US1034786A - Process of producing alloy steel. - Google Patents

Description

A. E. GREENE.

PROCESS 0F PRODUCING ALLOY STEEL.

APPLICATION FILED JAN. 6, 1909.

1,034,786. Patented Aug. 6, 1912.

, UNITED STATES PATENT; OFFICE-i..

ALBERT E; GREENE-"0E CHICAGO, ILLINOIS, AssIGNon v:tro AMERIcANf-ELECTBIC sMEL'rING AND ENGINEERING coMIANY, or sfr. .I .oUIs, MIssoURI, A coiiPonArIoN 0F MISSOURI.

T0 all whom it may concern.'

Be it known that I, ALBv ,citizen of the United States, residingat Chcago, in thecOunty of Cook and State of Illinois, have invented a certain newv and useful Improvementv in 'Processes of Producing Alloy Steel, of which the following is a full, clear` concise, and exact descrip-y sist) of any one or more of the following,

namely, titanium, silicon, lnickel, cobalt, molybdenum, tungsten, chromium and the like.

The process of my invention .has for its' object in general the production,l in :a rapid and etlicientinanner, of alloys free to the desired deg/te from such impurities as carbon, siliconjsulfur, phosphorus, etc.

In the-case of iron alloys the process has for its object more particularly the production of the type of alloys known as steel, approximately free from phosphorus and sulfur andy having their content of carbon regulated as desired from a miximum to a minimum, While retaining inthe alloys any of the aforementioned metals that may be desired to retain therein.

The processes now in general use for producing alloy steels are basedvon the addition of a low-carbon ferro-alloy to thedesired grade of steel and thus producing the alloy-steel. For example, manganese-steel is commonly produced by adding low-carbon ferro-manganese to ordinary steel ivhilethe latter is in a molten condition. In the production of such low-carbon ferroalloys it has heretofore been found easier to reduce the oxids of the metals 4with an excess of carbon, either in a blast furnace or in an electric furnace, and then to refine the resultant product, containing an excess of car bon, to produce the low-carbon ferro-alloy. The refining operation has been either by the Bessemer process or else by an electric furnace process. These processes are unts aspects'my invent-ion con-` PaocEss or riionUcING Annoy s'rEE'L.-

Specification of Letters Pate-uta .Pa,te11ted-ug, 6, f Appnavtidn,nl gi-'Ia'uary 6,'1'909;"' serial meer f Satisfait-aff; fai aie rasa 'aia f @ma cost-ly 'and ineicient.

"The refining by the Bsisema-aaa the' ii'iherenti objectinfoflack of tempera,- ture, "regulation, Vresul t ir'1g"` in, an {inefficient} control ofthe process.` lNIoreover i n'," s lfich refining processihe metalto be reti'ri'edfitself su'ffersfloss by, oXidat-ion.`j Forgthese .reasons the refiningbysuchf'processwof alloys of iron with such metals as'jmanganese andnickel to produce an alloysteelhas even been found impossible. It'hsrinugeneral been 'found morfeconomicali for the production of] low-carbon a'lloylsteels-,` to

produce a refined higlipercent(V lloyfand add vthis tothe refined y steel insuchpioprtions'as Vto give thedesiredprodiict.

metals like chromium, tungst'emtli'tanium, etc., Whichitis more economical toft-reat ,in

an@ electric furnace', difficulties have been experienced in the' elimination ofmtheiexcess of carbon, such eliminationrequiringconsiderable length of time -With' a .resultant increase in cost, and also, in=certain cases being attended with a loss of the I desired metals themselves by oxidation.

My invention contemplates the production of the. refined steel or other. alloyrv directly from the ore or from tlieproduct-:of the blast furnace, as may be deemed desirable, 4i'n the case of themore easily reducible metals, and in the case of alloys of the more refractory metals to produce such alloy in concentrated form free from impurities. So far as I am such impurities as carbon, silicon, sulfur y and phosphorus, andto remove any or all of such impurities tothe desired degree, while retaining .in the'bath the metalA which it is desired to alloywith the iron to pro,- duce the alloy-steel.

