TURE OF STEEL CASTINGS

The official exchange p a p e r from th e A m erican F o u n d rv m en ’s A ssociation, by M ajor R. A. Bull, Research D ire c to r of th e E le c tric a l Steel F o u n d e rs’

Research G roup, w as re a d in a b s tra c t by M r. H . Cole E ste p , who said M ajo r B ull deeply re g re tte d

* “ The Steel F o u n d ry ,” 2nd edition (1822), by J o h n Howe H all.

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t h a t h e could n o t be p re s e n t. H e h a d been an x io u s to come because of th e g r e a t im p o rta n c e w hich he a n d all th e d ire c to rs an d officers of th e A m erican F o u n d ry m e n ’s A ssociation a tta c h e d to th e se m eetin g s of business m en in v a rio u s co u n tries. T hey w ere of g r e a t te c h n ic a l an d p ra c tic a l v a lu e ; th e y also h a d a la s tin g effect on th e re la tio n s betw een n a tio n s, w hich, a f t e r all, w as m ore im p o rta n t th a n steel c a stin g s. M a jo r B u ll’s p a p e r w as a com prehensive one.

Mi*. M elm oth’s P a p e r w as re a d in a b s t r a c t by M r. V. C. F a u lk n e r , who p o in te d o u t t h a t i t covered ro u g h ly th e sam e g ro u n d as M a jo r B u ll’s P a p e r, e x cep t t h a t th e a u th o r confined h im self to sm all steel castin g s.

The discussion was o pened by th e re a d in g o f tw o com m u n icatio n s fro m Mr. Vi c t o r St o b i e, o f D u n - ston-on-T yne, who w ro te : —

Major B ull’s Paper.

The E x ch an g e P a p e r w hich M a jo r B u ll h a s p re ­ sented to u s th is y e a r is a sp len d id in tro d u c tio n , n o t so m uch to w h a t o u r co n frè re s in th e U n ite d S ta te s a re doing as to th e m e n ta lity h u ilt u p in th e m inds of th e te c h n ic a l h ead s of t h a t c o u n tr y ’s fo u n d ry in d u s try as a re s u lt of th e i r p a r t ic u l a r b ir th an d g row th.

M ajo r B ull r ig h tly ta k e s i t fo r g r a n te d t h a t th is I n s tit u te is n o t afflicted w ith in s u la rity in con­

te m p la tin g accom plishm ents in th e fo u n d r y w ork of his c o u n try . H e to u ch es lig h tly , n e v e rth e le ss, o n ju s t one p o in t w hich m ig h t colour th e p e rs p e c ­ tiv e he lays b efo re us, o n e p o in t w hich we a re im m ediately p re p a re d to concede, a n d w hich we c an assu re h im is only ju m b led in m e a n in g in some of th e d a ily P re ss, b u t, alm ost, n o t a t all am o n g B ritis h te c h n ic a l fo u n d ry m e n . T h a t p o in t is th e s p ir it b eh in d m ass o r, as he p u ts it, q u a n ti ty p ro ­ d u ctio n . O nly w rite rs in th e d aily P re s s c a n afford to d is re g a rd logic in th e b u ild in g u p o f k a leid o ­ scopic w o n d erm en t, an d th e p ic tu re s such w rite rs c o n ju re u p of th e “ p re s s -th e -b u tto n -a n d -th e -p la n t- does-the-rest 11 ty p e o f in d u s try in th e U n ite d S ta te s is well qualified to m ak e all serio u s te c h ­ n ic ia n s over th e r e feel th e y a re b e in g m is u n d e r­

stood. W e can assu re M a jo r B u ll t h a t we o f th e fo u n d ry tr a d e in th is c o u n try well recognise t h a t

q u a n tity p ro d u ctio n would have died a m ost early an d w ell-m erited d e a th h a d q u a lity n o t played a sufficient role in such p ro d u ctio n .

American Specialising Not Possible Here.

S p ecialisin g in th e S ta te s h a s been c a rrie d to a d egree u tte r ly im possible in th is c o u n try . A r e ­

view of som e figures given by M a jo r B ull will m ake th is clear. H e tells u s t h a t th e o u tp u t from open- h e a rth fo u n d rie s in th e S ta te s in 1917 was 1,357,700 tons. C om pare th is w ith th e to ta l o u tp u t of steel c a stin g s in th e U n ite d K ingdom fro m open- h e a rth , c o n v erter, cru cib le an d electric fu rn a c e s in 1917, viz., 230,027 tons. W ith an o p e n -h e a rth de­

m and alone of six-fold th e to ta l w eig h t of o u r o u t­

p u t and w ith , undo u b ted ly , no g re a te r d iv e rsity of usages fo r th e m a te ria l, sp ecialisin g should be " on v e lv e t.” O ur A m erican frie n d s a re lucky to h av e such o p p o rtu n itie s. T hey have m et th e re q u ire ­ m ents, an d g r e a t c re d it is due to th em for th e excellent com m ercial re s u lt.

The o u tlin e th e a u th o r gives us of th e h isto ry of th e gro w th in fav o u r, in th e S ta te s, of th e acid electric fu rn a c e was, he believed, th e first p rin te d account. In th is c o u n try we a re n o t all q u ite so convinced t h a t a steel c astin g of 0.055 p er cent, su lp h u r will he o rd in a rily an d alw ays equal in te c h ­ nical v alu e to a c a stin g o f 0.015 p er cen t, su lp h u r.

The m ain reason is because th e fa c to r, “ I f all o th e r co n d itio n s a re e q u a l,” which M ajo r Bull adds to his s ta te m e n t of th e p rev ailin g A m erican opinion, is, in p ra c tic e , so easily u n o b tain ab le.

Balling Up of Sulphide Inclusions.

I t is know n t h a t one p rin c ip a l re s u lt of a n n e a l­

ing steel castin g s is th e b allin g up, h ere an d th e r e in th e s tru c tu r e , o f th e m etallic sulphides which previously enm eshed th e steel cry stals. I t is also known t h a t i t is n o t alw ays th e case t h a t all m a te ria l placed in an a n n e a lin g fu rn a c e receives equal tr e a tm e n t. Such differences as do e x ist in th e su lp h u r c o n te n t of castin g s will, th erefo re, affect th e b rittle n e ss of th e m a te ria l if an d when the a n n e a lin g is n o t v aried to th e re q u ire m e n ts of th e case, and unless each an d every c a stin g in a fu rn a c e a t one tim e is considered in th e lig h t of its sulphur c o n te n t. Such co n sid eratio n of th e in d i­

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v id u al c a stin g is u n d e sira b le an d u su ally im pos­

sible.

An a d v a n ta g e of low s u lp h u r in steel c a stin g s is th e s h o rte r a n n e a lin g n ecessary p ro p e rly to t r e a t them .

Importance of Economisers.

M a jo r B ull m e n tio n s a m a t t e r of w hich h e was aw are p e rso n ally , b u t w hich w as re m a rk a b le in view of th e u su a l A m erican c a re o f th e c e n ts w hich m ake u p th e do llar. H e s ta te s t h a t th e use of “ econom isers ” fo r electrodes is uncom m on in A m erica. As some people a re aw are, t h e w rite r was th e first to design a n d use econom isers on elec­

tr ic ste e l fu rn a c e s. The S to b ie econom iser d a te s back six o r seven y ears, an d is so m eth in g q u ite d is tin c t from th e m ere sealin g of th e e le c tro d e holes in fu rn a c e roofs. I t effectively p re v e n ts an y flam e o r even gas from p assin g o u t o f th e fu r n a c e , a n d p e rm its t h a t ti g h t sealin g w hich th e a u th o r rig h tly considers as so n ecessary to in c re a se th e efficiency of th e p la n t an d to give m ore effectiv e c o n tro l in th e adm ission of oxygen to th e b a th . W h en he first d esig n ed th e a p p a ra tu s , M r. S to b ie h a d in m in d only th e avo id an ce of th e w ear a n d t e a r o f th e ro o f a n d th e elec tro d e g e a r, cau sed b y th e c o n tin u o u s u p w a rd ru sh of flam es th ro u g h th e e lec tro d e h o les;

