US2125175A

US2125175A - Method of removing metal from the surfaces of billets or similar metal bodies, and the product

Info

Publication number: US2125175A
Application number: US198196A
Authority: US
Inventors: Homer W Jones
Original assignee: Union Carbide and Carbon Corp
Current assignee: Union Carbide Corp
Priority date: 1933-10-28
Filing date: 1938-03-26
Publication date: 1938-07-26
Anticipated expiration: 1955-07-26

Description

July 1938.. Y H. w. JONES 2,125,175 c METHOD OF REMOVING METAL FROM THE SURFACES OF BILLETS 0R SIMILAR METAL-BODIES, AND THE PRODUCT Original Filed Oct. 28, 1933 2 Sheets-Sheet '1 4/ F21 '75 e01 INVENTOR.

HOMER W. JONES BY ATTORNEY 2,125,175 BILLETS H. W. JONES METHOD OF REMOVING METAL FROM THE SU RFACE S OF OR SIMILAR METAL BODIES, AND THE PRODUCT Original Filed Oct. 28, 1933 Jl lly 26; 1938.

2 Sheets-Sheet I 2 INVENTOR. HOMER W. JONES .4 TT ORNE Y Patented July 26, '1938 METHOD OF REMOVING METAL FROM THE SURFACES F .BILLETS OR SIMILAR METAL BODIES, AND THE PRODUCT Homer W. Jones, Westfield, N. 3., aasignor, by

mesne assignments, to Union Carbide and Carbon Corporation, a corporation of New York Original application octosel- 2c, 1933, Serial No.

695,570. Divided and this 26, 1938, Serial No. 198,196

application March 16 Claims. (c1. 148- 9) My invention relates to a method of themechemically removing metal from the surfaces of metallic bodies, such as steel billets and the like of rectangular cross-sections, and to the resul- 5 tant article or semi-finished body.

This application is a division of my copending application Serial No. 695,570, filed October 28, 1933, entitled Apparatus for removing metal from the surfaces of metallic bodies."

It has generally been the practice heretofore to employ heavy machine tools, such as planing, shaping, milling, and chipping machines, for removing or cutting metal from the surfaces of I metallic bodies. Such machines are not entirely satisfactory, because they remove metal at a very slow rate. Further, they are expensive, and their operating costs are high because power is required both for relatively moving the cutting tool and the metallic body and for carrying out a cutting operation. In such machines, also, the greater the hardness of metal the greater is g the amount of power required to make a cut.

Within the last few years the objections of heavy machine tools have been avoided by employing blowpipes having nozzles particularly adaptable for removing surface metal from metallic bodies. These nozzles are constructed so as to permit the passage of a comparatively large I volume of oxidizing gas at a relatively low velocity in such a manner that surface metal is removed and grooves or channels are produced having gradually sloping sides. By making cuts in this manner, the sloping sides of the channels will tend to flatten out and will not fold over and be rolled into the metallic body upon further rolling thereof.

In removing surface metal in steel mill operations it has been the. practice for an inspector to draw chalk marks around. the defects and.

46 seams on the surfaces of a semi-finished shape.

An operator employing a blowpipe of the character just described then removes the defects marked on the top surface of the metallic body and, after such defects are removed, the metallic body'is turned or rotated to present other surfaces to the operator in order to enable him to remove easily the defects in the metallic body.

It. has not been entirely satisfactory to re- 50 move defective metal from the surfaces of metallic bodies when different surfaces of a bar or slab or successive portions of the peripheral surface of around billet are presented to form a top surface, because in this position there is a tendency generally for fin material to remain billet.

on each side of a groove or channel so cut in the surface. The formation of fins is due to the washing effect of the slag as it is forced out of such cut and over the surface of the work by the force of the oxidizing gas stream. The slag may comprise both oxidized and fused or molten metal, and the latter has a tendency to freeze on the sides of the channel and is exceedingly difficult to remove.

I have found that the amount of fin material formed can be reduced considerably by applying the oxidizing gas streams so as to simultaneously impinge obliquely against regions extending across each of the surfaces to be conditioned, such as the top, sides, and bottom of a metallic body. By this method, the oxidized and fused or molten metal is forced out of the channel by the force of theoxidizing gas stream and falls awaytherefrom by the force of gravity. When surface metal is removed in this manner, a substantially smaller amount of fin material is producedon the sides of the channeland a desirable corner formation of the body results. Since it is desirable to utilize the force of gravity for reducing the amount of fin material produced on the sides of the channels, my method is particularly adaptable for simultaneously removing surface metal from all sides of a multisided steel billet or for removing surface metal from the entire peripheral surface of a round In such cases the fin material will be greatest where the force of gravity is least effective in carrying away the metal removed by the oxidizinggas stream. 'lhe body produced by desurfacing in this manner is provided with a clean smooth'new surface free of slag having an improved metallurgical structure as hereinafter described, and having a plurality of contiguous longitudinal shallow channels formed by the oxidizing gas streams.

An object of my invention, therefore, is to remove metal simultaneously from opposite surfaces of metallic bodies with oxidizing gas streams in such a manner that the force of gravity is utilized for carrying away the metal removed.

Another object of my invention is to remove surface metal simultaneously from all sides or the entire peripheral surface of a metallic body by applying oxidizing gas streams against the metallic body along a zone extending about the entire perimeter thereof, and by moving the oxidizing gas streams and metallic body relatively to each other.

A further object of the present invention 2 anamvs therefore is to provide a new article of manufacture produced by thermochemically shallow layes of surface metal from the longitudinal surfaces of a semi-flnished'steel shape such as a 5 steel billet. A further object of the invention is to provide a semi-finished steel billet or the like which has a new surface substantially free of defects, an improved metallurgical surface structure, and longitudinal contiguous shallow surface chanrels.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. In the drawings:

Fig. l is a side elevation, partly in section, of an apparatus for producing the semi-finished article according to the present invention by removing metal from the surfaces of the side walls and top and bottom of a metallic body, the groc-ves formed by the removal of the metal being omitted for clearness;

Fig. 2 is a fragmentary sectional view taken on line 2-2 of Fig. 1 to illustrate more clearly the portion of the apparatus for removing surface metal from a side wall ef the metallic body; Fig. 3 is a sectional view taken on line 3-3 of Fig. 1 illustrating the contiguous shallow channels and rounded corners produced by the surfacing operation;

4 is a sectional. view taken on line 4-4 of E. I Fig. 5 is an isometric view showing an article produced in accordance with thepresent invention; and

Fig. 6 is a view showing a photomicrograph of a portion of the article shown in Fig. 5.

' 40 Referring to the drawings, the apparatus for supporting and moving a number of metallic bodies, such as rectangular shaped billets II in the direction of their length, through an opening formed in a frame F for supporting the cut-.

ting gas-apparatus. The frame structure F may comprise a base i4 and vertical side members I! to which are secured upper and lower transverse members l6 and i6, respectively.

The billets It may be moved in any suitable manner, and as shown a variable speed driving motor M having a pulley iI secured to the shaft thereof drives a belt I! whichis connected to a pulley l9 secured to one end of a shaft l l for driving a roller i2. Although only one roller I2 is shown as driven, it is to beunderstood that other rollers I? may be driven in a similar manner to insure a continuous movement of a number of billets is toward and away from the frame structure'F. T

In the apparatus shown, the oxidizing gas.

I stream applying devices are arranged to apply theoxidizinggassoastoimpingeagainstazone of surface extending entirely across' all four faces of the billet i3 and comprise gangs of blowpipe nozzles 20 at an acute angle to the direction in which the applied streams advance over the surfaces of the top, bottom-and side walls. Eachnozzle is adapted for applying heat ins jets and/or oxidizing gas streams on the sur faces of thebillet l3 remove metal therefrom is removed in the form of molten metal which '1 is blown away with the oxidized metal. by the oxidizing gas streams. To remove metal a portion at least of the surface must be raised an ignition or kindling temperature before the oxidizing gas stream is applied thereto. The entire 15 metallic body can be raised to an ignition temperature, as in a furnace, or successive portions of the surface metal can be progressively raised to an ignition temperature prior to the application 7 of the oxidizinggas stream, as by the blowpipe 29 nezzles 20.

The blowpipe nozzles 20 are so constructed that they will permit the passage of a comparatively largevolum'e of oxidizing gas at a relatively low velocity, and may comprise a central passage for 25 an oxidizing gas to provide an oxidizing gas stream. A plurality of passages surrounding the central passage may be provided for a combustible gas to produce a heatingflame to raise the metal to be removed to -an ignition temperature. Suitable nozzles of the character indicated are disclosed and claimed in applicant's cownding aggicaticn Serial No. 695,571, October 28.

As shown in the drawings, a plurality or gang 35 of nozzles 20 are arranged adjacent to each other and inclined relatively tothe top, bottom, and side surfaces of the billet i3 to'aDDlY oxidizing streams obliquely against and lengthwise of said surfaces for removing metal in a single pass from 0 the entire peripheral surface of the billet. The nozzles 20 are threadedlysecured to nozzle heads 2| having an oxidizing gas passage and a'combustible gas passage communicating with similar passages in the nozzles 20. The noymles'disposed 45 at the top and bottom of the billet I! are ar-.

Theoutsidenozzles 20 may be arranged sumciently near the corners of the bar orxbillet so.

that the oxidizing gas streams will flow over such corners. In this manner, thesurfaces'of the corof oxygen and air, and a combustible gas, such as a mixture of oxygen and acetylene, maybe delivered froma suitableso'urce of suppiy through A 1 flexible conduits (not shown) to manifoldsll and 2' having

connections

25 and 2!, respectively, communicating with the oxidizing and combustible gas passages in the heads 2-] and 2|. 5 r

m removing metal by moving thebillet ii with respect to the nozzles II, itav be. desirable under certain conditions to permit the tips offile males to rest or ride on the bottom of the chans no], that is, on the newly-exposed and 70 I \mderothcr conditions it may be to I maintain the tips of the noz'saes spaced from the surface, as will be hereinafter explained when surface metal is removedwith use" of the noa'xlesriding on the newly-exposed sit '15 2,195,175 face, it is desirable that the tips of the nonles.

only'bear lightly on the surface of the work, so

as tominimize the friction and chattering be tween the nozzles and the work. For this reason, the groups of nozzles 20 and heads 2| disposed at the top and bottom surfaces of the billet II are counterbalanced in a suitable manner, so that the top and bottom groups of nozzles II will bear lightly and yieldingly follow the channel formed.

weight Zllwhich is sildably mounted at one endof a lever arm 253. IZhe weight 28 counterbalances the weight of these nozzles 20' and heads 2i through a parallel linkage A comprising a pair of horizontal linirs 3t arranged in the same horizontal plane in spaced and parallel relation, and a second similarly arranged pair of horizon- "tal links 36 below and in the same vertical planes the upper and lower transverse members I! and 56', respectively, oi the frame structure F. The opposite ends oi the links it and 3| are pivotally connected to the upper and lower ends and to the opposite sides of a block it which serves as a vertical linir in the parallel llage A, and which may be formed integral with the bar 28 to which the nozzle heads 28 are secured. The lever arm lit forms an extension of one of the horizontal links 8t, 'anol hy properly positioning the weight 21% thereon by a set screw 32, the weight oi the' nozzles 2t and heads 25 can be readily counter: balanced, so that the tips of the nozzles 28 will bear lightly on the newly-exposed surface. of the billet as the nozzles 36 and billet are moved relatively. to each other.

Each group of nozzles 255s disposed at a side of the billet it may be maintained in contact with a side surface thereof by a parallel linkage C biased to move the nozzles 29 toward the billet l3. Each line C comprises a pair oi? upper horizontal links it arranged in the same horizontal plane and in'spaced' and parallel relation, and a second similarly arranged pair of lower horizontal links it below and in the same vertical planes as the links it. The links so and ii nearest the billet iii are secured at one end thereof to a vertical pin 42 which is plvotally mounted on

brackets

43 and 46 attached to the vertical side members l5 of the frame structure F, and the outer links 4e and iii are secured at one end thereof to a vertical pin 42 which is pivotally mounted on projections 43' and It attached to the vertical side members it of theframe structure F. The opposite ends of the links 49 and H are pivotally connectedto the top and bottom corner portions of a block I! which serves as the vertical link of the linkage C and which may be formed integral with the bar 23' to which the nozzle heads II at the side of the billet I; are secured. I

To cause the linkage C. to swing toward the side of the'billet ll so that the tips of the nozzles II will contact the side surface thereof, the end of the upper and outermost link I, which is secured to the pin 0', is provided with a right angle extension extending toward the billet IS; the link 40 and its projection 46 forming a bellcrank, as shown in Fig. 2. In the space between the upper links 40 and lower links 4|, a lever arm I! having a weight is slidably mounted thereon, is plvotally connected at one end thereof to a projection 49 attached to a vertical side member I! of the frame structure I", as most clearly shown in Fig. 4. The pivotally connected end of the lever arm I! is provided with an upward extending extension 56, the upper end of which is adapted to contact the extension 48 of the upper and outermost link 46 and cause the linkage C to swing on the pivotally mounted pins 42 and 82' .toward the billet it. By properly positioning the weight on the lever arm' 41 by a set screw 5i, the moment of force of the weight and lever arm can be so adjusted that the nozzles 28 will be moved by the linkage C to contact the surface of the billet IS with the tips of the nozzles bearing lightly on the newly-exposed surface as the.

pneumatically, by providing cylinders E adapted to be connected to asuitable source of compressed air (not shown), and having therein movable pistons 56 connected to piston rods [52 extending agrarian an opening in the end wall of the cylin- As shown in Fig. l, the air cylinder E at the top of the frame structure F is mounted on a plate 53 attached to the upper transverse frame member It. The end of the piston rod 52 is pivotally connected at Bill to one end. of a link 55, the opposite end of which is plvctally connected at 58 to the upper end of a link El forming a right angle extension of one of the horizontal links 30 of the linkage A. The horizontal link 3i! and its extension bl form a bellcranl: for converting the straight line motion oi the piston rod 52 to an angular motion of the linkage is. When the piston ti is caused to move to the right by admitting air under pressure into the cylinder E, the bellcrank, which is pivotally mounted on the projection as, will turn to the right and swing the linkage A and nozzles 2% carried thereby upward against the movement of force of the lever arm 28 and weight it. The distance of the tips of the nozzles 20 from the top surface of the billet can be readily controlled by regulating the pressure of the air in the cylinder E.

A cylinder E is mounted on the "case 66. of the frame structure F, and the piston thezein is con- .nected to the lowerlinkage A in the same manher. as described .above for moving the lower group of nozzles 20 away from the lower surface of the billet and for adjusting the lower nozzles in reference thereto.

The linkages C at the sides of the billet it are likewise pivotally connected to the pistons in cylinders E for maintaining the tips of the nozzles 2|! spaced from the side surfaces of the billet.

As shown in Fig. 2, the cylinder E is mounted on g a plate I attached to the side member I I of 7s 4 the frame structure '1". The piston rod 52' is pivotallyconnected at 59 to one end of a link 60, the opposite end of which is pivotally connected at 6| to the outer end of a link 62 forming a right angle extension of one of the upper horizontal links of the linkage C. The outer link 40 and its extension 62 form a bellcrank for converting the straight llnemotion of the piston rod 52 into an angular motion of the linkage C; and, as explained above in connection with the linkage A, the pressure of air in the cylinders E at the sides of the billet canbe controlled so as to regulate the distance of the tips of the nozzles 20 from the side surfaces of the billet.

In the event it is desired to remove surface,

metal from round billets the nozzles 20 may be arranged on a circular head adapted to encompass the billet so that the nozzles converge on the axis of the billet and form an acute angle therewith of between 10 and 35. The head may be made in a plurality of sections and operated by linkage mechanism similar to that shown in the drawings. Y

The operation of the apparatus illustrated in the drawings is substantially as follows: It will he assumed that the billet It or other work to be treated is mounted on the rollers l2 and in proper alignment, with the right hand-end of thebillet i3 adjacent the tips of the nozzles 20; that the positions of the counterweights 28 and on the

lever arms

29 and 21, respectively, have been ad'- justed so that the nozzles zcw n bear lightly on the bottom of the cut; that the source of compressed air is not connected-to the,cylinders E V l and that thepistons therein will move freely:

and that the manifolds 25 are supplied with a mixture of oxygen and acetylene, respectively.

With the above assumed conditions, the combustible gas'issuing from the,tips of the nozzles 20 is ignited so that the heating flames will be applied to the entire peripheral surface of the billet at the right hand end thereof. As soon as "the portionsjof the peripheral surface at the end of the billet have reached an ignition temperature, oxygen is supplied to the

manifolds

24 and 1 the motor M is connected to-a suitable supply of electrical ener (not shown) to drive the billet [3 from left to right, as indicated by the arrow shown in Fig. 1. The oxidizing gas streams issuing from the orifices of the-nozzles 20 areap- 4 plied, at an acute angle to the surfaces of the billet 13 and will. oxidize the surface metal at the right hand end thereof which has been raised to an ignition temperature by the heating flames; and this oxidized metal, along with molten metal,

: will ,be-blown ahead of the nozzles 2. in the form "of ,a slag bythe force of the oxidizing streams. JT-he several-oxygen streams issuing from the four groups of nozzles 20. thus effect superficial metal [combustion along a relatively wide transverse 7 zone of each surface of the billet i3 and, during ;the movement of the billet relatively to,the nozzles 2', the volume, velocity, and angle of imof the billet latter."

-jpingement of the oxygen streams aswell as the rate ofsuch movement are so correlated as to maintain. such superficial metal combustion on successive1surface zones from onexend of the g Ibillet toitsopposlte end, to produce continuous gtyanduniform thermo-chemical removal of a .wide shallowlayervof 'metal from each of the surfaces throughout the-entire lengths of the "Ihejtips of the we, a may reston the: bottom of. the out at the righthand end of I' W ll lv ereupon the latter is moved relablown ahead of the zone of 'reaction by the force of the oxidizing gas streams; while at the sides and bottom of the billet such oxidized and molten metal are effectively carried away by the force of gravity to fall clearof the nozzle supporting mechanism which holds the nozzle offset a substantial distance from the supporting frame.