The process of my present invention is in general similar to the process set forth in my co-pending applications Serial Number 444,740, filed July 22nd, 1908 and Serial based upon a corrlined regulation of the furnace temperature and of the'pressurefcfy dissociation of the active-constituent or con-.-

stituents of the gaseous agent employed for producing reactions in the' molten material under treatment,

My invention further consists in 'regulating the temperature and-actual pressure in the furnace chamber in which the ma! terial is being treated in such manner AAthat. volatiliz'ation of the metalsfforming the,

alloy is lessened lor prevented, and in meanwhile blowing the bath withfa' gas havinga pressure of dissociation or partialy pressurel a type of 'electric furnace in which the -ccny centr-ation of high temperatures 'at'.,onejor more points avoided, since'ksuchfconcen'- tration of temperatures is yhable to cause a volatilization of the 'vola't'izable Velements of=` the bath.4 While the practiceof this ,process 5 is not confined toA any'iparticular type "of furnace', ,and though 'aHeroult or Girod furnace may be employed, I preferablypractise this process in connectionwith arinduction furnace or other furnacein whichthe bath is uniformly 'heated throughout 'pandgfprefl erably yuse a furnace without carbon:elec4 trodes whenever the carbonisfn'ot desired'` in the alloy. In theaccompanyingjdrawin s two such types'of furnaces are shown. n'said drawings, Figure 11 is asectional "It'ievt of an electric furnace on'the line 1 9-1 of Fig. 2, showing one type of furnace with ,which my invention may epra'ctis'ed. Fig. 2 is a sectional view on the l1 ne"'2-2 of Fig. l. Fig. 3 is a'vertical section"of 'an.induc tion furnace with which the' process may be practised; 'and Fig. 4 is a plan View of thelfurnace shown in Fig. 3. l u A.

-Similar reference characters Y'are used to designate similar parts wherever shown.

Referring to Figs. 1 and 2 thesteel casing 1 of the furnace is supported from trunnions. 2, 3, in order that the furnace maybe tilted in the usual manner. The side walls 4 are made of refractory material, and the crucible 5 is provided with aremovable top 6 of silica or other suitable material, Electrodes 7 7 extendthrough the side walls of the furnace and dip through the slag 8 into the metal 9 of the bath. 'H OWeVer, by tilting the furnace, the ,electrode on one side of the furnace can'be made to dip only into the slag, and the electrode on the other side into the molten metal. By thus causing the electrodes to dip into the bath, the formation of an arc is avoided, this being desirable for the `reason that the high temperature of the arc concentrated at one or more points lil-telly tibi-@cause H:a volatiliz-ationiof certain v olatillzable elements whichitmay be desirable'to-retain inthe metal. Sincerthe elecvoltage and high amperage Aisiemp'loyed, and

lthe'current?may "be regulated 'by varying the voltage. Either direct or alternating :current -m'ay be einloyed, but in'some cases Ilpreferablyem 'loyjdirect current to assist by electrolysis t e reduction of the metallic oxlds. The trunnionwQ is hollow topprovide a, passage-,10 Vcommunicating with the twyer "pipe"11. ""Twyers' 1:2," 12' extend downward .through thewall 4r (see Fig. 2)`. The blowing""'gas fisfintroduced" under pressure throughv the passage 10 to A,the twyers'12 in the usual manner; Saidtwyer's'are inclined downward inorder that the gas ,may be more thoroughlyblown into the bath. The exhaust gas'is preferably led out through theexha'ustpipe -13;.since such gases are ordinarily collected on account of their value.

Figs 3a1id`4 showa'well-known type of induction furnace'fwThe' steel casingv 14 thereof maybe supported in' any 'v suitable niannerfITl'ie' walls 1,5 inclosed inr'said' casing' are' annular Lin shape and' surround vone leg'lof the"trans fr1rier core I16. Said core is vp'fou'niiwith"one4 lo-rgimore lcoils v17, 'which serve 'aslfthe{priiiiary` ofthe transformer, the sondaiy'thereofbonsi'sting of the metallic batlrlS contained in the furnace chamberf1'9. Thevolt'age impressed on" the primary of 'theiinductio'n furnace may be varied at will,l thereby regulating'l lthe temperature ofthe'bath "The'chamber fis provided with a cover',"which is preferably made in a plurality 'of sections 20.' Gas is admitted from the"gas'main 21 and the'tiowvthereof is controlledv by the valve 22. he twyers 23 which are connected by means of pipes 24 with' the 'gas main extendl through thecover 20.! The exhaust gas passes out through eX- haustI gas pipe`25."