b u t v e ry soon c o n sid erab le sav in g o f e le c tro d e an d c u r r e n t w as seen to r e s u lt fro m its use. S e ek in g for a s u ita b le com m ercial d e sc rip tio n o f th e a rra n g e m e n t, th e w ord 1 ‘ econom iser ” w as u l t i ­ m ately decided u p on. T he w ord h a s now , u n f o r ­ tu n a te ly , becom e th e g e n e ra l a p p e lla tio n o f all ty p es o f ro o f seals, an d th e d iam o n d of te c h n ic a l ad v an ce h a s become te m p o ra rily lo st am o n g th e p a ste of s a le sm a n s h ip !

A Sand Query.

T he g r e a t d ifference b etw een A m erican a n d B ritis h p ra c tic e in m oulding san d s, o u tlin e d by th e a u th o r , is of c o n s ta n t in te re s t. W o u ld M a jo r B u ll te ll u s if ex p erien ce in th e S ta te s h a s show n an y a d v a n ta g e as betw een fe rru g in o u s a n d , p ra c tic a lly , n o n -fe rru g in o u s clays fo r m ix in g w ith th e silica sa n d ? T h is is asked, of course, on a c c o u n t of th e v ery d iffe re n t p e rc e n ta g e of hygroscopic w a te r which th e tw o clays, d ifferin g g re a tly in iro n oxide c o n te n t, will ta k e u p to give a p p ro x im a te ly s im ila r b o n d in g values.

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M ajor B u ll’s P a p o r is on© of those “ m eaty ” ones which a re alw ays so welcome, and h© wished to a-dd his th a n k s to its a u th o r for th© p leasu re and in s tru c tio n deriv ed from it.

Mr. Melmoth’s Paper.

M r. M elm oth’s P a p e r is an in te re s tin g resum e of'-—

c e rta in p ra c tic e s in steel c astin g m a n u fa c tu re , encourages discussion of several p o in ts / A n

t £

Fluidity of Electric Steel. ( The in te re s tin g question as to th e fliiiditV jfoi should it be viscosity?) of electric steel compSsSdf I E J w ith c o n v erter steel a t th e sam e te m p e ra tu re isT— — one which th e follow ing episode m ay help to d e c id e

:—-L a s t y e a r, M r. S tobie m ade some electric steel for a c astin g of a b o u t 3 | to n s w eight. The forem an in ch arg e of th e fo u n d ry m ade a n e rr o r as to th e w eight of m olten steel re q u ire d , w ith th e re su lt t h a t th e steel p rovided did n o t rise p a st th e bottom of th e m ain head , which w as of la rg e size. M r.

S tobie was asked if he could p rovide some more steel to fill th e head. N ot h av in g any finished steel available, he took h a lf a to n of steel, which was a t very o rd in a ry “ s la g g in g ” te m p e ra tu re , from a n o th e r fu rn ace. This steel was c e rta in ly now here n e a r th e necessary te m p e ra tu re fo r th e c a stin g of o rd in a ry elec tric steel, even in to ingots, an d would probably have s e t in th e nozzle h ad i t been finished and ta p p e d a t t h a t h e a t. H ow ever, th e lad le was p u t u n d e r th e fu rn a c e an d h a lf a to n of th e u n ­ slagged w ild steel was ta p p e d in to it, h av in g p re ­ viously p u t ab o u t th e sam e p e rc e n ta g e of ferro - silicon and alum inium in to th e lad le as is th e p ra c ­ tic e in those w orks fo r th e ir co n v erter steel.

