The Iron Age 1931-09-10: Vol 128 Iss 11

THE IRON AGE NEW YORK, SEPTEMBER 10, 1931 ESTABLISHED 1855 VOL. 128, No. ONWARD MARCH HEAT TREATING IMPRESSIVE the years since the founding the American Society for Steel Treating Chicago 1919, the art heat treating has become essential many lines the metal working indus- tries. There are few important iron and steel products whose properties and uses have not been enhanced heat treatment. developments have been many that with that one can keep touch with them. Gray iron, which only few years ago had never been heat treated, has been improved thermal treatment. Steel castings, particularly alloy, are today quenched and drawn their great benefit. Malleableizing has been radically shortened. ‘Tool steels have been multiplied composition because they can success- heat treated. The large increase classes standard alloy steels has been made possible heat-treating equipment and processes. Some examples are the chrome and chrome-nickel rust and heat-resisting steels, the structural alloy steels, the automobile and steels, such chrome-vanadium and chrome-molyb- denum, the carburizing nickel and other steels, and on. Even the light aluminum and magnesium alloys are now subjected heat treatment and welding has introduced new problems. With the coming heat-treating furnaces and incidental equipment, complex alloy steels, new heat-treating processes, new paths have had trod. Fatigue testing and magnetic analysis also have become associated with heat treating. Nitrid- ing has revolutionized the case hardening steel and its uses. few these problems and developments are discussed the articles which follow this, annual steel treaters’ issue, brought out signalize the National Metal Con- gress, which holds forth Boston the week Sept. 21. “Crackless plasticity,” property metals which neither strength nor ductility and which almost absent from heat- treated alloy magnetic analysis, being used check certain heat-treating results; the control atmospheres heat- treating furnaces; magnitude electric heat-treating operations the Ford plant; high copper alloy steels; heat treatment making gears: these are some the questions discussed. article phase nitriding will used later issue. -- 673 ab 4 a 4 m pi § 4 \ 7 = i 4 q a 4 4 lines erains by Tibor Ver LIP LINES SHOWING PLANES ALONG CRYSTALLINE GRAINS PURE HAVE YIELDED UNDER STRESS have different directions Magnification 312 diameters As all a IRON —Note that these slip different crystalline Micrograph made the metallographic laboratories the testing steel determine its either raised lowered the service which stort ire have shown that piece metal subjected. Millions cycles low tar means simple stress raise the endurance limit most metals appre- that test can used ciably. While piece metal may withstand without prediction trength steel fracture thousands cycles stress well above the was felt that true” elasti peated overstress not infrequently starts cracks the teel below which the metal which greatly reduce its ability withstand eur under lition service further cycles ordinary working stress. rapt and later the tests Tests the University Illinois have shown that dea specimen axle steel, the endurance limit that ela rested the assumption that steel reduced somewhere between and per iniform and indefinitely divisible without ents its original this connection must The microscope and the remembered that nearly all maximum stresses togr snow! this not true and machine parts occur some surface the part and nat tal netal ertain planes that surface metal free from irregularities eakne illustrates this point. and, quite possibly, minute cracks invisible even under With development testing under the microscope. ted stress was thought that the Crackless Plasticity Defined mit ight prove the criterion for the strength teel used machine part However, seems evident that important property apparent steel its ability stand occasional overstress with- out the development crack which, subsequent hil Royal ervice, spreads failure. this article the ten- 674—The Iron September 10. 1931 Urbana, PROPERTY METALS HERE seems property metals, says this eminent authority, which neither strength nor ductility revealed tension test and which appears important, namely, the ability resist fairly large numbers loads which cause very slight plastic action, without crack. offers the term plasticity” denote the property. Suggested methods experimental study this property include fatigue tests following period overstress, notched-bar impact tests and tests the damping vibrations the metal. structive spreading crack spoken its “crack- Battelle Memorial Institute, and possibly others, less plasticity.” that would worth while have extensive This crackless plasticity steel not dependent tigation the fatigue properties various steel ipon ductility ordinarily measured tension made something after this general plan: The endur old-bend alloy steel has high ance limit steel would determined the usual elongation and high reduction area, yet seems way, and then the endurance limit specimens the relatively low crackless plasticity. Elongation same steel which had been subjected various and reduction area and good results the cold- grees overstress repeated for various numbers bend test are measures the ability steel undergo cycles would determined. This rather elaborat deformation under one very severe overload. series fatigue tests would then repeated for each steel studied, and the reduction endurance limit not all certain that steel which will resist extreme overload without fracture until high elongation reached will resist small overstress might furnish inverse measure the crackless plasticity of a steel. verloads without starting spreading fatigue crack Perfect Elasticity Desirable Property? vhen each overload causes stress above the endurance although not the sort determined the ordinary ten- have certain exceptions when applied metals subjected to repeated stre Ir ri ly teel, not surprising that have present least variation from perfect alinement would for the measurement this property. high stress the heal natural think the notched-bar impact (Charpy (See What actually hay ich Izod) test this connection, but here