US2400283A - Alloys - Google Patents

Description

Patented May 14, 1946 ALLOYS Edward J. Boyle and Edmund A. Anderson, Palmerton, Pm, assignors to The New Jersey Zinc Company, New York, N. Y., a corporation of New Jersey No Drawing.

Application June 24, 1944,

Serial No. 542,002

Claims. (Cl. 35-178) This invention relates to zinc base alloys and more particularly to zinc base alloys containing chromium, and aims to provide an improved zinc base alloy containing chromium and cadmium.

The zinc base alloys of the invention contain from 0.01 to 1.6%, and preferably from 0.05 to 0.5%, chromium and are characterized by additionally containing from 0.05 to 1.5%, and preferably from 0.1 to 1%, cadmium. Alloys of the invention may advantageously contain 0.1 to 0.2% chromium, 0.3 to 0.6% cadmium, and the balance zinc. The zinc base of the alloys is preferably high grade zinc. Alloys of superior creep resistance, that is resistance to prolonged static loads well below the ultimate limit, and of fine grain size when cast result from the use, as the zinc base, of metal of high purity, such as zinc at least 99.99% pure. On the other hand, satisfactory alloys are obtained with zinc oi the grade commonly used in the production of commercial rolled zinc, for example zinc metal containing 0.10% lead, 0.012% iron and 0.005% cadmium. The presence of 0.1% leadis suificient,

however, to impart to the alloys (as cast) a coarse, columnar grain structure similar to that of ordinary cast zinc. If the alloy is rolled or otherwise mechanically worked. the coarse grain structure disappears, and the micro-structure and physical properties of the rolled or worked alloy are substantially independent of the grade or purity of the zinc base within the limits hereinbefore mentioned.

The alloys of the invention are particularly adapted for rolling. When transformed to sheet or strip by suitable rolling procedure, the alloys possess good creep resistance. The alloys may be hot rolled at metal temperatures of from 150 to 300 C., temperatures of from 200 to 240 C. giving very satisfactory results. The hot rolling may be a finishing operation consisting of say three or more passes through the rolls, and may be applied to metal either hot or cold rolled prior to the hot finishing. Cold rolling tends to decrease the creep resistance, but the creep resistance can be substantially restored by subsequent heat treatment such, for example, as annealing for a short period at a temperature of from 150 to 400 C., annealing in oil for about five minutes at a temperature of about 275 C. giving very satisfactory results. Cold rolling, at least in the final stages, imparts to the alloy certain advantages, especially with respect to hardness. Alloys of the invention are to be considered cold rolled when the rolling (or other mechanical working) is carried out under thermal conditions resulting in a temperature of the rolled strip or sheet after the final rollinr pass (final coil ternperature) due simply to the mechanical working. and are to be considered hot rolled when the rolling is carried out under thermal conditions resulting in a final coil temperature of from to 300 0.. and preferably from 200 to 240 C.

In the production of the alloys of the invention, it is preferable to prepare an intermediate zinc base alloy containing a relatively high proportion of chromium. Conveniently, the intermediate alloy may contain about 4% of chromium, and is prepared by heating a mixture of 96 parts of zinc and 4 parts of chromium in a clay-carborundum crucible at a temperature of 800 C. for about 8 hours. The intermediate alloy is cast into a thin slab and crushed to a convenient size for alloying. The final chromium content of the cast intermediate alloy usually does not depart far from the contemplated 4%. The contemplated chromium content of the alloy of the invention is then readily obtained by adding the calculated amount of the intermediate alloy to a predetermined weight of molten zinc. Cadmium, in amount calculated to give the desired content thereof in the final alloy, may be added as such to the molten mixture of zinc and the intermediate zinc-chromium alloy, or the cadmium may be included in the zinc, or melted down with the zinc and intermediate ainc-chromium alloy.

The alloys of the invention are characterized by good creep resistance, dynamic ductility, tensile strength, tensile elongation, and cold bending properties. These physical characteristics of the alloys (among others) are shown in the following table for a typical alloy of the invention containing 0.17% chromium, 0.49% cadmium, and the balance high grade zinc. The specimens were cold rolled to a gauge of 0.02 inch, and were subsequently annealed for five minutes at 275 C. in oil. Dynamic ductility is measured as the maximum depth in inches of a cup that can be formed by a standard plunger in an uncut sheet of the metal without fracture Temper is determined by the degree to which a standard test strip returns to its original position after being wrapped around a mandrel. Tensile strength is measured in pounds per square inch, and tensile elongation is measured in percent in a two-inch test strip. The creep rate or creep resistance is measured with the grain and is expressed as the inverse creep rate (higher inverse creep rates indicating better creep resistance), which is the number of units of time (days) required to produce an clonga' tion or creep of 1% (that is days per cent) in a standard test piece when subjected to a dead load of 15,000 pounds per square inch at constant room temperature (25 C). The cold bend values represent the diameter of uncracked 180 bends in multiples of sheet thickness (gauge), and the lower values indicate better bending properties.

