claim 7 wherein the alloy consists essentially of about 35 to about 38% nickel, about 35 to about 38% iron, about 17 to about 20%
cobalt, about 8 to about 10% tantalum, and about 30 to about 60 ppm boron if the alloy is to be cast or about 80 to about 100 ppm boron if the alloy is to be wrought.
8. The alloy of Claim 7 wherein the alloy consists essentially of about 35 to about 38% nickel, about 35 to about 38% iron, about 17 to about 20%
cobalt, about 8 to about 10% tantalum, and about 30 to about 60 ppm boron if the alloy is to be cast or about 80 to about 100 ppm boron if the alloy is to be wrought.
9. The alloy of Claim 8 wherein the alloy consists essentially of about 36 to about 37% nickel, about 36 to about 37% iron, about 17 to about 19%
cobalt, about 8.5 to about 9.5% tantalum, and about 30 to about 60 ppm boron if the alloy is to be cast or about 80 to about 100 ppm boron if the alloy is to be wrought.
cobalt, about 8.5 to about 9.5% tantalum, and about 30 to about 60 ppm boron if the alloy is to be cast or about 80 to about 100 ppm boron if the alloy is to be wrought.
10. A method for improving the high temperature strength properties of a niobium-containing nickel base superalloy by replacing substantially all of the niobium contained therein with tantalum on an atom-for-atom basis.
11. The method of Claim 10 wherein the alloy comprises at least about 30 weight percent nickel, about 8 to about 16 weight percent tantalum and one or more elements selected from the group consisting of chromium, iron, cobalt, molybdenum, titanium, aluminum, tungsten, boron and carbon.
12. The method of Claim 11 wherein the alloy further contains one or more elements selected from the group consisting of zironium and hafnium.
13. The method of Claim 11 wherein the alloy has been heat treated at about 2000°F for about 1 hour, followed by hot isostatic pressing at about 2050°F at a pressure of about 12 to about 15 ksi for about 3 to about 5 hours, followed by heating at about 1925°F for about 4 hours, and followed by heating at about 1600°F
for about 2 hours.
for about 2 hours.
14. The method of Claim 13 wherein the alloy is further heat treated at about 1350°F for about 8 hours.
15. The method of heat treating a tantalum-bearing substantially niobium-free nickel base superalloy comprising the steps of heating said superalloy at about 2000°F for about 1 hour, followed by hot isostatic pressing at about 2050°F with a pressure of about 12 to about 15 ksi for about 3 to about 5 hours, followed by heating at about 1925°F for about 4 hours, and followed by heating at about 1600°F
for about 2 hours.
for about 2 hours.
16. The method of Claim 15 wherein the alloy is further heat treated at about 1350°F for about 8 hours.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US33535389A | 1989-04-10 | 1989-04-10 | |
| US335,353 | 1989-04-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2010147A1 true CA2010147A1 (en) | 1990-10-10 |
Family
ID=23311419
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002010147A Abandoned CA2010147A1 (en) | 1989-04-10 | 1990-02-15 | Tantalum-containing superalloys |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPH0317243A (en) |
| CN (1) | CN1046944A (en) |
| AU (1) | AU624463B2 (en) |
| CA (1) | CA2010147A1 (en) |
| DE (1) | DE4011129A1 (en) |
| FR (1) | FR2646171A1 (en) |
| GB (1) | GB2230274B (en) |
| IL (1) | IL93341A0 (en) |
| IT (1) | IT1240749B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4906570B2 (en) * | 1996-06-03 | 2012-03-28 | ソニー株式会社 | Power plug, electric device having power plug, and method of manufacturing power plug |
| US8226886B2 (en) * | 2009-08-31 | 2012-07-24 | General Electric Company | Nickel-based superalloys and articles |
| CN106041105A (en) * | 2016-05-25 | 2016-10-26 | 安徽省春谷3D打印智能装备产业技术研究院有限公司 | High-strength cobalt-tantalum-molybdenum alloy medical 3D-printing metal powder and preparation method thereof |
| EP3257956B2 (en) * | 2016-06-13 | 2022-02-16 | General Electric Technology GmbH | Ni-base superalloy composition and method for slm processing such ni-base superalloy composition |
| CN106435324A (en) * | 2016-10-31 | 2017-02-22 | 张家港沙工科技服务有限公司 | Low-resistance composite tube used for mechanical equipment |
| CN114892042B (en) * | 2022-04-20 | 2022-12-13 | 嘉兴鸷锐新材料科技有限公司 | High-temperature-resistant iron-nickel alloy and preparation method and application thereof |
