The Iron Age 1941-05-22: Vol 147 Iss 21

New Uni | this newest type Galvanizing Equipment These Alloy 502 carburizing baskets and grates are not bulky. Yet they are strong and durable. All our metal melted high frequency induction furnaces which provide fine control composition, and thus assure quality that uniformly good. All our years manufacturing experience has been essentially with made” alloys—which has made accuracy control the basis all operations. All this reflected good alloy, good castings, and what customers tell smart design. Our alloys are also available hot-rolled material. Hoskins Alloys interest you, please give plenty time for delivery. Hoskins Company, Detroit, Michigan. 4 floor space. Hydrogen consumption economical. The Chromel ele- ments are extremely durable. Heating chamber, wide Hoskins Brazing Furnaces are the small, compact type that conserve (or less) high, and most any length. Described Catalog 58. PRODUCTS PRC gar VAN DEVENTER Cleveland MAY 22, 1941 VOL. 147, NO. President and Editor BAUR Vice-President and General Manager WRIGHT Managing Editor Machine Tool Associate Editor Editor WINTERS Art Editor Washington Editors MOFFETT JAMES ELLIS Resident District Editors CAMPBELL HERMAN KLEIN Pittsburgh Chicago Detroit Editorial Correspondents DEARING ROBERT McINTOSH Buffalo Cincinnati FRAZAR CHARLES POST Boston San Francisco HUGH SHARP JOHN C. McCUNE Milwaukee Birmingham SANDERSON ROY EDMONDS Toronto, Ontario St. Louis LEROY ALLISON Newark, N. J. News Editor Technical Editor Editorial Feeding the Elephant....... Technical Articles Wear Resistant Coatings Produced Resistance Magnesite Open Hearth Hydro-Blast Cleaning Jobbing Foundry........... How Pre-Clean Metals.... Heat Treating Facilitated Mechanical Handling..... Report American Foundrymen’s Association 1800 Tool Steels............ Features the Assembly Washington the West News and Market Reports 116 Summary the Week 118 The Industrial 120 District Market 122 Products Index Advertisers........... Copyright, 1941, Chilton Company DIX, Manager Reader Service Advertising Staff Emerson Herman, Chilton Bldg., Philadelphia Hottenstein, 1012 Otis Bldg., Chicago Leonard, 100 East 42nd New York Peirce Lewis, 7310 Woodward Ave., Detroit Ober, 100 East 42nd New York Warren, Box 81, Hartford, Conn. Don Harner, 1595 Pacific Avenue, Long Beach, Cal. Member, Audit Bureau Circulations Member, Associated Business Papers Indexed the Industrial Arts Index. Pub- lished every Thursday. Subscription Price: United States and Possessions, Mexico, Cuba, $6.00: Canada, $8.50; Foreign, $12.00 year. Single copy, cents. eee Non-Ferrous Market Machine Tool Scrap Market and Construction Steel .... Iron and Steel Warehouse Prices Sales Owned and Published CHILTON COMPANY (Incorporated) Executive Editorial and Office Advertising Offices Chestnut and Sts. 100 East 42nd Philadelphia, Po. New York, U.S.A. OFFICERS AND DIRECTORS MUSSELMAN, President JOS. HILDRETH, Vice-President 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 & 52 127 128 132 140 142 for STEEL-BUYERS Many new sizes and larger, handy, pocket size mechanical binding, and host other time-saving features make this new blue and grey Ryerson Stock List the most helpful guide for every steel buyer. The wide range Certified Steel products listed the new Ryerson Stock List includes more than 1500 new kinds, shapes and sizes added Ryerson stocks many them special analyses demand for airplane construction and other exacting defense requirements. Make this new Ryerson Stock List your guide every steel requirement. you have not received your copy, write the nearest Ryerson plant. Joseph Ryerson Son, Inc. Steel-Service Plants at: Chicago, Milwaukee, St. Louis, Cincinnati, Detroit, Cleveland, Buffalo, Boston, Philadelphia, Jersey City. 36—THE IRON AGE, May 22, ESTABLISHED 1855 Feeding the Elephant ARS has insatiable appetite for durable goods. eats steel and machinery like nobody’s business. Our industry has feed him and doing have place the second table those whom have normally issued meal tickets. Which reminds story. Once upon time there was elephant that became afflicted with elephantiasis. Elephantiasis, you know, disease that causes inordinate growth certain parts the body: Under the impact this affliction, physical proportions and ratios are amazingly altered. This elephant, which have referred, suffered from elephantiasis the legs. They grew and grew. They grew fast that pretty soon found that his trunk was longer able reach the ground. But his legs still continued grow until this vital organ became rela- tively short that could not feed himself without assistance. However, this did not immediately interfere with his nourishment, since the inhabitants his country, having pressing need for elephants that time, commissioned the government feed him from stepladder. But after time, this crying need theirs for elephants passed. And our long legged friend found himself dilemma. Either would have grow longer trunk, have his legs cut off. Now elephant with amputated legs not much elephant. cannot get around very well under such circumstances and his over- head becomes too heavy for what left his legs carry. this elephant chose the alternative way out his dilemma. determined lengthen his fodder purveyor. And happy report that through carefully selected diet pills, ironized yeast and vitaminized bamboo shoots, finally succeeded making his trunk match his elongated legs. The analogy his experience ours is, think, quite clear. Our expanded productive capacity corresponds the lengthened legs. Our merchandising power corresponds his trunk. Today govern- ment, not sales effort, feeding the metal working elephant from stepladder. Some day will have face the alternative shortening the legs lengthening the trunk. think will choose the latter. There plenty better new products, ironized yeast new merchandising ideas and all sorts growth vitamins cost and price reduction. Better thinking about where look for these trunk growers before the stepladder removed. As MAY 22, 1941 | | Hundreds of special instruments and controls (like these in the open hearth department) are used throughout the Inland Plants Science, Teamed With Skill, Assures