US2686715A - Nickel base nickel-copper alloy castings - Google Patents

Description

Patented Aug. 17, I954 NICKEL BASE NICKEL-COPPER ALLOY CASTIN GS PierreEmile Le Grand, Plainfield, and Theodore Ephraim Kihlgren, Berkeley Heights, N. J assignors to The International Nickel Company, Inc., New York, N. Y., a corporation of Delaware No Drawing.

Application July 31, 1952,

Serial No. 301,974

4 Claims. (01. 75-170) 1 The present invention relates to improved castings characterized bysubstantially improved properties and made from high nickel-base alloy containing less than 40% copper, and more'particularly, to castings made from a high nickelcopper-silicon alloy and having a nickel-copper ratio of about 2:1 and having controlled proportions of columbium to counteract the adverse effect of lead contamination. Heretofore, high nickel castings containing a minor amount of copper usually contained from 1.20% to 1.80% silicon which was added for the dual purpose of obtaining castability and imparting good strength to such castings. The tolerance for such tramporsubversiveuelements as lead was extremely low and was least at the desirable higher silicon levels. Although many attempts were madeto overcome the foregoing difficulties and other disadvantages, none, as far as we areaware, were entirely successful, especially when carried into practice commercially on an industrial scale.

Wehave discovered that the problem of producing high nickel alloy castings having'the important property of good castability without sac-. rificing other desirable properties due to the presence of lead as a contaminant can be solved by the inclusion of silicon and columbium in critically controlled or balanced proportions.

It is an object of the present invention to provide high, nickel-copper castings containing critical amounts of silicon and columbium to provide good castability and overcome the delelowing description.

Broadly stated, we have found that silicon promotes cracking in high nickel-copper castings that contain lead as a contaminant. The detrimental effect is probably of a complex nature and is possibly a silicon-lead effect, the latter element (lead) never being wholly absent and 002% to .003% being present even under conditions of close foundry control. As pointed out hereinafter, the lead content can be as high as 0.01% or more. We have found that, by the introduction of columbium into the lead-contaminated high nickel-copper casting, hot cracking of the casting can be eliminated or reduced to negligible proportions at the silicon levels required for good castability. We have further found 2 that columbium increases the tolerance for lead to the extent that deliberate additions of lead, in quantity sufficient to make weld repairs impossible in prior art castings, had relatively little effect on the columbium-modified castings with controlled silicon content. The columbium content also appears to neutralize deleterious effects of sulfur and may increase the tolerance for this element as well.

Tests in foundry operations have shown that improved lead-contaminated high nickel-copper-silicon alloy castings containing critically controlled amounts of columbium possess increased resistance to hot cracking when subjected to shrinkage and contraction stresses during solidification and cooling. Thus, even when weldability is not a factor, there are instances where casting size and shape will be such that the advantages of the present invention will make possible the production of pressure-tight castings.

In carrying the invention into practice, the improved high nickel-copper castings: containing lead as a contaminant and having controlled silicon and columbium content for obtaining castability and resistance to hot cracking may comprise, beside lead as a contaminant, the amounts of the elements set forth in Table I.

It will be noted that the ratio of nickel to copper is about 2:1 and that the nickel is about two-thirds of the composition and copper is about one-third in the preferred embodiment while the aforesaid composition is preferred, nevertheless, other high nickel alloys containing lead as a contaminant can be used where the nickel constitutes the major portion or component and copper the minor portion or component, provided the copper is less than 40% and is preferably not more than about 35%, the nickel is at least and the combined nickel and copper content is at least and preferably at least As will be understood by those skilled in the art, impurities commonly associated with nickelcopper and columbium or ferro-columbium in commercial forms may be tolerated in the new castings, except subversive elements. .It will be 3 further understood that alloying additions of other elements may be made without detriment to'the new castings or with the attainment of some modification or improvement of their properties and without affecting their novel characteristics.

For the purpose of giving those skilled in the art a better understanding of the invention and of the advantages to be obtained therefrom, the following illustrative example is given.

In the ensuing example the'crack test rating is based on the X-weld crack test, herein described, wherein the instances of cracking are based on the average number of underbea'd cracks per inch observed in cross sections of the test pieces along with an estimate of their length and width. The crack test is made by forming a weld between two 3-inch lengths or blocks of one-inch square cast bars along the 3-inch edge with a double V-groove weld. The weld passes are laid in, two at a time, at alternate sides of the double V formed by the two bars with suflicient time lapse between each pair of passes to permit the specimen to cool to below 100 F. After welding, the specimen is sectioned twice on planes perpendicular to the direction of welding and the sectional surfaces are polished with a rubber-bonded, fine abrasive wheel, etched, and examined under a binocular microscope for underbead cracks.