again ase slight localized plastic distortion which great ive data which form reliable judgment cuts down the magnitude this localized stre are some data available which show that high nder reneated loading. localized machines, but definite quantitative relation fatigue crack. have has been suggested Dr. Gillett the have good deal adjustment and mitigation local H kampf ALS Vi ) tre ind an te! re t ‘ t I dy r duc for tigu failure. The Iron Age, September 10, 1931—675 { LINED both shaft and bearing were per elastic material, there would enormous stress con both exhibit slight plastic tion, this stress concentration greatly mitigated ried Paris material which has very nearly elastic action under stresses right fracture There almost plastic action tracture occurs. can see that machine parts ild not made such material plaster Paris without very great danger fracture, int the absence any appreciable amount tress-mit ting tic seems perti I les nelast act n, the energy f stress ad istment not direct function the ability tretch under single load before fracture occurs. method studying this ability metal delicate load and appa- some well the stre train when plotted show hysteresis loops shown However, the width the hysteresis loops inch, they probably vary width with the num stress applied, and the direct deter natior the area such “hysteresis” loops extremely delicate apparatus and test methods Measuring the Damping Vibrations | ‘ eS } Fe | Brunswik i! +} } a e ef t h tere rats my? ne ont ¢ rn dan l ) | ed t thi ountt ) H ne paratu | | | men S j \\ +} rrent mayne coils forth and DIA GRAM SHOWING HYSTERESIS exaggerated this figure over the width which would shown scale which would give this general shape diagram 676—The Iron Age, September 10, 1931 moved clockwork. Fig. shows some typical records from such machine. The record duralumin special interest. has been found very difficult with duralumin detect any metallographic evidence plastic action (such slip bands, visible under the microscope) before crack developed under repeated while strong and fairly ductile shown tension tests, cracks relatively easily. noted that its vibrations show very slow damping; that is, there very little energy absorbed each vibration. Com- paring its diagram with that structural steel, rreater damping qualities the latter are evident. Heat-Treated Alloy Steels Show Little Crackless Plasticity Heat-treated spring steel again shows compara tively little damping, does heat-treated alloy steel IG. 4.—Diagram coke apparatus for testing the damping free vibrations metal The ductility alloy steel (as measured elonga reduction area the ordinary tension test) much higher than that heat-treated spring steel. Both heat-treated spring steel and heat-treated teel are very strong; heat-treated alloy steel duc- tile according tension test results; but neither steel shows high degree “crackless repeated stress. This crackless plasticity steel may have bearing the preference which many engineers have for the use wrought iron soft steel resist peated stress. Such preference usually found uch fields railroad work, where the machine tructural parts are subjected ally heavy loads unknown magnitude. These loads make only small proportion the total loads applied service and the ability material resist such loads with adjustment tresses crackless plasticity may, quite possibly, fully important actual strength. Here again becomes evident that ductility, measured elongation reduction area, does not seem insure crackless plasticity under occasional repeated heavy load. Taking rather marked case, some the copper-nickel alloys show good elonga- tion and reduction area but not seem abk J 1 maa S 4 (ay { A | Y | | ; 1 fj hy / f Spring Steel Heat-Treated Alloy Steel Structural Steel Duralumin 5—DAMPING TEST DIAGRAMS METALS :—These diagrams are not taken from any definite tests, but are typical the general type diagram obtained for each metal absorb much energy plastically without starting may pointed out that, even metal high degree of crackless plasticity, vet under re- haustion would prevented, least delayed, the progressive mitigation localized stress due the plastic action the first few loadings. Plastic action tends equalize stress, and reduce the stress peaks metal under subsequent loadings the number loadings increases the intensity alized stress diminishe S, less a crack farts, and less and less will the drain the remaining crack ess plasticity the metal. If, however, crack tarts, tends keep state stress-concentra its end, and the mitigating effect plastici absent, least markedly reduced. the “breaking in” the shafts and gears Crackless Plasticity and Notched Specimens \nother indication the importance crackless metals found the behavior notched According the imens under repeated stress. trength due given notch should the same what ver the material the specimen. Actually this ery far from the truth. Very pure metals and metals seem the most sensitive effect notches. ensitiveness notch effect has been called tenderne although this term has technica tanding. Whether this question tenderness tch effect connected with the crackles (a) (b) 6—TWO TYPES STUD BOLT:—Type (a) failed service connecting rod steam engine; type gave satisfactory service + ] ‘ steel al Sts art Perhay whether the results notched-bar impact correlated with this questions which seem worthy investigation. property of steel art contrasting conditions service for hel onditions, the stress (a) ngs and for bolts. helical springs, whil concentration com TYPES GROOVED SPECIMEN FOR FATIGUE TESTS UNDER REPEATED STRESS:—Specimen developed higher fati gue strength than did groove (b) were cut with IMPACT The thread (a) and the the same lathe tool 4 ¢ ( 1) THREE TYPES SPECIMEN TESTED TENSILE Specimen (a! required much less energy fracture than either specimen specimen \ re eT riny Loy ire ovided that there limit placed the stress which can developed the pring, while such limit for bolt tension. For springs lly important that any permanent set should light bolts the minute plastic the root the thread isually dit trouble long crack started springs, then, the for the rrent pra ising very strong, rather brittle steel the bolt, the other hand degree ticity the root the thread nearly alwa ent, does harm lor pread ! not tarted Breakage Bolts the Sweet this connection the experier John old steam engine and early engines Mr. Sweet had much trouble with the reakage bolts the connecting rod. replaced soft steel bolts with stronger steel and the trouble ntinued. then reduced the shank the bolt, hown Fig. that the area the shank rreater than that the root the thread. Thi topped the trouble. enormously increased the ime subjected slight elastic action and consequent i¢ one on The Age, September 10, 1931—677 — en in. there some stress concentration and rather paratively low, while bolts the stress concentration re ' at the roots of the threads is very high. (b) a q el] | 1} — > (b) | peated loading this plasticity may gradually hausted. But, after few cycles stress, this ¢g \ i t 4 HEAT TREATING, FORGING AND MELTING WITH ELECTRICITY GLENN COLEY Detroit Edison Detroit ITH connected load 85,000 kw., the Ford Motor Co. scribed the largest user electric heat the world. Electric heat used the forging department and the heat treating many vital parts the Ford cars and trucks. Some the features these large and small furnaces are described the author. There also brief account the electric furnaces for duplexing blast and cupola iron the foundry, and indirect arc furnaces the brass foundry. Ford Motor Co. the largest user parts are close, being rigidly held during process- electric heat the world, having about ing. Some Ford parts have probably the highest 000 kw. connected load. this amount unit stresses upon them any car the market. over 15,000 kw. was added during 1930 and Ford engineers can design these parts with light- further expansion being made continuously. This weight sections without having worry about pos- load would sufficient supply all the electrical sible failures, because the materials used and needs city 150,000 population. The Ford the precision with which they are heat treated. company uses electric heat wherever possible, al- though produces about 6,000,000 cu. ft. 500 Furnace Just Another Machine B.t.u. coke-oven gas per day. straight-line production methods Dear- Manufacturing tolerances various heat-treated born are the model for many plants doing similar silicon-carbide rod resistor furnaces for heating forging stock the upset department. 678—The Iron Age, September 10, 1931 q - ‘ts 4 heating before up- setting. vork. Any machine find application here must equipped with rod resistors in. fit into this line, and furnace looked upon and in. long, and has connected load 320 kw. ust another machine. Electric furnaces fit into this The stock loaded hand in. diameter and cheme because they are clean, compact, not heat heated for length about The furnace the surrounding shop and produce accurately operated about 2300 deg. heat-treated product with minimum labor and Forgings for the cluster gear the transmission upkeep. Some the more interesting application are continuous furnace (Fig. 3). Billets of 10 ae are the rj ara- ‘ electric heat are described the following para in. diameter and in. long are placed, with their axes right angles the length the Sixty Furnaces Upset Forging Work nace, rails the charging end. The walking Sixty silicon-carbide rod resistor furnaces for beams, shown the four levers ide the ornare ve forwar an wh MNositing eating forging stock are installed the upset de- furnace, move up, forward and down, partment. The gear end the truck rear-axle drive- the billets the rails again. The walking beams shaft heated for upsetting rod resistor furnaces are returned their place the single lever shown shown Fig. This type furnace has front the picture between the two left-hand beam levers slot ft. long and ft. deep, with opening that The work discharged gravity into chute. The 7 Ford car. The Iron Age, September 10, 1931—679 q 4 q | s q q 5 q 4 § 3 q { 2 5—This leaf spring eye-bending furnace really two furnaces with chain con- veyor between them. (at right) 680—The Iron Age, September 10, 1931 4—This furnace heats connecting rods before restriking after drop forging and trimming. will heat 1500 rods hour, sup- plying two hammers. 6—In naces this type springs are hardened after the eyes have been formed. = ant. SSS D perated that billet standing ete the cycle without being tipped 5 end Wilil Com- mot r-driven pusher type. Two rows of connecting over. rods are edge alloy rails the charging end, The furnace equipred with rod resistors and the pusher, just under the operator’s in. diameter and in. long, with connected moves forward specified distance, after whi 540 kw. The resistors are mounted over the returns its original position for more work earth extending across the width the furnace, placed the rails. The rods are loaded and vhich operated about 2300 deg. Since the loaded hand. This furnace has rod resistors temperature automatically controlled, possible in. diameter and in. long with connected Transmission laneous parts are annealed this stock around the plant. the steel thorough soaking heat without load 300 kw. will handle 1500 connecting rod ind wear the dies. This furnace heats 350 bil- hour temperature 2000 deg. F., supplying ets, approximately 3500 Ib. steel, hour two hammers. anger burning, making fill out this The furnace for bending eyes the ends leaf tricate forging with minimum amount power prings reality two furnaces with chain con rate about 5'» Ib. per kw.-hr. and feeds two up- veyor between them. The width the unit, hown the right-hand sketch Fig. about Fig. shows furnace used for heating connect- The slot between the two halves the unit rods before restriking, after have ft. The actual hearth the irna about furnace the ft. and the charging point ft. above the floor drop forged and trimmed. This The Age, September 10, | | | | q | 4 A | > ~ § heating elements are the rod-resistor located above the hearth, shown The conveyor consists motor-driven series plates with two stops extending upward each plate carry the stock through the furnace. The flat and carried into the furnace shown where about in. each end the spring heated the springs reach the dis- spring stock loaded the conveyor to about 2000 deg. F. ’ = 682—The Iron Age, September 10, 1931 IG. three-zone coun- terflow furnace, ft. long, rear axle drive gear forgings are ized. Output lb. per kwhr. net charging end, they drop down chute level about even with the eye bending machines. After being discharged, they are placed the bending machines where both ends are bent the same time. This furnace has rod resistors in. diam- eter and in. long, with connected load 360 kw. The furnace will produce 240 springs hour. After having the eyes formed, the springs are naces shown Fig. These furnaces are imme- double- deck roller hearth furnace for wrist pins. The double- save space. 