INLAND QUALITY STEEL VERY heat Inland Steel the product science teamed with the skill expert steelmakers. Inland research constantly seek- ing better methods for producing special steel, that when Inland customer makes known his needs, Inland already knows the best method produce the steel, its chemical and physical characteristics, and how will perform during fabrication and service. High quality ore, coal and limestone are scien- tifically blended and measured. Inland engineers, working with America’s leading consultants and SHEETS BARS PILING TIN RAILS TRACK ACCESSORIES equipment builders, have selected vised the construction modern blast furnaces, open hearths, rolling mills and vital auxiliary equipment. Years research and development are back the extensive laboratory apparatus and the many special instruments used with Inland mill equipment for controlling pig iron and steel production, ingot heating, quality products from rolling mills. All this vast background scientific develop- ment, teamed with Inland expert steelmakers, as- sures maximum production Inland PLATES FLOOR PLATES STRUCTURALS REINFORCING BARS i | | | | | | | ° ° CHESTERS Research Department, United doubtful whether any fur- nace calls for great variety refractory materials the basic open-hearth furnace. Further- more, the refractories required vary, not only with the type open-hearth furnace, i.e., whether “cold pig “hot metal fixed,” “hot metal tilter,” but also ac- cording the rate drive and the type steel being made. The pres- ent discussion concentrated the smaller (80 ton) type fixed furnace charged with cold pig iron and scrap and fired with producer gas, but periodical reference will made hot metal furnaces, par- ticular the 300-ton Talbot tilting furnaces fired with mixed gas. Figs. and show photograph and pictorial section through cold pig fixed furnace the 80-ton class. consists essentially the above stage section, sometimes re- ferred the “laboratory” the furnace, since here that the steel undergoes changes; and the below stage sec- tion which although less interest- ing from the point view re- fractories, nevertheless the dis- tinguishinug feature the Sie- mens open-hearth furnace. This Hearth Steel Companies Ltd., Stocksbridge, Near Sheffield, England ° ° ° —Construction data and refractory technique above the sill plate level. latter section consists essentially four chambers filled with firebricks which serve remove heat from the exhaust gases their way the stack and return much possible this heat the incom- ing gas and air. Above the stage level, the fur- nace can divided into the roof (both the main section and the ends ramps); the side walls (back, front and end); the ports (or burners) and the hearth. The latter the only part that should come contact with the molten steel, but the whole the inside the furnace bathed with at- mosphere rich iron oxide and lime and hence must constructed materials capable resisting basic dust temperatures high 1700 deg. (3092 deg. F.). The below stage section can divided into checker chambers and their fillings; the which act dust catchers and thus reduce the rate which the check- ers choke with dust; the down- takes from the ports; and the flues which connect the checker cham- bers with the stack and the pro- ducer via the furnace valves. The refractories required for the tilting furnace, the laboratory which rotates facilitate the tapping the metal and slag with- out emptying the furnace, are es- sentially similar those used fixed furnaces but the back wall cannot built silica bricks since when the furnace tilts, becomes covered with basic slag rich CaO, FeO MnO. Furthermore, since the hearth rarely seen, be- ing almost always covered with metal, every precaution must possible the start campaign. Nomenclature Furnace Parts The Open Hearth Refractories Joint Panel Great Britain re- cently adopted standard nomen- clature for open-hearth furnaces. The agreed procedure which has been published the Iron and Steel Institute Special Report No. 26, 1939, reproduced Fig. will seen that this does not differ all seriously from the no- menclature generally used Amer- ica, though certain terms, e.g., bulkhead (equivalent “wicket” are not employed. In- deed the similarity between British and American usage great that thought that the British nomenclature can employed with- out any misunderstanding. the present article the refractories used and will described together with the conditions they must with- stand and the normal causes failure. attempt will also made indicate possible lines future development. THE IRON AGE, May 22, ‘ | ° ° . 2—Section drawing 80-ton cold pig iron fixed open- hearth furnace, showing the path the gases. 40—THE IRON AGE, May 22, 194! 80-ton cold pig fixed basic open-hearth furnace tapping into the ladle. METAL CHARGE. : DOLOMITE CHAMBER ARCHES CHAMBER AIR FLUE BOTTOM HALF CHECKERS TOP THIRD HIGH ALUMINA BOTTOM TWO THIRDS MEDIUM ALUMINA One axiom must always kept mind, namely, that, for convenience the furnace sub-di- vided into many parts, unit and should ideally run for long period and then all collapse once. true that certain repairs can made furnace without loss production, particularly dur- ing the short week-end shut down; but roof, for example, that lasts only few weeks longer than the back and front walls, does not offer any great advantage since does not pay put furnace back into commission with roof only pable few weeks additional life. One the other hand, roof that will last twice long the back and front walls more than twice valuable, since the labor the sec- ond installation saved. The Roof (Sections and (A) CONSTRUCTION Shape: The roof may flat cambered one two direc- tions. may have knuckle between the main roof and the ramps Venturi furnace, furnace. Generally speaking, the simpler the design the less the sudden changes contour usually lead localized wear. Ribs: SILICA CHROME-MAGNESITE BRICK BACK FRONT WALLS, _BLOCK NOSE GAS PORT SOLE. BRICK. The relative merits fi I s 4 Gas Ends. Gas Uptakes. Air Ends. Air Uptakes. Ramp Roofs. Main Roof. Bath Bottom. 