US1314022A - Cabbon -chbome-wickel steel - Google Patents

Description

Application filed June 15, 1918, Serial No. 240,211.

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JAMES RAMSEY SPEER, OF TRAPPE, MARYLAND.

CARBON-CTIROIvIE-NICKEL STEEL.

No Drawing.

Specification .5 Letters Patent.

Illateni ed Aug. 26, 1919.

Renewed April 26, 1919. Serial No.

. Chrome-Nickel Stecl,of which the following is a specification.

The present invention is an alloy steel, and particularly a hardened carbon-chromenickel steel, and the method of producing the same. The product comprises an alloy composed of relatively high carbon steel in combination with chromium and nickel, wherein the manganese, silicon, sulfur and phosphorus vary, within the usual propor' tions for steel mixtures, and which product hasthe qualities hereinafter specified.

The object sought is a carbon-chrome nickel steel which is relatively simple to roduce, at a comparatively low cost, which heat treated to a degreewhich classes it in performance with the most expensive and most diflicult alloy mixtures known in the art, and which,when so hardened and heat treated, is very hard and tough and therefore well adapted to uses in which resistance to penetration from hard blows is a necessary quality.

Various special chrome-nickel steels have heretofore been made. Much has been written upon the subject and many patents for such alloy steels have been taken out. Practically all the literature, and the patents themselves, dwell upon the great diiiiculty of producing such alloys and place great emphasis upon the large amounts of nickel and.' chromium necessary to obtain the desired results. One conspicuous example of such prior nickel-chromium steel emphasizes the necessity of limiting the manganese content to less than 30%, also the exactness of the metallurgical operation in the production of the steel (practically to the destruction of the carbon, silicon and manganese content therein), and also the necessity of such exact metallurgical operation in order to produce the desired results. Prior investigators and inventors in this field have relied primarily upon the alloying elements, chromium and nickel, for the effects to be produced, and have added these elements, and especiallythe nickel, in large quantities.

According to my invention the. carbon in the steel is rimarily relied upon to produce the desirabl ia qualities, and the alloying elecan be .hardened and rectly because of their intrinsic qualities.

The performance of my alloy depends primarily upon the various forms and character of the interlocking carbids, and because 'of the small quantities of chromium and nickel there is pract' :ally no risk of forming any of the oxids and ferro combinations which result from the use of large amounts of those elements. Because of the simplicity of this carbon control, the manufacture of the product is greatly simplified, and its cost of production is much reduced.

In steel alloys which are high in chromium and nickel, there is a certain lack of digestion of the chromium and nickel, and such alloys are subject to more than usual segregation. In the alloys which contain the higher percentages of chromium this is manifested by a great tendency to brittleness,-in some cases of almost explosive character. In the alloys which contain the higher. percentages of nickel this is manifested by a lack of uniformity due to the segregation of the nickel which frequently gives serious trouble.

In my new alloy steel the relatively large quantity of carbon is merely controlled, and its effect strengthened, through and by means of the alloying compounds to fix the carbon in the best forms, as a result of which the product is capable of uses where the metal is subject to very severe service or abuse. Plates one-half inch thick made from my allo when properly quenched and heat treated, lave resisted penetration of the latest United States Army model of armorpiercing bullet of 2800 feet muzzle velocity per second at a distance of fifty yards. This is the maximum test of resistance for such plates, thus showing that the alloy steel is admirably adapted for light armor such as is used for gun shields, armored tractors and automobiles, tanks, and general ordnance work.

These one'half inch plates were rolled froma cast slab of initial thickness of t inches,a reduction from 8 to 1,-which is one-fourth or even less of the reduction in rolling similar armor lates. Notwithstanding the limited worcing. this allov tool adapted for the uses qualities of the most expen-' its fineness of texture and shows the best sive steels, and

silkiness of grain, together with its ability mor plates were shown when the plates were quenched from an initial temperature of 1 100 to 1450 Fahrenheit. This quenching was limited to some extent, however, so that the plates were not cooled to too low a point from their initial heating. They were then reheated and drawn at a temperature of 800 to 1000 Fahrenheit, and then allowed to cool. These plates showed a Brinnell hardness test of 370 to 418, and the best results for -bullet resistance were obtained by drawing at 850 Fahrenheit, when the Brinnel test showed about 4:18. I

The relative degrees of hardness and toughness can be readily controlled by the heat treatment. For exanrple, when the' quenching was from the same initial temperature as that above given but was carried to a lower point and the plate again heated and drawn at a temperature of about 600 Fahrenheit and allowed 'to cool, the

.Brinnell hardness test showed about 500,

toughness to the matrix.

but the plates were somewhat too brittle,

and showed a tendency to crack under the, bullet test named. On the other hand, when the quenching was from the same initial temperature, but not carried to so low a point, and the further heating and drawing was at a temperature close to 1200 Fahrenheit, the Brinnell test showed 250 to 300, and the plates were not quite so hard, but were very tough and resisted complete bullet penetration.

