US2467288A - Nickel base alloy - Google Patents

Description

April 12, 1949. e. A. BAKER ET AL NICKEL BASE ALLOY Filed May 3, 1947 INVENTOR euv A. BAKER JQQAES A. PARSONS ATTORNEYS Patented Apr. 12, 1949 UNITED STATES PATENT OFFICE NICKEL BASE ALLOY Guy A. Baker and James A. Parsons, Dayton, Ohio, assignors to The Duriron Company, 1110., Dayton, Ohio, a corporation of New York Application May 3, 1947, Serial No. 745,745

- 1 Claim. 1

The present invention relates to nickel base alloys and is concerned primarily with an allo of this type which has improved corrosion resistant properties.

A nickel base alloy of the type with which this invention is concerned includes, as essential elements, nickel, chromium, molybdenum, iron, and small amounts of carbon, manganese, and silicon. In the past many of the alloys of this type have also included tungsten. One of the properties required of such an alloy is that it be corrosion resistant.

This invention has in view, as its foremost objective, the provision of a nickel base alloy of this type which has corrosion resistant properties to a degree higher than anything heretofore attained.

To the end of improving the corrosion resist ance in an alloy of this character the tungsten is completely eliminated. Moreover, the ferrous content is held down to a proportion lower than anything heretofore attained and the carbon con tent is also kept down to a minimum which is below anything heretofore achieved in a nickel base alloy of this type that includes iron.

A highly important object of the invention is to provide a nickel base alloy including a ferrous content because with iron present the product exhibits many of the characteristics of stainless steel and which characteristics are extremely desirable. However, in providing this ingredient it is important that its proportion be held down as low as is consistent with obtaining the desired ferrous properties. With this condition obtaining the remainder of the allow is enriched as to its nickel, chromium, and molybdenum contents.

With a ferrous content present in a nickel base alloy of this type it becomes important to keep the amount of carbon present down to as small a degree as possible as this increases the corrosion resistant properties of the alloy.

Accordingly, a further object of the present invention is to provide a nickel base alloy of the type indicated which includes iron and in which carbon is present in a proportion of about .07 per cent.

A further object of the invention is to provide a nickel base alloy, of the character aforesaid, in which nickel is present in the proportion of about 60 per cent, substantially equal proportions of molybdenum and chromium each in the amount of about 18 per cent, and 3 per cent iron with the remainder of the alloy made up of .07 per cent carbon and traces of manganese and silicon.

It will be noted that there are three factors which mutually contribute to provide improved corrosion resistant properties. In the first place, the alloy is free of tungsten which is an important factor when iron is present. Secondly, the iron content is held down lower than anything heretofore achieved in this art and, thirdly, the carbon content is a percentage which is distinctly new in a nickel base alloy of this type having a ferrous content. The alloy provided by this invention is not only highly resistant to corrosion but it is also machinable which is another desirable factor.

Various other and more detailed objects and advantages such as arise in connection with carrying out the above noted ideas in a practical embodiment will in part become apparent and in part be hereinafter stated as the description of the invention proceeds.

The invention, therefore, comp-rises a nickel base alloy having a ferrous content of 3 per cent or less, a carbon content of .07 per cent, and in which nickel is present in a proportion of. about per cent with the remainder of the alloy made up of substantially equal parts of chromium and molybdenum.

For a full and more complete understanding of the invention, reference may be had to the following description and accompanying drawing wherein the figure is a microphotograph depicting the surface of an alloy enlarged 200 times and made in accordance with the precepts of this invention.

The alloy of this invention includes certain ingredients the proportions of which are critical. Thus, carbon should be present in a proportion ranging from .04 to .10 per cent with .07 per cent the optimum. Iron must be included but in a proportion no greater than 3 per cent; that is, the amount of iron must never exceed 3 per cent.

Nickel should be present in the proportion of about 60 per cent while chromium and molybdenum are present in equal proportions each making up about 18 per cent of the alloy.

At this point it is well to note that the percentages referred to in giving the proportions are by weight.

Following the above noted principles a typical example of an alloy which embodies the invention is set forth as follows:

Percent Chromium 17.00 Molybdenum 17.00 Silicon 1.50 Manganese .75 Carbon .07 Iron 3.00 Nickel 60.68

Of the proportions above specified some slight deviation from the exact amounts indicated is permissible. Thus, chromium and molybdenum may be present in proportions of 18 per cent rather than the 17 per cent indicated although it is important to remember that the amount of one should be substantially identical with that of the other. Moreover, the iron content may be less than the 3 per cent indicated as this figure is intended to denote the maximum iron content permissible. In the event that the iron is present in less than 3 per cent the difierence will be compensated for by an increase in the amount of nickel. While the carbon content may be varied over the range from .04 to .10 per cent, the .07 per cent specified is believed to be the most desirable.

Another example of an alloy which follows this invention is set forth as including:

Per cent Nickel 60.00 Molybdenum 18.00 Cromium 18.00 Iron 3.00

Carbon .07 Manganese and silicon together .93

The drawing illustrates a surface of the alloy of the present invention which has been enlarged 200 times. An examination of this drawing indicates that a second phase is present. It is important to note that the grain lines are not clearly delineated. I

The alloy provided by this invention may be described as being characteristically half nonferrous and half stainless steel. Thus, many of the desirable properties of a non-ferrous alloy such as monel are exhibited and many of the desirable properties of stainless steel are also present. The alloy has a high tensile strength and a correspondingly high yield point. Its casting shrinkage is down within reasonable limits and it has good welding properties as well as being machinable. Its hardness is of a high Brinell and the co-eflicient of expansion is relatively small. All of these characteristics are highly desirable of an alloy of this type. The main factor, however, is that the alloy is highly resistant to corrosion and is well able to withstand the attack of acids.

While a preferred specific embodiment of the invention is hereinbefore set forth, it is to be clearly understood that the invention is not to be limited to the exact proportions described because various modifications of these details may be provided in putting the invention into practice within the purview of the appended claim.

What is claimed is:

A nickel base alloy comprising an iron content of .3 per cent, a carbon content ranging from .04 to .10 per cent, molybdenum from 17 to 18 per cent and chromium from 17 to 18 per cent, a silicon content of 1.5 per cent, a manganese content of .75 per cent with the balance being made up of nickel.

GUY A. BAKER. JAMES A. PARSONS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,115,239 Parr Oct. 27, 1914 1,955,856 Moore Apr. 24, 1934 2,108,051 Egeberg et a1. Feb. 15, 1938 2,196,699 Franks Apr. 9, 1940 2,309,136 Neiman Jan. 26, 1943 2,392,821 Kreag Jan. 15, 1946 2,403,128 Scott et al July 2, 1946

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