| CN117431432B (en) * | 2023-12-20 | 2024-03-12 | 北京北冶功能材料有限公司 | Nickel-based high-temperature alloy foil with good long-term oxidation performance and preparation method thereof |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1011785A (en) * | 1963-11-12 | 1965-12-01 | Bristol Siddeley Engines Ltd | Nickel-base alloys |
| GB1052561A (en) * | 1964-07-10 | |||
| GB1260982A (en) * | 1970-06-08 | 1972-01-19 | Trw Inc | Improvements in or relating to nickel base alloys |
| GB1381859A (en) * | 1971-05-26 | 1975-01-29 | Nat Res Dev | Trinickel aluminide base alloys |
| DE2311998C3 (en) * | 1973-03-10 | 1978-04-06 | Thyssen Industrie Ag, 4300 Essen | Use of a nickel alloy for components with high creep strength |
| GB1409628A (en) * | 1973-06-26 | 1975-10-08 | Avco Corp | Nickel base alloy containing hafnium |
| IT1070255B (en) * | 1975-10-22 | 1985-03-29 | Cabot Corp | IRON-BASED WELDING WIRE..CHROME..NOBEL AND NICKEL AND WELDING OBTAINED WITH SUCH WIRE |
| US4662951A (en) * | 1983-12-27 | 1987-05-05 | United Technologies Corporation | Pre-HIP heat treatment of superalloy castings |
| US4719080A (en) * | 1985-06-10 | 1988-01-12 | United Technologies Corporation | Advanced high strength single crystal superalloy compositions |
| IL80227A (en) * | 1985-11-01 | 1990-01-18 | United Technologies Corp | High strength single crystal superalloys |
| CA1315572C (en) * | 1986-05-13 | 1993-04-06 | Xuan Nguyen-Dinh | Phase stable single crystal materials |
| GB2191505B (en) * | 1986-06-09 | 1991-02-13 | Gen Electric | Dispersion strengthened single crystal alloys |
-
1990
- 1990-01-04 AU AU47652/90A patent/AU624463B2/en not_active Ceased
- 1990-01-22 GB GB9001431A patent/GB2230274B/en not_active Expired - Fee Related
- 1990-02-11 IL IL93341A patent/IL93341A0/en unknown
- 1990-02-15 CA CA002010147A patent/CA2010147A1/en not_active Abandoned
- 1990-03-30 FR FR9004113A patent/FR2646171A1/en active Pending
- 1990-04-06 DE DE4011129A patent/DE4011129A1/en not_active Withdrawn
- 1990-04-10 IT IT19977A patent/IT1240749B/en active IP Right Grant
- 1990-04-10 CN CN90102010.9A patent/CN1046944A/en active Pending
- 1990-04-10 JP JP2093260A patent/JPH0317243A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| FR2646171A1 (en) | 1990-10-26 |
| GB2230274B (en) | 1993-10-06 |
| GB9001431D0 (en) | 1990-03-21 |
| DE4011129A1 (en) | 1990-10-11 |
| IT1240749B (en) | 1993-12-17 |
| GB2230274A (en) | 1990-10-17 |
| JPH0317243A (en) | 1991-01-25 |
| IT9019977A0 (en) | 1990-04-10 |
| IL93341A0 (en) | 1990-11-29 |
| AU4765290A (en) | 1990-10-11 |
| AU624463B2 (en) | 1992-06-11 |
| CN1046944A (en) | 1990-11-14 |
| IT9019977A1 (en) | 1991-10-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| RU2289637C2 (en) | Nickel base alloy | |
| EP0361524B1 (en) | Ni-base superalloy and method for producing the same | |
| US4981644A (en) | Nickel-base superalloy systems | |
| EP2770081B1 (en) | Nickel-base alloys and methods of heat treating nickel base alloys | |
| CA1085655A (en) | Low expansion superalloy | |
| US5338379A (en) | Tantalum-containing superalloys | |
| EP2430204B1 (en) | Nickel based alloy useful for valve seat inserts | |
| EP0234172B1 (en) | High-strength nickel-base superalloy for castings, treated by means of hot isostatic pressing | |
| JPH0581653B2 (en) | ||
| KR20080025297A (en) | Cobalt-chromium-iron-nickel-alloys amenable to nitrides strengthening | |
| JP7138689B2 (en) | High-temperature, scratch-resistant superalloys, products made from the alloys, and methods of making the alloys | |
| EP0544836B1 (en) | Controlled thermal expansion alloy and article made therefrom | |
| EP1197570B1 (en) | Nickel-base alloy and its use in forging and welding operations | |
| JPS6253583B2 (en) | ||
| CA2010147A1 (en) | Tantalum-containing superalloys | |
| US4006011A (en) | Controlled expansion alloy | |
| GB2148323A (en) | Nickel-base superalloy systems | |
| US4095976A (en) | Weldable alloy | |
| US5207846A (en) | Tantalum-containing superalloys | |
| EP0693566A2 (en) | Weldable heat resistant alloy | |
| RU2791029C1 (en) | Nickel alloy with good corrosion resistance and high tensile strength and method for production of semi-products | |
| US5066458A (en) | Heat resisting controlled thermal expansion alloy balanced for having globular intermetallic phase | |
| US3212886A (en) | High temperature alloy | |
| JPS6353234A (en) | Structural member having heat resistance and high strength | |
| CA1109298A (en) | Weldable alloy |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |