US1684841A - Steel and its manufacture - Google Patents

Description

J. R. C. MARSH STEEL AND ITS'MANUFACTURE Sept. 18, 192 8. 1,684,841

Filed Jan. 19. 1922 Ill Patented Sept. 18, 1928.

UNITED STATES PATENT OFFICE.

JOSEPH RUSSELL CORNELL MARSH, OF ARLINGTON HEIGHTS, ILLINOIS, ASSIGNOR TO FRANCIS NORWOOD BARB, OF CHICAGO, ILLINOIS.

STEEL AND ITS MANUFACTURE.

7 Application filed January 19, 1922. Serial No. 530,261.

My present invention relates broadly to the introduction of modifying elements into metals, and more particularly to increasing the carbon content of metals 'such as iron and steel, and includes'the introduction into the metal of a carboniferous material in such a form that it will readily combine with the metal with the introduction of the minimum of objectionable material into the resultant product and with the minimization of presence'of any objectionable characteristics, and further includes the introduction of this carboniferous material in a manner that will give the most oflicient results with the least deleterious incidents, with the greatest facllity and accuracy.

Among the principal objects of the present invention are the production of a metal having a modifying element introduced therein, such for example as steel having a predetermined carbon content, accurately produced and reproduced on a commercial scale, a process for introducing the modifiying element i such as carbon during the course of production in such a manner as to gain closely predetermined results, and an improved resultant product, such as steel being within closely predetermined limits and free from objectiona le characteristics.

In the accompanying drawing I havethus treated the manner in which the molten metal entrains the flakedparticles of carbon preferably employed by me.

In the aforesaid drawing which I have provided for the tain steps in the carrymg out of my improved method of introducing a modifying element into a metal in the manufacture, for example, of steel having a predetermined carbon content- I v Figure l is a sectional viewof a mass of flake graphite disposed in a ladle;

' Figure 2 is a sectional View illustrative of the position the contents of the ladle assumes as the streamof molten metal is introduced thereinto; and

Figures 3 and 4 are views similar to those of Figures 1 and 2 illustrative of prior art to an extent desirable for the proper and adequate understanding of my present invention;

As willbe understood on viewing Figures 1 and 2 of the vdrawing, the bottom of' the ladle is indicated at 10, thev mass of flake graphite at 11, the descending stream of mol characterized by purpose of illustrating certen metal from the and the mass 13 It will be observed on inspection of Figure 1 that the flakes of graphlte lie flat in the ladle and being thin consequently quickly attain the proper temperature when the ladle is properly heated.

As the stream of molten metal strikes the flakes of graphite broadside, it turns and entrains them and carries them edgewise downwardly and laterally, and inasmuch as the graphite thus entrained consists, as noted, of very thin flakes, of great superficial area which may quickly and thoroughly absorb heat, they will be readily taken up by and combined with the molten metal and thoroughly disseminated throughout the mass thereof owing to the gyratory motion imparted thereto through the action of the stream 12, and thus a homogeneous product is attained.

That part of the molten mass which is out of the path of the stream 12 floats upon and rises with the top of the rising mass of molten metal contained within the ladle, 10, but is drawn into the mass as the stream of molten metal 12 continues to run into the ladle 11.

On comparing the illustration of Figures 1 and 2 with those of Figures 3 and 4, it will be observed that when carbon in such forms as ground anthracite coal, coke breeze and the like, which is illustrated at 11, is employed, a much greater quantity is necessary in order to have the supply of carbon of the same initial quantity as that indicated at 11.

It will be appreciated also that owing to the relatively impure form of such organic forms of carbon, the volatile matter may be as much as 60% as against 2% in the case of flake graphite. It will readily be discerned that owing to the relative thickness of the particles of such organic forms of carbon not only is a much longer time required for heating them, with consequent oxidization, but also when such organic forms are forced into the mass of molten metal, the volatile matter is entrained and atmospheric air is carried along in such a way as to produce large and most undesirable quantities of hurtgases such as C0, C0,, H 00 and the 1 e.

In the practice of my present invention I have found it desirable or purposes of introducing carbon into metal such as in the manufacture of steel forthe purpose of producing a definite carbon content combined therewith, to employ highly comminuted graphite preferably in the form of flakie graphite. Such graphite is generally commercially pure in respect to sul hur, phosphorus, carborundum and the ike, and is otherwise free from any detrimental content.

In the utilization of flake graphite to be introduced into the metal, as above suggested, I have found it desirable first to introduce into the ladle or other container to be used a predetermined quantity of the flake raphite which is heated and maintained in aheated state in the ladle, preferably by preheating the ladle at least to a red temperature.

The molten metal, such as steel from the furnace, is then introduced into the ladle onto the to of the heated graphite, the temperature o the mass being that required for makso practiced ing steel and the temperature of the gra hite being such that on one hand there will no appreciable chilling action on the metal and on the other hand all volatile or combustible matter will be ex elled.