10A Gas Port Arch, Gas Slopes, Wing Walls, 10D Air Port Arches (if present). Jambs. Gas Slag Arches. Air Slag Arches. Slag False Walls. Slag Top Paving and Protection Walls. Checker Bridge Walls. Gas Checker Arches. Air Checker Arches. Gas Checker Side Walls. Air Checker Side Walls. Checker Front Walls. Checker Wickets. Checker Bricks. Back Wall. Bridge Bank. Banks. Blocks, comprising Front Wall. Doors. Door Arches. Door Gas Slag Walls. Air Slag Walls. Slag Wickets. Slag Slopes. Slag Bottom Paving. Checker False Walls. Checker Beorers Bearer Walls. Checker Floors. Checker Top Paving. Gas Valve. Air Valve. Flues. Intermediate Blocks. Fig. 3—This diagram illustrates the nomenclature the various sections open-hearth furnace. ribbed and plain roofs have been recently discussed McDowell. The main object the ribbed roof provide additional strength without corresponding increase roof weight. Examples have been seen, however, where the use ribs has clearly introduced compli- cations. Thus, the position the ribs the roof can sometimes seen from the inside the furnace due local spalling melting either along between the ribs. the United States, the 12-in. roof with 16-in. ribs, the and 15-in. roof with 18-in. ribs, and the 18-in. roof with ribs, would appear normal practice. Great Britain roofs tend thin- ner, the 12-in. roof with 14-in. ribs being more general. Bonding: Many men prefer the bonded roof without ribs since this obviates one very se- rious risk with the ordinary “straight roof, namely, the falling entire ring due its having become thin one point. The bonded roof takes more time install and requires more care construction, but experience points its being more satisfactory job particular more likely main- tain its shape. Suspension: The suspension roof steel hangers has certain notably the advantages, avoidance the great stresses pro- duced the inside the brick during the heating period. presents, however, certain serious difficulties, particular that protecting the hangers against oxi- dation the roof grows thin. can also questioned whether the removal the pressure between the bricks during the heating period actually advantage, since thermal spalling occurs the side pressure may keep the frag- ments position until such time the roof glazes over. true that the arch can repaired any point without the fear that the re- mainder the roof will fall but equally difficult repairs are achieved 4—Zoned structure silica roof brick after use open-hearth furnace. Zone zones and B2, mainly tridymite; zones and similar the unused brick. THE IRON AGE, May 22, with spring roofs replacing the centers anl cutting out the damaged portions; and for silica bricks, least, there would not appear any great advantage suspension. The sprung arches have one-piece skew-back which number types have been designed avoid vertical slip and/or burning the skew-back channel. The importance keeping the latter good condi- tion and true alignment cannot over-emphasized. One the diffi- culties experienced making good sprung arches has been the poor shape silica roof bricks. Thus, one time, bricks ordered with slight taper were liable vary from brick brick more than the amount the taper. With mod- ern bricks, however, made loose lined steel plated molds, the shape excellent and the roofs can built entirely from end-arch bricks. With sprung arches number wedge bricks are usually left above the general level, and these are driven home until the roof lifts from the centers before the latter are removed. Thickness: Most open hearth roofs Great Britain are in. thick, whereas the United States much thicker roofs are usual. Thus, according Buell, for furnaces more than 125 tons capacity the tendency towards 18-in. roof with ribs. Rise: Great Britain tial roof rise 114 in. in. per ft. chord usual but, accord- ing Buell, much greater rises are common the States. The use lower rise, say in. per ft., liable lead flattening one section and eventual collapse the roof due its “breaking its back.” should, however, noted that even with relatively hard bricks and normal rise, roof having span only ft. may rise during the heating period According Buell the horizontal thrust the skew-back open- hearth furnace roof given the equation: pounds. pounds. feet. feet. (2.0). 42—THE IRON AGE, May 22, The coefficient empirical safety factor included take ac- count thermal stresses developed within the roof while under heat. The formula interesting that shows that roof too flat, i.e., too small, the horizon- tal thrust will very great and possibly too much for the skew- back system too withstand. Expansion allowances: gen- eral the allowance for expansion roofs made from hard fired silica bricks approximately equal the thermal expansion 1000 deg. (1832 deg. F.), about 1.25 per cent. This allowance made either series wide gaps parallel the roof rings bonded roof means spacers, e.g., felts placed between every other brick planes perpendicular the length the roof and in. apart. expansion allowances are made from back front. Since means certain that the expan- sion individual bricks trans- mitted through considerable lengths roof side walls, the distribu- tion the expansion allowance into large number small gaps very desirable. The use felt has proved advantageous not only because burns out compara- tively low temperature, yielding small amount ash, but because provides cushioning action even the outside the roof and dur- ing the early stages heating up. Cement: Certain furnace build- ers still employ cement for setting roof blocks. very doubtful whether any advantage gained from this practice, particularly the bricks are good shape. If, however, cement used, essen- tial that should refractor- iness almost equal that the bricks themselves. Insulation: great deal has been written the merits and dangers open-hearth roof insula- tion. Sufficient work has been done, mostly the States, show that insulation can economical both fuel and refractories, but there little doubt also that over- heating roof occurs more dangerous with insulated roof where temperature gradient less steep, than with uninsu- lated one. For this reason, the use insulation should hand hand with roof pyrometry. Where roofs are insulated the most common method the use expanded Vermiculite (ex- panded mica), which not only has very low