The Iron Age 1942-03-12: Vol 149 Iss 10

ARCH 12, 1942 Timken 4-Row Roll Neck Bearings applied the roll necks modern mill, sstrenuous period emergency the superior dependability and endurance Roll Neck Bearings source great fication and relief rolling mill operators. previous time have these bearings been put test nor more completely justified their users. mills, sheet mills, plate mills and bar mills leep the steel coming through without un- interruptions for bearing changes. Timken Roll Neck Bearings are cred- KEN vith the lowest bearing cost per ton rolled TAPERED the steel industry. This advan- ROLLER Manufacturers Timken Tapered Roller Bearings for automobiles, motor trucks, railroad cars and locomotives and all kinds industrial machinery; Timken Alloy Steels and conditions return. Carbon and Alloy Seamless Tubing; and Timken Rock Bits. vill particular value and when severe “Ours but carry spare THE IRON AGE, published every Thursday the CHILTON CO. (INC.). “This day-and-night process and our equipment run continuously. But don’t even bother carry spare parts for our writes the Plant Engineer Eastern corporation. “Years ago, began discarding other types drives favor worm gearing. first began installing Clevelands 1923 and have bought more than them far.” Continuous operation your plant operation these times even single break-down can disastrous. Cleveland Worm Gear Speed Reducers can help you secure the same trouble-free machine operation. For years, Cleveland has built Worm Gearing exclusively—has grown the largest manufacturer the industry. will glad have Representative call. The Cleveland Worm Gear Company, 3252 East 80th Street, Cleveland, Ohio. Affiliate: The Farval Corporation, Cleveland, Manufacturers Centralized Systems Lubrication Canada: PEACOCK BROTHERS LIMITED WORM Philadelphia under act March 1879. $6.00 year S., Canada $8.50, Foreign $12.00. Vol. 149, No. Entered second class matter November 1932, the Post Office f 4 : — wt q fice at MARCH 12, 1942 VOL. 149, NO. VAN DEVENTER President and Editor BAUR Vice-President and General Manager Managing Editor, LIPPERT News Markets Editor, ROWAN Technical Editor, OLIVER Associate Editors JAMES Art Editor, WINTERS Editorial Assistants Washington Editor MOFFETT Resident District Editors CAMPBELL HERMAN KLEIN Pittsburgh Chicago Cleveland Detroit CHARLES POST San Francisco Editorial Correspondents Buffalo Cincinnati FRAZAR RAYMOND KAY Boston Los Angeles HUGH SHARP JOHN McCUNE Milwaukee Birmingham SANDERSON ROY EDMONDS Toronto, Ontario St. Louis Newark, Seattle ° ° ° DIX, Manager Reader Service ° ° °o Advertising Staff Herman, Chilton Bldg., Philadelphia Hottenstein, Otis Bldg., Chicago Raymond Kay, 2420 Cheremoya Ave., Los Angeles, Cal. 100 East 42nd New York Peirce Lewis, 7310 Woodward Ave., Detroit Ober, 100 East 42nd St., New York Robinson Johnson, Market Research Hayes, Production Manager. Baur, Typography and Layout. ° Member, Audit Bureau Circulation Member, Associated Business Papers Indexed the Industrial Arts Index. Pub- lished every Thursday. Subscription Price United States and Possessions, Mexico, Cuba, and South America, $6.00; Canada, $8.50; Foreign, $12.00 year. Single copy, cents. ° ° Owned and Published CHILTON COMPANY Executive Editorial and Offices Advertising Offices Chestnut and 5éth Sts. 100 Eost 42nd St. Philadelphia, Pa. New York, U.S.A. U.S.A. OFFICERS AND DIRECTORS MUSSELMAN, President JOS. HILDRETH, Vice-President GEORGE GRIFFITHS, Vice-President EVERIT TERHUNE, Vice-President VAN DEVENTER, Vice-President BAUR, Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JULIAN CHASE, THOMAS KANE, HARRY DUFFY CHARLES HEALE This Week in... Editorial Technical Articles Heat Treating Tips Features Assembly Washington West Fatigue Cracks Dear Editor News and Markets This Industrial Week News Industry Construction Steel Machine Tool Activity Non-Ferrous Metals Scrap Markets ...... Comparison Prices Finished Steel Prices Warehouse Products Advertised Procedures “Plug” Welding Replaces Electric Steel Plant Refractories Extinguishing Magnesium Fires How Savage Arms Makes the Browning Machine Breaking Long Shell Steel Stove Builds Boats Personals and Obituaries Iron and Steel Scrap Prices Index Advertisers IRON Labor Restriction War New Equipment: Small Tools and Gages ... Copyright, 1942, by Chilton Company (Inc.) 1 Whenever Joseph Ryerson Son, Inc., Chicago, Milwaukee, St. Louis, Cincinnati, Detroit, Cleveland, Buffalo, Boston, Philadelphia, Jersey City. 44—THE IRON AGE, March 12, 1942 peace and war, good times and bad—year-in for century—Ryerson stocks steel have been American prompt, dependable source supply. Today, wat production requirements come first but Ryerson serving, too, the needs other essential industries from which flow the goods that feed, clothe and house the nation,—that supply its power, its minerals and other raw materials all part and parcel the mighty war endeavor. The two-fold Ryerson function supply steel where needed, without delay—and aid the most effective, intelligent use that steel every way that experience and skill can suggest. Wartime demands have made inroads Ryerson stocks, but Ryerson resources are your command, assist you meeting any problem steel supply application. THE RON AGE ° ° MARCH 12, 1942 ° ° ESTABLISHED 1855 Labor Restrictions War Output airplane tank gun any caliber cannot much war business unless has ammunition. And Uncle Sam has taken care that end placing orders with American manufacturers for plenty shells and bombs. doubt they will good shells and bombs when get them and God knows that need them. Uncle Sam has done his part designing, specifying and placing the orders. now industry turn these things out the greatest possible number and the shortest possible time. There will not any lack materials; priorities take care that. There will lack efficient shell making equipment; our machine tool industry has seen and seeing that. that brings the responsibil- ity down the management and the labor the plants that have shell contracts. inconceivable me, and think will you too, that the American people, with sons, brothers and husbands war, would will tolerate for moment, any artificial and deliberate “slow down” shell production