The ladle an d c o n te n ts w ere ta k e n aw ay to th e mould, and th e steel w as p oured in to th e h ead . I t was fe lt th a t th e steel m ig h t n o t ru n p ro p erly , b u t as he had previously been in te re ste d in th e p resen t question of th e c o m p a ra tiv e viscosity of d ifferen tly m ade steels, he was in te n t on n o tin g all th e d etails of th e h a p p en in g .

The lig h t-in te n sity of th e steel as it cam e from th e fu rn ace in to th e ladle was, beyond any question, th e lowest he had ever seen a t th e ta p p in g of an electric fu rn a c e except when th e m etal h as been

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c a s t iro n . T he steel, as it e n te re d th e m ould from th e ladle, was m ost clearly “ c o ld ,” ju d g in g a g a in fro m its li g h t- in te n s ity ; b u t i t w as fu lly as fluid as e le c tric steel a t fu ll h e a t. W hen th e m ould h e a d was fu ll, a sm all b a la n c e of steel w as r u n o u t of th e ladle, an d th e lad le a n d nozzle w ere as c le a r of m e ta l as th e y w ere a f t e r th e c a s tin g of th e p r e ­ vious h ig h -te m p e ra tu re e lec tric steel.

Electric Steel is Quiet.

I n several w orks w here c o n v e rte r steel h a s been m ade, an d w here S tobie elec tric fu r n a c e s h a v e b een in stalled , he h a d h a d o p p o rtu n itie s of o b se rv in g th e c a stin g o f b o th ty p e s of steels. T he e le c tric steel is no ticeab le fo r its q u ietn ess im m e d ia te ly i t is in th e m o u ld ; b u t th e sam e is n o t so t r u e o f con­

v e rte r ste e l. Two re s u lts a rise fro m t h i s f a c t ; th e su rfa c e of th e elec tric steel c a s tin g is alw ays sm oother a n d b lu e r th a n th e c o n v e rte r ste e l cast­

ing ; an d th e r e a re few er c o n tr a c tio n cra c k s d u e to p u llin g .

I t is in te re s tin g to n o te t h a t M r. M elm oth uses s y n th e tic m o u ld in g san d s in h is fo u n d ry . C an h e give us an y in fo rm a tio n on th e i r u se c o m p ared w ith n a tu r a lly bonded san d s?

Acid Electric Steel and Output.

M r . W . H . P o o l e (K eighley) said he h a d th e p leasu re d u rin g th e w ar of o p e ra tin g w h a t he th o u g h t w as th e first acid e le c tric f u r n a c e in th is co u n try of th e S n y d e r ty p e . I n th e firs t case he tr ie d a basic lin in g , b u t ow ing to q u e stio n s o f h ig h v o ltag e th e y h a d endless tro u b le w ith re f ra c to r ie s . The acid lin in g e le c tric fu r n a c e g av e a p a r tic u la r ly w onderful p erfo rm an ce. F ro m th r e e sm all 30-cwt.

fu rn aces, w orking 24 h o u rs a day, he w as ab le to get 150 to n s of steel p e r week.

Slag Inclusions and Fluidity.

The m ost im p o rta n t q u estio n he w ished to m e n ­ tion was a b o u t th e flu id ity . They h a d a v ery p ecu liar exp erien ce in t h a t resp ect. Som e of th e he a ts w ere a t a te m p e ra tu re ex c e p tio n a lly h ig h , checked 'by a m an w ith a p y ro m e te r, b u t no sooner, h a d th e m e ta l been p o u red in to th e lad le th a n i t s ta r te d to solidify. The an aly sis of th e m etal w as q u ite n orm al. I n f a c t co m p arin g it w ith a v e ry