conductivity but sufficiently resistant heat capable recovery for use second campaign. principle that must not ignored connec- tion with insulation that applied should applied evenly over the whole the roof surface, since otherwise local overheating and consequent melting bound occur. (B) MATERIALS: Specifications: There would not appear any British Ameri- can specifications for roof bricks for open-hearth furnaces, but there German specification (D.I.N. 1088) which can summarized follows: Chemical analysis: >94.5 per cent, <2.0, CaO <3.5. Pyrometric cone equivalent: least Seger cone 32. (3110 deg. F.) Refractoriness under load: Be- ginning failure kg. per sq. cm.) (2966 deg. F.). Total porosity: <25 per cent. Specific gravity: Cold crushing strength: kg. per sq. cm. watertight specification for silica roof brick, but the following clauses have been found useful: Specific gravity, “no brick over 2.38 and the average the consignment less than 2.36”; and chemical analysis, >94.5, alumina <2.00 and lime <2.50 per cent.” Periodical tests are also made melting point and bulk density, and for these minimum 3110 deg. and 1.7 per are con- sidered desirable. Grading: Until recently the best roof bricks were considered coarse grade containing par- ticles large in. size. There little doubt that the use such coarsely graded (and usually soft fired) bricks facilitated the heating new furnace, but recent results suggested that least good life obtained using finer ground batch the coke oven brick type. Such bricks are generally better shape, glaze more readily and wear more evenly. Shape: essential that roof bricks should excellent shape. they are warped, and bricks are placed the roof with their con- cave surfaces together, they may rupture heating and fall into the bath. Accuracy size not essential where bonded | t v i | | ii u 4 | | | | | | | | 4 5—Cristobalite network zone roof brick 6—Tridymite zone roof brick after weeks after weeks service basic open-hearth furnace. service basic open-hearth furnace. Ordinary light, Ordinary light, diameters. diameters. LEFT 7—Monochromatic X-ray pinhole photo- graph unused silica roof brick. x ig t ABOVE LEFT 9—Monochromatic X-ray pinhole photo- graph zone showing coarse crystallinity tridymite crystals. THE IRON AGE, May 22, roof being built. Roofs are some- built mainly squares with bricks big taper, but more recently have been made throughout with 3/2% in. bricks. Analysis: Chemical analysis has already been referred under pointed out that the maximum lime content 2.5 per cent unusually high and that recently improved results have been obtained with bricks made without any lime bond all. This has only been possible the use dense gradings and heavy molding pressures, but there little doubt that the additional refractoriness obtained this way will prove advantageous. Melting point: bricks are found melt the temperature range 3110 3146 deg. determined Seger cones. Some the poorer brands melt temperatures low 3074 deg. F., while exceptional cases have been found where collapse had occurred until Seger cone (3182 deg. F.) was reached. Data obtained series roof bricks are summarized Table The methods used obtaining such data were discussed previous article THE IRON AGE. Specific gravity: The use the specific gravity test the control silica brick quality has already been discussed previous section this series articles together with examples covering month period. Considerable experi- ence this field suggests that the greatest danger the open-hearth furnace not the use soft fired Code No. Apparent Porosity, per cent Bulk density, per c.c. ib. por cu. ft. ...... True Specific Gravity Permeability air (perpendicular working face and through skin) After Expansion hr., 1500 deg. per Refractories under load, maintained deg. for hr. per sq. in. Thermal shock resistance (450 deg. test) Pyrometric cone equivalent Microscopic examination Approximate per cent quartz tridymite IG. nace, showing due local overheating. silica brick much the use batch bricks covering wide range specific gravities. clear that few hundred soft fired bricks (say specific gravity 2.45) are built into roof whose average specific gravity only 2.35, then local expansion leading the roof and sub- sequent spalling, liable occur. Both microscopic and X-ray exami- nations are useful check specific gravity and general tween the residual quartz content and the values determined the specific gravity test. further check, after-expansion tests 2-in. prisms cut from the test bricks and fired for hr. 1500 deg. (2732 deg. F.) are useful. Thus, for example, will seen Table that the soft fired brick specific gravity 2.39, also shows the highest after-expansion. Bulk density: There little doubt that the use brick high bulk density tends in- crease roof life. Thus, most the existing records have been obtained with bricks whose bulk density was the order 1.90 per c.c. will seen from Table however, that very few roof bricks have bulk density even approaching this value. With the unfired brick high bulk density relatively easy obtain good grading the quartzite, but firing the porosity tends increase and the bulk density fall. The produc- tion bricks having bulk densi- 1.85 per should, how- ever, possible with most the quartzites used for making, and this standard could maintained, there little doubt that improvement roof life would result. Refractoriness under load: Most bricks withstand load per sq. in. for hr. 1600 deg. (2912 deg. F.) without collapsing more than about per cent. view this and the fact that practice large part the load carried the cooler part the roof, there little likelihood roof failure due sotening the bricks. Cement for use with silica roofs should, already stated, high refractoriness, melting point least 1690 deg. (3074 deg. F.) being considered desirable. must plastic that can readily troweled and must retain its water for sufficient period enable the bricks set before the cement becomes dry and brittle. gen- eral, such cements TABLE Properties Open-Hearth Furnace Roof Bricks (Silica) BRITISH 25.4 22.7 22.8 23.6 1.73 1.79 1.83 1.76 108 110 114 110 2.33 2.36 2.32 0.079 0.049 0.083 0.0 0.5 0.5 0.6 0.7 sheared 0.0 per cent per cent