which machines these plants capable turning out shells are kept idle, those work are permitted perform far below their rated and tested output capacity. machines that might used are idle, the responsibility that management. they are slowed down because union restriction daily hourly output, the responsibility rests upon labor. Last week, traveling about the country, heard in- stance this sort that deserves attention—and action. came from unimpeachable authority whose name withholding because the political other reprisals. Machine tool builders had provided certain manufacturer with equipment that had been demonstrated capable turning out, say, shells caliber every hours. Management the plant was anxious run this equipment capacity 24-hour basis and had provided enough men operate that scale. But previous equipment, operated that plant, had turned out but two similar shells per day. And the union insisted that the new equip- ment should operate the same basis. Now not for moment think that this attitude typical labor out and corrected, there would little difficulty giving Donald Nelson the modest per cent increase production for which asks. think that there should confidential bureau established government which both management and labor could refer such cases for investigation, with assurance anonymity prevent plants being struck men being fired. | | | | | | | | | ° ° | — ZZ — Help Overcome the Critical Shortage! Are you listening America’s call for scrap—scrap, the magic metal that can melted and refined into steels for the fighting forces America and her Allies? Charging scrap into furnaces not new steelmaking method. has been practiced for years, conserving millions tons valuable iron ore resources. Last year scrap collect- ing facilities made available 25,000,000 tons help maintain the output America’s steel The need urgent, however, that even greater effort must applied that all steelmaking furnaces can operate full capacity. Make search for scrap throughout your plant. You may find discarded machinery, rusty shaft, broken rail, twisted beam, old boiler, obsolete crane, unused switch track, steel trussed building too costly repair and use. What about the “bone pile,” where odds and ends have been rusting for years? Possibly you can find only few pieces scrap, weighing only fraction ton. Start them the way stee mill! Your local scrap dealer, gathering piece scrap here, and one there, will soon fill car. Carloads from other dealers will grow into trainload. Trainloads arriving mills will assure steel output capacity. Remember that pounds steel means another 105 mm. shell; tons another tank; and, 25,000 tons will place new cruiser and several cargo ships under the American flag. Time and materials are precious our men the fighting fronts. not handicap them— answer America’s call today —send your scrap refined into useful steel. 2 { “> 3, a ; j 4 x: = : j Dearborn Street, Offices: Milwaukee, Detroit, St. Paul, St. Louis, Kansas City, Cincinnati, New planes and ordnance and the progressive severity demands placed upon the materials going into these war products have fo- cused attention magnaflux important means making non- destructive tests these metals. These tests are being applied cur- rently various stages manu- facture and are also being used during periodic overhauls while the machines are actual service. With the increased use this non-destructive method testing, have come demands for equipment suited production inspection and need for clearer understanding how the tests should applied. aid filling this need for clear understanding testing, the investigation reported this article was undertaken de- termine what should govern test- er’s choice method and inspection medium for locating surface and subsurface defects. convenient classify all de- fects discoverable the magna- flux method the basis whether they are surface sub-surface character. Under the first category are included, among others, quench- ing cracks, forging laps, grinding checks, surface seams and fatigue cracks. The first four named are introduced manufacture, but fatigue cracks are produced only service. They are, therefore, the main consideration the over- haul inspector. The second category, sub-surface defects, includes sub-surface seams, sub-surface defects welds such slag pockets, and shrinkage cavi- ties and porosity castings, all which are manifestly produced during manufacture. considering the technique Magnafluxing Procedures Results investigation into the efficacy the vari- ous techniques which can employed with this non- destructive method testing for surface and subsurface cracks reported this, the first section two-part article. ° Magnaflux Corp., Chicago ° the inspection procedure, the mag- naflux operation performed two steps: (1) The part magne- tized, and (2) the inspection medi- applied. These two opera- tions can performed successively simultaneously. For convenience, each the above steps may further sub- divided into two headings accord- ing the kind magnetizing cur- rent employed. All magnetization procedures commonly used pres- ent depend the use either a.c. d.c. for the magnetizing opera- tion. Two Inspection Mediums The inspection medium, consist- ing finely divided ferromagnetic material, can also applied either two general ways—as dry powder*, suspension light oil distillate. The first these procedures called the dry method, the second the wet method. The operator, therefore, has the choice using either a.c. d.c. for magnetization, and the choice using either the dry wet method applying the inspection medium. ° There also third choice whether magnetize the part and apply the inspection medium after- wards, performing the two opera- tions successively and relying the magnetic retentivity the specimen for the indication (called the residual method), use the continuous method which the inspection medium applied simul- taneously with the current flow shot. The current may flow for ex- tremely brief interval time, brief 0.00001 sec. the case flash magnetization, but during that time the ferromagnetic ma- terial present the vicinity the defect and attracted the leakage field which the defect pro- duces. The requirements for the so-called continuous method are therefore fulfilled. The part this investigation completed date covers compari- son the results obtained with a.c., d.c. and rectified a.c. magnetizing currents locating surface and sub-surface defects, and compari- son the relative value the wet and dry methods for locating these defects. does not cover compari- THE IRON AGE, March 12, 1942—47 | ° e: the for ing ons ect- > hat ind ave ing eel rap im. ag. lay Col. Current sons the residual and continuous methods. The specimens used illustrations were selected each case from large number and were chosen giving representative pat- terns. Investigation Procedure The first step this investiga- tion was check the experimental error involved the procedure used making these tests. Three standard units were em- ployed for the magnetization work. suspension standard magnaflux red paste No. was used for all tests. light oil distillate having the following characteristics was used for the suspensoid: gravity 46, Saybolt viscosity sec., flash point, tag open cup 175 deg. initial boiling point 390 deg. F., end point 490 deg. F., color Say- bolt. Approximately 1.5 oz. paste were used each gallon suspen- soid. avoid pattern variations due possible differences the amount ferromagnetic material suspension, the same suspension 48—THE IRON AGE, March 12, 1942 Col. (Battery) Current IG. produced surface seam air- craft piston pin under various testing procedures. Meter reading was 850 amp. each test. was used all cases, being trans- ferred toto from one unit the other each series tests was made. study the characteristics vari- ous powders used for magnetic testing contained the article “Magnetic Test- THE Ace, Oct. 1941, 64. aircraft piston pin contain- ing inclusion partly surface and partly sub-surface character was used the first test specimen. set five patterns was made with magnetizing unit furnishing cycle, single phase a.c. Another set five patterns was made with magnetizing unit furnishing d.c. from storage batteries. third set five patterns was made with Col. Rectified Full Wave dry type rectifier unit furnishing full wave rectified a.c. from three phase, cycle a.c. meter read- ing 850 amp. was used each case, this amount current was found, after numerous tests, adequate produce satisfactory indications with this specimen. The wet continuous method was em- ployed all cases. Timing the relay system was set sec. Circular magnetization was used all cases, and special attention was given centering the current carrying conductor through the pis- ton pin and also maintain uni- form flow inspection liquid each time the operation was repeated. The indications were carefully dried place, using carbon tetrachloride. They were then picked using cellophane coated with adhesive (Scotch tape) and transferred sheets plain white paper for photographing. The patterns produced are illus- trated Fig. and are seen very consistent for each machine. There little difference between an . : ‘ 3 4 « ~ | } j = 3 ] | J } # | | | ‘ > } | Specimen 1500 Amps. 1/2 sec. sec, the individual patterns each group that they are for all practical purposes indistinguishable. therefore safe conclude that pat- terns produced different mag- netizing procedures may com- pared and the differences attributed real differences leakage fields and not experimental error. determine the effect dura- tion the current flow pattern formation, build-up, another series tests was made. Two speci- mens, each containing representa- tive surface seam, were selected for the test. The results are seen Fig. which columns and show patterns obtained with speci- men No. and column those ob- tained with specimen No. All the tests this series were made with magnetizing unit de- livering full wave rectified a.c. described above. column 1500 amp. were used; column 550 amp.; and column 150 amp. The duration the current flow was for periods 0.1, 0.5, 1.0, 2.0 and 3.0 sec., respectively. Examina- tion each column reveals grad- ual increase intensity field > IG. 2—Effect the duration current flow the pat- tern build up. Magnetizing cur- rent was three-phase full wave rectified ° ° from top bottom, which due the general field leakage from the entire specimen. the duration the shot extended, there increasing build-up particles over the en- tire surface the specimen. column magnetizing current only 550 amp. was used, which, according prevailing practice, would considered rather light magnetization. While there still gradual darkening the general background from top bottom this column, indicating increase the general leakage field, the increase darkening not nearly This illustrates that within rather definite limits, both magnetizing current and time are effective determining the general background build-up. generally agreed that excessively dark backgrounds are undesirable for this type Col. Specimen 1500 j inspection for the reason that they may minimize the contrast between the indication and the background. Conclusions may concluded from the re- sults these tests that where adequate amount magnetizing current used the indication ob- tained with current flow 0.1 sec. would considered satisfac- tory most cases. The indication obtained with current flow 0.5 sec. entirely satisfactory even where the magnetizing current was only 550 amp., which, according present practice, would consid- ered too low. Finally appears that there little gained permitting the current flow for period longer than one-half sec- ond. The same specimens used for the determination experimental er- ror due pattern variation illus- trated Fig. were also used for comparison a.c. and d.c. for locating surface defects with the wet continuous method. Referring these patterns and comparing columns and the patterns THE IRON AGE, March 12, 1942—49 Col. 550 Amps. 1/10 sec. 1/10 1/10 sec. 1/2 sec. 1/2 sec. sec. h ~ 2 ? 1185 Amps. 1185 Amps. Col. Col. Col. Cycle Batteries Pull Wave Rectified Amps. 300 Amps. 300 Amps. 420 Amps. 420 Amps. 595 Amps. 595 Amps. 1185 Amps. Fig. 3—Comparative results grinding checks. Indicated amperes are meter readings. Col. Col. Cycle D.C. From Storage Batteries 2000 Amps. 2000 Amps. eet * 3000 Amps. 3000 Amps. Fig. 4—Flow lines brought out intense magnetization. 50—THE IRON AGE, March | f 4 ¥ 4 \ agair twee! units gre time: This tion, high wher 1200 Amps. 1200 Amps. | rents umn which were made a.c., d.c. and full wave rectified a.c., respectively, seen that the indications ob- tained were more clearly brought out a.c. than d.c. The basic current comparison, course, r.m.s. amperes against d.c. amperes; this, however, normal basis comparison be- tween a.c. and d.c. magnetizing units. Theoretically a.c. should show greater magnetizing effect the surface the magnetized specimen the peak the a.c. wave 1.41 times higher than the straight d.c. This peak, although short dura- tion, effective producing higher magnetization the surface where there question lack penetration due eddy cur- rents. The indications the third col- umn from full wave rectified a.c. 450 Amps Amps 3000 Amps 5—A comparison the various procedures tested the same surface seam. ° ° are comparable those obtained from the battery unit the second column, and are also distinctly in- ferior those obtained from a.c. This result furnishes double check the two methods. Fig. illustrated the re- sults obtained from specimen containing surface seam and number grinding checks. Meter readings from the three magnetiz- ing units are given the illustra- tion. will seen that the indi- cations obtained with a.c. (shown the first column) are considerably sharper than those obtained either d.c. full wave rectified a.c., favorable proportion being Col. Wave Rectified 600 Amps Amps 1500 Amps Current Strength Effect interesting note how the indication builds with increased strength current. This true not only the general density the pattern, but also true cracks which are theoretically unfavorable angle the direction circular magnetization. Here again the results obtained d.c. and full wave rectified a.c. are prac- tically identical. comparison the indications Fig. the basis the peak value the alternating current against the value direct current. For ex- ample, the patterns can matched follows: 300 a.c. 420 d.c.; 420 595 d.c.; 595 a.c. 840 d.c.; 840 a.c. These compari- sons are currents which the peak THE IRON AGE, March 12, (Battery) ° 4 ‘ 4 * > 1500 2000 2000 2000 Amp § 3000 Amps 3000 Amps | ig q § — the a.c. rather than the r.m.s. value equal d.c. Study Fig. this basis reveals the fact that the a.c. indica- tions are good better than comparable d.c. indications, except for the two highest currents where the pattern completely brought out that reaches what might called saturation point. addi- tional important advantage a.c. that for equivalent sensitivity the surface, least 1.4 times much d.c. a.c. required. the case either type current, the heat generated function the current actually being pro- portion the square the current indicated the meter reading. follows that the amount heat generated using d.c. will twice that for a.c., the surface sensitiv- ity adjusted the same level both cases. The additional amount generated heat may may not detrimental depending the shape and size the part under test and the ultimate use which the part put. Fig. illustrated the phe- nomenon called “flow which show only intense magnetiza- tion. Flow lines from the stand- point magnaflux inspection may considered surface indica- tion, the excessive current bringing out the direction grain flow the forging. This series patterns shows little difference between a.c. and d.c. for given meter reading. Illustrated Fig. are compara- tive patterns obtained a.c., d.c. and full wave rectified a.c. vari- ous currents from the same surface seam. current densities are in- creased from minimum 450 amp. maximum 3000 amp., Welding Replaces ing being used replace threaded staybolts the con- struction double walled sterilizer units used hospitals. With this type equipment, appearance important factor that the elimination staybolt heads the interior very much desired. Use welded spacers between the inner and outer walls shown the sketch makes much easier obtain smooth, polished surface the interior, and steam-tight construction assured. Tests have shown that the plug welded struc- ture will withstand steam pressures per cent higher than with the staybolt construction, because the possibility leakage eliminated. Referring the sketch, will seen that the inner wall not penetrated the T-shaped spacing NEW method “plug” weld- bars and that the outer wall sealed thoroughly the weld. The previously used staybolt construc- tion shown the right. The 52—THE IRON AGE, March 12, 1942 very considerable darkening the entire background takes place. This the same effect referred previously discussing the effect duration current flow pat- tern build-up, and due the gen- eral increased leakage field from the entire specimen due increased intensity magnetization. This series patterns also confirms the preceding results and indicates that a.c. better than d.c. for surface seams, and that d.c. obtained from batteries gives practically identical results with that obtained full wave rectification. Editor’s Note—In the next and con- cluding section this two-part article, the author compares wet continuous and dry methods magnafluxing for sub- surface cracks and summarizes the ad- vantages and disadvantages each pro- cedure related specific testing prob- lems. Staybolts inner walls are constructed from flange quality steel 55,000 65,000 tensile strength, with interior finish aluminum bronze. Nickel monel clad inner surfaces are also used. This welded construc- tion has been patented the American Sterilizer Co., Erie, Pa. ABOVE LEFT showing the new arc welding method (left) and the old staybolt method (right) suspension the in- ner walls hospital sterilizers. ABOVE staybolt heads have been eliminated this hospital sterilizer unit the substitution the plug weld- ing technique shown the sketch. Ex- cept for welded longitudinal seam, the new design presents smooth interior. LEFT WELDER fabricating tank for steril- izer unit, using jig hold the welded. Tank support the form cantilever beam the cylindrical work can slipped over the end. Photographs by courtesy of the Lincoln Electric Co. sma aut tric qua met (1) ° ° ° CHESTERS Central Research Department, United Steel Companies, Ltd., Stocksbridge, England ° ° ° LTHOUGH the