. In certain cases, aswill hereinafter more fully appear, the process ma be advantageously expedited by control ing the pressurein the'furnace chamber. I may, therefore, employ'fa suction fan 2G 'for removing the exhaust gases asformed through the exhaust pipe 25', thus kmaintaining the atmosphere withinthe"chamber und'er a' reduced pressure. While'the twyers'are shownas directing thegas down upon the surface of the bath, any well known arrangement-of twy'ers for introducingthel gas into the bathmay be substituted for 'th'e varrangement shown. Tn practice I wor-krat a'temperature as slightly as is practicable above the melting point of the materialu'ndertreatr'nent, as'for example, 1500o C.' 'to 1600 'in tine/'casey of manganese alloys. To 'remove the oxidizable impurities the molten .bathj'is blown with a gas having an oxygen pressure at said temperature which renders it an oxidizing agent impurities.

Withl 'respect 'toi the limpurity or impurities whichit is desired to eliminate by, oxidation, but Which'acts as a non-'oxidizinglor-even a reducing lagent Withrespect to the -metals which' it is desired toret'ain'in the bath.' In

the 'treatment' of alloys vcontaining mangaaiding in the removal of carbon as a compound ivith oxygen. This 'method of-expediting the action by reducing the pressure on the bath of the gases .escaping therefrom is especially applicable to cases-in which the metal 4or "metals to'fbe reduced are volatile only' at a high tem' Arature, as for example titanium.` It will bel understood, therefore,

that the charaeterof the charge andthev de vree' of eliminationfdesired must be taken into considera-tion in determining the tein- `perature, vtotalA pressure' yfof'tl'ie gas, the inactive constituent of the gas, and the oxygen pressure thereof" For example, Where excessive pressure"conditionsif are desirable 1in order'to diminish vaporiza-tion of the volatilizableinetal, vI Vavoidfcontaminating the metal with nitrogen by substituting Water or hydro-carbon or products resulting from the desired'reactions for nitrogen in the gaseous mixture. The requisite pressure of oxygen'in the gaseous mixture may be obtained without the'presence of nitrogen by substituting ltherefor steam together with a reducing gas, as for example carbon monoxid or hydrogen. This might be done by mixing ivith water gas (as for example a gas containing by volume 45% CO, 45% H, and 4% CO2 and vtraces of nitrogen), .a suitable amount of carbon dioxid, steam .or other oxygen containing gas yto give the desired oxygen pressure. Furthermore, in treating metals which have astrong afiinity for can 'boinand which reduce carbon from carbon containing gases, as does chromium, I einploy'aii oxidizing gaseous mixture of the vproper oxygen pressure freefrom carbon compounds. In such event the desired partial pressure of the oxygen can lie-obtained, for example by diluting oxygen or air or steam `with a reducing gas, such as hydrogen,

not containing carbon.

iVliere sulfur and phosphorus are present,

I l melt with the bath a calcium orvother alkaline earth containing flux to slag oft these ln suoli case the treatment of the inateiial by the above described selective oxidation process will eliminate the oxidiz- -followsl (1)All the heat generated is sayedr;

able impurities without oxidizing-the metals of-t-he bathpand since the slagisftliusf kept praeticall free from metallic Aoxids, Vas yfor example iron'oxid,; it-.will also readily take upthe sulfuras a slag.- 5 ;l ,f E y lpreferto removethe carbon'v orotheroxidizable impurity in the manner described herein, and-then to-blow -tlieubath with-a gas havingless oxidizingfand @more reducing propertie's,'as I have found that such subsequent treatment results in a further removal of sulfurzand phosphorus.

There `are severa-l advantages resulting from conductingall the operations on the product of the vblast` furnace in the electric furnace, rather than first treating it in an ordinary converter to remove the carbonand then continuing the treatment in the electric furnacel' Sonie of4 these advantages-.areas (2) vthe carbon monoxid generated during' the-removalothe carbon reacts lititli the slag and .causes conditions favorable to the removal .of sulfur and phosphorus; 3) the slag is heated Vduring the processpf removing the carbon by what Wouldothervvise be :Waste-heat; and (It) the temperature-can at all stages of. the trolled.

