US2403337A - Zinc base alloys - Google Patents

Description

I though having suilicient cold to enable it to be readily workedhas a relamost of its ductility as it 4 predominantly consists.

Patented July 2 1946 OFFICE 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 March is, 1943, Serial No. 479,113

7 Claims. (Cl. 75-178) This application is a continuation-in-part of applicants copending 421,811, filed December 5, 1941.

My invention, which will be best understood from the following description, "relates to zinc base alloys, and has among its objects th production of mechanically workable zinc base alloys of improved haracteristics, particularly in respect to' suitability for fabrication into articles by hot working.

Commercially pure zinc, it has been found, al-

plasticity when hot, or

tively low tensile strength defect of losing its tensile and the most serious strength, hardness and ages at room temperatures.

As illustrative of the action of zinc in the above mentioned respects applicant has found that hot rolled zinc having a tensile strength oi about 17,000 pounds per square inch and an elongation in 2 inches of about 45% will, after being subjected to the standard mining the effect of age on zinc and its alloys, have a tensile strength of about 11,000 pounds per square inch and an elongation in 2 inches of only about 2%.

The low tensile strength of commercially pure zinc, and it deterioration with age, make it unsuitable for use in making strong articles. Applicant however has found that great strength may be imparted to zinc, while retaining requisite ductility and malleability, by adding controlled amounts of copper and phosphorus to it, the resulting alloys having a high degree of stability in these respects. These effects, it has been found, will be secured with additions of, approximately, 0.1 to- 7.5% copper and 0.01 to 0.75% phosphorus, provided phosphorus does not exceed a value which varies from 0.15% when 7.5% copper is present to 0.75% when 0.1% copper is present linearly and inversely with the amount of copper, that is to say. as the copper increases from 0.1 to 7.5% the permissible maximum amount of phosphorus present should decrease linearly from 0.75% when 0.1% copper is present to 0.15% when 7.5% copper is present.

Applicant recognizes that phosphorus is commonly added to copper and other. metals for deoxidizing them. Such phosphorus, however, to act as a deoxidizer must chemically reduce the metal oxides present to form oxides of phosphorus, as distinguished from the phosphorus alloying or combining with the metal as is the case with the improved alloy. In fact zin itself is a deoxidizer and is commonly used as such for certain alloys, and further phosphorus will not deoxidize zinc of which latter the improved alloy application Serial Number accepted test for deter- I p 2 The improvedalloys having up to 7.5% cop'- per may be readily hot worked b commercial practices, as much a 50% reduction being possible by hot rolling when the slab is presented tothe rolls at an initial temperature of about 650 F. without the necessity of reheating the metal during thecourse of such reduction. As the copper content is increased within the above speci fled limits 2. decrease in the cold plasticity of the alloys occurs, rendering those containing the maximum amounts of copper or phosphorus com-- mercially unsuitable for severe cold working operations, and in general rendering those having 2.2 to 6.2% copper in combination with -more than 0.25% phosphorus, the variable maximum phosphorus value being 0.25 to 0.58% for this range of copper, most suitable commercially for hot working. Those within the above specified limits having not more than 2.2% copper in combination with not more than 0.25% phosphorus are commercially satisfactory for deep drawing and other severe cold working operations, while those having up to 3.3% copper in combination 'With up to 0.3% phosphorus are commercially cold rollable into sheets. Nevertheless the alloys within the above specified limitshaving amounts of copper not over 3.3% in combination with 0.3% or more phosphorus have fair cold working properties enabling them to be satisfactorily employed for light forming and stamping operations. The alloys having 1.5% and upward of copper do not self anneal during cold working, and therefore may be hardened by such working, and, unlike zinc, do not with age lose such properties so imparted. The preferred alloys, with respect to their meeting the demands of most commercial applications for which they are suited,.in competition with other zinc base alloys, contain 1.75 to 3.25% copper and at least 0.2% phosphorus.

