Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
  • C22C38/105—Ferrous alloys, e.g. steel alloys containing cobalt containing Co and Ni
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium

Definitions

• the present invention relates to ferrous-base alloys and, more particularly, to strong, ductile weldable ferrousbase alloys for use at temperatures up to about 1000" F. and higher.
• maraging steels are characterized on the whole by ease of formability both by hot-working and cold-working processes, by case of weldability and by freedom from major distortion during hardening heat treatment.
• an alloy for high temperature use should resist oxidation and/ or scaling at least as well as materials in current competitive use.
• Another object of the invention is to provide a novel ferrous-base alloy for use in structures, components, parts, etc., employed at elevated temperatures up to about 1000" F. and higher.
• the invention also contemplates providing a novel coldworkable steel.
• his a further object of the invention to provide a novel age-hardened ferrous-base alloy for use at elevated tempertures up to about 1000 F.
• the invention further contemplates providing novel structures including components, parts, welded assemblies,
• the present invention contemplates a novel ferrous-base alloy containing, in percent by weight, about 14% to about 16%'nickel, about 8.5% to about 9.5% cobalt, about 4.6% to about 5.2% molybdenum, about 0.1% to about 0.8% titanium, about 0.1% to about 1.2% aluminum, up to about,3% vanadium, up to about 0.03% carbon, up to about 0.2% manganese, up to about 0.2% silicon, up to about 0.01% boron, up to about 0.1% zirconium, up to about 0.05% calcium with the balance being essentially iron together with small amounts of impurities and incidental elements normally occurring in ferrous-base alloys and/or associated with said alloying elements.
• the ferrous-base alloy composition of the present invention is correlated so that the number resulting from the summation of five times the percentage of titanium, plus three times the percentage of aluminum plus the percentage of vanadium is at least equal to about 4.5 and is less than about 7.
• H the number resulting from the summation of five times the percentage of titanium, plus three times the percentage of aluminum plus the percentage of vanadium is at least equal to about 4.5 and is less than about 7.
• alloys in accordance with thepresent invention contain about to about 0.9% aluminum and con, manganese, boron, zirconium, rare earth elements (from the addition of mischmetal), lithium, magnesium, uranium, calcium, etc.
• the alloy is then cast at temperatures of about 2800 F. into ingots.
• the ingots are subsequently hot worked at starting temperatures of about 2300 F. and finishing temperatures of about 1500 F., advantageously in more than one direction to facilitate homogenization of the microstructure.
• the alloys are advantageously annealed at about 1800 F.
• the alloy can be cold worked, machined, etc., and thereafter hardened by aging at a temperature of about 800 F. to
• annealing heat treatment can consist of heating for about 1 to about hours at 1500 F. to about 1800 F. with the longer times being employed at temperaturesin the lower end of said temperature range.
• Iron includes small amounts of silicon, manganese, boron, zirconium and/or calcium within the limits of the ranges set forth hereinbefore together with residual andunavoidable amounts of impurities ane incidental elements.
• Table II shows that alloys in accordance with the present invention exhibit a high combination of strength and ductility over the wide temperature range of about room temperature (70 F.) to 1000 F.
• alloys in accordance with the present invention can be successfully employed in situations involving cyclical variations in temperature over a wide range.
• Table III shows that at elevated temperatures of about 800 F. to about 1000 F, alloys of the present invention exhibit extraordinaryresistance to creep under very high stress. This resistance to prolonged high stress at elevated temperatures coupled with the extraordinarily high combination of tensile characteristics over the temperature range of about 70 F. to about 1000 F. as shown in Table 11, indicates wide commercial utility for the alloys of the present invention as parts and components subjected in use to elevated temperatures and high stress for extended periods of time which are intermittently subjected to lower temperatures.
• Alloys of the present invention can be modified to contain up to about 5% chromium with the chromium replacing nickel weight for weight.
• the chromium replacing nickel weight for weight.
• alloys of the present invention can be expected to show a weight gain of less than 0.2 mg./cm. after a total of 100 hours at 1000 F.
