US2482900A - Corrosion-resisting composite metal - Google Patents

Description

- CORROSION-RESISTING COMPOSITE METAL Original Filed June 23, 1941 61/ JPN/7 Patented Sept. 27, 1949 Paul G. Chace, Attleboro Falls, Mass., assignor to Metals and Controls Corporation, Attleboro, Mass., a corporation of Massachusetts 7 Original application June 23, 1941, Serial No.

399,398, now Patent No. 2,366,178, dated January 2, 1945. Divided and this application November 11, 1944, Serial No. 563,016

13 Claims. ((129-1955) pheres and mediums; the provision of composite thermostatic metal of the class described which has both good hot-rolling and good cold-rolling properties; .and the provision of composite thermostatice metal of the type indicated which is relatively simple and economical to manufacture. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the ingredients and combinations of ingredients, the proportions thereof, and features of composition, which will be exemplified in the products hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing in which is illustrated one of various possible embodiments of the invention, the single figure is a representation of a bimetallic element showing a strip of iron chromium alloy fused throughout its length to a similar strip of copper silicon alloy.

Many of the thermostatic elements commonly in use are subject to corrosion when used in the presence of moisture in places such as steam radiators, or water mixing valves, or in other installations where corrosion-promoting fluids or atmospheres come in contact with the thermostatic metal. As a result, such elements frequently need replacing, and inasmuch as corrosion tends to reduce their activity in life, such corrosion may set up, unknown to the user, dangerous conditions which might result in loss of life or injury. To avoid this corrosion of the composite metal element," it has sometimes been customary in the past to treat the thermostatic metal surface to make it less subject to corrosion, as by plating it with a corrosion-resisting material, such as cadmium, tin, zinc, lead, or chromium. This, however, has the disadvantage that the plating increases the cost materially and does not assure satisfactory life for the thermostatic element. Furthermore, such plating is not entirely satisfactory since an eleetro-voltaic potential may be set up which produces pitting and eating away of the protective metal.

It has sometimes been the practice in the past to make a composite metallic element from an iron alloy having a high chromium content, and a metal alloy-having a higher coefficient of expansion. The metal used for the high coefficient of expansion side has been one of the brasses- The mechanical properties of these brasses have presented manufacturing difliculties, which in many instances have prevented the manufacture of an adequate and satisfactoryycomposite metal. For example, the cold-working properties of brass are so different from those of the chromium iron alloy that it has been diflicult to satisfactorily cold-work the metal after it has been put together to form a thermostatic bimetal. Moreover, it is highly advantageous in the manufacture of bimetal to hot-roll the material down from its thick ingot size to an intermediate stage.

The brasses are not adapted to this, since their hot-rolling temperatures diifer too much from that of the chromium iron alloy. The manufacture of the brass-chrome iron bimetals has therefore been a relatively expensive process compared to the manufacture of bimetal in accordance with -the present invention. The ingot size of the brass-chrome iron bimetals must be kept small because of the aforementioned difliculties and properties.

Where other constituents have been proposed for corrosion-resisting bimetals, it has been found relatively impossible to directly bond the metals together. For this reason, an intermediate solder layer has been used which led to two serious disadvantages. First, the use of the solder layer decreases the corrosion-resisting property of the economical, and a highly corrosion-resisting thermostatic metal is obtained.

According to the present invention a thermo- I static element is provided which is corrosion-resisting per se, particularly to air, water and water vapor, thus eliminating the need for surface plating. In addition, the present invention provides a thermostatic element made of composite thermostatic metal of the corrosion-resisting type which has a direct bond between the layers thereof.

together over their entire areas by a direct 'bond. One 01 the layers, in the present invention, comprises a corrosion-resisting metal having a low coei'flcent of expansion. The other layer comprises a second corrosion-resistingmetal having a relatively high coefficient of expanslon.

For the metal having a low ooefllcient of expansion a high chromium content stainless iron is employed. The composition of this alloy may be as follows:

Per cent Manganese 0.2-0.6 Carbon 0.010.2

Chromium 12-20 Silicon -1.5 Copper 0-1.5 Iron Remainder For the high expansion material an alloy of copper and silicon is employed. The composition of this alloy may be as follows:

Per cent Copper 96-99 Silicon 0.5-4 Manganese 0-1 Tin 0-2.5

properties of the copper silicon alloys described are sufllciently near to the same properties of the chrome-iron alloys that the two metals work wen together and may be easily cold-worked. This makes the manufacture thereof more economical. As a result of obtainim a direct bond between the metals comprising the present invention, a thermostatic metal having a higher strength, greater activity, wider usable temperature range, longer life and better corrosion-resisting properties than, the corrosion-resisting bimetals hitherto known, is obtained. Former metals allegedly designed to have these desirable properties have instead been relatively weak, corrode relatively easily, are more difllcult to manufacture, and in general are not satisfactory.

As specific examples of alloys which may be advantageously employed in the present inven- Manganese 4" Copper-silicon alloy No. 2

Per cent C pper 97-98.5 Silicon 1-2.5 an anese .l5-.35

Copper-silicon 4110:! No. 3 r Per cent Copper 98 Silicon 1.25 Manganese 0.75

Attenrtion is directed to my copending applications, Serial Nos. 563,013, 563,014 and 563,015, all filed November 11, 1944.

In view of the above, it will beseen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above alloys without departing from the scope of the invention, it is intended that all matter contained in the above description shah be interpreted as illustrative and not in a limiting sense.

' I claim:

'1. A corrosion-resisting thermostatic metal composed of an iron alloy containing: manganese approximately 0.2-0.6%, carbon approximately 0.01-0.2% chromium approximately 12-20%, and the balance iron; and a copper alloy containing: silicon approximately 0.54%. manganese approximately 0.15-1 and the balance copper {the surfaces of said alloys being fused together at the junction.

2. A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition:

Per cent Manganese 0.4 Carbon 0.05 Chromium 12-16 Iron Remainder and an alloy having essentially the followin composition:

Per cent Copper 97-99 Silicon 0.75-1.75 Manganese 0.2-1.0

the surfaces of said alloys being fused together at the junction.

3. A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition: 1

and an alloy having essentially the following composition: tion, the following examples are given. They are Per cent illustrative only: Cpper 97-99 Silicon 0.75-1.75

v chmme'im" Per cent Manganese 0.2-1.0 Manganese 0.4 the surfaces of said alloys being fused together Carbon at the lunction. Chromium- 1640 4. A corrosion-resisting thermostatic metal Iron Balance composed of an alloy having essentially the lol- 7 7o lowing composition:

Copper-silicon 41101! No. 1 Per cent Per cent Manganese 0.4 Copper 97-99 Carbon 0.05 Silicon 0.75-1.75 Chromium 16 0.2-1.0 Iron Remainder and an alloy having essentially the following composition:

Per cent Copper 97-99 Silicon 0.75-1.75 Manganese 0.2-1.0

the surfaces of said alloys being fused together at the junction.

5. A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition:

Percent Manganese 0.4 Carbon ...1 0.05 Chromium 12-16 Iron Remainder and an alloy having essentially the following composition I her cent Copper 98 Silicon 1.25 Manganese 0.75

the surfaces of said alloys being fused together at the junction.

'6. A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition:

Per cent Manganese 0.0 Carbon 0.05 Chromium 16 Iron Remainder and an alloy having essentially the following composition:

Per cent Copper 98 Silicon 1.25 Manganese 0.75

the surfaces of said alloys being fused together at the junction.

7. A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition:

Per cent Manganese 0.4

Carbon 0.05 Chromium 12-16 Iron Remainder and an alloy having essentially the following composition:

Per cent Copper 97-98 Silicon 1-2 .5 Manganese 0.15-0.35

the surfaces of said alloys being fused together atthe junction.

8. A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition:

I Per cent Manganese 0.2-0.6 Carbon 0.01-0.2 Chromium -12-20 Iron Remainder and an alloy having essentially the'following composition:

Per cent Copper 97-985 Silicon 1-2.5 Manganese 0.15-0.35

the surfaces of said alloys being fused together at the junction.

9. A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition:

Per cent 5 Manganese 0.2-0.6 Carbon (ml-0.2 Chromium 12-20 Iron Remainder and an alloy having essentially the following the Junction.

10. A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition:

20 Percent Manganese 0.4 Carbon 0.05 Chromium 16 Iron Remainder and an alloy having essentially the following composition:

Per cent Copper 97-985 Silicon 1-2.5 Manganese 0.15-0.35 the surfaces of said alloys being fused together at the junction.

1 A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition:

Per cent Manganese 0.4 Carbon 0.05 Chromium 16-20 Iron Remainder and an alloy having essentially the following composition:

Per cent Copper 97-99 Silicon 0.75-1.75 Manganese 0.2-1.0

the surfaces of said alloys being fused together at the junction.

12. A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition:

Per cent Manganese 0.4 Carbon 0.05 Chromium 16-20 Iron Remainder and an alloy having essentially the following composition:

Per cent Copper 97-985 Silicon 1-2 .5

Manganese 0.15-0.35

the surfaces of said alloys being fused together at the junction.

13. A corrosion-resisting thermostatic metal composed of an alloy having essentially the following composition:

Per cent Manganese 0.4 Carbon 0.05 Chromium 16-20 76 Iron Remainder 7 8 and an alloy having essentially the following com- UNITED STATES PA'IEN'IS position: Number Name Date C Per 3; 1,650,951 Matthews Nov. 29, 1927 fl 1 25 1,929,655 Scott Oct.10, 1933 a 5 1,936,397 Jennison Nov; 21, 1993 angmese 1,991,439 Wohrman Feb. 19, 1935 the surfaces of said alloys being fused together at 2,075,014 Bassett Mar. 30, 1937 the junction. 1 2,157,149 Smith May 9, 1939 PAUL G. CHACE. w 2,327,500 Chace Aug. 24, 1943 REFERENCES CITED OTHER REFERENCES Pp. 1000-1002 of The Making, Shaping I1 Treatg b ifi ggggff 111g of Steel, 5111 ed., 1940, pub, by Carnegie-Illi- 2101s Steel Corp, Pittsburgh, Pa.

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