TRANSACTIONS O F THE AblERICAN INSTITUTE O F MINING ENGINEERS. [SUBJECT TO REVISION.]

DISCUSSION O F THIS P A P E R IS INVITED. It should preferablv be presented in person nt the Kew York meeting, October. 1913, when au abstract of the paper will 6e read. If this is i~upossihle, then tliscussiun ill writing may be sent to the Editor, Americlun Institute of Mining Engineers, 29 \Vest 39th Street, New Tork. N . T., for presentation by the Secretary or other representatire of its author. Unless speclal arrangement 1s made. The d~scussion of this paper \rill close Oct. 1, 191:;. ~ r l ~ e n Val. SLVI. of the Tru~tetf,:lio~~n will go to press. Any discussion offered thereafter should preferably be i n t h e form of a new paper for pal~licatio~i in Vol. SLVII . (with si~itable cross references in both volumes).

Over-Oxidation of Steel.

BY \V. R. SHIalER AND F. 0. KICHLINE,* EASTOX, P A .

(Sew Yrlrli Meeting, October, 1!113.)

THE illvest,igatioli herein 1lescril)ed n7as carriecl out for the l>urpose of stnc-lyiug, 130th h\: cllemicnl nncl inetallogrnphical mesus, the extent of over-oxiclat,ion of steel that can be accoi~~plished by excesai,ve orer- l ~ l t ~ w i ~ l g in a Bessenier converter. 111 ;tcldition there are appendecl some resiilts of basic. open he?rth aud crucible steels.

Remarks 012 C'iienziccr.1 Nethods. The test Block used mas heniispherical in shape, 4.5 in. i u tlinm-

cter :ind 2 in. thick. Drillings for analysis 1vel.e o1)t~inecl l:,y cLrilli'ng t l~rough the eutire solid part of . t he . block, carefully avoiding all craclis and I-)low-ht:)les and mixing tliese tlrillings thoroughly. Drill- i~ lgs were ci~refully esa,ulined for scitle nncl the finest were gone over \vith a microscope to be sure all s cde froin whatever source hacl Ijeen

. renloveil. Oxygen was ilet.ermil~ed by the \~t?l l - l i~low~l nlethotl of Leclebur,

~nodifiecl according to Cosl~man,' with, however, the r e l ~ o v r ~ l of t,he preheating tube, wllich ~ v a s f o u ~ ~ d unnecessary. This methot1 has beeu founcl to give concorclaut results. Blanks run from 0.OC)OS to 0.OOOG g. ~jupl icate cleternlinntious varied not more than 0.001 to 0.(:103 per cent.

I t seems to be generally supposecl that the hyclrogell method gives o111y t,hnt oxygen which is combined with iron. Whether this be true or not, the content of osygen existing as iron osicle no doubt preclomiuntes su%ciently, so that the result. obtained is suficieut to iudicitte whether the steel is over-oxidized or not.

W e are well aware that the oxides of nlal~ganese n~icl chromium, ~ v h e n existing alone, are not r e c l u c ~ l by l~ytlrogeu a t a red heat. To learn of their itctiot~ in steel the follo\ving work mas carriecl out : A sarnltle of ferro-manganest: nn(l of ferro-chrome were each exposecl

* Non-member. . . . I Jotc.r~&cd I , ~ d t ~ ~ / r i ( i I (111(1 Etqlitccriny Chemistry, vol. i i i ; , p. 372.

2363 . OVER-OXIDATION' OF 'STEEL._

in the electric foruaCe to an at,mosphere of oxygeu until completely osiclizecl. These powderecl oxides were then run for oxygen- b r tlie usual hyclrogen methocl, but only a rery small percentage of the total osygeu was obtained in eit,lier case.

A saniple of rail steel of the following cornl.lnsition mas osidizeci in the electric furnace as before : C, 0.740 per cent. ; Mn, 0.82 per cent.; P, n.024 per cent.; 8, 0.042 per cent. ; Si, 0.098 per cent. One-half gram of these completely osidizecl clrillings were run for osygeu by the hydrogen met,hocl. The percentage of oxygen fonncl was slightly higher than the theoret.ica1 amount. These reduced clrillings were' then ruu for osides. by the iron-ioclide method; A resitlue of less than (1.10 per ceut. iron was obtained, carryiug with it only traces of maugauese.

With the same ol~ject in view a sample of elrillings from a nickel- chrome steel of a~proximately the follo\ving composit~ion was oxidized as before: C, 0.35 per cent.; MI], !l.:38 per cent.; P, (3.036 per ceut.; S , 0.028 per cent. ; Si, 0.058 per ceut. ; Ni, 3.85 per cent. ; Cr, 1.95 per cent. The oxiclized clrillings were theu transferrecl to the appa- ratus for deternliuiug vxygen a.nd run as before. To insure thorough reclnctioii, the clrilliugs were run for oxygen the seconcl time. A slight increase in weight was obtained. A thircl run gave no further reaction for osygeu. The percent,nge of osygen fonlicl was again greater thau the theoretical figure. The clrillillgs were theu dissolrecl i n irou iodide. A slight residue only was obtained, coutainiug merely traces of Fe , Mn, and Cr.

The foregoing esper in~e~l ts t,end to show that. when maug,anese aucl chromi~uu are oxiclized, while alloyed with irou, their oxicles are readily reducecl by liydrogeu. This can a t lgast be t rue when they esist iu such amounts as they are usually found in steel.

Ou this ,poiut Fe might quote froin a valuable paper by G. Mars,? in which he says : The oxides of both ll~etrtls [meaning irou and manganese] are elistiuguished from each other in this may; \\-hen manganese oxicie appears alone i t will not be reduced by hydrogen, but if both osides are present then the hydrogen will recluce them." A few of the results for osygen by t,he hydrogen methocl were checked by the iron-iodide method and agreed closely.

The esperimetits were carried on in a Besseiiler couverter blowing steel for the Duplex process. Hot metal used, with t,he esceptiou of Heat I, had the follo~viug composition : C, 3.50 per cent.; Mn, 0.70 per ceut.; P, 0.450 per cent.; S, 0.050 per cent,.; Si, 1.30 per cent.

. .

Die Bestimmung.der.Scl~lackeneinschlusse.im . . Stihl, A'krhi ~ c i d Eisen.

OVER-OXIDATION OF STEEL. 2363

Experinze~zts. Heal A :-45,000 lb. of iron were blown iu the usual may for soft

steel, the converter was tarned over and Test 1 taken, which aualgzecl as f o l l o ~ ~ s : C, 0.06 per cent. ; Mn, 0.02 per cent. ; 0, 0.027 and 0.0% per cent.

The vessel was then tnrnecl up and the heat blo~v11 until the dame sho~vecl extensive over-osiclatiou and the metal was getting cold. I t was then tnraecl c l o ~ ~ n and Test 2 taken i~umecliatel~-.

Test 2 analgzecl : C, 0.03 per cent. ; Mn, 0.01 per ceut. ; 0, 0.074 per cent.

The oxygen content is not as high as might have been expectecl in' a steel, after iliakiug such a vigoroos attempt a t over-osidation, kc1 when n7e co~lsider that the test xvas l~ourecl ~vhile the steel still con- taiuecl the full a m o i ~ ~ i t of entangled oxides aucl chilled before they conlcl separate out.

To the metal in the vessel after takiug test sample No. 3 was adclecl 3,000 Ib. of hot metal. To iusure thorough misiag the vessel was manipulatecl nucl just a puff of air blown through. I t was then turned clown al1c1 allowed to rest about one minute, and Test 3 mas taken while pouring into the ladle.

Test 3 analyzed : C, 0.15 per cent. ; Mn, 0.03 per cent. ; 0, 0.023 per ceat.

This test showed how clnickly the over-osiclizecl, or over-ldown, heat was deosiclizecl by the acldition of the hot metal.

No rnicmscol~ic samples were tal;en of Heat A. Heat B :-Since Test 1 (Heat A) \vas blown very low in carbon,

Heat B was blo~vn to leave more carbon in the bath, ancl Test 4 taken. Heat B ~veighecl 40,000 lb.