proportion the total steel output made electric furnaces still small, vital importance due the demands airplane and automobile manufacturers for high grade alloy steels. The use elec- tric rather than gas fired furnaces enables steel more consistent quality and lower content non- metallics made. Two main types electric fur- nace are employed, namely: (1) THE ARC FURNACE. This type according whether the cur- rent passes from one electrode another, only heating the steel “indirectly” radiation from the arc, passes through the metal bath, part the heating being done “directly” the resistance the metal, the Héroult furnace. (2) THE INDUCTION FURNACE. This type furnace consists es- rounded water cooled coil through which passes alter- Electric Steel Plant Refractories Continuing the series articles steel plant re- fractories, the author discusses refractories for basic arc and induction furnaces and considers the merits and brick linings. nating current. The metal the crucible heated eddy currents induced and the coupling efficient and the insulation the crucible ade- quate, the metal melts. The bulk electric steel made 3-phase are furnaces the Héroult type. These are usually lined with basic refractories, but acid lined are furnaces are also employed, for example, melting high grade scrap steel foundries. The lining such fur- naces similar that the acid open hearth furnace, the side walls and roof being silica brick and the hearth silica sand ganis- ter. The present survey deals solely with basic furnaces and particu- lar with the intermediate size, that is, the 10-ton type shown Figs. and Arc furnaces only 1-ton capacity less are however em- ployed, for example, steel foun- dries, while least one furnace 100 tons capacity has been built. most furnaces the current completes its circuit through the bath, but the Greaves-Etchells furnace the conducting hearth acts the third electrode. The hearth made mixing steel turnings with the basic refractory, the cur- rent passing through the hearth leaving copper plate the furnace bottom. general, there are three car- bon electrodes about ft. diameter which vertically through the central region the roof and are arranged the cor- ners equilateral triangle. The electrodes are made graphite amorphous carbon and are raised lowered automatically electric maintain steady The voltage varies considerably with the size furnace and the stage melting refining, but for 10-ton furnace Since the power input high, the amperage with this low voltage must also high. the order 10,000 amp. per electrode. Amor- phous. carbon. electrodes. have higher electrical resistance than graphite electrodes and, therefore, must larger diameter. Recent are furnace installations contain number improvements. Thus, they usually include basket charging, illustrated Fig. THE IRON AGE, March 12, | ig - | | | \ \ ° ° j / 4 3 a | | This much more rapid than hand charging. With some furnaces the body the furnace can rotated; refinement that advantage both from the point view steel making and the life the hearth. With 10-ton furnace the melting time about two hours and the refining time about three and one-half hours, four charges being made per day. The general arrangement the refractories basic arc furnace shown diagrammatically Fig. The construction much less complex than that open hearth furnace and only three major divi- sions are considered necessary, namely, the roof, the side walls and the bottom. The Roof Construction: The roof either domed like that beehive brick kiln has flat central area shown Fig. For the latter type construction special shaped blocks are required, whereas the simple domed roof can built almost entirely squares and end arch brick. With both types roof special ring brick, usually several inches thicker than the roof whole, used form the electrode holes eyes.” Both with the simple domed roof and the flat topped roof, the rise less than that the open hearth 54—THE IRON AGE, March 1942 roof, being about in. per ft. chord 10-ton furnace. Most are furnace roofs are approximately throughout, but certain plants definite advantage claimed for the use ribbed structure. This generally the radial type, the ribs being made either silica sillimanite. With such roofs, possible for small area become abnormally hot and thin without any serious risk the roof whole collapsing. doubtful whether the use ribs offers any great advantage for small furnaces but for the larger type stated well worth while. Arc furnace roofs appear vary less thickness than open hearth furnace roofs, figure in. being typical. Where ribs are em- large, ton, 3-phase, electric arc fur- nace with flat top roof. ployed, these are generally about in. thicker. With silica brick the use ex- pansion allowances brick considered essential. This generally taken care tarred roofing sheet placed between the brick intervals. The brick can set dry except where they have cut and resurfaced. There objection, however, the use cement this considered desir- comparable with that the roof brick themselves. Even best, the life arc furnace roof short and hence not surprising that insulation such roofs has not been adopted. The use insulation would not necessarily lead increased in- side temperature, but, with the TABLE Grading Basic Induction Furnace Linings o | Sample No. Per Cent Tyler Sieve Sieves Equivalents 150 mesh 150 mesh Through 150 mesh Through 150 mesh ton Mat 2 wit! nac clay tha’ the rial left for tim ~ ; 10.0 34.0 21.0 14.0 21.0 IG. 2—Tap- ping the ton electric arc furnace into ladle. open hearth furnace, would result specifications appear have far greater wear local over- been issued for silica brick for use heating occurred. arc furnace roofs, but generally speaking, the properties required are those already discussed con- Most are furnace roofs are made nection with open hearth furnace with silica brick, but for fur- roofs.