3 — type, ring gears for | ~ 4 ately behind the men shown the picture and ing elements the two decks give iniform the chrome-nickel resistance type. Springs tribution temperature. Boxes are placed the are put through the furnace walking beam and rolls monorail chain hoist. Before packing fter being heated are quenched fixtures which the carburizing compound, alloy plugs are inserted form the springs the same time that they each end the pins prevent carburization hol The double-deck principle was resorted Transmission gears and miscellaneous parts are nnealed counterflow annealing furnace, Fig. Ring gears for Ford tru carburi work moves through the furnace two paths site directions the hot work coming out gives some its heat the cold entering work. Parts are discharged temperature 700 1000 deg. depending upon the speed the pusher. Trans mission gears are loaded directly the grooved while miscellaneous parts are loaded trays man each end the furnace loads and unloads the work. The chamber this furnace ft. long, ft. in. high and ft. wide, with con- nected load 420 kw. and three zones control. furnace will produce net per kwhr. Rear axle drive gear forgings are normalized novel furnace the metallic resistor, counterflow has overall length ft. with cen- There are three zones tral heating zone ft. long. 160 kw. Gear control and connected load blanks are pushed through edge alloy troughs. The right-hand row gears enters the furnace left-hand row leaves. With this type pusher, material going through the furnace pro- at duction basis; hence output over Ib. per net obtained. Fig. shows double-deck roller hearth fur- for carburizing wrist pins. Three rows noving in boxes are placed each deck, the decks Opposite directions. This gives the same recupera- tive principle the more common single-deck, 12—After i ernate-row furnaces. Proper spacing the heat The Iron carburizing the ring gears are hardened this vertical semi-continuous furnace. ige, September 10, 1931—683 this oun - a axle ings net vel ter ing ne, m- ire ir- 1e- — 4 4 3 { j ‘ £ ad : a 3 4 j (Left).—There are more than gears this side this high-speed rotograv ure press. They are not usu ally visible HEAT TREATMENT ASSUR DEPENDABLE GEARS rplane pilot books, bills lading, sales books, trolley Gears and rapid transit tickets and transfers, baggag hecks, theater tickets, can wrappers and labels, and milk bottle caps and cellophane products, which lve operations such punching, perforating, dry aviation. past ing, demagnetizing, creasing, folding, numbering, have played prominent part. stacking, printing, slitting and rewinding. The Meisel air would also presses for high-speed ears vital parts had production color and rotogravure printing. ant completely equipped with the most printing presses gears are also modern facilities for machining operations and heat treating department omplexity and variety Which can meet the Boston institution, the roduction gears. lucing gears for over years. only carefully company for heat treated. but been aircraft cor ears, besides making them for there orporation its many kinds steels airplane engine. This type from which gears used Army, Navy, mail, altitude speed and transportation planes. The set includes the two gears top Gears are also used the com elght approximate these pages. are 684—The Age, September 1931 4 — major necessity, and U 4 4 4 the rotogravure press. Over gears here also EARS are vital the successful functioning aeroplane engines large and small printing presses and many other intricate machines that their composition and heat treatment must carefully stipulated. This article tells something the practice manufac turer large printing presses that produces such gears large scale for its own use, well for makers aeroplane engines and heavy machinery. The heat treatment and program control which the metallurgical and heat-treating history every piece can traced are 0.10 0.20 per cent carbon. Then there } an ] } n Nror chrome-Vanat I ( 1? fr\y | rl = \ / The Iron Age, September 10, 1931—685 outlined. tle nd the te? ra r pertection. 7 steel certain products were made that they can reliably traced. attain this aim, the heat number stamped the steel, and retained transferred this product even finally found the This also the practice the case symbol, with the heat num- usually bar form, all stages production. finished product. forgings. smaller practical number, also used, which tied manner. breaks while use during other bad can Therefore any part undue visible, the original heat and all other experimental tests, wear features are prematurely ecalled, steel tne steel can gears made from that batch necessary. Should research prove that the was the cause the trouble, this fact guide results the Should the steel mill exonerated, then possible refer the the steel maker obtaining better ture repla cing the mate record heat treatment through which the piece has passed and locate and correct the error. product upon which life 4 alrplane attention. the system used the Meisel plant, itself depends, such engine, must given the most careful reliable record available which leaves doubt what was done each piece steel and how was done. piece from product, representing its heat number, always available for each quantity that product test piece the heat treatment applied. Fifty pieces are often used quantity. such case, the from bar stock, test each bar are necessary. 