US2471385A - Zinc base alloys - Google Patents

Description

Patented May 24, 1949 ZINC BASE ALLOYS Edward S. Bunn, Rome, N. Y., assignor to Revere Copper and Brass Incorporated, Rome, N. Y., a corporation of Maryland No Drawing. Application June 10, 1943, Serial No. 490,326

4 Claims.

My invention, which will be best understood 4trom the following description, relates to zinc case alloys, and has among its objects the pro- Vision of zinc base alloys of improved characlteristics.

It will be understood by those skilled in the art that commercially pure zinc, when worked hot or cold, possesses a moderate tensile strength and a high degree of ductility. However, both the hot and cold worked metal as it ages is subject to grain growth, causing it gradually to lose much of its tensile strength and most of its ductility.

The standard accepted test for determining the effect of age on zinc and its alloys is to subject articles made of them to moist steam at 95 C. for days. Hot rolled zinc having a tensile strength of approximately 17,000 p. s. i. and an elongation in 2 inches of approximately 45% when subjected to this test has a tensile strength of about 11,000 p. s. i. and an elongation in 2 inches of only about 2%.

Applicant has found that adding small amounts of copper to zinc will, among other things, progressively increase its tensile strength as the amount of copper is increased within the range of about 0.2 to 7.5% copper, but only with a marked sacrifice of its ductility for amounts of copper over about 2.7%, the resulting ductility however not seriously decreasing with age for many uses of the alloy.

He has further found, that by adding small amounts of manganese with the copper in somewhat critical proper proportions within the range of 0.05 to 0.5% manganese, the tensile strength of the zinc will be markedly further increased in both the aged and unaged condition without any decrease in its ductility with age. However, adding manganese with the copper will secure this result only if the amount of copper is about 2.3% or more. If the amount of copper is less than about this value the addition of manganese will result in a markedly unsatisfactory decrease in the ductility with age.

But he has found that when a small amount of silver within the range of 0.03 to 0.25% is added with the copper and manganese in proper proportions the tensile strength of the zinc will be increased more than when the manganese alone is added with the copper, and that the ductility will be rendered satisfactorily stable with age with amounts of copper less than 2.3% as well as amounts of copper over 2.3%. Further, when silver is added with the manganese and copper within proper proportions the amount of manganese in general may 'be materially increased, commonly up to about 0.75%, thus enabling a higher tensile strength to be secured by reason of the presence not only of silver but of an amount of manganese greater than would be possible were the silver absent. Still further, he has found that by adding the silver in combination with the copper and manganese the shock resistance of the zinc is very markedly increased.

Iron and nickel, it has been found, will act the same as manganese when added to zinc with copper or with copper and silver except that when added in the same amount as manganese they will not secure quite as high a tensile strength or ductility. The permissible amount of iron or nickel, and the efiect of the addition of silver on that amount and on the permissible proportions of iron and nickel with respect to the copper, are the same as with manganese.

Cobalt also has in general the same effect as manganese when added to zinc with copper or with copper and silver. Cobalt may be added in amount up to about 0.75% with copper to the silver-free zinc, that is to say, may be added up to the same amount as the manganese, iron or nickel when any of the latter are added with copper and silver. Further, whether the copper is above or below 2.3 cobalt when added with the copper will increase the tensile strength of the silver-free zinc without unsatisfactorily impairing its ductility for many uses of the alloy. Thus besides securing other beneficial efiects the addition of silver makes the alloys containing manganese, iron or nickel act the same as the alloys containing cobalt in respect to broadening the range of copper. Adding silver with the copper and cobalt in proper proportions however will secure the same effects as when manganese, iron or nickel is add-ed with silver, that is to say, the tensile strength and ductility of the zinc will be increased more than if the silver were not added and without rendering the alloy unstable in respect to tensile strength or ductility with age.

