US2019688A - Alloy - Google Patents

Description

Patented Nov. 5, 1935 UNITED STATES PATENT OFFICE ALLOY James M. Lohr, Morristown, N. J., assignor to Driver-Harris Company, Harrison, N. .L, a corporat ion of New Jersey NojDrawing. Application June 14, 1935,

Serial No. 26,622

3 Claims.

5 oxidation at high temperatures is essential. The

alloys forming the subject matter of my invention are characterized bythe ability to resist oxidation and by a prolonged life, exceeding that of other known alloys, when used under high temperature conditions.

While nickel-chromium and nickel-chromiumiron alloys having the ability to resist oxidation at high temperatures are known, their period of usefulness in service is often not as long as de-. sired. I have found that the addition of small quantities of zirconium to such nickel-chromium alloys greatly increases their period of life when employed under conditions where they are subjected to high temperatures. The alloys forming the subject matter of the present application may also contain small quantities of either sili-, con or manganese or both of these elements.

In carrying out my invention I add small quantities of zirconium with or without silicon or manganese to nickel-chromium or nickel-chromium-iron alloys. The nickel-chromium alloy most generally used in the art consists of 80 parts of nickel and 20 parts of chromium and I find it advantageous to add the other metals mentioned above to nickel-chromium alloys of substantially these proportions. The proportions of nickel and chromium in the alloy may be varied. Thus the chromium content may be from 15 to 25 percent and the balance nickel.

Likewise the most generally used proportions of nickel, chromium and iron in nickel-chromium-iron alloys is 60 percent nickel, 10 to 15 percent chromium and the balance iron and I find it advantageous in many cases to employ substantially these proportions of those ingredients, and add the zirconium. These proportions may also be varied, the nickel, however, forming the major part of the alloy, and the nickelchromium content being such that the alloy will have the characteristics of a non-ferrous alloy.

I may employ from 7 to 22 percent chromium, 8 to 30 percent iron and the balance nickel.

In preparing alloys containing zirconium, the quantities of it are subtracted from the iron content, as for example, when zirconium is added to an alloy containing 60 percent nickel, 10 to 15 percent chromium and the balance iron, the final alloy will contain 60 percent nickel, 10 to 15 percent chromium and zirconium in the percentages herein stated and the balance iron.

The proportions of zirconium may vary within certain limits. I have found that best results are obtained when this metal is present in the nickel-chromium or nickel-chromium-iron alloy within the following limits:

Percent .01-.50

If manganese or silicon are employed, they may be used within the following limits:

Zirconium Percent 10 Manganese 0.02-2.0 Silir'nn 0.022.0

The preferred proportions of the alloying Nickel-chromium and nickel-chromium-iron .0

alloys containing zirconium within the proportions given have been found by tests to have a greatly increased period of life when exposed to high temperatures. For the purpose of determining the life of such alloys at high temperatures I have tested them by the method of test outlined in Tentative Accelerated Life Test for Metallic Materials for Electrical Heating" of the American Society for Testing Materials described in vol, 29 of the Proceedings of the Thirty- Second Annual Meeting of the American Society for Testing Materials beginning on page 613. The method is substantially as follows:

A sample of the wire to be tested, free from kinks, approximately twelve inches long and of about .025" diameter, is mounted vertically on the test board, the upper end being held in position by means of a suitable binding post. A 10 gram weight is attached to the lower end of the specimen. A short piece of wire is attached to the 10 gram weight and projects downward into a cup of mercury where it may move freely up and down. A rheostat and an interrupter are connected in series with the specimen to the power supply. The test is run on constant temperature at a standard temperature chosen for the alloy under consideration for the first twenty four hours. Thereafter it is run ori' constant voltage to the burnout. a 10 percent increase in resistance is known as useful life while the life to the burnout is known as total life. Throughout the test the power is on two minutes and off two minutes. This is accomplished by means of an interrupter. X

The life in hours up to 50 In testing the alloys of my invention according to the above described method a reference sample composed of 60 percent nickel, 15 percent chromium and percent iron and no alloy addition having an approximate life of '70 hours was used. This value is considered as 100 percent and the useful life of the samples tested is determined in corresponding percentage values.

The addition of zirconium to such alloys within the limits set forth above greatly increases the useful life where the wire is exposed to a high temperature as shown by the following example:

Percent useful um In the alloys referred toiherein, small amounts of phosphorous and sulphur may be present as impurities. The nickel may also contain about 1 percent of cobalt.

I claim:

1. A nickel-chromium-iron alloy containing 7 to 22 percent chromium, 8 to percent iron, .01 to percent zirconium, balance nickel.

2. A nickel-chromium-iron alloy containing 7 to 22 percent chromium, 8 to 30 percent iron, substantially .25 percent zirconium, balance nickel.

3. A nickel-chromium-iron alloy containing 10 to 18 percent chromium, 17 to 30 percent iron, .01 to .50 percent zirconium, balance nickel.

JAMES M. LOHR.

CERTIFICATE or CORRECTION.

Patent No. 2,019,688. November 5, 1935.

JAMES? M. LOHR.

lt is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 8, claim 1, for "50" read .50; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 10th day of December, A. D. 1935;

Leslie Frazer Acting Commissioner of Patents.