150 from such bar, product made pieces are made three test pieces are 686—The Age, September 10, 1931 elected from that forging from lot 1000 from the one part for each pieces product. only 1000 pieces forgings are used, same heat test piece ings must used test pieces for product divided into lots pieces. important that test pieces shall like product represent the same results from hea treatment. used test pieces. Disks and simple plain objects are not frequently happens that cent completed that then cut test piece almost 100 per is, that stage, actually product. into many parts will make test pieces left whole test piece. partment used for normalizing, nealing, ing, hardening, tem pering, and carburizing simple, alloy and tool steels. The usually immediately after the step the that product becomes test piece the product whic! carries the load performs the most important rol the finished product ways and bearings are the which makes the portion Thus gear the teeth, key- important parts. Afte + the last these are made, the product can cut test pieces. & PECIAL heat treating furnace for gear stock with two units rear Furnaces this Two Basic Operations Involved Samples new materials, before being placed quantity machined and heat for all physical tests applied the finished This includes all chemical tests. There are two steps the production program. product ion, are The first basic operation rough-machine material somewhere near the finished size and shape, removing all scale from the forging bar = e ‘ . \ a t the gears made the Meisel company. The thin walls reveal some the treating The gears cut apart Suiza engines used the World War single seater fighting planes the French front. Whole gears are the same not cut apart. OMPLICATED na- ture some heat- problems. material and leaving ample stock for subsequent oper- ations. The second step has two objectives,—machine- ibility and uniform correct metallurgical structure, the latter being necessary finally harden with mini- distortion and dimensional change. ‘hese two basic operations are nearly always per- ormed alloy steels and nearly always simple steels, regardless the possibility that the material annealed before reaching the gear The second step may involve spheroidizing, rmalizing heat involving juenching and drawing. This experimentally done } may maker. refining treatment earn which will give the best metallurgical struc- How Judge Machineability ‘ a ypiovuldl that, gives the best machineability, must has been found transform directly during the final required physical properties, ardening into the inimum distortion and change dimensions and vithout the necessity going through phases tha ill endanger such results. the material after the second production ROW fired furnaces are also part the equipment + During hea I ed there i nun er id ‘ontrol Is no metallurgical Broaching file causes glaze, the nractical structure perat ions,” IS SaVvs produce machineability because a planing operations Mr. filed with good chips resulting hin the range accepta ness the glaze fine cut file, the mat fine cut and coarse cut file, either condition not satisfactory. too tenacious for good in prime lazed ight, how dependin fa glaze too hard hineability hardness tne nportance the ba Special Numbers Indicate Each Stage he firs + vhere ye The Iron ough September 10, 1931—687 machining it ifs bot machineability eat IS a gl nace It with the hard rule, ce results from erial diz and stringy em 2 tool hould ture. rather than turn poll introduced the first the series vhich show each stage the HEAT TREATMENT CHECKED MAGNETIC ANALYSIS 1.—Oscillograph quenched from different tempera tures LEWIS REID Chief Engineer, Magnetic Analysis Corpn., Long Island City, ANY finished and semi-finished steel parts small secondary coil which picks the induced are made specifications demanding magnetism the materials inserted the large heat treatment control. quick non- coils. These search coils are opposed and the bucked destructive test which can applied current carried oscillograph, which meas- finished part ascertain whether has ures, light wave, the differential rate change eived the correct heat treatment, has responded magnetism between the standard the one coil it, all instances desirable and and the specimen the other coil. inserting mal nstances necessity. the one coil standard known properties, the this connection magnetic analysis has been likeness differences the properties the sed some extent, and being tried out and used rial inserted the other coil will show varia greater degree more knowledge tion the shape amplitude the light wave pro duced the oscillograph screen. ing acquired. The apparatus employed consists two mag- Strip Steel for Razor Blades netizing coils constructed that magnetizing fields equal intensity are produced. Suitable instru- specific instance, showing what may accom ments are inserted the circuit control and vary plished analysis, brought out Figs. the magnetizing force. Inside each these coils 1,2 and The material was strip steel used steel quenched and drawn Vraws? difference obtained strip steels 1450 Deg. different drawing temperatures Drawn 688—The Iron Age. September 10, 1931 7 = - | | i | awe” . . | ‘ | | | EON ve IPOUVS | ALCAN (“POU (FOULED ’ ~ . — PECIFICATIONS for made steel demand extremely close control the heat treatment. Magnetic analysis now affords quick, non-destruc- tive test ascertain whether such products have been correctly heat treated. This article reveals some applications this test checking the heat treatment razor blade steel and the patenting wire. ced manufacture razor blades. Fig. the ference 100 deg. the quenching solid line the one obtained when ienched from 1450 deg. compared trip quenched from the same temperature. The tted line shows the difference when the enched from 1450 deg. ite Fig. shows the effect the curve strip ria vhich has been drawn. The solid line that tained when strip quenched from 1550 deg. mpared with another strip quenched from the temperature. The dotted line shows the curve tained when strip quenched from 1550 deg. and then drawn 470 deg. compared with strip igs. quenched from deg. Fig. shows the difference obtained different patenting o structure left) steel wire before the peration IG. Sorbitic right) steel wire after the patenting structure ration structure Fig. compared with ther piece wire having the same struc ture ter erature trip deg. and drawn 460 