Test 4 ana1-j-zecl : C, 0.95 per ceat. ; Mn, 0.04 per cent. ; 0. 0.027 per ueut.

The vessel ~ v a s turnecl 1111 an11 blown to :tppareut over-osiclation, when Test 5 was talien in the usual \v\i:ty.

'lest 5 analyzecl: C, 0.04 per ceut.; hlu, 0.02 per cent.; 0 , 0.033 per cent.

This heat was recarburizecl with 9,000 11). of hot metal, the vefisel JTRS manipulateel to insure thorough misir~g, and Test 6 takeu while pouring into the ladle, after allowing a few minutes for the reclucing action of the metalloicls to be exerted. The analysis of Test 6 showed : C, 0.780 per cent.; Mn, 0.13 per cent.; 0, 0.024 iber cent.; Si, 0.140 per cent.

See micrographs Nos. 4, 4a, 5, 5a, 6, Gn, on Plate I. Micro- graphs 4, 5, and 6 (taken before etching syecimens) represent Tests

2364 OVER-OXIDATION OF STEEL.

Fig. 4.-l:netchcd. Fig. 4a.-Etched. C, 0.25 per cent. ; 0, O. on per cent.

Fig. .-Unetched. Fig. 5r!.-Etched. C, 0.04 per cent. ; 0, 0.OCl2 per cent..

Fig. 6.-Unetched. Fig. 6a.-Etched. C, 0.780 per cent. ; 0, 0.024 per cent.

PLATE I.-SAMPLES ~'ROM HEA.T B. ALL SECTIONS MAGNfFIED 140 DIAMETERS.

OVER- .XIDATION OF STEEL. 2365

Fig. 7.-Unetched. Fig. 7a.-Etched. C, 0.744 per cent. ; 0, 0.OB6 per cent.

Fig. 8.-Unetched. Fig. 8a.-Etched. C, 0.03 per cent. ; 0, 0.064 per cent.,

Fig. 9.-'-:Unctched. Fig. 9a.-Etched. C, 0.430 per cent. ; 0, 0.029 per cent.

PLATE n.-SAMPLES FROM HEAT C. ALI, SECTIONS MAGNIFIED 140 DIAMETERS,

'

I . 2366 OVER-OXIDATION OF STEEL.

4, 5 aucl 6 and sho\v substantially the same proportiou nf iml~urities as the chemical results for osygen. ;,N_os. 4 and 6 contain fewer pits

I theu No. 5. Also, ~ lo te in 5a (sanlple after etching) tllat the oxicles occur. in t,he s 1:)ouncl:~rieu of the ferrite crystals. This structure is almost pure ferrite, since there is practically no carbon in this sampl e.

I11 the allore experiment we were unable tq over-l~lon to ally great extent on accou~lt nf the hot metal being too lorn in si'lico~l. . ~ W e therefore awaitecl an opportunity \vIleo the iron was hc)t." (d. e . , high in silicon), s_i, n-e coulcl give n long over-blon. (say 5 mii~.) ti1it.h- out clanger. .This moulcl give a . re l -y hot blou;\in metal and i~lfo~v sat,iefnctory cnnditiona for over-c,siclat,ion. . .

Hrnt C!: 45,000 lb; were blown and , Test 7 taken, n~hich analjzcd : C, 0.744 per cent.; Mn, 0.05 per eel-~t,.; 0, 0.036 per cent. T l ~ e heat. was t,heu blotvn soft. (to ahout 0.10 per cent. c:irbon) a ~ ~ d then, since t,he rnetal mas very hot, a prolougecl aft,er-blow of aboilt. five minutes nras given. The vessel n7as turned clo~vn and Teat S was tak'en, which analyzecl : C, 0.08 per cent. ; Mn, 0.01 per cent. ; 0, 0.064 per cent,.

T o the vessel was added 5,600 lb. of hot metal for recar1:~nrizatiou aud after holding foi. two minut,es, the heat was pourecl nncl Test 9 was tnkeo. The analysis of ~ e s t ' 9 showed: C, 0.480 per dent. ; bf~;? 0.04 per cent,.; .0, 0.039 pcr cent,.