In the description of the operation of the apparatus, it has been stated that the oxidizing gas streams blow away oxidized and molten surface metal, and this mixture of oxidized and molten surface metal has been termed a fslag, Although the surface metal removed can be reduced completely to an oxidized form, it has neither been desirable nor necessary to do so inpractice. For example, it, has been calculated that approximately 4% cubic feet of oxygen are required to oxidize completely one pound of an ordinary grade of low carbon steel containing about .2% carbon. In

feet of. oxygen. It is therefore apparent that a portion of the surface metal removed is in an oxidized state, and that the remaining portion is in a partially oxidized state and in an unoxidized'state or molten form. By removing a substantial portion of surface metal without completely oxidizing the same, considerable economy can be efiected inthe amount of oxidizing gas required to remove metal from the surfaces of metallic bodies.

'Although the removed metal or slag blown Y ahead is reduced substantially to a non-adherent state, there is a tendency for the molten metal a forming partof the slag to freeze, on the sides 5 of the nozzles fromthe work. Asstated above,.

however,- it is generally not desirable to completely oxidize the metal removed in order to' remove surface -metal as economically as possible. It has been found that fin material formed on the sides'iofxa cut when the slag is not completely oxidized is extremely small when the force .of gravityvcanbe. utilizedto carry away the slag fromithe'sur face of the work. Forv this reason,

' it isa distinct, advantage to remove surface metal fromthe 'sidesan'dbottom of a metallic body, and

at the same time remove such metal with a mini- I mum consumption of oxidizing gas. Where metal is tobe removed from a single side or. portion of a" peripheral surface or a body it can be so arranged thatthe force of gravity can be effectively utilined to carry awaythe metal removed. In cases where-metal is to be removed from all sidesor the entire" peripheral of a metallic body, it is preferable to remove the surface metal in a single pass of thenozzles relative tothe metallic body. force of., gravity-wil l carry. away removed metalfrom a considerable portion of the peripheral surface of the metallic body.

In the normal production work the new sur: faces produced are sufficiently smooth for all practical purposes. In certain instances,- however, it is desirable to produce particularly smooth surfaces. In order to make channels which are particularly smooth, the nomles 2. are adjusted so that their tips will be spaced from the bottom surface of the channels produced. This is accomplished by connecting the cylinders E to a source of compressed air so that the linkages A, B, and C will swing the nomles Ill away from the top, bottom and side surfaces of the billet it against the moments of force of the lever arms and weights associated with the linkages. By varying the pressure of the air supplied to the cylinders E through a suitable pressure regulating valve or similar-device, the distance of the tips of the nozzles 20 from the surfaces of theillet can be readily controlled. Although smoother cuts are obtained when the tips of the nozzles are spaced from the bottom of a cut, it is considerably more economical to remove metal with the nozzles riding upon the newly-exposed surface because in the latter case less oxidizing gas is required to remove a pound ofmetal, other factors remaining substantially the same.

The air cylinders E may also be employed to swing the nozzles 20 away from the surfaces of the work to start a cut at an end or at a point intermediate the ends of the work, or to align the nozzles with respect to the work before starting a cut.

It has been stated that the nozzles 20 are of such a typethat theywill permit the passage of a comparatively large volume of oxidizing gas at a relatively low velocity.. In-practice it has been determined that the best results under average conditions are obtained in most cases when the pressure of the oxidizing gas is'adiusted to produce an oxidizing gas stream havinga velocity between 550 and-750 feet per second. However, higher or lower oxidizing gas stream velocities may be used to suit different conditions and results desired. The velocities of the oxidizing gas streams stated herein are the calculated velocities of the gas discharged from the nozzles based on the assumption that a measured quantity of gas discharged in a given time has a temperature of 70 degrees F. and is at atmospheric pressure.

The newly-formed grooved surface. produced on a billet is illustrated in Fig. 5 where the contiguous parallel shallow channels are indicated at 66. The channels have sides which slope gradually to ridges 61 that define the contiguous boundaries between the channels. The desurfacing process described herein provides a desired convexly rounded contour of the corners 65. I

The depth of the grooves or channels '6 and the height of the ridges 61 between them may be made more or less pronounced than illustrated herein to suit the working conditions. The depth and width of the channel are affected by" the velocity of the oxidizing gas stream, both the depth and width increasing with an increase in the velocity of the oxidizing gas stream. The nozzles employed in the present apparatus are capable of producing individual cuts or grooves about 1% inches in width and $5 inch in depth when the discharge velocity of the oxygen is about 585 feet per second and the rateof movement of the nomle with respect to the surface is about 6 feet per minute. Cuts of'such rcla tively wide width are clearly shown in Figs. 3 and 5. The depth and width of the channels, therefore, can be partially controlled by varying the velocity of the oxidizing gas streams.

