The Iron Age 1938-12-22: Vol 142 Iss 25

FRITZ J. FRANK President VAN DEVENTER Editor Managing Editor News Editor Editor Emeritus Machinery Editor Art Editor Metallurgical Bdttor Associate Editors JURASCHEK Consulting Editor Washington Editor Resident District Editors CAMPBELL ROBERT BINGHAM Pittsburgh Chicago Cleveland Detroit Editorial Correspondents London, England Cincinnati FRAZAR FIDRMUC Boston Hamburg, Germany MEYER CHARLES Post San Francisco SANDERSON ROUNTREE, Jk. Toronto, Ontario Birmingham Newark, N. J. St. Louis TURNER, JR. Buffalo Owned and Published by CHILTON COMPANY (Incorporated) Publication Office Chestnut and 56th Sts., 239 West Philadelphia, Pa. New York, OFFICERS AND DIRECTORS President FRITZ FRANK, Executive Vice-President FREDERIC STEVENS, Vice-President JOSEPH 8S. HILDRETH, Vice-President GEORGE H. GRIFFITHS, Vice-President EVERIT B. TERHUNE, Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JOHN H. VAN DEVENTER, JULIAN CHASE, THOMAS L. KANE, CHARLES 8. BAUR, G. CARROLL BUZBY, P. M. FAHRENDORF BAUR, General Advertising Manager DIX, Manager Reader Service Member, Audit Bureau of Circulations Member, Associated Business Papers Indexed in the Industrial Arts Index. Published every Thursday. Subscrip- tion Price: United States and Pos- sessions, Mexico, Cuba, $6.00; Can- ada, $8.50; Foreign, $12.00 a year. Single copy, 25 cents. Cable Address, “Tronage, ADVERTISING STAFF Emerson Findley, 621 Union Bldg., Cleveland B. L. Herman, Chilton Bldg., Chestnut & 56th Sts., Philadelphia, Pa. H. K. Hottenstein, 802 Otis Bidg., Chicago H. E. Leonard, 239 W. 39th St., New York Peirce Lewis. 7310 Woodward Ave., Detroit C. HL Ober, 239 W. 39th St., New York W. B. Robinson, 428 Park Bidg., Pittsburgh D. C. Warren, P. 0. Box 81, Hartford, Conn. RON Contents DECEMBER 22, 1938 Not Thy Right Hand Know Heat Conservation Magnesium Foundry Practice Bethlehem Enlarges Johnstown Axle Plant New Furnace Broadens Use Tools Recent Designs Power Transmission Equipment Drop Forgings Commercial Aspects Stainless the Assembly Line Statistics Metal-Working Activity Washington News THE NEWS BRIEF Rate Activity Capital Goods Weekly Ingot Operating Rate Plant Expansion and Equipment Buying Just Between Two Products Advertised Index Advertisers Copyright 1938 Chilton Company (Inc.) Production Costs Cut with Certified Alloy Steels You can depend better results less time when your heat treater guided the Ryerson alloy data charts. These charts show him the exact properties the steel with which working and tell him how get the de- sired results. does not have test. takes chances. Spoilage eliminated and sound dependable job high accuracy and uniformity assured. addition saving production costs, the Ryerson Certified Alloy plan benefits the Purchasing Depart- ment they can keep detailed record the exact Principal products stock for Im- mediate Shipment include— Bars, Structurals, Plates, Iron and Steel Sheets, Tubing, Shafting, Strip Steel, Alloy Steels, Tool Steels, Stainless, Babbitt, Welding Rod, etc. analysis every alloy purchased. Thus possible duplicate particularly desirable close range specifica- tions repeat orders. The Metallurgical Department benefitted too for they can call for any reasonable physical requirement and sure the Heat Treater can produce the desired result. Ryerson Certified Steels also include carbon, tool and stainless steels that meet definite quality standards. They offer many advantages steel users. Let tell you the complete story. Write for booklet. Joseph Ryerson Son, Inc. Plants at: Chicago, Milwaukee, St. Louis, Cincinnati, Detroit, Cleveland, Buffalo, Boston, Philadelphia, Jersey City. : 16—THE IRON AGE, December 22, 1938 ESTABLISHED 1855 THE IRON AGE ... DECEMBER 22, 1938 Vol. 142, No. “Let Not Thy Left Hand Know What Thy Right Hand HIS Biblical injunction, written many centuries ago St. Matthew, referred charity. St. Matthew did not deal prophecy like St. John, who Revelations may have foretold the New Deal his description wheels within wheels and strange things come. However, St. Matthew's injunction apparently being followed the letter present day Federal administrative agencies, although not altogether respect charity. For example, there the O'Mahoney Monopoly Investigating Committee which has just broken the ice two-year probe business practice. The announced pur- pose this find out what wrong with private industry and improve its effi- ciency that customers will get more for their money. this connection good deal emphasis being laid upon the necessity decreased costs and prices, any rate, the latter. the other hand find other Federal agencies whose chief purpose and sure life seem find ways increasing costs and prices the consumer. For example, consider the experience contractor with the PWA which de- scribed letter which follows. Names have been deleted for obvious reasons. "We recently rented bulldozer backfill 300 ft. water pipe trench company having contract under PWA lay pipe Pennsylvania State institution. had this machine nearby and had our operator, whom pay per hour, run the machine over the job. Because was PWA job, the contractor had use union operator hour. Our man would have backfilled this trench two hours cost for himself and bulldozer. The union operator worked all one day and most the next before finished the job. This was rent the bulldozer hour $48. "When the contractor tried pay off the operator for two work $16 found that the union required him paid for week, was Philadelphia operator and hired out-of-town job for less than week. This meant $48 for six days which worked only two days. instead costing $8, the cost this 300 ft. backfill was same machine when left the PWA job was transferred private job nearby and four hours with our own operator backfilled 500 ft. trench, for which received $35 for machine and was recently remarked the President, now seem going places. But why, might ask, opposite directions the same time? Re 4 7 4 HEAT CONSERVATION way toward increased profits the utilization recent improvements blast furnace stoves, and thermal recuperators and exchangers. general capital outlay sharply cut and operating efficiency greatly improved. the development the steel in- dustry from