It \\rill be ~ioticed 1101~ quickly the addition of the hot, metal de- osirlised t l ~ e batli.

See Plnt'e II., wllioll slrows micrograqhs 7, S a~lcl' 9 (unetclrecl) a ~ ~ d 7a, 8% a i d 9a (etched). No. 7 contnius fewer a11d d s o s ~ ~ l a l l r r pits (or oxide spots) than No. 8, and, in No. 9, t:he spots are of a differe1,t nature; not oxide pits, since they contain bright centers. (Thcse are probably jrva phosl>hide, out of so1utio1-I, as there was nbont 0.480 per cent. phosphorus in the blo~vn metal, and this \vas thrown out of.solution nhen the recarbnrizer v7au added.) It will l)e noticed in the etched micrograph 9a that t,he ferrite 1:1ands cont,ai~l a peculiar gray center, not foun(l in orcliaary steels, \vl:~ich is pliosphide of iron,. or steaclite.

The three tests, Nos. 7, 8 a,nd 9, were forgecl with the follo\ving results : . .

No. 7 fell to pieces nuder tbe first blow of the hammer. No.,S fo_rged.-readily to a 0.75 in. square bar. No:.9 fel l to pieces iu the same nlauuer as-NO. 7 . - - -

'

NOS. 7 a i d 9 (11otl1 h i i l l in carbon) contai~led pllosphicle of iron, out of soh~tion, which causecl them to break '(luring forging.

OVER-OXIDATION OF STEEL. 2367 . ' . ,:"

Micrograpll 8f (Plate 111.) shows t,he structure of No. 8 sal-~il~le after forging. The .large -dark gray portion is a, blo\v-hole forgecl together.

Heat D : A heat of 42,340 111. was b l o i ~ n soft inimediately after Heat C, ancl Test 10 was t,a.ken. The an;ilysis of Test-10 ga.ve : C, 0.08 per cent. ; Mu, 0.02 per cent. ; 0, n.027 per cent.

Then the vessel was turned u p ancl the heat given afive-minute after- blonr and Test 11 talien. Test 11 analyzec-l : C, 0.03 per cent,. ; Mn, 0.02 per cent. ; 0, 0.048 allcl 0.049 per cent,.

Theu 7,630 Ib. of hot nietal were added to tlle vessel, \vhicli was manipulated to nlis the bath, ant1 Test 1 3 nras taken inlmecliately, the analysis being: (2, 0.G4S per cent. ; 0, 0.031) l ~ e ~ cent.

The heat was tl- en held three ~~liul i tes ancl poured out; Test 13 was t,akell while 1)ouring iot,o the ladle. The itnalysis of this t,est showed: C, 0.610 per c e n t . 0, 0.033 per cent,.

See micrographs Ros. 10 to 1 3 ancl 10a t,o 13a aucl 13a.,, Pla.tes 111. aiid IV.

No, 10 shows less oxides than No. 11. No. 11.-Some parts of the sample were better and sorne worse tl~all

the part photographed. No. 12.-This piece shows less oxicles than No. 11. No. 1 3 shows lower oxides thii11 No. 13. The large spot,s sho~vu

in the print are slag iuclasions. The etched pieces are shonrti by micrographs lOa to 13a ancl 13a,.

They show the represeutative struct,ures of the cliffereut tests. Nos. lira and l l a , not .having niuch carbon, shorn almost. p r e ferrite. I n l l a t.1ie oxide spots occur along the boundary lines ,of the crystfils.

Nos. 12a, 13% aucl 13a., sho~il the tests coutaiuing the higher cnrl~nn (after recarburizat,ion), n7hicll llns thrown tlie iron phosphide out of solnt,iou. Tlie ferrite iu:tliese print,$ contains dark centers ; these a.re the irou phosphide. This esplaiins t.he nature of the peculia,r spots in the unetched tests, Nos. 12 and 13, which are not of the same appear- ance as osicles. Microgr:~phs 10f and l l f (Plate IV.) sllom t.lie apljearance of the respective tests after forging. The gray spots are forged-out blow-holes. Note the absence of pearlite in these bests.