dey. quenched from 1450 Patenting Wire and Magnetic Analysis connectior vith heat treatment itentl! ot Vire Be ore tne patent oO} pearlitic structure how tructure compared with having ime structure the curve VA obta ned (¢ The September 10, 1931 689 } Pear! tev Pear/ te j L450 ty +} ar: a 17 n 1] ry} ru t} OT oe. CONTROLLING THE ATMOSPHERE ROBERT KEENEY Connecticut Light Power Hartford, Conn. LTIMATE solution the atmosphere prob- lem some heat-treating processes has become probability during the past Furnaces heated with fuel electricity have been placed plant operation through control the atmosphere, scaling and oxi- entirely, almost entirely, elimi- during the heating number metals and Within the past decade, considerable progress was made control furnace atmosphere, but the major development heat-treating furnaces was their conversion from simple furnaces reliable production machines. Intensive research fundamental principles involved the 690—The September 10, 1931 best furnace atmosphere for heat treating iron, and non-ferrous metals has aroused the interest the metallurgist, furnace engineer and heating engi neer the point where the optimist tends con- sider the conditioning furnace atmosphere too simple—as simple air-conditioning the Although the practical application control fur- nace atmosphere doubtless will proceed slowly and with grief, well with the expenditure much time and money, its present trend indicates ultimate- major development heat treating with the production product improved quality, requir- ing little cleaning. course, the problem controlling furnace at- mosphere has been realized for long time, but its IL-FIRED car fur- nace, developed Ryan Scully Co., bright anneals cold- rolled strip steel un- der rustless hoods with producer gas atmosphere Wallingford Steel Co., Wallingford, Conn. lly — this field. ste con 0 be ome fur- and nuch production. at- its lution seems have been delayed tendency search for the answer through the source heat, ither than through consideration artificial at- spheres. Although automatic temperature con- rol and combustion control have resulted im- proved conditions atmosphere combustion fur- ces, now recognized that for many heat-treat- operations this method has limitations. some furnaces, conditions have been improved furnace pressure control well temperature and com- control, with automatic control all vents with combustion control. For many heat-treating operations, the atmosphere produced ped ontrol temperature, combustion and pressure satisfactory, viewed from present standards, but even combustion furnaces there exists trend toward the use artificial atmospheres for num- ber heat-treating processes. atmos- phere its combination with the combustion atmos- phere may prove the solution some opera- the electric furnace conditions are different. Except its atmosphere may changed oil the work emission gases from the work high temperatures, the electric furnace heats the single fixed atmosphere unless artificial itmosphere introduced. the electric furnace the metallic resistor type, the furnace chamber normally contains comparatively inactive air and will oxidizing until the per cent oxygen the air has been consumed burning oil the work any other combustible matter present or, the HEAT-TREATING FURNACES LTIMATE solution the problem atmospheric control heat- treating furnaces now seems certain, says Mr. Keeney, authority Practical application such control will doubtless proceed slowly, states, but promises become major development heat treat- ing, resulting improved products, requiring little cleaning. Some installations have been made which scaling and oxidation have been largely eliminated. The trend toward the use artificial atmos- pheres, which are now finding increasing application for bright annealing. Economies arising from atmospheric control include elimination metal loss, avoidance pitting resulting from pickling and higher rate bsence either, combination with the surface work form oxide. the furnace air tight has great infil tration air, oxidation stops and heating proceed ducing there was oil the work when loaded situation and the lack the constant move ment atmosphere which exists the combustion furnace account for its ability produce product with surface, satisfactory under present stand ards, what apparently oxidizing atmosphere Although control atmosphere the electri furnace, beyond the equilibrium normally set its operation, must secured through arti ficial atmosphere, the electric furnace not mate rially handicapped. Although some application the desired results may secured the combus tion furnace without use artificial atmosphere, its results probably cannot made positive would the case with artificial atmosphere, due the numerous variables involved control mosphere through combustion and pressure control The electric furnace operated with artificial mosphere seems have advantage over the com bustion furnace operated with artificial atmo phere the probability easier application de- sign and lower maintenance cost Metallurgy Complicates Control Atmosphere The problem contro] atmosphere become complicated with the recollection that, the case steel, not simply necessary avoid oxidation The Iron Age, September 10, 1931—691 | | CONTROLLING THE ATMOSPHERE ROBERT KEENEY Connecticut Light Power Co., Hartford, Conn. LTIMATE solution the atmosphere prob- lem some heat-treating processes has become probability during the past year. Furnaces heated with fuel electricity have been placed plant operation through control the atmosphere, scaling and oxi- dation have been entirely, almost entirely, elimi- nated during the heating number metals and alloys. Within the past decade, considerable progress was made control furnace atmosphere, but the major development heat-treating furnaces was their conversion from simple furnaces reliable production machines. Intensive research fundamental principles involved securing the 690—The Iron Age, September 10, 1931 best furnace atmosphere for heat treating iron, steel and non-ferrous metals has aroused the interest the metallurgist, furnace engineer and heating engi- neer the point where the optimist tends con- sider the conditioning furnace atmosphere