min. per cent collapse collapse collapse cone 32, 32, 32, 33, 1730 deg. cristobalite 44—THE IRON AGE, Moy 22, AMERICAN GERMAN 26.5 25.8 23.5 20.7 1.75 1.72 1.78 1.85 109 107 2.39 2.30 2.32 0.105 0.189 0.138 0.017 0.2 0.4 0.4 sheared sheared 1.4 0.4 after after per cent per cent min. collapse 32, 32, 33, 1730 deg. t } | | | tively little material over mesh size. Originally such cements were made ground ganister with small amount either lime clay bond, but more recently quite satisfactory results have been grinding used silica bricks, which are both cheap and easy grind and still yield cement high refractoriness. The properties chrome mag- nesite bricks for use open-hearth furnace roofs have already been discussed earlier article THE IRON AGE (1940, Vol. 146, No. 35, No. 39), and will not therefore referred herein. (C) LIFE AND CAUSES FAILURE: The life open-hearth fur- nace roof varies from about eight weeks year, according the rate drive, the material melted, the furnace design, and various other factors. For 80-ton fixed considered reasonable. The life obtained can seri- ously impaired improper treat- ment during the heating-up period. The actual heating schedule em- ployed varies greatly from plant plant but general the total time before gassing the furnace tween and hr. Thus, Dodd suggests for 70-ton furnace the following schedule which en- ables the furnace gassed 200 deg. C., rate heating deg. per hr.; from 200 300 C., rate heating deg. per hr.; above 300 deg. C., rate heat- The furnace usually gassed when the roof temperature, de- termined the thermocouple pro- truding through hole the roof, about 600 deg. (1112 deg. F.), and experiments carried out temperature gradients the roof suggest that this procedure safe one. many plants, even the above schedule not considered safe and similar but much slower rate heating employed. What- ever the schedule used, essen- tial that the rate through the cristobalite inversion range (200 300 deg. C.) should low and that after passing 300 deg. the furnace should not al- lowed fall below this tempera- dampers are opened too wide. general, the heating-up done either with coal fires the hearth with coke flares brought into the furnace doors. With care the scheduled rate heating can obtained either method with considerable ac- curacy. The use big wood fires, e.g., Yrailway sleepers, avoided, since the long hot flame which results liable cause spalling due local overheating the roof. Wherever possible, the roof thermocouple should con- nected recording instrument that the heating-up schedule available for subsequent reference, should any spalling the roof oc- cur. When such recorder avail- able desirable that the sched- uled rate heating marked the graph the beginning the heating period, that the melter has definite ideal follow. Even when the roof brought temperature without tured” “seasoned.” has long been common knowledge with open- hearth furnace melters that roof that has been maintained close its melting point but not above during the early stages the cam- paign has better chance long life. There are certain obvious rea- sons for this, for example, roof that has glazed over less likely collapse during shut down period, but the real reason for the improve- ment shown examination used great deal has been published (c.f. the bibliography) the zon- ing roof bricks open-hearth furnaces, but one point still re- quires emphasis, namely, that the working face the brick gener- Zone Zone Length the zone 3.0 4.0 Apparent porosity, per cent 17.9 16.3 Bulk density, 2.09 2.04 Specific gravity, apparent 2.55 2.44 Permeability air, per- pendicular zone in- terface and through the Pyrometric cone equivalent. (a) Cut cone, deg. 1730 1710 Crushed cone, deg. 1700 1690 Microscopic cristobalite tridymite examination. magnetite magnetite glass. glass. *As low 0.0002 some ally more refractory after months service than was the begin ning the campaign. This not apparent the test cones are made from crushed brick, since the cristo- balite network that has formed the working face destroyed, but following data show, the cone cut from the working face. The vision into zones used the pres ent tests, illustrated Fig. Open-hearth roof bricks are fre- quently divided into many nine different zones according their color, was done for example Harvey, but for practical pur- poses four five zones are prob- ably adequate, namely: (a) The gray working face. (b) The black section between and the so-called transition zone (c) The relatively narrow pale yellow zone between and the re- mainder the brick. (d) The reddish section the cool end the brick. the present work, zone was subdivided into sections and B2, had been found earlier work that zone was essentially similar properties (see below) unused brick, while there was marked difference properties between the inner and outer halves zone Both the above brick and the brick zone analyses shown page were obtained from 300- ton tilting furnace, but extensive studies made bricks from fixed Zone Zone Zone 6.5 1.5 8.0 23.5 23.7 2.10 1.81 1.81 2.28 2.37 2.37 0.004 0.056 0.046 1700 1690 1700 1690 1680 1690 tridymite Similar Essentially quartz similar glass. Un- unused identified brick mineral (25 per high cent raw bire- quartz). fringence. THE IRON AGE, May 22, | } | furnaces reveal similar character- istics. Zone Zone B2* Zone 84.50 88.75 94.80 ... 1.31 1.80 0.91 ... 6.56 6.24 3.36 0.95 TiO, 0.18 0.17 0.24 0.13 1.07 0.93 0.28 0.09 ... 5.55 4.95 1.80 0.83 0.80 0.42 0.36 Zone was not analyzed this case but generally found similar composi- tion that Zone and the unused brick. The above changes during ser- vice may summarized follows: (1) That part the working face the brick above 1470 deg. (2678 deg. F.) changes net- work cristobalite crystals. Al- though considerably richer fluxes than the original brick, this ma- tured face refractory, denser and (apart from occasional large holes) more impervious than the original brick. Furthermore, general glazed and will pre- sumably reflect the radiated heat from the flame more than the new brick. (2) There big difference thermal expansion characteristics between zones and and zones and and hence not sur- prising that old roof heated too quickly spalls along one other these interfaces. (3) More detailed studies show that there concentration fluxes the interface between and which explains why spalling that exposes this face frequently followed localized melting spite the fact that the roof must somewhat cooler this point due the smaller roof thickness. (4) The crystal size the crist- obalite zone and the tridymite and X-ray examination (Figs. pared with that the original brick. For more detailed information zoning, the reader referred the excellent descriptions given Larsen and Schroeder, Harvey and the other workers referred the bibliography. 