* The shape the brick must naces better results are sometimes excellent and there much obtained with high alumina fire- said for the use few special clay sillimanite brick. stated shapes possible. that when sillimanite employed, the thermal expansion the mate- rial small and uniform and its thermal shock resistance high that expansion joints need Roofs have also been constructed left. There little doubt that but using magnesite, chrome-magnesite, for its price, which three four and fused alumina brick, but the times that silica, sillimanite results obtained not appear would more widely employed. have warranted the continued use Materials: Open Hearth, Above Sill Plate Level,” THE IRON AGE, May and 29, 1941. TABLE Influence Magnesia: Alumina Ratio the Firing Expansion Spinel Forming Mixtures Ratio Linear Firing Alumina Per Cent Per Cent Per Cent Per Cent these materials except for very special purposes, for the manu- facture ferroalloys. Life and Causes Failure: The life are furnace roofs short and variable. some plants reasonable, while others 100 200 heats are expected. The life ob- tained varies greatly according the practice, for example, hot charg- ing less severe furnaces than cold charging, and long refining periods are clearly worse for the brickwork than short refining peri- ods, particularly the former in- volve the use good deal limestone, the dust must factor roof corrosion. Most the wear appears the result attack dust from the furnace atmosphere, but roof heated cooled too rapidly, particularly the early stages its life, spalling may occur. The marked maturing observed with open hearth furnace roofs does not seem take place the furnace, possibly because the sur- face layers melt away before they have time mature, possibly because the strongly reducing atmosphere. X-ray examination shows that the first zone the particular are furnace roof exam- ined did not consist cristobalite like the zone open hearth THE IRON AGE, March 12, 1942—55 il 4 P # 4 3—Charging 10-ton electric arc furnace means basket type charger. roof, but tridymite, shown Fig. This surprising result would suggest that the average tempera- ture the roof surface was less than 2680 deg. F., the tridymite- cristobalite conversion temperature. difficult believe that the temperature was fact low dur- ing the refining period and were, that the roof would wear away rapidly. Both equilibrium data and prac- tical experience with open hearth furnace roofs suggest that strongly reducing conditions greatly de- crease the durability silica re- fractories slagged with iron oxide, and probably this condition to- gether with periodical intense over- heating that explains obtained with most arc furnace roofs. Often roof must taken off before has been uniformly worn out because there weak spot. Thus the electrode rings frequently show premature wear, 56—THE IRON AGE, March 1942 due erosion and corrosion hot gases escaping between the elec- trodes and the brickwork. Replace- ment such roof sometimes overcome the insertion new set electrode rings old roof. The brick the outer rings the roof often show little reduction thickness except where spalling has occurred. The spalling are furnace roofs can largely eliminated careful handling the furnace, provided the melting program does not re- sult its being subjected fre- quent heating and cooling below red heat. Where the furnace worked periodically, the use su- perduty fireclay other brick. higher thermal shock resistance recommended. Longer lives could doubtlessly obtained the use high bulk density silica brick and possibly the use brick made without lime bond, but any marked improvement likely require the change more slag resistant material. According Leun, consider- able increase life can obtained using sillimanite brick the electrode rings spokes about in. width built radially. The real need, however, is, with the open hearth, for all basic furnace, the roof which would have much higher refrac- toriness and vastly improved resistance basic dust. The diffi- culty the way this develop- ment the tendency magnesite and chrome-magnesite show structural spalling fore they have corroded away. With furnaces manufacturing stainless steel the use such refractories permissible, but cases where chromium pick-up would serious, the use chrome containing re- fractories undesirable because the rapid rate which spalled brick fragments become converted chromium metal the strongly reducing slags. Side Walls Construction: The side walls basic fur- naces may built brick may rammed monolithic struc- ture. The former procedure more common, but where graded dolomite available, for example, basic bessemer plants, this material often used for the arc furnace side walls and hearth. general, mono- lithic side walls are built with outward slope give added stabil- ity, the material being rammed between the fireclay brick lined case and steel faced template. When brick employed, the wall generally vertical and the fettling possible order give the bricks maximum protection against slag. With 10-ton furnaces the brick side walls are commonly in. thick. Thus, they may consist, Fig. flat and two outside soldier courses, the one close the usually fireclay brick. The cylin- drical section the linings gives added stability since the bricks are keyed position and are not likely fall into the bath they would be-in wall. Expansion allowances are made the side walls either putting insulating material, which read- ily compressed, between the re- fractory lining and the steel case, leaving vertical joints the brickwork. With some furnaces, the the cial wal spli Mat ere bas bot for cen rep bri anc the abo dial nac (2) sem (3) gap left between the outside the brickwork and the inside the case, the expansion allowance being about per cent the furnace diameter. The bricks are set good quality cement since essential that they bind together form solid mass that any cracked brickwork remains position. This par- ticularly important with furnaces having rotating hearth since there then pressure between IG. 4—This cross-sectional dia- nace shows the typical arrangement refractories: (1) The silica roof; (2) magnesite, chrome-magnesite semi-stable dolomite brick side walls; (3) dolomite magnesite monolithic hearth and dolomite magnesite brick sub-hearth. ° ° ° the roof and the side walls give the latter added stability. spe- cial shapes are required for side walls, ordinary standard squares, splits and tapered brick being em- ployed. Materials: Magnesite brick may consid- ered the standard lining for basic are furnace. They are