.v Y, Havingset. fortli in .a general Way the variable conditions to be regulated in carry? process bev readilyjconf ving-out the processof this` invention in its several applications, I Will now describe one of its specificapplications to the production of low-carbon manganese-steel. A charge consisting of a molten spiegeleisen orother form of ferro-manganese containing such proportion of manganese asiivill give the desired percentage of that metalV in the resulting steel is introduced into .the crucible of an electric furnace, preferably an induetion furnace suoli as shown in Figs. 3 and 4 of the drawings. Close temperature regulation is essential in order to avoid volatilization of the. manganese by excessive heat. I have found that al temperature of approximately 150()o C. may be maintained Without excessive volatilization of manganese; and that by selecting suitable gaseous mixtures the several reactions necessary to refine the material may be brought about at said temperature. A fiux consisting of burned lime, calcium tluorid, or other alkaline earth composition, is added in sufficientquantities to slag the sulfur and phosphorus as suliid" and pliosphid, respectively. The amount of flux should be slightly in-exeess of the thcoretical proportions -iiecessary to` slagV ythe impurities, as. for. example. where` lime is used' about fifty pou-nds of lime-per ton of metal.

The bath maintained at the temperature above stated is blown with a gas having the required oxygen pressure for oxidizing the carbon ivithoutoxidizing the iron or the ioo manganese. "For example, blast furnace gas containing "ap roximately 20% of carbon dixid, 10% o ,carbon rmonoxid, and the remainder 'of nitrogen, -hydrogen, etc., will give a satisfactoryremoval of: carbon, silicon, 'sulfur and phosphorus without lessening the'content'ofaron and manganese. If an especially complete"- elimination of sulfur and 'phosphorus isdesired,the gaseous mixture -is 'changed towardt-he -end of the abovedes'cribed fblowv tolone jcontaining Aa higher percentage of reducinglgasyfor example, to a'gas'ous mixture containing 40% of carbon monoxid,740%of*liydrogen and the remainder 'of nitrogen, carbon dioxid, or hydrocarbons. "-ff' i Whilemlose' "regulation-' 'isfessential, I do not Wish f it toY be understood that any .particulartemperatu're 'is lessentiaL" The regulation referredfto' is a. combined regulation 1off"'teliiip`e"i"atire andf pressure tof dissociation, 'as'l set forthl "i'n' my aforementioned applica- `tion'fo'r' Letters PatetLUThus, for example,

viftit`bef des'ir'e'd' to retain manganese in the hill'f'tfrcmovingsulfur and phostemperature of approi'rimatelyl-11750o C., and

4reriainde'r 'of some -inert gas "like nitrogen 'orlsteain Afpressure .of approximatelyv 2O pounds s'ho'uld be maintained to lessen volaltilization'.: lThe use of sucha gas at the temperature' mentioned causes `no oxidation of the manganese, vWhile it vgives a satisfactory removal of "sulfur and phosphorus.v

sol

`be increased to 140 millimeters,

the use of such gas' atithe temperature of 17500 C. will result in the'entire elimination of the manganese.

'To lessen the' loss ot the metal or alloy by volatilization I preferably Work ata comparatively lowl temperat-ure'and use a gaseousy mixture having va lcorrespondingly low oxygen pressure in order to oxidize the carbon without oxidizing either the manganese or the iron.

The application of rthe process to the production of the 'other"a.lloysteels hereinbebefore mentioned lis in general-similar to that just described in detail with respect to manganese steel. A brief statement of the conditions desirable in the application of the process to--theproduction ot such other alloy-steels will therefore suffice. Silicon steel containing approximately 3.25% of silicon, 0.5% of manganese, l0.20/2l ot carbon maybe produced from a char-gc ot pig iron containing, for example 3.5% of silicon, and 0.6% manganese.' The molten pig iron is poured into an lelectric ,furnacevv provided with twyers, -andfthe A,temperature of the bathis raised electrically to about. 1500 `C. Slag is preferably -melted on.top. ,.o'fA the bath. Such slaginay consistpf limeand silicain approximately equal proportions. The molten bath of iron is blown, with a gaseous mixture containing .approximately 15%- of COT-and 12%I ofk 1- 0, and Athe vrseinainder of somednertgasa, such-,as ,nitrogen leave practically all thesiliconiand the-manganese inthe bath. Testsamples of the metal after the blow; is :nearlyl completed serve `to determine when ,thel lcarb0nis llow enough. If the silicon A,content is too high vvhen the carbon ,ishdown to specification, lime may be added, and the-heat continued. This-will rapidly take thesilicon do\vn.,