In the drawings the nozzles II are shown at an acute angle of approximately 25 degrees with respect to the work. Satisfactory cuts have been made with nozzles at acute angles varying from 10 to 35 degrees with respect to the surface of the work. Although the nozzle heads II are shown fixedly secured to the bars 2] and 2|, it may be desirable to provide means for varying the acute angle of the nomlcs with respect to the work, and to provide suitable indicating means for setting the nozzles at a particular acute angle. Although the depth of a cut does not change appreciably with a change in the angle of the nozzle with respect to the work, a marked increase in the width of a cut is obtained with an increase in the angle at which the nozzle is set.

At very low speeds satisfactory cuts are not obtained. This in part is caused by the metal slag piling up ahead of the nozzle. In order to avoid the undue reaction of the oxidizing gas stream on the surface of the work, it is moved relatively to the work at a speed sufllcient to prevent the oxidizing gas stream being applied for too long a time at any particular portion of the surface of the work. By way of example, satisfactory cuts have been made on cold metal by moving nozzles relatively to the work at speeds varying from i to feet per minute, i. e., at a substantially uniform rate of speed higher than the maximum speed heretofore conventionally employed for severing metal by means of an oxygen jet.

For example, when using well known high velocity oxygen jets for cutting or severing mild and structural steels at room temperatures, conventional machine cutting speeds for propelling the cutting nozzleor blowpipe relatively to the steel body vary from about 2.4 inches perminute for steel of 12 inches thickness to 32 inches per minute for steel of one-eighth inch thickness.

1 Removing surface metal in the manner described above is particularly advantageous in steelmill operations where semi-finished steel shapes are at an elevated temperature, such as 1600 F. or higher, for example, after'a rolling operation which reduces the cross section of the semi-finished shapes and'elongates them. .When machine tools and chipping tools are employed to remove surface metal, it is necessary to allow the bars and billets to cool beiforesurface metal can be removed with appreciable accuracy. With my improved apparatus, surface metal can immediately be removed from bars and billets that are at an elevated red heat temperature during tion of oxidizing gas streams than metals of lower hardness, such as the low carbon Since the harder metals respond more readily to the action of an oxidizing gas stream than metals of lower hardness, the costoi' removing sin face metal does not increase with the-hardness of the metal cut, as is the case with the heavy machine-tools heretofore used where the amount cf power required to make a cut increases with the hardness of the metal.

The resulting article produced, when a body of ferrous metal is desurfaced in accordance with the invention, has a new envelope with properties whereby the article may be identified and differentiated from the metal of the body before being processed and also distinguished from that of similar articles produced by other processes. The new envelope has a surface which is clean, smooth and glass-like and relatively free from discoloration and is characterized by a series of contiguously formed uniform parallel channels or paths traversing the surface. The photomicrograph depicted in Fig. 6 shows a portion of the envelope, extending tothe surface, of a typical etched and polishedsection of such desurfaced body; the portion being composed of four zones or strata of different crystal structures, deneted respectively d, e, f, and g. Here the lowermost stratum 9 shows the unchanged interior structure'of the body, while the strata d,;,e, and ,f are seen to consist of a changed or new flne grain structure that is substantially free from mechanical deformation and is of increased hardness.

' The zone f, comprises largely troostite which is formed by ;rapidly cooling from a temperature just above the transformation temperature; while zone e comprises mainly martensite formed by cooling from a higher temperature. The topmost stratum d is seen to consist of a layer that contains needles of martensite, embedded in a matrix of austenite whose presence shows that this zone has an excess of carbon over that of the average composition of the body, which carbon is relatively uniformly distributed and imparts to the body a surface having increased hardness andresistance to oxidation. The appearance of zone the desurfaced face indicates that portion was cooled from the fused state.