too simple—as simple air-conditioning the home. Although the practical application control fur- nace atmosphere doubtless will proceed slowly and with grief, well with the expenditure much time and money, its present trend indicates ultimate- major development heat treating with the production product improved quality, requir- ing little cleaning. course, the problem controlling furnace at- mosphere has been realized for long time, but its IL-FIRED car fur- nace, developed Ryan Scully Co., bright anneals cold- rolled strip steel un- der rustless steel hoods with producer gas atmosphere Wallingford Steel Co., Wallingford, Conn. 7 Da. 4 HEAT-TREATING FURNACES LTIMATE solution the problem atmospheric control heat- treating furnaces now seems certain, says Mr. Keeney, authority this field. Practical application such control will doubtless proceed slowly, states, but promises become major development heat treat- ing, resulting improved products, requiring little cleaning. Some installations have been made which scaling and oxidation have been largely eliminated. The trend toward the use artificial atmos- pheres, which are now finding increasing application for bright annealing. Economies arising from atmospheric control include elimination metal loss, avoidance pitting resulting from pickling and higher rate production. solution seems have been delayed tendency search for the answer through the source heat, rather than through consideration artificial at- mospheres. Although automatic temperature con- trol and combustion control have resulted im- proved conditions atmosphere combustion fur- naces, now recognized that for many heat-treat- ing operations this method has limitations. some furnaces, conditions have been improved furnace pressure control well temperature and com- bustion control, with automatic control all vents synchronism with combustion control. For many heat-treating operations, the atmosphere produced control temperature, combustion and pressure satisfactory, viewed from present standards, but even combustion furnaces there exists trend toward the use artificial atmospheres for num- ber heat-treating processes. artificial atmos- phere its combination with the combustion atmos- phere may prove the solution some opera- tions. the electric furnace conditions are different. Except its atmosphere may changed oil the work emission gases from the work high temperatures, the electric furnace heats the work single fixed atmosphere unless artificial atmosphere introduced. the electric furnace the metallic resistor type, the furnace chamber normally contains comparatively inactive air and will oxidizing until the per cent oxygen the air has been consumed burning oil the work any other combustible matter present or, the absence either, combination with the surface the work form oxide. the furnace air tight has great infil tration air, oxidation stops and heating proceeds ducing there was oil the work when loaded. This situation and the lack the constant move- ment atmosphere which exists the combustion furnace account for its ability produce product with surface, satisfactory under present stand- ards, what apparently oxidizing atmosphere. Although control atmosphere the electric furnace, beyond the equilibrium normally set its operation, must secured through arti- ficial atmosphere, the electric furnace not mate rially handicapped. Although some applications the desired results may secured the combus- tion furnace without use artificial atmosphere, its results probably cannot made positive would the case with artificial atmosphere, due the numerous variables involved control at- mosphere through combustion and pressure control The electric furnace operated with artificial mosphere seems have advantage over the com- bustion furnace operated with artificial atmos- phere the probability easier application sign and lower maintenance cost. Metallurgy Complicates Control Atmosphere The problem control atmosphere become complicated with the recollection that, the case steel, not simply necessary avoid oxidation The Iron Age, September 10, 1931—691 | | flame gas- fired forging furnace the Surface Combus- tion Co. HIS 54-kw. continu- ous-belt nace, (below) designed j a but decarburization and carburization must also prevented. Scaling takes place the presence } carbon dioxide and water ‘ization without scaling may result atmos phere dry hydrogen and dry hydrocarbons and, with sealing, from carbon dioxide and wet hydrocar- bons. Carburization without scaling may duced dry carbon monoxide and dry hydrocarbons ind, with scaling, wet carbon monoxide and wet 1\ drocarbons. With theoretical combustion gas, the furnace atmosphere contains carbon dioxide, water vapor and nitrogen that both ing and decarburization may result. With excess air combustion, in- and decarburization reduced. With excess gas, scaling reduced and arburization increased. has been found possible keep scaling and decarburization minimum partial combustion, using large ex- cess gas with dehydration both gas and air before they enter the furnace. thus apparent that control furnace atmosphere somewhat complicated problem, especially when attempted combustion control, and that involves considerable fundamental metal- through careful furnace design and skillful operation. Gas Blanket Eliminates Scale Forging Recent extensive research the fun- damentals heating stee! forging has been applied number large experi- mental gas-fired forges which the stock, protected layer raw gas. heated intensely luminous flame resulting 692—The Iron Age, September 1931 from diffusion flame combustion. Oil has always been favored fuel for forging because the intense luminosity its flame, caused incandescent car- bon, results rapid transfer heat the stock radiation. the usual method combustion gas, the fuel and air are premixed and burn with almost total absence flame, that heat trans- ferred mostly the slower process diffusion flame combustion, air and gas are not premixed but issue from the burner separate lay- ers with combustion taking place progressively q q | | | SCal q — : 4 a 4 air meets unburned gas. oxygen not present which the moisture has been removed. With brass initially sufficient quantity, the