In the application ofiny process to, a

titanium-iron alloy to inakeatitanium steel I-'proceed almost in the samenianneras for silicon steelff 'Iit-aniuin-v may. be reduced with the iron inthe blast furnace and; by proceeding `asfdescr-.ibed above,but using a veiyacid slag preferably. iconsisting:entirely of SiO2 and maintainingga, temperature of aboutv 16509-0, the .carbommaybe eliminated- While ,-the` titanium.. -is retained. In the production of nickelv steel v,and .cobalt steel a slag 'is preferably maintained on top ot the bath, and the temperature, especially for low carbon nickel steel, is maintained somewhat higher than for manganese steel, that is, at about- 1550o C. fornickel steel to contain .20% carbon. The gas is preferably 4made more reducing, forcxainple, itl might contain 20% CO and 15%- CO2. Thus a charge of.J molten niclrelpigv iron containing 8% nickel and 4% carbon may be converted directly into nickel steel. It is preferable with this steel to provide a lime slag. y Y' f In the manufacture of tungsten steel and molybdenum-steel or tungsten-molybdenumsteel, 0r steels containing eitherof these elements and chromium, I prefer to use anfacid lined electric furnace. AfterA providing a molten hath of the metal to .be refined containingsuch elements, a slag is provided consisting largely of silica. A temperature of about 1550o C. is maintained it the tungsten, molybdenum,V or chromium does not exceed 20%, and the bath blown with a `gas containing about 20% CO and 10% :COT This will give a satisfactory elimination of carbon with a minimum loss of the metal. In retining such alloys containing more than 2 of the alloying metals, I prefer to use water gas containing 20. to 30% of vhydrogen and 10 to 1270-002. In suchfuseI '15 This treat-ment `Will remove thecarbon and iron alloy containing 7 ycarbon to onecontaining .5% carbonVthe ferro-chromium, under a straight lime slag, 1s blown with water gas, the bath being meanwhile raised to a temperature of at least 1750o C. to avoid the reaction between CO and chromium (Cn). If the temperature is maintained high enough the chromiunrwill 'notjtake up carbon from the` CO.` The. Water gas should analyze approximately 8% H, 10% CO2, 5% H2O and 10% COVand the rest nitrogen with the exception of small. amountsy vof other hydrocarbons. In case acid elements are desired in the steel they may be retained in the molten metal by in-4 creasing the reducing conditions and mak'- ing the slag more acid. If it is desired to l remove silicon from a bath of steellivithout rapidly taken up by the slag. If it'is de.

sired retain silicon the slao' is made acid and with the same gas as Just described,

- j the silicon will be retained.

It yis to be understood that I may practice the process of this invention in a continuous manner, as described for the treatmentof ores in my co-pending application Serial Number 426,334, filed April 10, 1908.

In such case the charge is smelted and re-` duced in the upperpart of the blast furnace shaft, and the refining takes place in the Crucible at thebase of the furnace. The result of such' procedure would be to keep from reduction undesirable elements and then Ato remove them in a slag instead of oxidizing them.

VThe words high carbon and low carbon i as here used are relative terms, and are not-intended to specify any particular percentage of carbon.