The average depth or extent of thisnew structure below the surface is 3; inch. 3 billet desur- 45 faced according to the present invention thus has the further advantage, as an intermediate product to be processed in the steel mill, over a billet otherwise desurfaced, that the excess of carbon engendered in its'surface counteracts the "surface decarburization usually encountered in cpnnection with the reheating of such intermediate products, since there exists'in the surface of a billet, when thus desurfaced, a desired excess of carbon. i Z

While I have shown and described 55 v a particu- 'lar embodiment at my invention including a rectangular metallic body in which surface metal is v:removecrfrc'm' all sides, it will be apparent that modifications be'made for removing surface fmetal from any multi-sided or round metallic body,andthat certainfeatures can beusedindependently of others without departing from the spirit and seope of my inventiora. V

I claim:

1. A conditioned semi-finished billet of rectangular cross section having all four of its lateral sides consistinfof surfaces formed by thermochemically a'sballow layer of of said sides by applying oxi-' surface of parallel shaldizlnggasstremobliquelyagainstsglccessivelow ehannelsthermmchemically produced by ithe application of voluminous relatively low velocity oxidizing gas streams against and longitudinally of said surface when at ignition temperatureso as to remove metal from the entire lateral surface of said billet, said channels extending "con-.- tinuously lengthwise of said body from adjacent one end thereof to adjacent the other end thereof 5nd having substantially uniform depth and width throughout the entire length thereof 3; A thermo-chemically surfaced steel billet of rectangular cross section having a least two of its lateral surfaces substantially free from surface defects such as cracks and seams, and con'- sisting of contiguous parallel shallow channels thermo-chemicallygiroduced by the application of voluminous relatively low velocity oxidixing gas streams against said surfaces'when at ignition temperature so as to remove metal from such surfaces, said channels extending. continuously from adiacent one end of said billet to adjacent the other end of the same, said channels having sides sloping gradually to ridges severally defining the contiguous boundaries of said channels.

4. A thermo-chemically surfaced steel billet of rectangular cross section having all four of its lateral surfaces substantially free from ,surface defects such as cracks and scams; each of said surfaces consisting of contiguous parallel shallow channels thermo-chemically produced by the application of voluminous relatively low velocity oxidizing, gas streams to said surfaces when at ignition-temperature so as toremove metal from such surfaces, said channels extending continuously from adjacent one end of said billet to ad- 35 jacent the other end of said billet and having sides sloping gradually to ridges severally defining the continuous boundaries of said channels, the four iongitudinalcorners of said billet being convexly rounded;

5. As an article of manufacture, a body of ferrous metal which has been desurfaced with oxidizing gas impinged with a relatively low velocity, said body being" characterized by the formation of a'fnew surface envelope consisting of a layer having a hard, smooth, glass-like. 111stresisting surface produced by the impingement of I oxidizing gas at a relatively low velocity and in Qvoluminous amounts when said surface is at ig- 'nition temperature, and is composed of a substantially uniform fine-grained. structure that contains carbon relatively uniformly distributed therein and in excessofi that of the average composition of the body, said surface having a plurality of contiguous channels formed by the oxidizingjgas traversing the same.

6. an article of manufacture, a body of fer= rous metal which has been desurfaced by a thermo-chemical reaction with a stream of oxygen impinged with a low velocity, saidbody being characterized by the formation of a new envelope having a hardgf smooth, glass-like'highly rust-resistant surface produced by the impingement of oxidifing gas at a relatively low velocity and in volummous amounts when-said surface is fat igniition temperature, said surface being coniposed of a uniformly flnegrain structure that contains carbon substantially uniformly dis-' tributed in excess of that of the average composition. of the body, said consisting of 7 contiguous channels eyhich are substantially free elongated from steep sides, flnsland discoloration. i'L-As an article of manufacture. a semi-finished hot rolled steel billet which has been de-,

s i-f ces by a theme-chemical reaction of a hot rolled steel billet which has been desur-y faced by a thermo-chem'ical reaction of the surface metal thereof with relatively low velocity oxidizing gas streams progressively and longitudinally applied obliquely against and along the surfaces while'the latter are at an ignition temperature, said billet having a longitudinal surface comprising a new relatively thin surface envelope composed of a uniformly fine grain structure con- I taining carbon substantially uniformly distributed and in excess of that of the average composition of the billet.

9. The method of thermo-chemically removing a layer of metal from a surface of a body of fer-v rous metal such as a steel billet, which comprises relatively moving said body in the direction of its length with respect to a blowpipe device; delivering a high temperature heating flame and a.

voluminous low-velocity oxygen stream obliquely against a zone of metal extending completely across said surface to efi'ect superficial metal combustion along such zone; so correlating the volume, velocity and angle of impingement of said stream and the rate of such relative movement that a substantially uniform layer of surface metal is removed from said surface; and during such relative movement. maintaining said surface of the body at a substantiaiangle to a horizontal planeto cause the slag which formsat the zone of combustion to fiow transversely oil. the surface under the influence of gravity whereby substantially little fin material adheres thereon.