The same base composition was used in all test pieces, 1. e., the lead-contaminated preferred composition noted in Table I with the exception of the columbium-free compositions which were employed for comparing cracking with and without columbium.

Example Percent Cracks Melt No. Lead gg Perscient per Size of Cracks Added Inch 1 .005 0. 1. 50 Medium to long;

wide. 2 .005 2.0 1.50 2 Short to medium length. 3 .01 0. 1.50 12 Long; wide. 4 .01 2.0 1. 50 4 Short to medium length.

It is to be observed that the present invention provides high nickel castings containing a minor amount of copper and having combined silicon and columbium contents in controlled and critical proportions and in amounts effective to produce castings of good castability with the elimination of hot cracking of the casting due to lead contamination in the copresence of silicon and to solidification or casting stresses.

Furthermore, it is likewise to be noted that it is within the contemplation of the invention to provide as new articles of manufacture improved pressure-tight lead-contaminated castings made of high nickel alloys containing a minor amount of copper and having silicon Identical tests were also and columbium in critical and controlled amounts to secure pressure-tight castings being free from hot tears.

This application is a continuation in part of our ,co-pending U. S. application Serial No. 8'7 ,123,

filed April 12, 1949, now abandoned.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that the use of modifications, equivalents and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications, equivalents and variations are considered to be within the purview and scope of the invention and appended claims.

We claim:

1. As an article of manufacture, a casting made of a nickel-copper alloy having lead as a contaminant and characterized by the properties of good castability and improved resistance to hot cracking consisting essentially of about'1.5'% silicon,about 0.2% carbon, about 0.8% manganese, up to about 1.5% iron, about33% copper, about 0.005% lead as a contaminant, about 2% columbium to counteract the deleterious effects of said lead contaminant, and the balance nickel.

2. As an article of manufacture, a casting made of a nickel-copper alloy having lead as a contaminant and characterized by the properties of good castability and-improved resistance to hot cracking consisting essentially of about 1.5% silicon, about 0.2% carbon, about 0.8% manganese, up to about 1.5% iron, about 33% copper, about 0.01% lead as a-contaminant, about 2% columbium to counteract the deleterious effects of said lead contaminant, and the balance nickel.

3. As an article of manufacture, a casting made of a nickel-copper alloy having lead as a contaminant and characterized by the properties of good castabilityand improved resistance to hot cracking consisting essentially of about 1.5% silicon, about 0.2% carbon,about 0.8% manganese, up to about 1.5% iron, about 33% copper, lead as a contaminant in small amounts up to about 0.01%, about 2% columbium to counteract the deleterious effects of said lead contaminant,and the balance nickel.

4. As an article of manufacture, a casting made of a nickel-copper alloy having lead as a contaminant and characterized by the :properties of good castability and improved resistance to hot cracking consisting essentially of about 1.2% to 1.8% silicon, 0.05% to 0.4% carbon, 0.6% to 1.25% manganese, up .to-3'.5% iron, 25% to'35% copper, 0.002% to 0.01% lead as a contaminant, 1% to 3% columbium to counteract the deleterious efiects of said lead contaminant, and the balance nickel, the nickel content being at least 60% of the alloy.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,988,154 Bolton et al June 15, 1935 2,355,581 Wise Aug. 8, 1944 2,422,489 Kihlgren et al. June 17,1949 2,455,951 Kihlgren et a1 July 27,1948

OTHER REFERENCES Metals Handbook, .1939 :edition, page 1663; published by Amer. Soc. for Metals, Cleveland, Ohio.

Claims (1)

1. AS AN ARTICLE OF MANUFACTURE, A CASTING MADE OF A NICKEL-COPPER ALLOY HAVING LEAD AS A CONTAMINANT AND CHARACTERIZED BY THE PROPERTIES OF GOOD CASTABILITY AND IMPROVED RESISTANCE TO HOT CRACKING CONSISTING ESSENTIALLY OF ABOUT 1.5% SILICON, ABOUT 0.2% CARBON, ABOUT 0.8% MANGANESE, UP TO ABOUT 1.5% IRON, ABOUT 33% COPPER, ABOUT 0.005% LEAD AS A CONTAMINANT, ABOUT 2% COLUMBIUM TO COUNTERACT THE DELETERIOUS EFFECTS OF SAID LEAD CONTAMINANT, AND THE BALANCE NICKEL.