Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
  • C22C9/06—Alloys based on copper with nickel or cobalt as the next major constituent

Definitions

• the disclosure teaches novel copper base alloys having improved toughness and outstanding resistance to stress corrosion.
• the copper alloys contain, in Weight percentages, from 15 to 30% nickel, from 15 to 30% manganese, an element selected from the group consisting of aluminum from 0.01 to magnesium from 0.01 to 5 boron from 0.001 to 0.1%, zinc from 0.1 to 3.5%, tin from 0.01 to 3%, zirconium from 0.01 to 2%, titanium from 0.01 to 2%, chromium from 0.01 to 1%, iron from 0.1 to 5%, cobalt from 0.05 to 1%, and mixtures thereof, together with 0.005 to 0.1% of an element selected from the group consisting of arsenic and antimony, and mixtures thereof.
• Copper base alloys which contain relatively large amounts of nickel and manganese. Alloys of this type are highly desirable since they are capable of attaining yield strengths in excess of 200 k.s.i. upon aging. In addition, these alloys appear to have reasonable processing qualities and in particular are not quench sensitive.
• the copper base alloys used in springs and similar applications rely upon extensive cold work in order to achieve high strengths, for example, greater than 150 k.s.i. 0.2% offset yield strength.
• extensive cold work imposes severe limitations on the subsequent formability of the alloys.
• the alloy of the present invention consists essentially of from 15 to 30% nickel, from 15 to 30% manganese, and an element selected from the group consisting of aluminum from 0.01 to 5%, magnesium from 0.01 to 5%, boron from 0.001 to 0.1%, zinc from 0.1 to 3.5%, tin from 0.01 to 3%, zirconium from 0.01 to 2%, titanium from 0.01 to 2%, chromium from 0.01 to 1%, iron from 0.1% to 5 cobalt from 0.05 to 1%, and mixtures thereof, together with 0.005 to 0.1% of an element selected from the group consisting of arsenic, antimony, and mixtures thereof, with the balance essentially copper wherein the nickel to manganese ratio is at least 0.75 and preferably 1.0 or higher.
• the foregoing alloy has been found to obtain surprisingly improved fracture toughness while retaining the excellent strength characteristics of this alloy system.
• the alloy of the present invention is an excellent lower priced replacement for beryllium-copper, with increased fracture toughness.
• the alloy of the present in: vention achieves levels of fracture toughness approaching high alloy steels which are limited in applicability by poor corrosion resistance.
• the alloys of the present invention are superior to maraging steels in marine environments since the alloys of the present invention are not susceptible to hydrogen embrittlement.
• the alloys of the present invention are characterized by excellent stress corrosion resistance.
• the instant alloys contain from 15 to 30% nickel, and from 15 to 30% manganese.
• both the nickel and manganese contents should range from 15 to 25%.
• the nickel to manganese ratio must be at least 0.75 and preferably 1.0 or higher.
• the nickel and manganese contents have an effect on aging response, yield strength and workability of the alloys.
• increasing the amount of nickel and manganese has deleterious effects on the workability of the alloys during processing, especially over 30% each of nickel and manganese.
• the preferred nickel to manganese ratio is 1.0 or higher.
• the maximum aging response is obtained for a given amount of nickel and manganese when the nickel to manganese ratio is about 1.0. If the ratio is less than 1.0, an excess of manganese exists which can have adverse effects on the stress corrosion resistance of the alloy.
• a ratio greater than about 1.5 generally does not provide sufficiently improved results over a ratio of about 1.0 to justify the higher cost of the nickel.
• the alloy of the present invention contains an element selected from the group consisting of aluminum in an amount from 0.01 to 5.0%, magnesium from 0.01 to 5.0%, boron from 0.001 to 0.1% zinc from 0.1 to 3.5%, tin from 0.01 to 3%, zirconium from 0.01 to 2%, titanium from 0.01 to 2%, chromium from 0.01 to 1%, iron from 0.1 to cobalt from 0.05 to 1%, and mixtures thereof.
• Aluminum, magnesium, and boron act as deoxidizers and assist in the melting of the alloys.
• Aluminum is the preferred addition since it tends to form a protective oxide coating during melting.
• aluminum when aluminum is used as a deoxidant only, it should be added in an amount from 0.01 to 0.75%, and similarly for magnesium.
• the aluminum and magnesium may be used as advantageous alloying additions in amounts greater than 0.6% for increased corrosion resistance and fracture toughness. The aluminum when used at the higher levels, also tends to modify the cellular precipitate at the grain boundaries.
• zinc When zinc is an added component, it should be present in an amount from 0.1 to 3.5%. Increased amounts of zinc over 3.5% given rise to a decrease in the stress corrosion resistance and fracture toughness.
• the zinc addition tends to control the grain size, reduce the cellular precipitate at the grain boundaries, alter the morphology of the inclusions, promote sound castings and increase the aging response of the alloy. It is most surprising that so many advantages may be realized from a single alloying addition.
• the grain size control may be attributed to a fine dispersoid which is present in the zinc containing alloys.
• the increased aging response is due to an increase in the growth rate of the precipitate.
• the preferred zinc content is from 1 to 3%.
• Tin is a particularly desirable additive in an amount from 0.01 to 3% and preferably from 0.5 to 2.0%. Tin tends to alter the morphology of the cellular precipitate at the grain boundary.
• Zirconium and/or titanium are preferred alloying additions in amounts 0.01 to 2.0% each, and preferably from 0.15 to 0.30% each. These elements tend to effect desirable changes in the morphology and chemistry of inclusions and in the morphology of cellular precipitate at grain boundaries.