46—THE IRON AGE, May 22, Research carried out the United States, and less extent else- where, seeks aid roof life and possibly increase furnace produc- tion the application roof py- rometry. The difference tempera- ture between the melting point steel and brick small that essential that the maximum use made order give the highest possible production without damage the roof. This object can achieved the temperature the roof accurately known and the furnace maintained close this temperature possible, but never above it. Several types pyrometer have been developed for this purpose, the principal ones be- ing the hollow silicon carbide roof block with external Féry radia- tion pyrometer above it, the total radiation photo cell pyrometers focused through hole the side wall the central section the roof. The maximum temperature employed varies somewhat from works works but generally the range 1650 1680 deg. The installation roof pyrometer does not absolve the operator re- sponsibility for his roof since possible that the latter may melting point the furnace higher temperature than that which the pyrometer focused, but does provide him with tool that makes his job easier that least aware the general tempera- ture trend. The installation such pyrometers will doubtless much obviate the excessive running roofs illustrated Fig. 10. Given proper treatment, the wear combination erosion and corrosion iron oxide and lime. Spalling should considered pathological condition occurs proper rate heating employed both with new roof and reheating old roof after cooling down. Spalling rarely oc- curs during the cooling period since the time the critical tempera- reached, the rate cooling very low. The rate wear roof has been found increase greatly the atmosphere strongly reduc- ing such may occur when high percentage coke oven gas em- ployed when water vapor, e.g. from leaky port, comes into con- tact with the roof. The exact mech- anism the reaction still far from clear, but Dodd has shown laboratory experiments that silica bricks heated water vapor may have refractoriness much 100 deg. less than their refractori- ness air. Where roof side wall has patched with silica bricks while the furnace still operation, the amount spalling which occurs ‘an greatly reduced boiling the bricks tar dipping them creosote prior use. The advan- tage gained can scarcely due the bonding effect the tar-coke since such coke would formed with the creosote. probably the result the reduced rate heating through the cristobalite range due the heat required evaporate the impregnating liquid. (D)—LINES IMPROVEMENT: Possible ways increasing roof life may summarized follows: (1) The use silica bricks higher bulk density. (2) The use bricks made with- out added bond. (3) study the factors con- trolling glazing with view ob- taining roof that matures more readily. (4) The use basic refractories, e.g. chrome magnesite bricks po- sitions where the wear excessive, such over the taphole, sibly for the whole the roof. (5) The extended use roof pyrometry which not only provides means control, but also makes the furnace operator scious.” Ed. week the author concludes this informative survey the basic open hearth with de- tailed data the back and the front walls, gas and air ends, and parts. — ir. ~ | q | | | | | | | | | | | | | Merits Continuous Normalizing examine the merits nor- malizing the steel strip continuous furnace, Pomp and Niebch have carried out series tests, recently described Archiv fiir das The two investigators used large furnace ft. long overall, with 14.8-ft. furnace chamber which was electrically heated and divided into three zones graded heat. The strip was passed through the furnace, which contained atmosphere produced the com- bustion excess air grid gas, varying speeds determine the optimum rate transit for best results. Strip 1.6 0.039-in. section, which had been cold rolled varying degrees reduction, 10, 20, and per cent, was heated different temperature the range from 1202 1652 deg. F., and the mechanical properties the normalized product compared with similar material which had been normalized the ordinary way batch-type furnaces. Heating for less than min. the roller-hearth furnace proved sufficient for normalizing, and the product had practically the same mechanical properties the batch-furnace product. Two speci- mens strip were treated this way, careful control being kept thermocouple consisting the strip itself and welded-on con- stantan wire, which was also passed through the furnace give the actual strip temperature well the positive heat gradient and the maximum temperature reached. The final temperatures separate tests were 1202, 1292, 1472, 1652, and over 1652 deg. F., with speeds transit varying from 2.1 7.3 ft. per min. shuwn the two specimens ex- amined, the effects normalizing coming increasingly divergent higher temperatures were reached. final temperatures 1112 1202 deg. F., there was marked difference the two sets mechanical properties; 1292 deg. F., there was little difference heated sample, ultimate strength, deep drawing properties and yield point being, however, slightly better. the other hand, this temperature strip was not good the corresponding batch-furnace product, the elonga- tion and cupping values being alone comparable. This difference was more pronounced 1472 deg. the whole, the degree nor- malizing, i.e., the removal the stresses due cold working, be- comes more complete the tem- perature increased, yet the rate change with temperature the magnitude the mechanical prop- erties was not the same for the two steels. The