10. The method of desurfacing bodies of ferrous metal having a rectangular cross section which comprises raisingthe temperature of the surface to be removed to its ignition temperature. applying a relatively voluminous amount of oxidizing gas at acute angles to two adjacent sides of said body in the form of relatively wide streams of oxidizing gas impingingat a series of points extending entirely across each of said adjacent sides, compensating for the effects of such application on adjacent sides by the simultaneous impingement of similar relatively wide streams of oxidizing gas similarly applied to sides opposite said first named adjacent sides. and effecting relative motion between said body and said oxidizing gas streams whereby a body entirely desurfaced on foursides is produced in one pass.

11. Inthe process of hotrolling bodies of fer-' rous metal that have rectangular cross sections, the steps for'.;eifecting desurfacing of such body at a desiredp'oint in the mill processing the body being rolled, which consist in relatively moving said ;body at said point in the mill horizontally with to a device provided to deliver oxidizing gas while the average temperature of said body may be as greatas 1600 FL, and delivering a relatively voluminous amount of-oxidiling gas so as to impinge simultaneously on opposite sides with low velocities in-a substantially contimious series of points which extend entirely across the width of said impinged sides and inclined to said impinged sides at constant acute angles to the direction of advance,'said angles having values between 10 and 35 degrees. whereby surface metal is removed from said body from a plurality of sides in a single pass, the removed material falling away leaving clean sides and a corner forma tion relatively free from fins.

12. In a process of hot rolling bodies of ferrous metal that have rectangular cross sections, the steps for effecting desurfacing of such body at -a desired point.in the mill processing the body being rolled, which consist in relatively moving said body. at said point in the mill horizontally with respect toa device provided to deliver oxidizing gas while the temperature of the surface of,

direction of advance over said surface, said angles having values between 10 and 35 degrees, whereby surface metal is removed from said body from all four sides in a single pass leaving a body having rounded corners substantially free from fins 13. A proces for simultaneously thermo-chemically removing a layer of metal from eachsur face of two opposite longitudinal sides of a ferrous metal body of rectangular cross-section,

such as a steel billet, which comprises applying a high temperature heating flame and a voluminous low-velocity oxygen stream obliquely against a zone of metal extending across each of said surfaces to effect superficial metal combustion along such zones; effecting continuous relative motion between said body and such flames and streams lengthwise of said surfaces; aand so 001? relating the volume, velocity, and angle of impingement of each of said streams and the rate of such relative motion that combustion of superficial metal is maintained on each of said surfaces during such relative motion to produce substantially uniform thermo-chemical removal of layers of metal from both of said longitudinal sides in a single pass of said body said flames and streams. r

14. A process for simultaneously thermo-chemically removing a wide shallow layer of metal from each surface of two opposite longitudinal sides of a ferrous metal body of rectangular cross-section, such as a steel billet, which comprises continuously moving said body at a uniform rate and horizontally in the direction of its length while said body is at an elevated hot rolling temperature and while said sides are maintained substantially vertical; during such 'movement of said body applying a low-velocity voluminous stream of oxidizing gas obliquely against a zone of metal extending entirely across each of the surfaces of said vertical sides to effect 96 ficial metal combustion along such zones and so correlating the volume, velocity, and angle of impingement of each of said streams and the rate of movement of said body that combustion of superficial metal is maintained on each of such vertical surfaces throughout such movement to produce theme-chemical removal of substan relatively to vertical sides in a single pass of said body relatively to such streams of oxidizing gas.

15. A process for simultaneously thermo-chemically removing a layer of 'surface metal from each of the four longitudinal sides of a ferrous tion of the length of said body and from one end thereof to the other end thereoi; and so correlating the volume, velocity, and angleof impingement-of said streams and the rate of such relative motion that superficial metal combustion is maintained on each of said sides during such relative motion to produce thermo-chemical removal of layers of metal from all of said sides in a single pass of said body relatively toaaild flames g5 and streams.

16. A process for thermo-chemically removing a shallow layer of metal from the entire lateral surface of an elongated ferrous metal body, such as a steel billet, which comprises concurrently applying high temperature heating flames and relatively low-velocity voluminous oxygen streams obliquely against a zone of metal extending -around the entire periphery of said body to eflect superficial metal combustion along such periph-' eral zone; eil'ecting-continuous relative motion between said body and such flames and streams in the direction ofthe length of said body and at a uniform rate from one end of said body to the other end thereof; and so correlating the volume, velocity, and angle of impingement pf 7 said streams and the rate of such relative motion that superficial metal combustion is maintained at successive peripheral zones of impingement of said flames and streams during such relative motion to produce thermo-chemical removal of a shallow layer of metal from the entire lateral I surface of said body in a single pass of said body relatively to said flames and streams.

110mm, w. JONES.