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
  • C22C19/055—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 20% but less than 30%

Definitions

• This invention relates to precipitation-strengthened, hotworkable nickel-base alloys and more particularly to precipitation-strengthened tantalum-bearing nickel-base alloys.
• Precipitation strengthened hot-workable nickel-base alloys which are sometimes referred to in the art as age hardenable alloys, are primarily used in high temperature applications, i.e. 1000 F. to 1600 P. such as in wrought alloy components for jet engine parts.
• the alloys are usually provided as forged components, bars, sheet material, seamless tubing or in other Wrought forms obtained by the usual metal working processes, e.g. hot or cold working, extruding, drawing and the like.
• Yet another object is to provide tantalum-bearing prec1p1tation-strengthened alloy compositions which can be air melted without forming appreciable oxide inclusions.
• the present invention is based upon the discovery that a phase designated herein as A M wherein A consists essentially of nickel and M consists essentially of tantalum can be precipitated to strengthen a hot-workable nickelbase alloy. [It has also been found that this phase may be precipitated without the presence of aluminum and titanium in the alloy composition. It should be understood that this precipitation phase is distinct from the above mentioned gamma prime phase achieved through the use of aluminum and titanium in combination. It is known that the gamma prime phase has a crystal structure of the ordered face centered cubic (FCC) type. In marked contrast to this, the A M phase produced within the alloys of the present invention is non-cubic in crystal structure.
• FCC ordered face centered cubic
• the alloy composition of the invention consists essentially by weight of 15-22% Cr, 312% Mo, 5-10% Ta, the balance being nickel and residual impurities normally found in nickel-base alloys. It is important according to the invention that the residual impurities have not more than 20% Fe, not more than 10% Co and not more than 0.15% C.
• This alloy will consist essentially of a solidsolution matrix having dispersed therein an intermetallic phase of the abovementioned A M stoichiometry.
• Chromium is required in the alloy within the ranges as disclosed herein to provide strengthening and corrosion resistance. Less than 15% Cr yields an alloy with minimal corrosion resistance, over 22% Cr yields an alloy with reduced ductility.
• Molybdenum is present in the alloy, within the ranges disclosed herein to provide further solution strengthening and corrosion resistance as required in alloys of this class. Molybdenum is preferred in the alloy, although tungsten may replace molybdenum in whole or in part. Tungsten may be substituted for molybdenum in a ratio of about 2: 1 up to a maximum of 16%, but preferably about 12% nominally. For optimum mechanical properties, the alloy should contain an effective amount of molybdenum and tungsten; not less than about 3% molybdenum or the equivalent. Contents over 16% tungsten or 12% molybdenum result in alloys which may contain undesirable embrittling phases.
• Tantalum must be present in the alloy in an amount of at least 5% to promote adequate precipitation of the abovementioned A M phase; greater than 10% tantalum tends to limit the usual characteristics of hot-workability of the alloy.
• Columbium which is often found associated with the tantalum, may be present in the alloy up to a limit of 2.5% by weight of the tantalum content. If desired, vanadium may be substituted for part of the tantalum up to a maximum of 50% by weight of the tantalum content.
• the use of aluminum and titanium in the alloy compositions of the invention is not required. It is desirable that the aluminum plus titanium content should be as low as possible, and preferably less than 1.4%. If the aluminum plus titanium level is low, it will be possible to produce a good quality alloy with an air melting practice.
• Boron, silicon, maganese, magnesium and copper up to a total of about 2.5% may be present in the alloy within the ranges known in the art to be effective to enhance certain characteristics associated with these elements, i.e. the deoxidation step, casting fluidity, ductility and the like.
• the balance of the alloy is nickel and adventitious impurities generally known to be present in this class of alloys.
• Example I A five-pound heat of the following composition was electron-beam melted and cast. The resulting ingot was cold worked following homogenization at about 2200 F. and thereafter solution heat treated at 2150 F. Thereafter the material was cold worked with intermediate annealing treatments and reduced to 0.004" thick strip. This strip was solution heat treated at 2150 F., quenched and thereafter aged at temperatures between 1600 F. and 1100" F. to precipitate the A M phase as described hereinbefore. Extensive transmission electron microscopy and the diffraction studies were performed on the aged material. These studies showed the existence of the abovementioned A M phase in a homogenously nucleated, uniformly dispersed, coherent intragranular morphology in all conditions investigated.
• Heat treatment condition A As forged plus one hour at 1750 F., water quenched, then aged for 3.6 hours at 1430" F., then furnace cooled at 1206 F. and aged for TABLE I Ultimate Heat Yield tensile treatment strength, strength, EL, R.A condition Test temp. p.s.i. p.s.i. percent percent A Room temp... 167,000 197, 500 15. 00 25. 00 A... 1,200 F 143,000 163,500 12. 00 20.00 B. Room temp.-. 90,000 136,600 62.00 46. 00 B-.. 63,500 94, 200 48. 00 50. 50 C Room temp. 81,000 133,500 73.00 66.00 C 200 F 51,300 89,900 56. 00 43; 50
• a wrought, precipitation-strengthened nickel-base alloy which is substantially free of face-centered cubic structured precipitation such as the conventional gamma prime phase but which possesses an unusual combination of mechanical strength and ductility, especially in the temperature range of about 1000 through about 1200 F. consisting essentially of weight of with the balance being essentially nickel and residual elements normally found in nickel-base alloys and provided that the iron content must be less than 20%, the cobalt content must be less than 10%, and the carbon content must be less than 0.15% and there is present in the alloy structure an effective strengthening intermetallic precipitate of a coherent, noncubic structure having the general stoichiometry, A M, where M is predominantly tantalum and A is predominantly nickel.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Heat Treatment Of Nonferrous Metals Or Alloys (AREA)
• Forging (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=25268932

Family Applications (1)

Country Status (10)

Cited By (7)

Families Citing this family (3)

• 1969
  • 1969-06-20 US US835211A patent/US3668023A/en not_active Expired - Lifetime
• 1970
  • 1970-06-18 DE DE19702029962 patent/DE2029962A1/de active Pending
  • 1970-06-19 AT AT553770A patent/AT302671B/de not_active IP Right Cessation
  • 1970-06-19 NL NL7009045A patent/NL7009045A/xx unknown
  • 1970-06-19 BE BE752289D patent/BE752289A/xx unknown
  • 1970-06-19 CA CA086077A patent/CA925328A/en not_active Expired
  • 1970-06-19 FR FR7022848A patent/FR2052845A5/fr not_active Expired
  • 1970-06-19 NO NO02381/70A patent/NO129535B/no unknown
  • 1970-06-20 JP JP45054009A patent/JPS4817689B1/ja active Pending
  • 1970-06-22 GB GB3010770A patent/GB1320774A/en not_active Expired

Also Published As

Similar Documents

Legal Events