Test blocks Nos. 12 and 1 3 n~ould not forge; they both fell to pieces on acco~uit of their iron pllosphide content,.

Heut E.-TI, 48,340 11). of 11ot metal, 3,000 Ib. of magnetic ore was added, before l)lowiug, with the object, c:~f reducing the time of the blow and of st~ld;).i~g the estent to .which tlle .steel might .-be over-osiclizecl. Test 14 was taken imnlecliately after tlle blow. Test

NOTE.-Micrographs marked 1' represent the structures of forged tests, aft& etching.

OVErt-OXIDATION OF ST EL.2368

)'ig. 13a,.-Etched.Fig. 8f .-Structure after forging and etching. 0, 0.064 per cent.

Fig. 10.-Unetched. Fig. 10a.-Etched. C, 0.08 per cent. ; 0,0.027 per cent.

rig. ll.-Unetched. Fig. lla.-Etched. C, 0.02 per cent. ; ,0.048, 0.04\1 per cent.

PLATE TlI.-ALL SECTIOl\'~ l.\iAGNIFIED 140 DIAMETERS.

OVER-OXIDATIO£ OF ,TEET.. 2B69

Fig. 12.-Unetched. Fig. 12a.-Etched. C, 0.G48 per cent. ; ( , 0.0.30 per cent.

i'ig. lil.-Unetched. Fig. l~ja.·-Etched.

C, 0.610 per cent. ; 0, 0.023 pllr ('ent.

Fig. 10r.-Sample 10 forged 8.nd etched. Fig. lIf.-Sample 11 forged and etched.

PLATE IV.-ALL SECTIONS MAGNIFIED 140 Da~n;TERS.

OVER-OXIDATIOX OF STEEL.

14 analyzed: C, 0.08 per cent.; 0, 0.024 per cent. The blow just previous to this one (Heat D) and the one following (Heat F) each took 14 minutes to blow soft, while this heat, E, took only 12 mi\lUtes, a reduction of two minutes. From the oxygen content we see that the "teet was not over-oxidized. X 0 microscopic sampIes were taken of Heat E.

Heat F:-50,440 lb. of metal were hlowlI to 0.25 per cent. carbon aIHI 1,000 lb. of magnetic ore was added to the ladle. A violent reaction took place in the ladle. The ladle was taken to the op n llearth and Test 15 taken while pourin u' into the fnrna 'e. The time from filling the ladle to catf'hing the test was~O minute, thus giving the ore time to act and the bath to clear. The analysis of Test 15 gave: C, 0.13 per ccnt.; 0, 0.017 per cent.

It is interesting to note how low the content of oxygen is in this steel, 30 minutes after the ore addition to l;[(11e. No microscopic sample,.; were taken of HoatF'.

Heat G :-\Ve then blew a heat c1eall soft before adding ore and, further, aulded ore to the vessel, in order better to take care of the reaction, or boiling over. To carry out this experiment, 48,000 lb. of metal were blown soft and Test 16 taken, which analyzed: C, 0.08 per cent.; 0, 0.024 per cent.

While the vessel was resting' On its side, 1,000 lb. of ore were ac1(led and five minutes allowed for the reaction to take place. A large piece of mixer scull (about 5,000 lb.) remained in the vessel from a pre­vious heat and was partly melted away by the 'bath while holding the metal in the vessel for the action of the ore. Test No. 17 was then taken. Test 17 gave the following analysis: C, 0.14 per cent.; 0, 0.029 per cent.

Slag from this heat contained 48.42 per cent. Si02

• The carbon content here increased, instead of decreasing, as would have been expected from the action of the ore. This was caused by the pres­ence of the high-carbon iron scull. Therefore the same experiment was repeated when the vessel was clear and the iron hot.