authors point out that while this method gives rapid and satis- factory normalizing, apparent that the success the process de- pends not much the suita- bility the particular furnace used, but the characteristics the materials itself, witnessed the very different behaviors the two strips investigated. essential condition that the strip must capable recrystallizing during its short passage through the furnace and being relieved its internal stresses; this achievable the condition the product from the roller-hearth fur- nace equal that furnished the batch-type furnace. Life Magnesite Open Hearth Bottoms the magnesite measure the quality fused-on magnesite bottom open hearth, and expe- rience the Magnitogorsk Works, U.S.S.R., has shown per cent magnesia the optimum pro- portion, according Dement’ev, writing Stal, No. 12, 1939, and translated the Iron and Steel Institute (British). Further analyses showed that the main change the composition the furnace bottom during the period its service was reduc- tion the magnesia content. this paper the author deals with the causes the reduction the stability the bottoms. These are: (1) Diffusion into the fused-on bottom. This turn conditioned the difference the compositions the bottom, the metal and the slag, well the temperature and porosity the bottom. (2) The composition the bottom and the duration its burning-in. Ample time for burn- ing-in should allowed. (3) De- posits adhering bottom. These are caused mainly the practice charging lime directly the bottom the furnace. The best method charge layer clean fine iron scrap, which will protect the bottom from the lime and ore, and will also damp out shocks during charging. iron scrap not available, layer ore the next best thing. (4) Chemical activity the bottom. This partly the consequence (1), (2) and (3). The impurities which find their way into the bot- tom, particular ferrous oxide and manganous oxide, undergo re- peated reduction and oxidation dur- ing the various stages the open hearth process. Statistical investi- gations have shown that the oxi- dizing action the bottom during the time the furnace standing empty between heats directly connected with the time lost repairing bottoms. The oxidizing period during the heat has like effect. (5) Basicity the slag. The maximum stability the bot- tom obtained with lime/silica ratio the slag 2.6. (6) Carbon content the metal. The higher the carbon content, the lower the melting point and the higher the stability the bottom. THE IRON AGE, May 22, 1941—47 | ECENT installation Hydro- Blast wet sand cleaning ap- paratus the Advance Foundry Co., Dayton, Ohio, sav- ing this jobbing foundry $106 day casting cleaning costs and soon will return what appeared first rather heavy invest- ment for this operation. This medium sized foundry specializes the production medium and large castings for the machine tool industry and large stamping dies made both “die iron” and the company’s patented Strenes metal. molybdenum alloy iron which 48—THE IRON AGE, May 22, close grained material that can heat treated tensile strength 75,000 per sq. in. and Rockwell hardness 55. The foundry production averages tons castings day. Some the big machine tool bed cast- ings run ft. length and Knocking the cores out such castings with crowbars and brute strength was long and costly process and represented distinct health hazard, since ously dusty and dirty job. One the biggest gains from the adop- tion this wet cleaning method has been make the shop clean and reduce the silicosis hazard minimum. Aside from the pri- mary humanitarian angle and the fact that penalty premiums com- pensation insurance are avoided, the effect has been raise worker morale and efficiency throughout the foundry, well lowered time cycle cleaning. The dust level the cleaning booth ac- tually lower than for the outside air. These advantages cannot measured dollars and cents but are obviously factors importance. very definite cost saving core sand day. the former cost haulage spent sand dump heap, this item amounts minimum saving planned run sand from the dump through the classifying system this spring recover what merly been waste other big recovery economy rods and gaggers. Formerly, cost about $200 month purchase these stiffeners and cut them size. Since the Hydro-Blast clean- ing equipment was installed last November, the company has bought new rods gaggers. Saving scrap iron another factor, run- ning around 1000 day, roughly worth $10 under present market conditions. There also appreciable sav- ing labor, which means some- thing more than money these days when foundry workers any kind are difficult obtain. For example, hand methods used take four men hr. (40 man- hr.) clean 22,000-lb. planer bed. Now two men can the job ing saving man-hr. this typical item. Taken together, all the tangible savings add $106 day, even when offsetting power and water costs are taken into ac- count. Both these expense items are running under original esti- mates made the Hydro-Blast Corp. Water consumption gal. per min. when the machine running, and this eventually all discharged the sewer clear water free fines. The entrained sand delivered the nozzle the rate 225 per min. is, | | Jobbing Foundry course, all ultimately recovered, with the exception the fractured grains. Besides the matter reduced cost cleaning, there also the gain improved quality. Appear- ance castings has been improved 100 per cent, and customers say that the castings require far less Even sand that has been burned into the metal scoured free the highly erosive action the entrained the water. Tests show, for example, that fine beach sand entrained gal. water per min. 1200 lb. will eat away average gm. copper bearing steel plate 8-min. test interval. Chipping time the foundry has also been greatly reduced. The recovered sand being re- used for cores and facing with highly satisfactory results. ap- pearance, black color like molding sand. The moval dead bond which lowers the sintering temperature any foundry sand the prime reason for the superiority this washed sand. There also elimination most the non-magnetic iron oxides which are considered dele- terious most foundrymen. Fur- date, big