The flake grap ite being lighter molten metal, and the flakes lying in substantially a horizontal plane, the mass thereof floats as a stratum at the top of the molten content of the ladle, thus forming a protective coating to the metal and preventing oxidization thereof, and as additional molten metal in entering the ladle passes through this stratum it not only takes up in chemical combination a portion of the carboniferous material but also initiates a quasi-circulatory movement of a physically entrained portion through the mass, thus in fact bringing the carbon and the molten metal into intimate contact in the form of a physical mixture, and so facilitatin still further combination between the car n and the molten metal, and the process may be carried on even to the point of saturation.

As a result of the use of flake graphite as a carbonaceous material two important conseguences are effected which are broadly that:

rst, the desired chemical combination between the carbon and metal is effected to a high degree; and, second, the process maybe than the bon may be taken into the chemical combination and thepresence of free or uncombined carbon may be avoided.

By the foregoing practice the maximum contact between the particles of carbon and of molten metal is established, and as a result the maximum of chemical combination between the two is efiected. I

Aaa consequence the exact amount of carbon that will chemically combine with a predetermined amount of molten metal can be that substantially all of the caremploy carbon not in chemical combination,

such so-called grapliitic carbon will be uniformly distributed through the mass, and consequently the amount of carbon necessary to result in a predetermined proportion of graphitic carbon throu hout the mass can also be accurately gauge in advance by the employment of myimproved process.

By the use of carbon in'the form of flake graphite in the process described, I am enabled to obtain not only a steel having an increase of carbon content rise chemically combined of .047% but, with the same proportions between the carboniferous material and the molten mass, the desired results may be Quickly, uniformly, and consistently pro-.

need.

I have thus found in actual practice that the addition of each ounce of graphite (conof 85% ake graphite according to the process hereinabove set forth; Analysis of tie carbon steel so produced showed all combined carbon and no gra hitic carbon whatsoever.

Those who are skilled in the art will appre ciate that not only am I able to produce for example a steel havin a maximum carbon content, but also one t at is simultaneously of extraordinary purity and of maximum density and homo'eneity throughout owing to the ex ulsion o forei and volatile matters and e prevention 0 the occlusion of entrained impurities and gases giving rise to hard spots, pockets and other imperfections.

Owing to the flatness and thinness characteristic of carbon particles presented in the form of the flake graphite preferably emplo ed by me, these particles not only tend to cat on the mass of molten metal in a posii tion best adapted to be entrained by an impinging mass of molten metal but are obviously of a form most particularly adapted for instantaneous heatin and as a consequence combine most quic ly with the metal into contact with which they are brought as will be readily comprehended on consideration of the accompanying drawing.

a mechanical mixture of another portion of the carbon to form graphitic carbon.

it will thus be discerned that l am enabled.

to produce modified ferrous materials wherein. the quantity content of the modifying element, such as carbon, and also the nature thereof may be regulated with great nicety and precision.

it will furthermore be manifest that because of the freedom from volatile matter, sulphur, phosphorus, carborundum and other undesirable elements graphite in the form and condition employed by me, and the fact that such material does not tend to entrain atmospheric air or other gases, the practice of my improved process tends neither to produce carborundum or other hard spots nor increase the amount of occluded gases in, nor the sulphur and phosphorus content of the steel thereby produced but rather to produce and enable the reproduction of a steel characterized as being Within closely predetermined iimitaand consequently one not only free from objectionable characteristics but also one answering the desired specifications.

Having thus described my invention and illustrated use, What I claim as new and desire to secure by Letters Patent is 1. In the process of making steel, the steps which include adding stream of moulten metal to loose 'graphitie material in flake form and in a state or subdivision to be highly mobile whereby the stream of moulten metal will form an intermixed current or" graphitic material and metal to rapidly and completely carburize the metal.

2. In the process of making steel, the steps which include adding a stream of moulten metal to loose graphitic material in flake form, in heated condition short of i a state of subdivision to be ighly mobile whereby the stream of moulten metal will form an intermixed current of graphitic ma terial and metal to rapidly and completely carburize the metal.

3. In the process which include adding a stream of moulten metal to loose graphitic material in flake form and in a state of subdivision to be highly mobile and circulating the incoming stream or" metal in contact with the graphitic material to have substantial portions thereof form a sealing layer for the metal and continuing the circulation whereby the stream of moulten metal will form an intermixed current of graphitic material and metal to rapidly and completely carburize the metal.

a. In the process of making steel, the steps which include adding a stream of moulten metal to loose, unconfined graphite in flake form and circulating the metal relatively to the graphite material to form intermixed currents of metal and graphite.

5. lln the process of making steel, the steps nition and in of making steel, the steps i Which include impinging a stream of moulten metal through a bed of unconfined flake graphite in loose form and in a state of subdivision to be highly mobile, and circulating the metal and rents While substantially maintaining the moulten metal coated with a layer of graphite.

6. In the process of making steel, the steps which include impinging a stream of moulten metal against preheated flake graphite in a state of subdivision to be mobile and freely and completely circulate With the stream of metal and form intermixed substantially uniform currents thereof. V

In testimony whereof I have hereunto signed my name.

JOSEPH RUSSELL (Clllllillill. MARSH.

graphite in intermixed cur--

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