See micrographs 16, 17, and 17d, Plate V. Microsection 16, taken from Test 16, does not show an excessive

amount of oxides, the large spots being slag inclusions. Nos. 17 and 17d were both cut from Test 17; 17d was cut from

that part of the block from which the drillings for analysis were taken. The steel is low in oxides and the impurities shown in the micrographs are manganese silicate, formed from the mixer scull contained in the vessel. An analysis made on Test 17 gave 0.058 per cent. manga­nese silicate.

OVER-OXIDATION OF STEEL. 2371

Fig. 16. C, 0.08 per cent. ; 0, 0.024: per cent.

Vig. 17. C. 0.14 per cent. ; 0, 0.029 per cent.

Fig.18. C, 0.07 per cen t. ; 0, 0.038, 0.037 per cent

Fig. 17d. Si()" 0.058 per cent.

Fig. 20. C, 0.04 per cent. 0, 0.033 per cent.

ALL SECTIONS MAGNIFIED 140 DIAMETERS,

Fig. 19. C, 0.06 per cent. 0, 0.028, 0.029 per cent. Si02 , 0.052 per cent.

Pr,\TE V.-S.UlPLl':S FROM HEAT~ G .\:-"D H

2372 OVEl~-OXIDATION OF STEEL.

Heat H:-47,000 lb. of metal were blown soft and Test 18 taken. An analysis on Test 18 showed: C, 0.07 per cent.; 0, 0.038 and 0.0:37 per cent.

As in Heat G, 1,000 lb. of ore were added to the vessel, and Test 19 taken two minutes after.

Test 19 analyzed: C, 0.06 per cent.; 0, 0.028 and 0.028 per cent. After holding five minutes longer, the ore still working in the bath,

Test 20 was taken, which gave the following analysis: C, 0.04 per cent.; 0, 0.033 per cent.

Slag taken from this heat contained 37.36 per cent. SiOz, showing that the ore was passing into the slag as fa as melted. Ordinary Bessemer slags contain 60 to 62 per cent. SiO ' z

Note micrographs 18,19, and 20, Plate V. The oxides found with the microscope check with those found by chemical analysis. Large spots of manganese siEcate are seen in print No. 19. Test block No. 20 contained segregations of this impurity, but they were not photographed.

The drillings f!"Om Tests 17, 1 , 19, and 20, after removing the oxygen by the hydrogen method, were used for determining oxides by the iron-iodide method. Only a trace of cO was found, but resi­dues of 0.0;')8, 0.0;)4, 0.0;')2, and 0.050 per ee t. were obtained, which, on examination, proved to -be composed entirely of manganese sili­cate; hence the manganese silicate which is shown in micrographs 17, 17d, and 19. Ordinary steels contain a residue of about 0.01 per cent.

Heat I:-The opportunity presented itself of blowing a heat of Bessemer iron (phosphorus 0.090 per cent.). This was first blown for 0.75 to 0.85 per cent. carbon, for comparison with Tests 6, 7, 9, 12, and H, and Test 21 was taken. An analysis of Test 21 showed: C, 0.830 per cent.; Mn,0.30 per cent.; P, 0.120 per cent.; S, 0.031 per cent.; 0, 0.017 per cent.

The heat ,vai5 then blown soft, a 'iolent reaetion taking place, amI Test No. 22 wa;:.: taken. This test analyzed; C, 0.16 per cent.; .Mn, 0.10 pel' cont.; P, 0.120 per cent.; S, 0.030 per cont.; 0,0.020 per eent.

\Vhile the ve",,;e! was held in the inclined position, 1,000 lb. of ore were added and, after a]Jowing five minntes for readioll, Test 23, was taken. Tc"t 23 analyzed: C, 0.10 per cent.; .\.£n, 0.03 per cent.; P, 0.120 per cent.; S, 0.030 1er cent.; 0, 0.040 per cent.

See" micrograph" 21a, 22a, 23a, 21£, 22f, and 23f, Plate VI. :Mic­roscopic sample ~o. 23 showe,l ,vhen polished the highest oxygen content. All t1le"e micrograplls were taken after etching the samples.

OVER-OXIDATION OF SlEEL. 2373

F~. ~2a.-Etched. C, 0.16 per cen t. ; 0, 0.020 per cent.