The excellent properties of the improved alloys in respect to marked high strength combined with requisite ductility and malleability, and sta bility in these respects, are clearly shown by the following table of properties of the hot rolled alloys, in which table the steam test referred toy is the standard accepted test above mentioned consisting in subjecting the alloy to moist steam at C. for 10 days:

"ward, markedly increase Zinc base alloys commonly are subject to a deleterious increase in linear age the imfairly stable.

improved alloys. As little as about 0.005% vana- Y dium will produced marked efiects in this respect, and amounts of vanadium as low as about 0.03% will'cause the alloys, when subjected to the above mentioned steam test, to

exhibit a, substantially zero rate of increase in linear dimensions. Amounts of vanadium up to 0.5% maybe added without deleteriously afiecting the abovementioned valuable properties of the alloys, and in fact the higher amounts of vanadium noticeably increase their tensile Strength. Still further, very small amounts of vanadium, say in the order 'of 0.01% and upthe impact strength as well as the tensile strength of the alloys, and their stability in respect to impact strength as well as tensile strength.- Preferably, in respect to secur ing satisfactory. results, about 0.03% vanadium may be employed.

According to the preferred method of making the alloys the zinc is melted under a layer of charcoal to protect it against oxidlzation, and a molten mixture of the copper and phosphorus, containing also the vanadium when the latter is employed, is formed separately from the molten zinc. This molten mixture may be formed by adding to deoxidized molten copper a coppervanadium mixture rich in vanadium and then phosphor-copper rich in phosph rus, the molten copper being preferably formed either by melting deoxidized copper or by melting electrolytic copper and deoxidizing the latter by adding a small amount of phosphorus to it and permitting the residual phosphorus to reaches the molten state this molten mixture, containing preferably all the copper, vanadium dimensions as they f age, making many of them unsuitable for most commercial applications. j change in linear dimensions with 1 proved alloys are when subjected to 1 test they exhibit an increas in about 0.0002 inch per linear inch, which degree of stability is satisfactory-for most commercial However, in respect to For example,

the above mentioned steam dimensions of.

amounts of vanadium to the and phosphorus, is poured into it, preferably I slowly, Pouring the high temperature molten mixture into the relativel low temperature molten zinc causes a pronounced agitation and rise in temperature of ly to incorporate the mixture into the zinc. Preferably the alloy thus formed is poured without delay into a mold to form a, casting of suitable operations.

shape for the subsequent hot or cold working To insure satisfactory results, preferably the high temperature mixtureis poured into the molten zinc, and the resulting alloy poured into the mold, not longer than about 5 minutes after the zinc reaches the molten state. It will be understood that, within the scope of the appended claims, wide deviations may be made from the compositions herein. described without departing from the spirit of the invention.

I claim:

1. Workable alloys having, approximately, 0.1 to 7.5% copper and 0.01 to 0.75% phosphorus. the balance being substantially zinc, th percentage amount of phosphorus present not exceeding a valuewhich varies approximately from 0.15 to 0.75% linearly and inversely. with the percentage amount of copperpresent within the range of K copper specified.

. 4. Alloys'according to claim .value being 0.15 to 0.65%

2. Alloys according to claim 1 having 1.75 to 3.25% copper and at least 0.2% phosphorus, the variable maximum phosphorus value being'0.5 to 0.62% for this range of copper.

3. Workable alloys having, approximately, 0.1

to 2.2% copper and 0.01 to 0.25% phosphorus,

the balance being substantially zinc.

-1' having 2.2 to 6.2% copper and at least 0.25% phosphorus, the variable maximum phosphorus value being 0.25 to 0.58% for this range of copper, i

5. Workable alloys having, approximately, 0.1 to 3.3% copper and 0.01 to 0.3% balance being substantially zinc.

6. Alloys accordingto claim 1 having 1.5 to 7.5% copper, the variable maximum phosphorus forthis range of copper. -.7. Alloys according to claim 1 containing apfor an equal amount of the zinc.

' EDWARD S. BUNN. I

the latter, which act thoroughphosphorus, thevanadium substituted