the middle the nineteenth century, there have been several periods hesitancy dur- ing which time additional technical progress seemed most elusive. But each case, prominent technical ad- vances came the fore carry the industry new heights, greater efficiency, reduced cost and improvement product. Since 1930 the steel industry has labored through hectic rebuilding program, complete revamping rolling equipment. This phase has about run its course, and the results pricewise and quality product have been well publicized. Over longer period time, the first step steel production, the blast furnace, has likewise gone through slow evolu- tion, primarily the treatment ores and the handling furnace burden. The result has been that the number blast furnaces has been reduced more than half half century —575 blast furnaces were available then, compared with 236 now, even though output has quadrupled 51,- 221,000 tons. But despite numerous trends such the two mentioned, the has progressively been pressed com- IRON AGE, December 22, 1938 petitively, and the past few decades have witnessed steady decline profits relative capital investment. Consequently, the industry increas- ingly the qui vive for more efficient techniques, and few members have already seen that manufacturing procedure that uses heat tremendous quantities little more attention thermal efficiency can pay excellent dividends. Heat from fuel has always escaped two principal routes; way the refractory furnace linings and way the heat contained the exit gases the atmosphere. Most the latter heat can recaptured for use. For the former, note that refractories act like sponges for heat, and waste radiation comparable dripping water. And the larger the amount heat accumulation the furnace walls, the greater the loss whenever the metal charge drawn poured from the furnace. Furnaces made low-heat storage insulating refractories imprison the heat near its source liberation from the fuel, and, even more impor- tant, less furnace mass heated operation. The combination these two factors can possibly reduce the gas bill per cent and the oil COUTANT Fuel Consultant, New York ° ° ° bill per cent. Furthermore, the fur- nace output greater and products are often more uniform because higher furnace temperatures and greater con- trollability. forge furnace attains, say, 2500 deg. F., whereas the same furnace were lined with insulating refractories the temperature may rise 2700 deg. with the same fuel consumption. The amount heat reflected the metal per sq. ft. per hr. would doubled, will demonstrated later. Meth- ods for determining the probable per- formance such installations were 17, page 27-29, and Oct. 13, page 247- 254. not uncommon for actual ser- vice reports show advertisements concerning insulating refractories claim per cent reduction heat treating costs; $200 job paying for itself three weeks; instal- lation earn times its initial cost annually; furnace output doubled; working conditions improved; equipment meeting shorter working day demands; better products re- sulting. All these are the tangible re- sults more complete utilization imprisoned furnace heat. Heat escaping from furnace the ° : { q 7 per cent the total heat content the fuel, depending the tempera- ture the exit gases. This waste heat many instances partially re- captured means heavy fireclay regenerators em- ployed preheating combustion air. Such equipment has been more less successful depending the skill the furnace designer. But all are sub- ject refractory heat losses, coupled with leakage, breakage, porosity, etc., and all have very low rate heat transfer compared with metal. Thus, they are not ideal means for ar- resting run-away heat. very definite recent trend to- ward the use special heat resistant steels for hot blast stoves and recup- erators efficient means re- capturing heat from gases, and also means minimizing time lag fur- nace operations such starting and stopping. Last but not least the use steel permits great increases gas pressure, definite factor the speed- ing heat recovery. Recaptured heat returned the fur- nace with the combustion air does triple duty. exemplify this, con- sider oil-fired forge furnace made 2200 deg. F., the furnace temperature being 2400 deg. Referring Fig. the chart entitled “Heat Absorbed Hot Surfaces Different Furnace Temperatures” shows the left mar- gin rate 12,000 B.t.u. per sq. ft. per hr. for temperature 2400 deg. reflecting heat steel the fur- nace 2200 deg. F., probable per cent thermal efficiency. the same furnace lined with insulating refractories which permits furnace temperature 2600 deg. F., the re- Hected heat passes the rate 24,- 500 B.t.u. per sq. ft. per hr. Twice the amount heat radiated the metal with the same amount fuel given time, and the furnace ef- ficiency per cent. The exit gases from the furnace 2200 deg. carry away per cent the total heat from the fuel; some this can reclaimed metal heat recuperators and when returned the furnace, where imprisoned, the furnace temperature raised 2800 deg. Therefore, 42,000 B.t.u. are reflected per sq. ft. per hr. the re- fractories the work. The furnace output this means increased times, furnace efficiency advanced per cent, the same token the fuel bill reduced per cent. Radiant heat absorbed, b.t.u. per per hr. 400 2800 3200 4000 indicate various rates heat absorbtion different hot surfaces different furnace temperatures. number installations steel heat recuperators and steel hot stoves have confirmed these almost phenom- enal gains, made possible the ef- ficient recapture heat from gases follows return heat that does not again escape. (2) This heat increases the furnace temperature more than the lent B.t.u. value fuel; therefore the reflected heat intensity metal proportionally greater. This means possible 100 per cent increase furnace output, reduction tion, and there also increase radiation loss even though the fur- nace temperature greater because the reduced time necessary for heating. (3) This heat return cannot es- cape and extremely efficient compared with the performance burning fuel. The higher the temperature the more steel metal may heated each hour termine how quickly metal heated. The chart Fig. shows the heating time for using varying furnace temperatures, determined studies furnace heat transfer 2—Heating time for steel various furnace temperatures. Note that, course, infinite time the temperature the stock never quite reaches furnace temperature. THE IRON AGE, December 22, 200,000 2800 7 “Counterw hts Hot gases amp gases stee/ tubes tubes 3—The Schack vertical metallic heat recuperator. This 4—Metallic recuperator for use furnace flue. The design functions the counter-flow principle, and the sketch indicates three banks non-oxidizing steel tubes vertical tubes are under very slight tension means the counter-weights. gases l-in. steel bars made large agricultural implement company. Steel Recuperators Steel heat recuperators have nu- merous advantages and also many dis- advantages when improperly designed. advantages are: The most practical and nomical means for the recovery heat. Small space required for large heat recuperation. (3) Air and gas tightness. (4) Permits free expansion with- out rupture. (5) Permits use high gas and air pressures, also high gas and air velocities, both which enhance heat recovery. (6) Light weight; founda- tions are needed and only very light structural supports are necessary. (7) Low heat storage and there- fore the most adaptable equipment for intermittent operations. Eight years experiments the perfection metallic heat recupera- tors have brought out that failures are inevitable, they would steam when the designer does not take into consideration the relation pres- sures, strains, temperatures, and chem- ical attack encountered the char- acteristics and properties the par- ticular steels employed. Furthermore, proper control metal temperatures all times must maintained means careful correlation mass and velocity heating gases and cool- ing air. The better heating resisting steels will deteriorate during long period heating too high temperature. 20—THE IRON AGE, December 22, 1938 This deterioration may not only re- sult from oxidation, phurous other chemical attack, but may arise from mechanical deforma- tion which, traceable faulty design, produces rupture the system. Regarding some the properties and characteristics heat resisting steels, should pointed ‘out that chrome-nickel steels are more resistant deformation high temperatures but are more sensible attack from sulphurous and reducing atmospheres. cent carbon, per cent chrom- ium, per cent nickel has short time tensile strength elevated temperatures varying follows: 1400 deg. 44,500 Ib. per sq. in. 1500 deg. 34,600 per sq. in. 1600 deg. 24,000 per sq. in. 1700 deg. per sq. in. 1800 deg. Ib. per sq. in. 1500 deg. the “creep strength” per cent 10,000 hr.) 1100 Ib. per stress 500 per sq. in. has been used 1800 deg. with- out appreciable deformation the material. Chrome steels have been and are used for high temperature cuperator construction, usually having analysis per cent chromium for temperatures 1400 deg. and per cent chromium for tempera- tures 2100 deg. The latter steel may subjected oxidizing at- mosphere temperature 2500 deg. F., the metal temperature being 2100 deg. The metal course will soft. and two banks mild steel tubes. Calorized steel may used equip- ment operating under 1650 deg. without any oxidation, and may sub- jected gas temperatures of, say, 1800 deg. for preheating air 1000 deg. Chrome-aluminum steels are insensible very high tempera- tures the chemical attack sul- phurous and reducing atmospheres, but high temperatures are unfortunately susceptible deformation and rupture. metallic recuperator design that correlates practical manner me- chanical forces and temperature fea- tures with gas and air flow shown this particular equipment be- ing the Schack tube recupera- and auxiliary radiant heating surface are used for diminishing the temperature the gas before enters the convection section the recuperator. For high tempera- ture furnaces, open hearths, reheating and air furnaces, and, also, hot blast stoves, the radiant heat and tempera- ture gases are too high for direct contact with the tubes which receive flow cooling air their other side. Therefore the radiant heating auxiliary surface receives cold air. Because the greater difference between the ex- tremely hot fire and hot gases and the very cold air, the metal temperatures the auxiliary surfaces are main- tained comparatively low level. This particular recuperator functions ciple, and the vertical tubes are under very slight tension through the use counterweights; this latter ar- rangement which permits free expan- sion that the tubes not collapse Bho sep y + | ---- 5°6 ---- -- -------54 doe | | .- O/d air ' q buckle case little over-heat- ing. The Schack recuperators are lined with firebrick, which feature retards operation and diminishes covery. This, however, could easily remedied the use insulating refractories refractory laggings. Europe, Schack recuperators are being used serve 1200-ton hot metal mixer used preheat 64,000 cu. ft. air per hr. from deg. 1472 deg. and 70,400 cu. ft. blast fur- nace gas from deg. 752 deg. The advantages preheating both air and gas are considerable, the metal the moment pouring being deg. deg. hotter than that from other mixers that are fired with cold furnace gas and preheated air 572 deg. Desulphurization the metal thereby facilitated. heating the combustion air for 20- ton per hr. continuous heating nace, which charged with cold metal and fired with mixed gas, resulted the furnace fuel consumption dropping 1,216,600 B.t.u. per long ton. This represented per cent fuel econ- omy, against furnace operation with cold air. Another type metallic recuperator in. diameter, different types steel heing used. These tubes are placed the flue leading from the furnace the chimney, shown Fig. furnace flue tubular recupera- tor has been used for supplying hot Heat ex- change and exit gas temperature for different mass flows gas and air. orbed per sq.ft. per hr. per temperature drop B.t.u.ab air rotary iron melting furnace fired with pulverized coal. This important improvement the use this high flame temperature fuel, the slagging the coal ash check- ers and fireclay recuperators has pre- viously discouraged its use. This type flue recuperator for preheating