used both fired and unfired and the form Metalkase brick. More re- cently, magnesite brick replaced chrome-magnesite brick even semi-stable dolomite brick. These substitutes offer the advantage lower conductivity and higher thermal shock tance. The magnesite and chrome- magnesite brick used are similar those employed open hearth fur- naces, while the semi-stable dolo- mite brick, although not widely employed, finding increasing application. has good thermal shock resistance (25 reversals) and much higher slag resistance than stabilized dolomite brick. is, however, customary pro- tect these semi-stable dolomite brick from roof drip means top course chrome-magnesite brick. With large furnaces, the top section the side walls fre- quently built silica brick, but this procedure will probably dis- appear doing with open hearth furnaces when more satis- factory basic brick becomes avail- able. The charging arch built silica, since has been found the most suitable brick for this purpose, probably because its remarkably high refractoriness under load. Its slag resistance lower than that basic brick, but this serious disadvantage this position the furnace. Magne- site brick preferred for the tap- ping arch, part the furnace structure which frequently causes trouble. Attempts have been made overcome spalling difficulties the use chrome-magnesite brick, but this procedure has one serious disadvantage, namely, the risk BELOW 5—This the arrangement the brickwork flat top roof for 10-ton arc furnace. The special shapes used form the electrode rings are special interest. THE IRON AGE, March 12, 1942—57 ABOVE Sub-hearth 6—These Debye-Scherrer X-ray photographs show the working face open hearth furnace roof and arc furnace roof (below), indicating cristobalite and tridymite respectively the main phases present. chromium pick-up the dur- ing tapping. The use tarred basic (dolomite either monolithic form un- fired blocks, fairly common continental Europe and more re- cently side walls have been built with finely ground dry dolomite without any addition whatsoever. The life obtained with these mono- lithic linings would appear slightly less than that given brick, while they have the added disadvantage that the time required for repair considerably longer. This latter difficulty does not occur when tarred blocks similar those used basic bessemer converter linings are employed. Life and Causes Failure: 10-ton are furnace making alloy steel has side wall life three four weeks when lined with brick, and about three weeks when built monolithic struc- ture. This corresponds about 100 heats. When basic brick employed, most the damage the lining due structural spall- known regarding the changes which the brick undergo service, for example, the absorption iron oxide and lime the working face, but there still clear explana- tion the cause spalling. Such work has been done, for example, open hearth furnace back and front walls, suggests that more elasticity the slagged and un- slagged portions with consequent stress concentration the inter- expansion. Where the lining shrinks, either because under-fired because the presence slag, the lining curves inwards towards the top and may even collapse large sections. When the three four weekly re- pair carried out only the first in. the lining are cut out. This leaves safety course, usual- magnesite, and further in. firebrick between this and the shell. essential that least this first in. the inside in. slag resistance material since otherwise would necessary shut down the furnace soon the in. inside course fell away even though this involved consider- TABLE Variation Grading Commercial Brands Acid Induction Furnace Lining Materials No. in. Screen Screen Screen Screen Screen 2.0 13.0 11.0 27.0 5.0 20.0 34.0 30.5 5.5 19.0 10.0 38.0 27.5 2.5 10.0 37.0 32.5 5.5 20.0 11.5 39.0 24.0 13.0 11.0 41.5 32.0 1.5 13.5 11.5 46.0 27.5 10* 14.0 38.0 8.0 18.0 22.0 58—THE IRON AGE, March 12, 1942 able interference with the furnace program. The progress that has been made during the past few years and even months shows that great deal has still learned regarding the best type brick ramming ma- terial for use arc furnace side walls. There doubt that co- operation between the users and producers these refractories will result increased side wall life, but the meantime something might done from the furnace end changes design and the use such devices tie-in strips. One change that has al- ready been suggested the use furnace case having truncated cone section rather than cylin- drical section. This would help keep the refractory position whether the lining were mono- lithic brick, but has the disad- vantage that larger furnace required for given hearth area. Hearth and Banks Certain recent hearth tions, such those described the Crespi patent, are said made without the use hearth bricks, that is, the graded dolomite rammed the pan itself and only sintered position the heat the steel making process. This type construction is, however, still rare and for the most part least in. and often in. firebricks are used between the pan and the monolithic hearth. The number possible combina- tions brickwork large and there big furnace furnace variation. Thus, one furnace 3-in. high temperature insulating brick placed the pan and above this are laid 3-in. firebrick course and two 3-in. courses magnesite there insulation, the 3-in. fire- brick course being placed directly the pan and three 3-in. magne- site courses placed above it. yet another arrangement the firebrick course the pan maintained but the in. magnesite brick are replaced three courses stabi- lized dolomite brick. These are ar- ranged either parallel strips across the furnace series rings, starting from the outside the furnace and working towards the center. either case, the brick are placed stagger the joints and thus avoid any direct line through which slag metal might pene- trate. the brick are built rings, av. tap sev bon The cur foll por bri son pan mit but hea per tha for bri sim fur tha nac nac ria for con ran anc ran pov abc the pra con nes ine variety shapes required, the taper the bricks being more severe the center the furnace approached. Each layer brick independent, that is, there bonding