It will be seen from the table that the creep resistance of the alloy is very materially improved by annealing. Hot rolling of the alloy at. temperatures above 150 C. imparts superior creep resistance to the alloy, without materially affecting its other desirable properties. For example, specimens of the alloy hot rolled with final coil temperatures of 158 (3., 197 C. and 236 C. possessed an inverse creep rate of 0.030, 0.059 and 0.090, respectively.

We claim:

1. A zinc base alloy'containlng from 0.01 to Certificate Patent No. 2,400,283.

EDWARD J.

1.6T. chromium, from 0.05 to 1.5 cadmium. and

the rest zinc.

5 the rest zinc.

3. A zinc base alloy containing from 0.1 to cadmium,

0.2? chromium, from 0.3 to 0.6%

and the rest zinc.

4. A zinc base alloy containing from 0.1 to 0.2% chromium, about 0.5 cadmium, and the rest zinc.

5. A cold rolled and annealed zinc base alloy characterized by good creep resistance and containing from 0.01 to 1.6% chromium, from 0.05

to 1.5% cadmium and the rest zinc.

6. A hot rolled zinc base alloy characterized by good creep resistance and containing from 1.01 to 1.6% chromium. from 0.05 to 1.5% cadmium, and the rest zinc.

to 1% cadmium, and the rest zinc.

8. A zinc base alloy according to claim 7 containing from 0.1 to 0.2% chromium, from 0.3 to

0.6% cadmium, and the rest zinc.

and the rest zinc.

10. A zinc base alloy according to claim 9 containing from 0.1 to 0.2% chromium, from 0.3 to 0.6% cadmium, and the rest zinc.

EDWARD J. BOYLE.

EDMUND A. ANDERSON of Correction May 14, 1946. BOYLE ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows. Page 2, second column, line 18,

claim 6, for 1.01 to 1.6%

read 0.01 to 1 case in the Patent Office.

be read with this correction therein that the same may and that the said Letters Patent should conform to the record of the Signed and sealed this 13th day of August, A. D. 1946.

LESLIE FRAZER,

First Assistant Commissioner of Patents.

7. A cold rolled and annealed zinc base alloy characterized by good creep resistance and containing from 0.05 to 0.5% chromium, from 0.1

of time (days) required to produce an cionga tion or creep of 1% (that is days per cent) in a standard test piece when subjected to a dead load of 15,000 pounds per square inch at constant room temperature (25 C). The cold bend values represent the diameter of uncracked 180 bends in multiples of sheet thickness (gauge), and the lower values indicate better bending properties.

Table i As rolled As mull-aim! ran, 2m 3.2.1500

Certificate Patent No. 2,400,283.

EDWARD J.

claim 6, for 1.01 to 1.6%

case in the Patent Office.

1.6T. chromium, from 0.05 to 1.5 cadmium. and the rest zinc.

2. A zinc base alloy containing from 0.05 to 0.5% chromium. from 0.1 to 1% cadmium, and the rest zinc.

3. A zinc base alloy containing from 0.1 to 0.2? chromium, from 0.3 to 0.6% cadmium. and the rest zinc.

4. A zinc base alloy containing from 0.1 to 0.2% chromium, about 0.5% cadmium, and the rest zinc.

5. A cold rolled and annealed zinc base alloy characterized by good creep resistance and containing from 0.01 to 1.6% chromium, from 0.05 to 1.5% cadmium and the rest zinc.

6. A hot rolled zinc base alloy characterized by good creep resistance and containing from 1.01 to 1.6% chromium. from 0.05 to 1.5% cadmium, and the rest zinc.

7. A cold rolled and annealed zinc base alloy characterized by good creep resistance and containing from 0.05 to 0.5% chromium, from 0.1 to 1% cadmium, and the rest zinc.

8. A zinc base alloy according to claim 7 containing from 0.1 to 0.2% chromium, from 0.3 to 0.6% cadmium, and the rest zinc.

9. A hot rolled zinc base alloy characterized by good creep resistance and containing from 0.05 to 0.5% chromium. from 0.1 to 1% cadmium, and the rest zinc.

10. A zinc base alloy according to claim 9 containing from 0.1 to 0.2% chromium, from 0.3 to 0.6% cadmium, and the rest zinc.

EDWARD J. BOYLE. EDMUND A. ANDERSON.

Correction May 14, 1946.

BOYLE ET AL.

s in the printed specification of the above ollows. Page 2, second column, line 18,

and that the said Letters Patent should conform to the record of the Signed and sealed this 13th day of August, A. D. 1946.

LESLIE FRAZER,

First Assistant Commissioner of Patents.