fluid h e a t th e y found only a few p o in ts difference in th© analysis. I t was n o t u n til very ca re fu l micro- p h o to g rap h s had been ta k e n t h a t th e y fo u n d o u t w h at th e y considered was th e cause. I t c e n tred ro u n d th e question of slag inclusion, an d it m ig h t be of in te re s t if he s ta te d w h at th e y th o u g h t from th e ir experience was th e c o rre c t solution of th is problem . T he microscopic e x a m in a tio n showed a v ery p e c u lia r form of slag inclusion, th e slag being produced in g ra n u la r-lik e fo rm a tio n in ste a d of th e g lo b u lar fo rm atio n , which Was usually found in th e o rd in a ry way. The slag was in th e form of a fine film ro u n d th e m etal. In th e case of th e cold h e a ts th e y found th e te s t b a r would only bend very s lig h tly ; in th e case of th e good fluid h e a ts th e te s t b a r would bend p ra c tic a lly double a f te r an n ealin g tr e a tm e n t.

A n o th er p o in t t h a t he th o u g h t m ig h t be very m uch m ore em phasised w as th e question of th e a fte r-h e a t tr e a tm e n t of steel castings. To h is m ind it was one of th e m ost v ita l fa c to rs in o b ta in in g good physical resu lts. H e did n o t th in k th e very g r e a t value of th e su ita b le h e a t tr e a tm e n t of steel castin g s h a d been fu lly a p p re c ia te d . M ajo r B ull h ad em phasised t h a t steel w ith a phosphorus c o n te n t u p to 0.04 p e r c e n t., a f t e r su itab le h e a t tr e a tm e n t had excellent te n sile an d b en d in g te s ts. I t was a re g u la r p ra c tic e to ru n as high as 0.06 p er cent.

T he phosphorus could g e t up to 0.10 p er cent, w ith ­ o u t any d e trim e n t to th e physical q u alities, b u t it oug h t to h av e a p ro p e r h e a t tr e a tm e n t.

On th e question of c o n tra c tio n he would like M r.

M elm oth to give in fo rm a tio n as to w h eth er he had found any difference betw een Bessem er and electric steel in t h a t resp ect. P ersonally, he h a d found t h a t elec tric steel ten d e d to h ave m ore co n tractio n .

T here was one in te re s tin g th in g w ith re g a rd to slag inclusion which resem bled w h at m any fo u n d rv - m en experienced w ith o rd in a ry cast iro n . T he te m ­ p e ra tu re m ig h t a p p e a r q u ite h o t in th e cupola, b u t th e m etal very ra p id ly chilled off.

H e th o u g h t if fou n d ry m en would ta k e up th is question of th e globular slag inclusion, an d p erh ap s also a n o th e r p o in t, th e excessive kish or g ra p h ite , th e y w ould h av e an id ea as to w h a t h ap p en ed in th e case of steel solidifying so quickly. T he slag inclusion and th e presence of excessive kish in th e

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p ig -iro n — d u e of course to m a n u f a c tu r in g c o n d i­

tio n s —w ould cau se in o rd in a ry g rey iro n a like c o n d itio n in th e flu id ity w hich one saw in th e steel.

I t was th e p ra c tic e in th e sm all steel fo u n d rie s in th e S ta te s to p u t a m ax im u m n u m b e r o f n a ils in to th e m ould. T he B elg ian p ra c tic e w as v ery sim ilar in a m odified w ay, h u t if th e y to o k th e Sheffield p ra c tic e v ery few firm s m a k in g ste e l c a s t­

ings used n a ils in th e ir m oulds.

Casting Temperature.

Me. R h y d d e r c h said he h a d been v ery in te re s te d in b o th p a p e rs, b u t h e p a r tic u la r ly looked fo rw a rd to M a jo r B u ll’s P a p e r, because w hen ev er th e y h a d a p a p e r on A m erican p ra c tic e th e y g o t some som e v alu ab le in fo rm a tio n h e re a n d th e r e .