hydrocarbons acting catalytic agent, the methanol breaks down the gas are re-formed into hydrogen and free carbon. into carbon monoxide and hydrogen. the presence The carbon heated incandescence combus- methanol, the tarnishing which might expected tion the surrounding gases and becomes the from the carbon dioxide the flue gas does not take source luminosity the flame. The intensity place. use methanol has been possible luminosity produced this manner the gas flame bright anneal clean brass even some the lowest equal that the oil flame. temperatures specified, low 1000 deg. The fact that, diffusion flame combustion, air ever, the economic development the process and gas leave the burner separate layers permits concerned not only with the cost methanol but the ready segregation part the raw blanket which protects the stock from the products combustion. The large experimental forges installed plant operation are said heat the stock the speed oil forges, and with total absence scale. The diffusion flame combustion forge with its highly lumi- nous flame, rapid rate heating and al- most complete control atmosphere seems have wide field application the forge shop the completion its development. Artificial Atmospheres for Bright Annealing Intensive application artificial at- mospheres, combination artificial atmosphere and the products combus- tion, proceeding rapidly the anneal- ing ferrous and non-ferrous metals and alloys. Furnaces the batch, pusher and continuous types have been built for these bright annealing operations during the past year. One cold-rolled steel plant has electric furnaces the bell type annealing batches coiled Electric furnaces the bell type have been built capacities tons per charge. Other types batch and continuous furnaces have been designed for the use electricity, gas oil. With the ex- development but with every promise solution the problems atmosphere and construction which may arise HIS 125-kw. vertical electric furnace the Gas Equipment Engineering Corpn bright-anneals cold-rolled carbon steel and rustless steel strip continuously with plications processes extend. hydrogen producer gas atmospheres Wallingford Steel Co., Wallingford, Conn Gases used atmospheres connec- tion with bright annealing, either during heating cooling, include hydrogen, nitrogen, hydro- also with the cost removal heavy lubricants gen-nitrogen mixtures, city gas, natural gas, producer used rolling, before annealing, bright anneal gas, carbon monoxide, carbon dioxide, mixed gas from result, and both these must balanced re-forming butane, city gas natural gas from against the saving the elimination pickling. the dissociation anhydrous ammonia, and methanol. Electric bright annealing furnaces the pusher and conveyor types, present developed, include Methanol Furnace Atmosphere heating chamber which the work heated interesting recent development has been the nealing temperature suitable artificial atmo experimental application methanol, the phere and cooling chamber where cooled bright annealing clean brass gas-fired fur- suitable atmosphere down temperature below nace. Vapors methanol are added flue gas from that which would oxidize air. Where The Iron September 10, 1931—693 q > — 7 t L { . j pe : hydrogen used the atmosphere, correct furnace design great importance securing economical bright annealing with safety. The design should such that waste hydrogen kept low practi- cal. Where air and hydrogen come contact, they must ignited before explosive mixture forms use pilots other means. hydrogen burns inside the furnace, provision must made for removal moisture. Doors may used pusher furnaces not only the ends but between the heating and cooling with the hydrogen the heating cham- ber supplying the non-oxidizing atmosphere the ooling chamber when work moved from the heat- cnamobers, $ q ing chamber the cooling chamber. conveyor belt furnace one type, having doors, hydrogen forms the atmosphere the heating chamber but nitrogen used the cooling chamber. Hydrogen burns the entrance the heating chamber, but has been found advisable use inert, non-ex- plosive gas such nitrogen the cooling chamber with the outlet open and low temperature existing. The use hydrogen atmosphere bright anneal- ing with correct furnace design and common sense operation has apparently resulted great ex- plosion hazard. Control Atmosphere Economical? The extent which control atmosphere should applied the annealing processes indus- trial plant largely consideration the cost the annealing and the subsequent pickling. With the exception rolling mill brass, most metal and alloy products the mill will not require wash- ing before bright annealing. bright annealing eliminates pickling, the cost pickling must this basis bright annealing has cost equal the credited against the cost bright annealing. Iron Age, September 10, 1931 cost oxidizing annealing followed pickling, serious consideration must given its use be- cause other economies which are: Elimination metal loss oxidation, which may many cases higher grade product made because, with pickling, there can pitting the surface. Higher rate production and the ability fill rush orders more quickly. For some alloys, consideration must given the use non-oxidizing annealing annealing with- out scale but without securing bright surface the products, that weak pickle required after tn tr electric furnace, made the Process En- gineering Equipment anneals gold, silver stampings hydrogen Balfour Co., Attleboro, Mass. annealing, because its overall cost might prove less than that bright annealing. Some Relative Cost Data The relative costs oxidizing, non-oxidizing and bright annealing nickel-silver stampings push- er-type furnaces approximately the same size, one case were follows: Oxidizing, Non-Oxidizing, Bright, Per T Per Ton Per Ton Labor $2.25 $5.00 $2.00 Powet 2.90 Acid 2.25 Fuel oil and acid... 7.26 Hydrogen (pressure tank) 1.6 $7.40 $12.26 36.40 The cost hydrogen when used the form dissociated ammonia the form re-formed hydrocarbon gases materially lower than the cost pressure tank hydrogen. Dissociated ammonia hydrogen can produced the industrial plant about one-half the cost purchased pressure tank hydrogen, hydrogen, re-form