Fig. 22f.---Sll.lIlple 22 forged and etched. 0, 0.020 per cent.

F,ig. 21 f. -Sample 2l forged and etched. 0, 0.018 per cent.

Fig. 2::;a.-Sample 23 etched, " 0.10 per cent. ;

0, 1).040 per cent.

Fig. 2:3f.-Sample 23 forged and etched. Fig. 21a.-Sample21 etched.

PLATE VI.-SA.~IPLES OF HEAT ION BES ~IER IRON. ALL SECTIONS MAO~IFIED·

140 DIAMETERS.

OVER-OXIDATION OF STEEL.2374

Note the absenee of iron phosphide in the high-carbon Test 21a, this heing hceaw.ie the phosphorus is low as compared with all the previo\Hi heats.

These tests, 21, 22 and 23, all forged well. The high-carbon Test 21 was the only one in this high- arbon series which we were ahle to forge, due to the absence of phosphide of iron out of solution; Mi­crographs 21£, 22f and 23f show the etched struduros of the respec­tive forged test blocks; 23f contains a forged-ant blow-hole.

For the pnrpose of verifying our analytical results, we ran check determinations for oxygen on the forged bars. The results are as follows:

(h:IFlell Content.

As Cast. As Forged.

Test Block No.8 ········1 Per Cent. O.OM

Per Cent. 0.064

Test Block :No. 10 . 0.027 { 0.Ot5 0.044

Test Block :No. 21.. .. 0.017 11.011'> Test Block No. 22 . 0.020 0.020

Test Block No. 23 .. 0.040 ( 0.058 lO.058

Forged tests 10 and 23 were "ery rough, and full of seams and laps (the blocks, as cast, being of a bad shape and difficult to forge properly), and the drillings were not elean. It was impossible to avoid these cracks and seams in drming, which accounts for these tests (10 and 23) not checking with the original oxygen content in the blocks, as cast.

It will be noted bow closely tests 8, 21, and 22 check; these forged te"ts were free from seami:l, and, therefore, the drillings were clean.

Basi(; Open Hearth Heat, E-l4-, &~ :-Test 24 was taken from a hasic open hearth heat, just before ad<1ing ferro-manganese. The 'bath had been boiled down" flat" and held for some time. Follow­ing is the analysis: C, 0.05 per cent.; Mn, 0.05 per cent.; P, 0.023 per cellt.; S, 0.05;) per cent.; 0, 0.024 per cellt. It will be noto<l that the oxygen content of this heat is low, in spite of the fact that the heat was boiled down fiat and helel some time at a high tempera­ture, thereby affording the be~t conditions for over-oxidation.

Micrograph 24 shows the oxygen in the sample as polished. This checks satisfactorily with the chemical analysis for this element.

A few results on finished open hearth steel might be of interest; the drilJings for these determinations were not taken from test blocks, but from the finished product.

2375

Rail Steel. Structural Steel (about 0.19 p. c. C.)

OVER-oxmATION OF STEEL

Heat No. E-21,276.................

Oxygen.Pcr Cent.

0.018 I

Beat No. E-14.096..

Oxygcn. Per ·Cent.

0.024

E-17,244.................... { 0.015O.OlG

E-17, 104........ E-22,068..............

0.022 0.019

E-22.377............... 0.018 E-22,277.......................... 0.015 E-17,44l... 0.017 E-24,063 ,. 0.014 E-21,428........ 0.01 f) E-24,202.......................... 0.019 E-26,065.......................... 0.017

FIG. 24.-SAMPLE FRO { A B., C OPEN HEARTH HEAT.

e, O.Oli per cent; 0, 0.024 r cent. No manganese silicate.

Over-Oxidation of Steel.

The follo\ving are a few results taken while working basic open hearth heats, making structural steel:

Preliolinary Test No.2, IIPreliminary Test No.1, Ta.ken at Ta ping, Just Heat No. Taken y. Hour Befo Before Addfng FeMn Drilling. Taken from

Tapping. to Furnace. Finished Beam.

-------1--------1-------- ------ ­Per Cent. Per Cent. Per Ceni.