M r. M elm oth seem ed to t r e a t th e q u e stio n of flu id ity r a t h e r seriously. M a jo r B ull s t a te d t h a t th e e lec tric fu rn a c e h a d su p ersed ed th e c o n v e rte r in m an y cases. “ I t m u s t be rem em b ered t h a t m any electric steel fu rn a c e s in A m erican fo u n d rie s h a d su p ersed ed c o n v e rte rs, th e u se of w hich w as w ell-known to m an y seeking a m ore s a tis f a c to r y u n it fo r m ak in g c a stin g s of th i n se c tio n s, re q u irin g h ig h flu id ity .” M r. M elm oth, o n th e o th e r h a n d , said t h a t w ith th e e le c tric fu r n a c e one o b ta in e d a decrease in flu id ity . Of course o n e w as acid , and th e o th e r w as basic, b u t th e w hole th i n g th e r e , it seem ed to him , w as t h a t th e r e w as n o a tt e m p t m ad e to a sc e rta in th e c a s tin g te m p e r a tu r e . T he m eans th e y h a d a t p re s e n t of e s tim a tin g th o s e te m p e r a ­ tu r e s m ig h t n o t b e a c c u ra te to one o r tw o deg rees, b u t th e y w ere sufficiently a c c u ra te to give o n e a very good id ea of w h a t a c tu a lly did h a p p e n . Com­

p a rin g th e elec tric fu r n a c e steel w ith t h a t fro m th e bottom -blow n c o n v e rte r an d th e surface-blow n con­

v e rte r, fro m th e p o in t of view of im p u ritie s , h e supposed i t would be said th e e le c tric fu r n a c e w as th e p u re s t, th e n th e surface-blow n c o n v e rte r, a n d th e n th e bottom -blow n c o n v e rte r. W h en i t cam e to c a stin g th e r e w as no q u estio n t h a t th e su rface- blown c o n v erter h a d less im p u ritie s th a n th e bottom -blow n c o n v e rte r, an d m o re th a n th e e le c tric fu rn a c e , b u t if i t w as a q u estio n o f th e s e im p u r i­

tie s being p re s e n t an d affectin g th e flu id ity th e r e ­ la tio n th e r e w as u p s e t s tr a ig h t aw ay, b ecau se th ey

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h ad a p u re steel from th e e lec tric fu rn a c e becom­

ing less fluid or less “ lively ” th a n in th e case of th e bottom -blow n co n v erter. T h ere m ig h t be a suggestion t h a t i t was a question of reactio n .

Heat Units from Exothermic Re-actions.

H e took th e tro u b le d u rin g th e w eek-end to w ork o u t w h at th ey d id g e t, assum ing they had a c e rta in a m o u n t of fe rro u s oxide p re s e n t in these co n v erter processes, a c e rta in a m o u n t of silicon and a c e rta in a m o u n t of m anganese th a t were all oxi­

dised. I f 0.5 p e r c en t, of silicon was oxidised to silica, fo rm in g fe rro u s silicate, th e y g o t 120 deg.

rise of te m p e ra tu re . I f m anganese was oxidised to m anganese silicate th e y g o t 55 deg. rise. The effi­

ciency of th e m anganese, in o rd in a ry 0.25 p e r cent, carbon, say, was so m eth in g like 75 p e r cen t. The efficiency of silicon was som ewhere ab o u t 80 p er cent. W o rk in g i t o u t on t h a t basis, th e rise in te m p e ra tu re t h a t th e y would g e t bv th e a d d itio n of th ese v ario u s elem ents did n o t m ean m uch m ore th a n 5 o r 10 deg. T h a t figur»

ciency of th e m anganese, in o rd in a ry 0.25 p e r cent, carbon, say, was so m eth in g like 75 p e r cen t. The efficiency of silicon was som ewhere ab o u t 80 p er cent. W o rk in g i t o u t on t h a t basis, th e rise in te m p e ra tu re t h a t th e y would g e t bv th e a d d itio n of th ese v ario u s elem ents did n o t m ean m uch m ore th a n 5 o r 10 deg. T h a t figur»