• alloys of the present invention exhibit an outstanding combination of room temperature and elevated temperature characteristics making them particularly suitable for structures, parts, components, etc., subjected in use to high and/or prolonged stress at temperatures up to about 1000 F.
• Specificsteels outside the present invention are set forth in Table IV. It is to be noted with regard to Table IV that, for convenience, iron has been eliminated from the heading. It is to be understood that in each instance, the balance of the alloy is essentially iron together with impurities and small amounts of boron, manganese, silicon, zirconium and/or calcium and other incidental and/or deoxidizing and/or Alloy B, when annealed at 1500 F. prior to aging, exhibited a life to rupture at 1000 F.
• Alloy C had low elongation when tested at 1000 F. for tensile characteristics.
• Alloys N and O are representative of chromium-containing alloys which exhibit impaired oxidation resistance at 1000 F. It is to be observed that low yield strength, low ductility and/or impaired oxidation resistance at 1000 F. limits and/or restricts the commercial use of an alloy at ele vated temperatures.
• steels outside the pres-. ent invention can'exhibit low livesto rupture at 1000 F.
• alloy G in the condition resulting from annealing at 1500 F., cooling, aging at 900 F. for 3 hours and air cooling, exhibited Shours lifeto rupture at 1000 F.
• an aged steel of the present invention (alloy No. 2) exhibited a life to rupture of 834 hours at 220 k.s.i. load.
• Table VI shows, in comparison with Table 11 set forth hereinbefore, that the alloys of the present invention are much less detrimentally affected by temperatures up to about 1000 F.
• alloy No. 2 an alloy of the present invention, has a 0.2% yield strength of 186 l .s.i., whereas the commercially available steel exhibited a 0.2% yield strength at 1000 F. of only about 129 k.s.i.
• the alloy of the present invention maintains a high degree of ductility and toughness in combination with high yield strength at elevated temperatures up to about 1000 F.
• the alloys of the present invention are particularly "2? applicable for use as hot work dies and. tooling, for example, hot forging dies and hot extrusion dies, missile and aircraft components heated to temperatures up to about 1000" F. during service, for example, skirt parts of rockets, shafting and rotors for enerating equipment, mortar tubes, gun barrels, chemical plant equipment, etc.
• the alloy can also be used for fasteners and other, har
• a steel as in claim '1 which contains about 0.5% to about 0.9% aluminum and about 0.6% to about 0.8% titanium.
• a steel as in claim 1 which is annealed at about 1800 F. for about 1 hour.
• An annealed and aged steel having an advantageous combination of mechanical characteristics including strength and toughness at temperatures ranging from about room temperature up to about 1000 F. and consisting essentially, in percent by weight, ofabout 14% to about 16% nickel, about 8.5% to about 9.5% cobalt, about 4.6% to about 5.2% molybdenum, about 0.1% to about 0.8% titanium, about 0.1% to about 1.2% aluminum, up to about 3% vanadium, up to 0.03% carbon, up to about 0.2% manganese, up toabout 0.2% silicon, up to about 0.01% boron, up to about 0.1% zirconium, up to about 0.05% calcium with the balance being essentially iron, the titanium, aluminum and vanadium contents of said steel being so correlated so that the number X calculated by V is about 4.5 to about 7.
• An aged steel as in claim 4 which contains about 0.5% to about 0.9% aluminum and about 0.6% to about 0.8% titanium.
• a process for producing a high strength structure adapted to be employed at temperatures up to about 1000" F. comprising providing a steel consisting essentially, in percent by Weight, of about 14% to about 16% nickel, about 8.5% to about 9.5% cobalt, about 4.6% to about 5.2% molybdenum, about 0.1% to about 0.8% titanium, about 0.1% to about 1.2% aluminum, upto about 3% vanadium, up to about 0.03% carbon, up to about 0.2% manganese, up to about 0.2% silicon, up to about 0.01% boron, up to about 0.
• 1% zirconium, up to about 0.05% calcium with the balance being essentially iron, the titanium, aluminum and vanadium contents of said steel being so correlated so that the number X calculated by X 5 %Ti-

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Heat Treatment Of Steel (AREA)
• Heat Treatment Of Articles (AREA)

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Cited By (6)

Citations (3)

• 1962
  • 1962-08-03 US US214475A patent/US3166406A/en not_active Expired - Lifetime
• 1963
  • 1963-07-26 GB GB29765/63A patent/GB982637A/en not_active Expired
  • 1963-08-02 AT AT621763A patent/AT273194B/de active
  • 1963-08-02 CH CH962263A patent/CH452207A/fr unknown
  • 1963-08-02 ES ES290535A patent/ES290535A2/es not_active Expired
  • 1963-08-03 LU LU44202D patent/LU44202A1/xx unknown

Patent Citations (3)

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