com- bustion air for the rotary furnace has shown the following practical Hot gas (temperature entering hot air (temperature leaving steel re- cuperator) 878 deg. F.; cooled gas (temperature leaving steel re- cuperator) 1134 deg. F.; draft (resistance gas through steel re- cuperator) 0.16 in. water; resist- ance air through steel recuper- ator in. water; weight gas per hour through steel recuperator weight air per hour through steel 1410 heating surface the steel recuper- ator sq. ft.; velocity gas steel recuperator 7.6 ft. per sec.; and velocity air steel re- cuperator 45.9 120 ft. per sec. The theory heat transmission shows that the temperatures the metal walls not depend alone the relative temperature the hot gas and the cooler air, but also the rate heat exchange between the gas and metal, and then the heat exchange be- tween the metal and the air. Mass Flow Important There fixed formula for this heat exchange, though seems that the rate which heated gas gives its heat cooled surface al- most proportional the mass flow gas over the surface. Taking the actual performance about steel air preheaters service and plotting this the chart Fig. tends show that the proportion does exist for like conditions. evident that the gas exit temperatures above the metal and the air temperature below the metal are increasingly greater with augmented mass flow (in Ib. per sq. ft. per hr.). may interest take this practical data charted and see how can applied the actual per- formance basis and then calculate the temperature exit the tem- perature exit air; and the maximum temperature the metal. The weight gas per sq. ft. per hr. (1873/83) 22.516. Weight air per sq. ft. per hr. (1410/83) 17.16 the counter-current flue type recuperators receiving fan air 120 deg. F., the metal temperature some value above the air temperature according the mass flow Ib. which read (dotted lines) from the chart being 340 deg. F., and the heat exchange shown the chart being 4.25 per sq. ft. per hr. per deg. gas temperature drop. The metal temperature then 120 deg. The exit gas temperature will some value above the metal tempera- ture, according the mass flow 22.5 which can read from the chart being 540 deg. with heat etal temperature relationship, Gas- Lb. gas per sq.ft. surface per THE IRON AGE, December 22, 100 | | ] ] | joints burners burners blower 6—Duraloy two-unit horizontal flow heat recuperator, designed heat 1000 cu. air per min. (cold measure) 600 deg. F., when the temperature gases entering the recuperator equals 1500 deg. F., the pressure drop air equals in. water, and the pressure drop gases equals 0.04 in. water. exchange 5.6 per sq. ft. per hr. noted that the heat delivered greater than the heat absorbed the air, and therefore the metal hot- ter and the gas temperature higher 5.6 perature the gas above the metal. The temperature the exit gas (711 deg. 120 deg. 340 deg. F.) 1171 deg. The temperature drop the gases (1832 1171 deg. F.) 661 deg. The amount heat exchanged the air (661 83) 270,200 B.t.u. The temperature rise the air specific heat 270.200 0.2375 The temperature the exit air (800 deg. 120 deg. F.) 920 deg. Notice that the calculated tempera- tures the exit gas and air are high- than those found practice. This indicative small air leakage. 800 deg. The maximum metal temperature the end the recuperator where the hottest gases enter and the hottest air (1832 920) 1376 deg. This probably the most important value determined troubles and failures are avoided. Considerable mechanical skill de- sign required maintain the proper metal temperatures recuperators and leaves will mean 22—THE IRON AGE, December 22, 1938 metallic hot stoves; Schack’s design indicates one method preventing de- formation during excessive heating. The Duraloy Co.’s design shows how prevent overheating proper cool- ing and distribution the cooling air, Fig. This flue type recupera- tor made two sections, one heat resisting steel and the other ordinary steel. Each section has area 500 sq. ft. heating surface, total 1000 sq. ft. The recupera- tor receives air under blower pressure deg. and 4000 cu. ft, per min., which heated 600 deg. gases entering the recuperator 1500 deg. The pressure drop forcing the air through the recuperator 1.5 in. water gage, and the draft loss gases 0.04 in. water. The design takes into consideration that the quan- tity air flowing burners must fluctuate with the rate fuel burning; yet the rate cooling recuperator tubes must not fail, because although the fuel supply stopped there sometimes enough heat stored the furnace metal charge and furnace walls overheat the tubes. There- fore, the relief valve will open when the fuel burning rate diminished stopped and metal temperature maintained the cooling air. pres- sure 1.5 in. does not always insure equal distribution tubes, nor much margin for operating the relief valve. There therefore throttling orifices provided each tube that controls the mass flow contact and velocity flow contact with the metal, pressure will necessary. However, the additional power consumed will compensated for the better heat ex- change the air. Fig. shows the steel heat recupera- tors low-heat storage, insulat- ing, lagging refractory chamber. This also assists maintaining the proper metal temperatures, but also speeds furnace operation. Fluids Poor Conductors well known that all fluids are very poor conductors heat. They absorb greater rate contact than any other manner; therefore for fast heat exchange advisable have mass flow contact and velocity the data plotted represents steel air heaters tubes and plate heat- ers equal areas. Therefore desired use 34-in. tubes, the volume fluid per sq. ft. inside heating surface area one-third great. The velocity contact flow increased three times. Recent tests have shown that double the velocity contact flow in- creases the heat exchange per cent although the same mass flow contact maintained. Therefore, velocity contact flow tripled the rate heat transmission given Fig. multi plied 176 per cent. This practical data seems confirm the work some early investigators who found that the coefficient for heat exchange varies with some power the velocity. This was shown equivalent multiplied the square