one layer into another. The bricks are set follow the curvature the pan which also follows the curvature the central portion the hearth. Chrome brick plastic chrome cement layer between the firebrick the pan and the magnesite hearth brick. There naturally still some reluctance using stabilized dolo- but both the experience open hearth furnaces and first-hand ex- perience furnaces suggest that such brick quite adequate for the purpose. The magnesite bricks used the sub-hearth are similar those used open hearth furnaces, while the firebrick course that employed open hearth fur- nace doors. The general technique install- ing rammed monolithic hearth are furnace similar that employed with the open hearth fur- nace, but there has been tendency use more finely ground mate- rial. This undoubtedly due part the difficulty obtaining all conveniently the heat required for sintering the hearth. Great Britain, the hearth usually consists tarred basic, dolomite calcined high temperature, rammed successive layers and burnt position placing coke and old electrodes the fully rammed hearth and turning the power for burning-in period about hr. stated that with the dry rammed dolomite hearths practice similar that employed the induction furnace can used, that is, the metal charged can relied produce adequate sintering the hearth. The banks are built up, the open hearth furnace, using wooden templates and forming series steps. Both the hearth and the banks desirable that each course tarred basic roughened after ramming that the next layer can “knit” into it. The final depth hearth varies considerably but generally Whichever way the hearth made, should hard and smooth after the first cast and require very little fettling for long time. The life dolomite hearth varies greatly according the steel mak- ing practice and the size furnace. some plants, life only 200 heats considered satisfactory, but with 10-ton furnace life 600 1000 casts say six months year expected. The finishing slags are always strongly reducing and the basic the hearth turns white and becomes very dense. X-ray examination samples re- moved from one hearth showed consist essentially magnesia, lime and tri-calcium silicate. the United States, magnesite hearths are commonly employed, the material being bonded with basic slag, water glass clay. Alterna- tively, may burned position layers striking arc be- tween the electrodes and other electrodes placed the hearth which are removed and reset each new layer burned posi- tion. According Soler and Hite, Austrian and Washington mag- nesite, dead burned periclase dolomite, chemically precipitated magnesia, and Brucite, have all given satisfactory results. There doubt that, given careful fettling, arc furnace bot- tom could made last almost indefinitely, but once gets out condition, and particular when contains good deal metal, the amount fettling required goes up, and there serious increase fettling and “bad bottom” time. Since the installation new bot- tom comparatively simple and since the cost quite small when spread over the long life, better renew bottom than keep using when has obviously passed its optimum life, and might any time allow the metal break out. The increased use electric fur- naces during the last few years has led intensive research the technique and there little doubt that the refinements now being introduced will result improved bottom life and reduced fettling time. Other developments, such the employ- ment rotating hearth which distributes the intense heating over large area the bath, will also help. The refractories used the door and launder arc furnace are similar properties those em- ployed the open hearth furnace. Thus the doors are usually lined with per cent alumina fireclay brick having point about 3110 deg. F., while the launder lined with similar brick parged over with “ganister,” clay bonded quartzite. This latter material prepared the manner already described connection with open hearth furnaces.** “Basic Open Hearth,” THE IRON AGE, Aug. 14, and 21, 1941. Editor’s Note: The concluding section this article was inadvertently printed the issue March Mr. Ches- ters discussed refractories for induction type furnaces, etc. Extinguishing Magnesium Fires ARD coal-tar pitch granu- lated flake form superior sand, water spray and some other compounds for extinguishing mag- nesium fires, according Dr. Sayers, director the Bureau Mines. claimed that this pitch equally effective combating incendiary bombs. The hard coal-tar recommended the bureau sometimes called “fuel pitch” and said that can made available through number commercial firms reasonable cost. The granulated flaked form required because powdered pitch has explosive characteristics similar coal and other dusts. The hard pitch recommended the bureau will soften about 300 Deg. and while soft forms air-tight blank- over the fire, extinguishing the flames. addition its effectiveness blanketing small magnesium fires, the pitch method has the added ad- vantage industrial applications, according the bureau, that not abrasive and not likely damage machinery the event fire during machining operation. more detailed discussion the use pitch for smothering magne- sium fires contained the report “Methods Extinguishing Fires and Incendiary Bombs with Very Hard Coal-Tar Pitch,” Brown, Hartmann and John Nagy. Copies this report are available from the Bureau Mines, Washington. THE IRON AGE, March 12, q a a | | | | t ‘a 4 ' | | | 4 a | a | i “4 4 How Savage Arms Makes the America, peace years, achieving mass pro- duction war materiel due great part the Ordnance Depart- ment the Army. has three programs under way. First, has several manufacturing ar- senals operating full time; second, helping change over in- creasingly large portion indus- trial America the manufacture combat equipment and third, building many more plants for the production war materiel—a multi-billion dollar program Ord- nance-owned facilities. Among these latter projects several million dollar contract for equipping plant and producing 0.30 0.50 cal. Browning ma- chine guns. This was given the internationally known Savage Arms Corp., Utica, Y., which was already mass production the famous “Tommy” gun (Thomp- son s