14,334-0xygen...... 0.037 0.025 0.022 24,092-oxygen...... 0030 0.019I

Another basic open hearth heat of 0.60 per .ent. carbon was rolled into 4-in. square billets from a lO-in. square ingot. A section 1 in. thick was cut from the top, middle and bOttOlb of this billet, cor­responding to top, middle and bottom of the ingot, and drillings were taken from each ",ection t one-third the distance from the sur­face. These drillings were run over a 20-mesh sieve to separat the fine froIn the coarse; oxygen was determined in each, and the average oxygen content calculated from th proportionate weight of fine and coarse.

2376 OVER-OXIDATION OF STEEL.

Uriilings Remaining on Drillings Passing Calculated 20-Mesh Sieve. Through.Sieve. Average.

Oxvven. ~er 'Ccent. ,

Fop.. ... .. . . . . . . . . . . . . . . . . . . 0.0li Middle .... .. . . . . . . . . . . . . . . 0.010 Bottom.. ... . . . . . . . . . . . . . ..

I 0.011

Oxygen determinations were run on a few 0.60 per cent. carbon crucible steels, and showecl the follo~viag osygen content :

Sample No. 1.-Test dippecl out of a 90-11). crncible ancl cast into a small test block : Oxygen, 0.014 per cent.

Sainple No. %-Test clippecl out of a 1-ton ladle; same heat as sample No. 1 : Oxygen 0.014 per cent.

Sample No. 3.-Finishecl, rolled, bar : Oxygen, 0.010 per cent. Sainple No. 4.-Rolled bar picked out, a t ranclom, from the stock

ruck : Osygen, 0.010 per cent. Samples 1 aucl 2 mere dipped out of the bath and cast into snlall

molds, and were, therefore, somewhat porous, which no doubt ac- counts for their sho\ving slightly higher osygell than the finished bars, which were solicl.

Oxygen. Per Cent. '

0.0% 0.080 u.01.5

- Oxygen.

Per c'ent. 0.019 0.013 i~.01:!

. Every effort a t over-ositlation mas nlacle, both by over-1)lowing ancl by ore acldition.

1. The highest osygeu content obtained Ly over-blo\viug, were 0.074 (in Test 2); 0.064 per cent. (in Test 8) ant1 0.049 (in Test l l ) , not~vithstnncliug that the tests were taken irnn~ecliately, in orcler to get the highest oxygeu possible. Also the tests were cooled quickly so that no gas coulcl escape during casting.

2. While oxidizing with ore, we obtained 0.029, 0.028 nilel 0.033 per cent. osygeu, by taking test saillples imrnecliately after the ore begins working through the metal. When time was allowed for the

I

oxygen to escape after the ore aclclitiou (a* in Test 15), a co~lteilt of 0.017 per cent. oxygell war fountl.

3. A basic open hearth heat, untler osiclizing conditions, gave only 0.024 per cent. osygei~ (Test 24).

4. Juclging fro111 the results obtaineel fronl heats G aucl H, it :~p- llears that either an unfinishecl heat or an over-orecl heat will procluce slag iuclusions, such as manganese silicate, instead of iron oxide.

5. Fronl these results, consiclering the miinner in ~ ~ ~ 1 1 i c h they were taken, we lnay couclucle that escessive oxygen leaves :I bath of nlolten steel in ,z very short time. Also that cleoxidation is reaclily effected 11y the ncltlition of hot metal.

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OVER-OXIDATION OF STEEL. 2377

6. I t . will also be not,iced that, uuder the same conditions, the higher the carbon the lower ,t,lle oxygen.

7. Finally, it seems highly improbnl~le that, uucler the nsud cou- .ditions of Bessenler. and opeu hearth pract,ice, ~ \ ~ i t , h the addition of recarburizers, -that a steel of over 0.030 per cent. of osygen can be obtained, and that the highest obtaiuable uuder any couditious, without recarburiziiig, cnu hardly be over 0.075 per cent. Results higher thnn this must be froni drilliugs improperly t:iBen, or fl.om oxida~tion t,hat occurred dnriug t.eemiug.