root the velocity, heat per cent. The control man over pressures and temperatures places great period development before him. put- ting pressure atmosphere into arc light, the temperature raised from 7000 deg. 14,000 deg. F., comparable that the sun. The ap- plication such temperatures under pressure not the concern this article, but attention can directed the pressure gases increase the density and mass flow contact, where the air under lb. gage pressure and absorbs heat twice the normal rate. the pressure dissipated friction one atmosphere the absorp- tion one and one-half. the case employing 34-in. tubes compared with and reducing the pressure friction from atmosphere, the gain heat exchange may approxi- mate per cent. Thus, with the addi- \ Meter orifice Relief. A | | | tion this pressure the rate heat plied 248 per cent. The advantages steel recupera tors and rotary melting furnaces for short time melting, using oil firing are indicated the following table: Minutes Gas Tube Exit Gas Furnace Temp., Temp. Lighted deg.F. deg.F. deg. 500 356 698 572 698 1040 1184 842 1652 1292 860 1742 1200 Heat recuperation, and dry dust ex- traction for the raw gas coming out the blast furnace 500 deg. 700 deg. carrying grains more dust per cu. in., can done single unit shown Fig. suggested that the combination steel heat recu- perator and dry dust extractor placed down-comers from the fur- nace for preliminary air heating and per cent the blast furnace dust extraction. From this apparatus the hot gas with per cent dust can burnt metallic hot stoves, where more dust can collected. Metallic stoves are not subject dust troubles the same manner the Cowper type. known, blast furnaces had iron blast stoves the days when pre- heated blast was first used. These stoves contained wide tubes cast iron, but, cast iron scales red heat and also narrow tubes could not made with favorable ratio surface cross- section, only blast temperatures 840 deg. could obtained. tre- mendous advance was achieved the invention the brick blast stove William Siemens. was easy mat- ter for the metallurgists the old days work with the Cowper stoves and was long time before the dif- ficulties were overcome improving the design and employing cleaned blast-furnace-gas the heating me- Metallic hot blast stoves for blast furnaces have been service for more than year the Works (Saar) Germany, where one stove supplies the hot blast 500-ton per day furnace producing pig iron from oolitic iron ore and sintered flue dust. This stove built according the principles outlined Fig. The steel vertical tube hot stove shown Fig. consists three nests tubes ft. long, suspended vertical- and counter-weighted allow free expansion without overheated. The stove fired four burners, two each firebrick com- bustion chamber. The fuel consump- TABLE Comporison Cowper and Metallic Stoves Cowper Steel Hot Stove Hot Stove Number units per Furnace 2472 sq. 1553 sq. ft. Weight iron and steel 230 tons 200 tons tion approximates 176,757 cu. ft. blast furnace gas per hr. with 158,900 ft. air for its combustion temperature 2012 deg. This temperature diminished just before the gases enter the tube banks passing them through screen, auxiliary radiant heat absorbing sur- face, thus protecting the tubes from the direct radiant heat from the fur- nace. The tubes are “U” shape and re- ceive per cent the total air “cold,” which assures proper metal tempera- tures. About per cent the air heated, 1,871,695 cu. ft. per hr., enters the stove its top and passes downward inside the tubes, while the hot gases travel upward, taking zig- zag flow over the outside the tubes, being deflected baffles. Each nest tubes has independent free expansion and divided into two parts the top, six parts The tubes are made different kinds steel, weld- together. The nests the bottom are chromium-nickel steel while the six the top are made mild steel. The tubes are welded into headers, the bottom headers are welded chromium- nickel steel and the six the top are mild steel. The designers experienced some lit- tle difficulty calculating the stresses for the maximum blast pressure per sq. in. gage, with metal tem- perature around 1832 deg. The steel hot stove equipped with all up-to-date instruments for the read- Cooled gases expansion air Section B-B tion steel air preheater and dry dust extractor. conveyor for “Asbestos packed expansion tight casing air outlet Vertical section through tubes THE IRON AGE, December 22, 1938—23 it. t Hot gases enter ing pressures, temperatures and flow, together with all the regulating devices employed today for metallurgical furnaces. The tempera- ture the blast may changed the desired conditions very quickly, this regulation being made the blast fur- nace floor simply setting the point- temperature regulator. The supply gas and air for combustion once follows, automatically adjust- ing itself the new temperature maintained. The recuperator opera- tion entirely automatic, with results obtained without delay because the low-heat storage characteristic metallic stoves. type with steel hot blast stove for 500-ton capacity per day blast fur- nace tabulated Table The Velox steam generators burn- ing blast furnace and coke oven gas have shown remarkable results, par- ticularly their ability burn blast furnace gas 82.4 per cent thermal efficiency and meet fluctuat- ing loads quickly without appreci- able drop thermal economy. These results have suggested fur- ther application the Velox principle 24—THE IRON AGE, December 22, 1938 cuperator blast furnace with daily production tons Volk- lingen (Saar). for the heating blast for blast naces. However, the temperature combustion high pressure would prove too high for the air-heating sur- faces under pressure, Velox steam generator would used combus- tion chamber and proportioned that the gases are cooled 1780 deg. F., after which they pass into the second stage blast heater, where the gas tem- perature diminished 930 deg. The preheated air leaving the second stage attains temperature 1200 deg. before delivered the blast furnace. The gas 930 deg. and under pressure continues the gas turbine, driving the air and gas blower for the auxiliary boiler unit. The tempera- ture drop the