• chromium is a desirable addition in an amount from 0.01 to 1.0%, and preferably from 0.15 to 0.30%. Chromium tends to control the grain size and change the morphology and chemistry of inclusions.
• cobalt and/ or iron are desirable for providing desired controlof grain size.
• the cobalt may be employed in an amount from 0.05 to 1.0% and preferably from 0.2 to 0.5%, and the iron from 0.1 to 5% and preferably from 0.5 to 1.0%.
• single phase copper base alloys containing arsenic and antimony are known to be hot short, exhibiting such limited hot rollability that they must generally be subjected only to cold rolling.
• the alloys of the present invention are hot rollable and are single phase in the hot Working temperature range. It is quite surprising that a single phase copper base alloy containing either arsenic and/or antimony in these amounts is hot rollable.
• the casting of the alloy of the present invention is not particularly significant. Any convenient method of casting may be employed. Pouring temperatures in the range of about 1000 to 1200 C. are preferably employed, with an optimum pouring temperature in the range of 1050 to 1100 C. The arsenic and/ or antimony additions should be as a master alloy prior to pouring, for convenience due to the toxicity of these materials.
• the alloy of the present invention is processed by breakdown of ingot into strip using a hot rolling operation followed by cold rolling and annealing cycles to reach final gage.
• Preferred properties are obtained using an aging treatment.
• the starting hot rolling temperature should be in the range of 700 to 900 C., and preferably 750 to 850 C.
• the cooling rate from hot rolling should preferably be in excess of 25 C. per hour down to 300 C. in order to avoid precipitation of manganese-nickel rich phases.
• the cooling rate after 300 C. is not significant.
• the alloy is capable of cold rolling reductions in excess of 90%, but the cold rolling reduction should preferably be between 30 and in order to control the grain size.
• an average grain size less than 0.005 mm. is necessary in order to provide optimum stress corrosion resistance.
• an average grain size in the alloys of the present invention of less than 0.003 mm. is readily obtained.
• An average grain size of this order can be obtained by control of the cold rolling reduction, annealing times and annealing temperatures. In general, anneal-temperatures in the range of 550 to 900 C. for at least one minute can give the required grain size, with 10 hours being the practical upper limit and 2 hours being the preferred upper limit. It is preferred to anneal for from five minutes to 2 hours.
• the material After annealing, the material is cooled in excess of 25 C. per hour down to 300 C., as indicated above, and the cold rolling and annealing cycles repeated as desired depending on gage requirements. Generally, from two to four cycles of cold rolling and annealing are preferred.
• Example II was repeated for Alloy D except that the following manner.
• the alloy was melted from ele- 5 samples were cold worked 40 and 50% prior to aging. mental constituents except for the antimony which was Alloy C was treated with 40% cold work prior to aging added as a copper-antimony master alloy and chill cast for comparison purposes.
• the data is shown in Table B from 1200 C. into a steel mold. The ingot was soaked below.
• the hot rolled plate was cold rolled to 0.100" and annealed at 600 C. for minutes.
• the plate was cold rolled 60% to .040" and annealed at 600 C. for 30 minutes.
• the material was cold rolled 125% to a final gauge of 0.030".
• Samples of the 25% cold rolled strip at 0.030" were formed into 90 U-bends by bending a strip 6" long by /2" wide around a mandrel so that it permanently forms a 90 bend, and transverse tensile samples were fabricated.
• the U-bends and tensile specimens were aged for various times at 450 C.
• EXAM PLE II An alloy containing 25 nio'kel, l7 manganese, 2 zine, 0.5 aluminum, 0.04 arsenic (Alloy D) and balance copper was prepared in strip form by a similar practice to that described above. The tensile properties and stress corrosion results are also listed in Table A.
• a copper base alloy having improved stress corrosion resistance coupled with high strength and good fracture toughness consisting essentially of: from 15 to 30% nickel; from 1.5 to 30% manganese; an element selected from the group consisting of aluminum from 0.01 to 5%, magnesium from 0.01 to 5%, boron from 0.001 to 031%, zinc from 0.1 to 3.5%, tin from 0 .01 to 3%, zirconium from 0.041 to 2%, titanium from 0.01 to 2%, chromium from 0.01 to -1%, iron from 0.1 to 5%, cobalt from 0.05 to 1%, and mixtures thereof; and from 0.005 to 0.0% of an element selected from the group consisting of arsenic, antimony and mixtures thereof; balance essentially copper, wherein the nickel to manganese ratio is at least 0.75, said alloy having an average grain size of less than 0.005 mm. and a dispersion of fine precipitate throughout the interior of the grains and characterized by being hot rollable, single phase in the hot working temperature range and polyphase in the

Priority Applications (10)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23457460

Family Applications (1)

Country Status (10)

Cited By (13)

Families Citing this family (7)

• 1973
  • 1973-06-14 US US00369914A patent/US3824135A/en not_active Expired - Lifetime
• 1974
  • 1974-03-14 AU AU66666/74A patent/AU6666674A/en not_active Expired
  • 1974-03-15 SE SE7403533A patent/SE408186B/xx not_active IP Right Cessation
  • 1974-03-27 CA CA196,182A patent/CA1009480A/en not_active Expired
  • 1974-03-29 FR FR7411544A patent/FR2233407B2/fr not_active Expired
  • 1974-04-02 GB GB1457574A patent/GB1436915A/en not_active Expired
  • 1974-04-16 JP JP49041850A patent/JPS5017318A/ja active Pending
  • 1974-06-07 DE DE19742427653 patent/DE2427653A1/de not_active Withdrawn
  • 1974-06-10 IT IT51481/74A patent/IT1046318B/it active
  • 1974-06-12 CH CH805274A patent/CH611649A5/xx not_active IP Right Cessation

Also Published As

Similar Documents