industrial concerns have installed Hydro-Blast wet cleaning apparatus their own foundries, but Advance Foundry Co. the first independent jobbing foundry adopt this method. The savings made and advantages accrued are related this article to- gether with detailed description the equipment itself. thermore, probable that con- tinued re-use recovered sand eliminates the weaker silica grains with pronounced cleavage planes. fact, the Hydro-Blast sand re- covery system permits definite con- trol grain distribution and mois- ture content which previously have been rather indeterminate factors the operation foundry. ISCHARGE chute from flight conveyor deposits sludge into skip boxes for sub- sequent disposal. Sludge set- tling tank left and front pile rods, gaggers and lump sand dropped into skip box after passing over vibrat- ing screen. This large pile the Monday morning accumulation after heavy material beached the concrete slope under the floor grates during the week has been hosed down. the old days, castings were always ahead the cleaning de- partment and unduly clogged the floor and occupied valuable space, which has now been par- tially saved. operating the Hydro-Blast equipment three shifts day, the cleaning department can now get out five days what the foundry makes six. The floor plan views show the installation Hy- dro-Blast wet cleaning equipment Advance Foundry Co. This plant was especially engineered for clean- ing the large machine tool bed cast- ings made here and was the first built for jobbing foundry. The cleaning room proper ft. long and 16% ft. wide accommodate the largest castings encountered. Two blast guns are use the present time, although only one shown the floor plan layout, that two medium sized castings can cleaned simultane- ously, thus doubling the tonnage THE IRON AGE, May 22, | | ° ; wee output per day. tain suspended from wall jib swung into position make two rooms each ft. long. This curtain swung out the way against the corrugated galvanized steel wall when long castings are being cleaned cores. Perhaps the best way explain how the sand system works will trace the sand from the time leaves the blast tank. this tank the sand con- tinuously flooded, and from here the excess carried off dewater- ing skip boxes for drainage. The principle this blasting system use relatively fine jet en- trained sand and water high pressure—1200 per sq. in. The high pressure pumps, each driven 25-hp. motor, handles only pure water from the mains and hence requires special mainte- nance. Wet sand from the blast tank drawn the guns the injector principle, and the only part the guns subject rapid wear the nozzle itself. Its average life 400 hr. present, but new ma- terials are being explored and this life may bettered. The heavy hose connections the guns are suspended from overhead jib, and since the volume liquid han- rubberized cur- Upper sludge East wa//--> Lower trough tank elevation view corresponds the photograph the right. dled relatively small the gun re- action force low, eliminating the factor operator fatigue. the start the casting gen- erally laid its side, exposing the bottom, top and one side the blast jet. The casting rolled over with the crane expose the fourth side after most the core ma- terial has been sluiced out. Rods and gaggers are picked and put baskets for the crane handle. Entrained scouring sand and broken cores together with some the smaller rods are washed through the floor, which made standard subway grating, and the debris sluiced down incline slope made concrete discharge chute which delivers plan layout and sectional view the Hydro-Blast wet cleaning installation the Advance Foundry Co. Sludge Dewatering skip boxes Swing flume Blag. R.W. doors ana platform Ladder tank tank Catch basin pump Blast sana tank and cover 50—THE IRON AGE, May 22, 1941 West brace south wal/ -Lower Blast sand tank flume Angle ——- Flume Support Blast sand skip box the material over sloping vertical screen. Rods, gaggers, iron pieces and hard lumps are discharged into oversize skip hoist the right the pit, while the sand and water passes through the screen the sand sump tank. From here rub- ber lined sand pump driven 10-hp. motor elevates the water and entrained sand and sludge classifier tank the highest part the apparatus. Cleaning and classifying takes place the flotation principle. reach the blast sand tank below, the sand must pass through three vertical venturi tubes which column water shot regu- lated pressure and velocity. adjusting the pressure the coarse- spreader box oversize chute --Oversize Skip box z= \ 9 Apron 4 ring boxes Nw, trut at sana Hose Plan | ness the grains sand that drop through against the stream can controlled. All other sand, clay fines and scum are carried the top the tank whence they over- flow through sludge flume spreader box and tank. Fines that settle the bot- tom are removed flight con- veyor, discharging through chute large skip box. Most the water escapes through overflow trough the end the big sludge tank. pointed out previously, the blast sand tank flooded and excess sand and water overflows through flume one two dewatering boxes. These boxes are constructed with louver-like partitions the ends that effectively separate the water from the sand. Eventually, the loaded box picked crane and upended discharge the contents the heap, where the sand air dries. EWATERING skip boxes into which excess sand from the inundated sand blast tank discharged. When the bulk the water has drained through louvers the back boxes, the damp sand dumped crane the pile front where final air drying takes place. ° ° ° Water for the sand classifier booster pump. The vibrating screen requires motor, and air compressor for the operator’s hel- met takes another motor. There are also two motors used, one geared down for the sludge conveyor, the other drive chemical pump for introducing rust inhibitor into the water line. Motors are fully enclosed, fan cooled types and can washed down with hose. addition those pumps mentioned there also 3-hp. catch basin pump the sump, operated float valve. The gun operators wear air pressure helmet and rubber suit Every sec. series water jets wash any splashed dirt off thi