. I-claim:

1. The process of producing low-carbon alloy-steel, which consists in first producing a ferro-alloy high in carbon and containing the desired proportion of the alloying met-al with respect to iron, maintaining the product in a molten condition at an approximately uniform elevated temperature in a refining chamber, and then subjecting the same to the action of a gaseous reagent having a pressure of disassociation suitable for the action of said reagent on an element or elements Which it is desired to eliminate, but unsuitable for a like action upon the.elements which it is desired to retain. l

2. The process of producing low-carbon alloy-steel, which consists in first producing a ferro-alloy high in carbon and containing the desired proportion of the alloying metal with respect to iron, maintaining the product kinda molten condition atan approxi? matelylfuniform elevated temperature in a reiningchamber', and` then subjecting. the,V

same tothe/'action of an oxidizing gas hav.-v f

ing.V an oxygen pressure suitable for the oxidation of carbon but,v unsuitable for the oxi, `dation ofiron and the alloyi'ng metal.

3.*1hel process of producing 'low-carbon :alloy-steel, which consists intirst producing aA ferro-alloy high in carbona'nd containing the ldesired proportion of the alloying metal;

with respect lto iron, maintaining .thel prod-v uct in' a lmolten condition at] an approxi--- mately uniforml elevatedtemperature in a'y refiningchamber, mixing two, or more gasesl in ,proportionto produce .a gaseousagent.'4 having.y an` oxygen-pressure suitable, at the temperatureat whichthe bath is maintained,l

for theoxidation ofL an element oftheniolt-,en i

bath :which '.itds'desiredl to eliminate, but` unsuitable for the oxidation of the elements which it is desired to retain, andsuljjecting the molten bath to sald gaseous mixture. l

4*'The 'Process'of PlOducing low-carbon' -a.lloy-steel, which consists in first producing .a ferroalloythrigh 1 n carbon and -containingr the desired proportion of the Aalloying Ametal wit-h'respectto iron, heating almlte'n bath o ffsuch product .in an electric furnace, maintaining the temperature of the bathfbelow the point of excessive4 vvolatilization oi the alloying metal, ,and subjecting said bathlto theaction Iof an oxidizin'ggas having an oxygenpressure suitable at the temperature selected for the oxidation of an o ele-ment which it is desired to eliminate, but 'unsuitablevfor thezoxidation of the elements Vwhich itis desired to retain.

5. The process onproducing alloy-,steelV from .an lmpure mixture containing iron and the alloying metal in vthe Ydesired' proportions, Which consists in maintaining such mixture in a molten condition andv in subjecting the molten bath to a gaseousoxidizing agent having an oxygen pressure, atthe i' temperature of the bath, suitable for causing in the condition of a molten bath, melting a basic flux with said bath, and subjecting the molten bath to an oxidizing gas having an oxygen pressure suitable for the oxidation of an oxidizable element which it is desired to eliminate but unsuitable for the oxidation of the elements which it is desired to retain.

7. The processv of producing alloy-steel' from a mixture containing a ferro-alloy high in carbon associated with sulfur and phos# phorus, orl either of them, as impurities, which vconsists in maintaining lsuch mixture,` in the condition of a molten bath,"inelting a basic iux with said bath, and subjectingthe' molten bath to a gaseous mixturecontaining carbon dioxid in quantities regulated'toipr'o# duce, 'at"the temperature of j the bath, 'an oxygen pressure suitable forthe oxidation of carbon but unsuitablefor the oxidation'ofl iron and the alloyin metal." 8. The process o .producing 4alloy-steel' from a mixture containin'gfa ferro-alloy'liigh in carbon associated 'wvith sulfi'iry which" consistsy in maintaining suchv mixtiirefin the" condition lof a molten bath,` 'melting 'a tb'asicl flux with said bath, subjecting the molten? bathy to gaseous`reagents,'suitable at the'tem-f perature selected for oxidiziiigycarbon'wvith out yattendant oxidation" of iron or of 'tlie alloying metal and thereby producing* in2 said flux conditions favorable-for slagging" oisulfur. 9. The process of producing alloy-steel from a mixture containing a ferro-allo liigh in carbon associated with sulfurf-"andlplios-f' which' consists in maintaining@ siic'h1mixtur' in the condition of a' molten ba'tlijfmelting a basic flux with said 'bath', 's'ubj'ctiiig i theV moltenba'th to anoxi'dizinggas' having 'an `oxygen pressure suitable for-fthe oxidation which consists in first reducing suitable ores i in the presence of carbon, then electrically heating the resultant high-carbon ferro-al# loy to maintain the saine in the conditionof a molten bath having an approximately upiform predetermined temperature, andfsu'b jecting said-bath to the action of a'g'as -con-1 taining carbon dioxid in quant-ities:suit-ableI for the selective oxidizing action' of said 'gas on carbon at said predetermined `temperature but unsuitable for a like action 'on iron I4and the alloying metal. `y