The analysis of the material'in the above plates was as follows:

Carbon .8t Silicon .27 Manganese .59 Chromium .98 Nickels .60 Sulfur 022% Phosphorus 033% This alloy steel hearth furnace, in any suitable was made in an acid open but could have been made steel making furnace. It

' 18 not as high in carbon as some steels. The

amount of chromium is just sufficient to fix the most resistent character or forms of the carbon combinations. The amount of nickel is just sufficient to counteract the tendency of the chromium and carbon combinations to produce brittleness, and to add some The amount of manganese is just above the range of steels illustrate the thus reversing the usual, and long recognized as essential, relation between the chromium and nickel in such alloys. The proportions of' silicon, sulfur and phosphorus in the above analysis correspond closely to such as are found in the better grade of steels. Thequalities of the new alloy are due to triple relation of the carbon modified by the chromium and both under the'influence or effect of the nickel. Thehigh carbon, controlled and modified as to its forms by the chromium and nickel, is primarily depended upon to produce the quality of hardness, and

it is the determining factor in the excellence of the performance of the alloy and its sus ceptibility to ready control.

.Various other analyses could be enumerated, but the one above given is sufficient to principle of dependence on the.

carbon for the performance 0f,the alloy; and yet its performance clearly takes it out of the class of high carbon steels. .The proportion of carbon given, that is, 84%, is close to the middle of the carbon range, which may vary from 50% to 1.25%. I The amount of carbon used depends upon the desired hardness of the alloy. The higher the carbon the greater is the degree of hardness obtained, and the lower the carbon the less the hardness of the alloy, with a relatively lower power of resistance. The amount of chromium and nickel to best modify and control the carbon and produce the interlocking functions and effects described may, and preferably will, be varied according to the amount of carbon present. The chromium may vary from 25% to 1.25%. The nickel may also vary from 25% to 1.25%, but generally will be present in a lesser.

- amount than the chromium.

In producing the new alloy I follow the customary methods of steel makers, paying special attention, however, to the make-up of the raw materials in respect to their analy ses, so that the figured analysis of the combination of the raw materials, after allowing for the losses incident to all steel making methods, will approach the analysis desired for the finished heat. In this manner and without other than ordinary skill on the part of the melter, the additions necessary to make the heats are reduced to a minimum, and the substantially complete destruction of the carbon, the silicon and the manganese (which some have heretofore thought necessary in the reduction of such alloy steel) is avoided, and this useless waste is turned to good account. In other words, I make use of the carbon, silicon and mangathe nese content of the raw materials charged into the furnace, and by reasonable care in refining in thefnrnace secure an analysis of the finished product within permissible variations from the analysis desired. Consequently, the method of producing the alloy is simple, is economical, and contrary to the heretofore suggested substantial destruction and elimination of such elements; and the expensive ingredients, chromium and nickel, are added in quantities relatively low as'compared with such elements in similar products as heretofore contemplated.

It is entirely feasible to add one or more of the rarer alloying metals, to contribute somewhat to the variability of performance, but they are not essential.

I claim:

1. An alloy of steel characterized by great hardness and toughness, variable by heat treatment, wherein steel of .50); to 1.25% carbon forms 97.50 to 99.50 parts, chromium forms to 1.25 parts, and nickel forms from .25 to 1.25 parts.

2. An alloy of steel characterizial by great hardness and toughness, variable by heat treatment, wherein steel of 50% to 1.25% carbon forms 97.50 to 99.50 parts, and chromium and nickel together form from .50 to 2.50 parts, the chromium being not less than the nickel.

3. A hardened worked alloy of steel product characterized by great hardness and toughness, variable by heat treatment, wherein steel of 50% to 1.25" carbon forms 07.50 to 99.50 parts, and chromium and nickel to gether form from .50 to 2.50 parts, the chromium being not less than the nickel.

In testimony whereof I hai'e hereunto set my hand.

JAMES RAMSEY SPEER.

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