turbine would roughly 180 deg. F., and the gases ex- hausting from the turbine would then pass the first stage blast heater where the air preliminarily heated from 210 deg. 530 deg. The gas would leave the hot blast machine roughly 300 deg. With the proposed inlet gas tem- perature into the second stage stove 1780 deg. and final blast tempera- ture 1200 F., the maximum mean wall température the tubes would 1490 deg. This tempera- ture quite permissible with the pres- ent day high temperature alloy steels which are available. required, the all-metal stoyes can designed for hot blast 1550 however, any higher than this, and for most blast furnace plants this temperature will suffice. should also noted that the air and gas pressures are low, and are furthermore practically Con- sequently, the tubes will only sub- jected heat stresses and these are very low case thin-walled tubes such would used for these stoves. There are important which determine the economic possi bilities the all-metal stoves. (a) The use the “Velox” steam generator bring down the gas tem- point where ¢an used safely metal stove. (b) High gas and air velocities, ap- proximately 200 ft. per sec. this means higher tate heat transfer obtained and, consequently, the di- mensions the become com- paratively small, This simplifies con struction and the cost only stove. Zinc Group Protests Cut Import Duties American Zinc Institute, rep- resenting per cent the spel- ter mining, smelting and manufactur- ing industry the United States, has filed protest with the State Depart- ment against the tariff concessions granted zine ore and slab zine the recently trade agreement with Canada, uring that the new con- cessions According the institute, the jurious effects the agreement have become apparent the unset- tling the domestic market, threat- ened shutdowns mines and smelters and prospectiye wage reductions and layoffs employes. Since the announcement the trade agreement, ore prices have ton and slab zinc $11 ton. The new conces- sions, the institute states, invite impor- tations from all foreign producers ex- cept Germany, the favored- nation clause written into the agree- ment. | | » — | | main advantages arising alloys result from its low specific gravity about 1.8, compared with for aluminum and about 7.2 for steel. Although frequently classed to- gether light alloys, magnesium and aluminum differ certain essential features from the standpoint the foundry, the chief difference being the extreme combustibility the molten magnesium and the rapidity with which will react with moist sand. Melting Practice The development technique for the satisfactory melting and casting magnesium therefore centered around these peculiarities although, the case aluminum, the lightness the alloy combined with tendency form unsound castings has taken into account. steel crucibles oil-fired furnaces al- though coke furnaces are sometimes preferred. The steel used for the crucible has been the subject some considerable investigation since found that mild steel does not with- stand the action the fluxes and de- Polish International Foundry Congress and originally published Foundry Trade Devereux managing director High Duty Alloys, Ltd., and Magnesium Castings Products, Ltd., Slough, En- gland, and director Reynolds Rolling Mills, Birmingham, Magnesium Foundry Practice’ teriorates rapidly. choosing heat resisting steel important that the steel should have low nickel content account the marked tendency for magnesium absorb nickel from the crucible. Chromium are not easily absorbed. possible with extreme care melt magnesium crucible with closely fitting lid without the use flux, depending atmosphere sulphur vapor for protection against oxidation. This method is, however, since results dross inclusions and blowholes the casting. results have produced the use fluxes. German Melting Procedure castings, free from dross and flux, the choice flux and the method pro cedure call for the exercise con- siderable discretion. this respect should noted that the German, British, and American practices, al- though fundamentally similar, differ some important details. German practice two fluxes are used (British Patent No. 219,287), one having relatively high and the other low melting point. The procedure adopted follows: During melt- ing sufficient quantity the low melting point flux introduced prevent oxidation and when the metai completely molten further quan- tity added and the whole stirred order remove oxide inclusions from the liquid metal. The flux then cleaned and quantity the high melting point flux added, the metal 1560 deg. F., and then cooled the casting temperature which approxi- mately 1290 1330 deg. The ob- ject the pre-heating before melting refine the grain size the final casting. the British practice one flux only used (British Patent No. 427,316), this flux having the property fusing readily when added the molten metal and then caking form hard crust which easily removéd prior pouring. Green Sand Castings When molten magnesium comes into contact with moist sand will react immediately and vigorously and for this reason the early days its development, sand casting mag- nesium was extremely difficult and had carried out baked molds. the present time, however, possi- ble make satisfactory castings green sand the use inhibitors which are materials added the sand prevent burning the magnesium. the German practice, sulphur per cent,) and boric acid are added the sand. This mixture ex- tremely effective. the British prac- tice ammonium-bifluoride used and when the molten magnesium comes contact with sand containing this fluoride coating insoluble mag- nesium fluoride formed the metal and this has the effect preventing burning and corrosion. considerable effort has been made various in- THE IRON AGE, December 22, m es S, . ir l- d vestigators discover other more efficient inhibitors and although such materials ammonium boro-fluoride, naphthalene, resinous oils and volatile hydro-carbons and certain alkaline sulphites have been found effective they have not yet reached the com- mercial stage. Sand Preparation For the manufacture sand cast- ings any metal alloy the selec- tion suitable molding sand matter considerable