11. The process of producing low-carbon alloy-steels, which consists in firstproduc? ing a ferie-alloy high in carbon, electrically heating the product to a predetermined tem-v perature below that for excessive volatili'zation of the alloyin metal, and subjecting the electrically heated product to the action of an oxidizing gas suitable at said predetermined temperature for selective oxidizing action on carbon, but unsuitable forja like action upon iron and the alloying metal or metals. l

12. The process of producing alloy-"steel,v

`which consists in lfirst producing a ferro-allloy high in carbon, maintaining the product "in-a molten condition at an approximately uniform elevated temperature in a refining chamber,` subjecting the heated product to the action of agaseous oxidizing agent having at said temperature an oxygen pressure suitablefor an oxidizing action on the contained'carbon but'unsuitable -for a llike ac-r tion upon theeleinents which it is desired to retain in the steel, andmeanwhile re llat-- ingtheipressure of the gases liberated inthe refining chamber to control the volatilization of the alloying metal or metals.

'13. The process of'producing manganeseironalloys directly from an alloy of iron :and manganese having ahigh carbon contentj'vvhich consists in maintaining the material' in a molten condition at an approximately uniform predetermined temperature, and subjecting the molten material te the action-of a 'gaseous oxidizing agent having at Isaid temperature an oxygen pressurey suitlable for an oxidizing action on the oxidizableA elementor elements which it is desired tofeliminate but unsuitable for a like'action theelements which it is desired to retain@ 14; The process of producing manganesesteel directly from-spiegeleisen,V which con-- sists in maintaining saidy spiegeleisen at an approximatel uniform predetermined temperature slig'tly above its melting point and'subjecting themolten material to the action of a gaseous oxidizing agent having at said temperature ain-'oxygen pressure suitable for oxidizing carbon contained in the `o-duct under treatment vbut unsuitable for a like action on the elements which it is desired to retain in the steel.

15. The process of producing manganeseiron alloys directly 'from an alloy of iron and manganese having a high carbon lcontent and containing oxidizable impurities and slagforming impurities, which consists in maintaining such mixture in the condition of a molten bath, melting a basic flux with said bath, and subjecting the molten bath toan oxidizing gas having an oxygen pressure'suit'able for the oxidation of said oxidizable impurities but unsuitable for a likeacti'on uponiron and manganese.

'16. The process of roducing manganeseiron alloys directly om an' alloy of iron and manganese having a high carbon content and containing oxidizable Aimpurities andslag-forming impurities, which consists in maintaining such mixture in the condition of a. molten bath, melting a basic flux with said bath, subjecting the molten bath to an oxidizing gas having an oxygen pressure suitable for the oxidation of said oxidizable impurities but unsuitable for alike action upon iron and manganese and then -further subjecting the moltenbath'to al gas having lesser oxidizing properties than said first mentioned gas.

17. The process of producing manganese steel directly from spiegeleisen containing sulfur and phosphorus or either of them as impurities, Which-consists in maintaining such mixture in the condition of a molten bath, and subjecting the molten bath to an oxidizing gas having an oxygen pressure suitable for the oxidation of the contained carbon but unsuitable for a like action upon iron or manganese, and subsequently subjecting said bath to the action of a reducing gas.

18. The process of refining a molten bath of iron 'and manganese containing oxidizable impurities, which consists in subjecting said molten bath to a gaseous mixture having, at the temperature of the bath, oxidizing properties with respect to said impurities and non-oxidizing properties with re* spect. to manganese.

19. The process'of refining an alloy of iron andv manganese having a high-carbon content and also containing sulfur or phosphorus.y which consists in providing a molten bath of such alloy and a basic flux, and subjecting said molten bath to a gaseous mixture having,'at the.temperature of the bath,

oxidizing properties with respect to carbon ALBERT E. GREENE.

Witnesses GEORGE E. FOLK, ALFRED H. MOORE.

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