Further, the alloys without the addition of a small amount of silver are rather critical in respect to the amount of copper. The alloys containing copper as well as manganese, iron or nickel, but not silver, will not be stable in respect to ductility with age unless the copper is over about 2.3 as above explained, and then only if H the maximum permissible amount of manganese, iron or nickel varies approximately linearly and inversely with the amount of copper. The alloy containing copper and cobalt, but no silver, likewise is such that the maximum permissible amount of cobalt must vary approximately 3 linearly and inversely with the amount of copper to secure satisfactory results. These conditions make it impossible, unless a small amount of are exhibited by the following tables of properties of hot rolled alloys before and after the above mentioned steam test:

' Before steam test Charpy Tensile Elon ation impact Mn Ag Zn g g g in 2 inches strength, 1 it./p.s. i. l

"Per cent 'Per cent 'Per cent Per cent Per can 0 0 0 100 17, 000 45 48 2.15 0 2 0 balance. 32,000 45 220 l 2.15 0.2 0 balance 37, 000 30 480 2.15 0.2 0.1 balance 42,000 45 705 2. 35 0 0 balance 34, 000 43 225 2. 35 0. 2 0 balance 39, 000 40 485 2. 35 i 0.2 0.1 balance 43, 000 45 720 After steam test :Tensile arpy Elongation "impact Cu Mn Ag Zn g in 2 inches strength, it./p. s. i.

Per cent Per cent Per cent Per cent Per cent 0 0 100 11, 000 2 32 2.15 0 0 balance 27,000 45 11s I 2. l 0. 2 0 balance 32, 000 445 2. la 0. 2 0. l balance 39, 000 44 725 2. 0 0 balance 29, 000 43 121 2.35 0. 2 v 0 balance 000 45 450 2. 35 0. 2 0. -1 balance 40, 000 44 740 silveris present, to secure a satisfactory alloy in I claim:

respect to desired properties except within a limited range of manganese, iron, nickel or cobalt for any given amount of copper present.

- In respect to securing the above mentioned effects, and at thesame time securing a workable alloy, applicant has found that satisfactory results will be secured by adding to zinc 0.4 to 5% copper, 0.03 to 0.25% silver, and 0.06 to 0.75% metal-of the-group consisting of manganese, iron, nickel and cobalt,. provided the sum of the silver and .metal of saidgroup is not more than about one-third theamountof copper present. This alloy has excellent hot and cold plasticity, en-v abling iteto be readily worked hot or cold by rolling,ldrawing or extrusion. The marked resistance to impact loading above mentioned, instead-of diminishing with age as is the usual case, tends to increase, making the alloy suitable for use in situations where resistance to shock under moderate temperature conditions is required. As above mentioned, the alioy'further has a highentensilestrength and is more ductile than the silver-free alloys, and exhibits greater stability withagein respect to tensile strength, ductility, andresista-nce to impact than the silver-free alloys. Still further, the alloy has high dimensionalsstability, and is substantially free from intergranular corrosion. Best results will be secured inrespectto tensile. strength, ductility, stability with age, and hot and cold workability when from 0.4 to 3% copper is present; and with. any permissible amount of copper best results will be secured when the metal of the group is at least twice the amount of silver. The high shock resistance andits'tendency to increase with age are exhibited by all thealloys.

--The-"efiects 'of additions to zinc of copper, metal of the abovementioned group, and silver l. -Workable alloys containing-0.4 to 5% copper," 0.03 to 0.25% silver, at least one metal of the group consisting of manganese, iron, nickel andcobalt but not less than 0.06% or more than 0.75% ofmetal of said group, the sum of the silver and metal of said group not exceeding onethird the amount of the copper, the balance being zinc.

2. Workable alloys according to claim 1 having 0.4 to 3% copper.

. 3. Workable alloys according to .claim 1 in which the amount of'metal of thegroup of metals is at least twice the amount of the silver.

4.'Workable alloys according to claim 1 having 0.4-t0 3% copper, and :an amount of-metal of thegroup'of metals at-least twice the amount of'the silver.

EDWARD S. -BUNN.

REFERENCES CITED The followingreferences are-ofrecord in the file 0f this patent:

UNITED STATES PATENTS Number .Name Date 1,789,854 Wemple Jan. '20, 1931 1,933,490" Wemple all Oct. '31, 1933 2,011,987 'Tainton Aug. 20, 1935 2,048,288 Pierce Jul 21,1936 2,243,827- Schulze May 27, 1941 2,385,497 Bunn .Sept. 25,-1945 FOREIGN PATENTS Number Country Date 308,527 Germany Nov. 7, 1919 414,211 .Germany .May 26,1935