importance. the case magnesium alloys essential that the correct type mold- ing sand chosen. Many foundries casting the heavier metals, and even some foundries casting aluminum al- loys, use natural molding sands. These natural sands are sand mined quarried from particular sand pit and are such composition that they contain percentage clay other bonding agent. These sands are pre- pared for foundry use milling and mixing with certain percentage used floor sand. Often little considera tion given the physical character- istics such sands. the castings produced from them have smooth finish and are free from scabbing and surface blowholes the foundries are usually satisfied with these sands molding materials. the case magnesium, several factors have taken into con- sideration which are not such great importance the founding heavier metals. The first these considered density. Molten magnesium temperature 1290 deg. has density only 1.54. Owing this primary importance that any TABLE I—COMPRESSION STRENGTH BENTONITE-BONDED SANDS Soft Medium ram- ram- ram- ming, ming, ming, Lb. per Lb. per Lb. per Synthetic sand sq.in. sq.in. sq. in. per cent silica sand.. 1.4 3.1 3.1 per cent bentonite per cent silica sand.. 1.6 2.2 per cent bentonite per cent silica sand.. 2.2 4.0 6.1 per cent bentonite TABLE IRON OXIDE GREEN BOND STRENGTH Soft Medium Hard ram- Synthetic sand ming ming ming i=) per cent silica per cent bentonite. per cent oxide per cent silica .... per cent bentonite. per cent oxide .... 1.0 1.4 1.8 per cent silica ... per cent bentonite. per cent oxide .... per cent silica .... per cent bentonite. ~ 1.9 3.1 4.0 per cent oxide per cent silica .... per cent bentonite. per cent oxide gases contained the mold, such air, water vapor hydrogen, formed the reaction the molten mag- nesium with water vapor, have free exit from the mold. such exit cannot provided the use risers and vents alone, therefore essen- tial that the sand used has high permeability value order that the mold gases can readily escape. With natural molding sands this permea- bility value generally low. such sands were used for magnesium cast- ing, especially green state, the resultant castings contain many surface blow-holes which would avoid this synthetic molding sands are the use such sand possible control the most important factors, such meability and content, frequent checking with suitable ap- paratus. Such synthetic sands are obtained mixing selected grade dry silica sand and adding thereto specific quantity ‘of suitable binder. Sand Preparation and Control For preparation for magnesium foundry purposes the silica sand would mixed with colloidal clay hinder. Bentonite has been found suitable, the amount necessary obtain suitable bond being approxi- mately per cent. This mixture moistened with 4.5 per cent water while being milled suitable sand The permeability value this synthetic sand would between 140 and 170 c.cs. per min. Sands having low permeability value are generally unsuitable for magnesium founding. Synthetic molding sand with per cent clay binder contains only per cent water. This amount rigidly controlled any excess water green sand mold for magnesium cast ing would have disastrous Experiments have been made de- termine the optimum amount clay binder necessary obtain suitable green bond strength. Test samples have been rammed standard ram- mer the same type that used for preparing the sample for permeability TABLE PROPERTIES VARIOUS MAGNESIUM ALLOYS per cent Al. 0.2 per cent Mn. Remainder Mg. per cent Al. per cent Zn. per cent Mn. Remainder per cent Al. per cent Zn. 0.8 per cent Mn. Remainder Mg. Solution Solution Solution cast treated cast treated cast treated Proof stress 0.1 per cent, tons per sq. 4.5 5.5 4.5 4.5 5.5 4.6 4.5 5.5 Compression proof stress, 0.1 per cent, tons per sq. in......... 6.5 5.5 6.5 5.5 6.5 5.5 4.5 5.0 Fatigue range (20 million reversals) (plain bars), tons per sq. Therma! conductivity units deg. C.) ........... 0.32 0.31 0.30 0.32 0.82 Coefficient thermal expansion (cms. per deg. C.) (average) IRON AGE, December 22, 1938 | 1.9 2.1 1.2 3.3 4.6 2.9 4.7 6.5 | determinations. The samples cylin- drical form were placed the pan British Cast Iron Research Associa- tion compression testing apparatus, and pressure applied means screw thread. The load pounds was noted when the specimen crushed and this value converted into pounds per sq. in. Table gives comparative values for various percentages clay binder. These values are for the equiv- alent soft, medium and hard ram- ming. each case the percentage moisture constant per cent. general, synthetic molding sand containing between and per cent clay binder constitutes suitable molding material for magnesium founding. found that with per- centages above per cent the sand tends become sticky. This sand, however, suffers from one marked dis- advantage that cannot skin dried, the face the mold readily becomes friable. Another disadvantage that during hot and dry weather the sand rapidly air dries and some- what more difficult handle. Some experiments have been carried out with the addition hydrated iron oxide the silica clay mixture. The addition this compound has the ef- fect markedly increasing the green bond strength and the same time allowing the mold skin com- pletely dried without crumbling, and rendering less susceptible the air drying effect. Some values for bond strength with the addition iron oxide the synthetic sand are given Table IT. has been found that some the latter mixtures are too strong for or- dinary molding purposes and mix- ture with per cent silica sand, per cent bentonite and per cent hy- drated iron oxide the most satis- factory. While cannot stated that these Clerks Reject OLEDO.—Clerical workers the Willys-Overland Motors, Inc., voted three that they did not de- sire represented bargaining with the employer the United Auto- mobile Workers, which now repre- sents production workers. the same election conducted the National Labor Relations Board TABLE IV—MECHANICAL PROPERTIES (SOLUTION AND PRECIPITATION TREATMENT) per cent Al. 0.2 per cent Mn. Rdmr. Mg. Proof stress, 0.1 per cent, tons Ultimate stress, tons per sq. in. 15.0 17.0 Elongation in., per cent. Compression strength (ultimate), Compression proof stress, 0.1 per cent tons per sq. in.... 9.5 10.5 Fatigue range (20 million re- versals) (plain bars), tons Brinell hardness (500 10- gravity 1.81 Thermal conductivity units deg. C.)....... 0.32 Coefficient the thermal ex- pansion (cms. per deg. C.) 26.0 « 10—" mixtures fulfill the ultimate require- ments molding sand for magne- sium alloys there appears def- inite advantage the addition hydrated iron oxide mixture silica sand and colloidal clay. Mechanical Properties Compared with aluminum alloys may said that cast magnesium alloys possess lower proof and relatively high fatigue strength. The low proof stress coupled with moderately good resistance shock and the alloys are therefore quite suitable for components which are not subjected continuous high stresses, and are eminently suit- able for structural parts subjected temporary loads high order. view the good fatigue properties the alloys would expected that would suitable for the con- the maintenance mechanics and ma- chinists voted represented the Mechanics’ Educational Society America vote four. There were voids, blanks challenges either contest. Die sinkers the plant recently were conceded the Die Sinkers’ Union, division the International Association Machinists, affiliated with the AFL. Labor relations have been amicable struction components subject high fatigue stresses, but, ously pointed out, they are prone shrinkage porosity which generally located changes section. This defect, inherent magnesium cast- ings, would best overcome close co-operation between the foundryman and the designer directed toward pro- ducing casting free from those pe- culiarities which tend cause porosity the most highly stressed parts. The mechanical properties the three alloys most widely used are given Table III. Each the alloys detailed Table [II amenable heat-treatment and may used either the solution treated condition after double treatment (solution treatment followed precipitation hardening). Some these alloys may also hardened precipitation, shown Table IV. The heat treatment magnesium, which the case the binary alloys with aluminum consists maintain- ing the alloy 790 800 deg. for some difficulty owing the fact that there tendency for the alloys catch fire, particularly atmos- phere stirred air. Three methods are use overcome this difficulty. The German method consists car- rying out the heat treatment bath mixed dichromates (British Patent No. 448,994) electric furnace which there atmosphere con- taining sulphur dioxide. the Amer- ican practice the heat treatment may carried out vacuum furnace, and claimed that this method Ed. Note: For further details concern- ing American practice see “The Manu- facture, Characteristics and Use Magnesium Castings,” THE IRON Oct. 28, 1937, page 115. but the UAW Local 12, representing most the 3000 more production workers, claimed plant-wide jurisdic- tion. Harnischfeger Milwaukee, has ap- pointed the Butte Tractor Equipment Co., Redding, Cal., exclusive agents its area for P&H Hansen arc welders and Smoothare welding electrodes, and has named the Dixie Mill Supply Co. with offices New Orleans and Shreveport, exclusive agents for those products Louisiana. THE IRON AGE, December 22, 1938—27 . ie > » e y y 2, Kay axles Johnstown, Pa., dates back more than half century, May, 1885, when Cambria Iron Co. started shop equipped with two forging hammers, machines, three journaling machines and two shapers. Additions this plant have now been made through the recent com- pletion large expansion and mod- ernization program. New equipment includes additional forging ham- mer, two up-to-date heat treating fur- naces, and charging machine. modern axle finishing shop has been built—a model efficiency—equipped with number new cutting-off machines and lathes. During the first four five years the production the original plant was confined 334 in. axles, for cars. Gradually, the re- quirement for heavier rolling stock arose, larger and larger sizes were included. Today, the plant turning out all standard and special types axles for locomotives, passenger and Enlarges Johnstown Plant KENNEY Metallurgical Engineer, Bethlehem Steel Company freight cars, street railway cars and mine armature shafts for electric locomotives, crank pins, and piston rods. Equipment also available for overall grinding special axles in. diameter, and for production hollow axles. Rounds and any type special forgings are produced lengths 126 in. and 13% in. diam- eter. recent specialty precision forging axles and rounds which can made tolerance approaching that rough-turned parts. Forging driving axles and all special forgings done 10,000 Ib. 15,000 hammer, depending the size. These are forged directly from the heated bloom, without rolling the round mill. special heating furnace, with 252 sq. ft. hearth area, ORGING axle bloom the Johnstown axle used for these products. fired with coke oven gas, from three burners one end, with the flue arranged that the flame well distributed. Tem- peratures are controlled pyrometers. Blooms are charged from the heating furnace with charg- ing machine, which permits very rapid handling the heated bloom, from furnace hammer, with negligible heat loss. Most the heaviest pieces can, therefore, forged one op- eration, without reheating. This has important bearing the quality the forgings. Heat Treatment The larger part the production machined directly after forging. However, practically all axles and many special forgings call for heat treatment. Two heat treating furnaces latest type, each with 443 sq. ft. hearth area, are used. They are heated with coke oven gas and have full auto- matic control, with regulation from pyrometers each heating zone. Heat supplied two rows burners, one side and the other, equal- spaced and staggered and ar- ranged that the flame prevented from coming direct contact with the steel. The temperatures used the vari- ous treatments are governed the analysis the steel and the specifica- tions. all cases very slow and gradual heating observed, and the forgings are soaked thoroughly, al- lowing about one hour per inch diam- eter. proper flame used pre- vent excessive scaling the surface which would interfere with quenchi