The Iron Age 1928-06-21: Vol 121 Iss 25

THE IRON ESTABLISHED 1855 New York, June 21, 1928 Welding Ford Rear Axles Electrical Resistance Flash Welding Utilized Make Light, Strong Axle Housing Steel Sheet, Structural Channel and Forging FAY LEONE FAUROTE* NEW method assembly has been introduced the Ford Motor Co. the manufacture the Model A—a process mechanical integration which will far soon its value recognized other automobile manufacturers. This electric weld- ing, not for minor jobs and for petty parts, but for major operations the motor car. Welding has, in- deed, caused the advent new day motor fabrica- tion, new and surer way assembly, method building several parts into unified whole; later loosening can possibly occur—the assembly all one piece. press produces perfect stamping, the drop forge perfect forging. There initial adjustment two welding machine, pressure, throw the switch, flash, upset and weld and lo! the job done—a permanent combination metal finer form and greater strength and greater rate produc- tion. There are 1339 welding operations the new 845 them are spot welding, the rest are electrical resistance flash welds, arc welds and seam welds, with electric resistance flash welding leading importance and speed. There are the wheels welds each, brakes welds each, tire carrier two welds, bumper *Mechanical engineer, New York. two welds, rear axle housing eight welds, differential housing two welds, radius rod four welds, torque tube two welds, muffler welds, steering wheel four welds, battery support eight welds, equalizer rod one weld, foot pedals two welds, accelerator one weld, starter shaft one weld, breather pipe four welds, fan pulley welds, radiator rod four welds, tie rod two welds, oil pan welds, oil pump one weld, gas tank welds, equalizer shaft four welds, body welds. The several examples just given show the wide distribution the process throughout the chassis, body and acces- sories. Electric welding has been adopted only after much experimentation. Welding the cheapest method assembly known when using current any reasonable cost. There half million horsepower available Fordson. This power being produced under ideal conditions and low price. The wide uses elec- tric welding and electric furnaces, therefore, are nat- ural concomitants this condition. Electric resistance flash welding, used quite wide- the Ford Motor Co., gives joint which clean, strong and mechanically well suited for the assem- bling those parts which, under use, must maintain their physical integrity. This merely special type Fig. 1—Various Steps Manu- facture Two Sheets and One Forging into Rear Axle Hous- ing 1739 | | i VOL. 121, No. : q resistance butt welding, wherein the parts welded are gripped vises fixtures and complete the secondary coil electric transformer. current low voltage but high amperage flows across the joint, heating rapidly the plastic condition. this in- stant, suitably applied pressure forces the two parts to- gether, the burned metal pushed aside fin flash and true weld, comparable with that obtained from forge welding, results. The correct welding heat for flash weld from 100 200 deg. Fahr. less than the melting point the steel. Under test the frac- ture occurs not the weld but somewhere else the metal which the part composed. Radical changes have been made many the Ford welding machines make the process successful. Speaking generally, the resistance welders take their power from 440-volt line. comparatively high sec- ondary voltage used, the electrodes are unusually husky, the pressure applied more quickly and many times automatically, there provision for upsetting sufficient squeeze out impure oxidized metal and the same time prevent further deep-seated oxidation. upsetting pressure tons per square inch used. many jobs self-indexing fixture added. some machines two welds are made one time. Welded Rear Axle Unique Perhaps the rear axle housing one the most interesting and outstanding jobs assembled welding. made three main parts: (a) the bell, spun forging, (b) sheet metal tube, rolled and seam welded, and (c) combination brake and axle support, welded forging. These three main units are combined physical characteristics suited their needs, but nev- ertheless one piece. Then two these axle housings are attached the differential itself welded part consisting bent channel and forging. Fig. shows the various steps the manufacture 1740—June 21, 1928, The Iron Age 2—Battery Butt Welders for Joining Tapered Tube Bell Flange and Hub Forging. Note guards machines rear protect operators from flying sparks the axle housing. piece sheet cut the right shape, the edges are curled, then bent shape, and next the closed into tube. All these are press operations. Next the longitudinal joint welded, then the wheel hub butt-welded the small end the tube, and the bell butt-welded the larger end. The latter two operations are done battery flash welding machines, illustrated Fig. which utilize the electric resistance principle already de- scribed. (The bell end interesting piece, being spun from hot disk metal the machine shown Fig. 3.) The differential housing bell weighs the tube weighs lb.; and the wheel hub weighs lb. The fin- ished job, completely welded with flash ground off, weighs Differential Housing Also Fabricated Piece stated above, the car assembly the differ- ential housing bolted between right and left hand axle housing. shown Fig. this made bent structural shape and forging. The small chan- nel section rolled the Ford 14-in. merchant mill. Fig. shows stock the left. passes first through electrically driven shear and punch (not clearly shown, the rear center) which blanks size and pierces two holes the web. The first die operation (shown the left Fig. gives wave-like shape; the next machine, with die shown detail Fig. curls into circle. Next, the holes previcusly punched the web are heated placing them upon horizontal pipe and pushing them past series burners which heat seven rings time. This anneals the metal those spots the holes may flanged inward the press, shown the center Fig. fitted with punch and die. shown the illustration, the completed parts are car- ried forward the next operation hooking overhead endless chain conveyor. | Fig. 5—Fabrication Channel punch and cut off rear center (not shown), wavy form pressed left, curled ring press left center, holes web an- nealed group gas flames foreground, flanged inward punch center, and completed rings transported overhead conveyor (Above) Fig. 6—Press for Curling Chan- nel into Open Ring (at Right) Fig. 3—Hot Spinning Machine for Mak- ing Bell End from Flat Disk (at Left) Assembled Butt Welding Fig. 4—Bent Channel and Drilled Forg- Differential Housing (Below) The Iron Age, June 21, into | | q Differential neck and ring are assembled welder (Fig. Ford design and construction, built the main tool room Fordson. The view shows the guard open, ready for loading. The three-quarter circle channel placed between the jaws the welding machine, and the forging placed above them (just opposite the position Fig. 4). Turning air valve clamps the two rigidly correct position. The door Fig. Resist- Welder for Making Two Welds Simultaneous- Differential Housing ance Less floor space per unit—75 per cent the original machine. Welding more uniform—the human element has been removed from the actual welding cycle. This housing weighs the area weld 1/16 sq. in., which the largest weld production Model this time. Muffler Made Composite Method interesting example composite construction found the muffler. production the outer shell, made 0.037-in. sheet, blanked, formed into tapered tube in. long with crimped flat side seam. baffle plate mid length held with three rivets. the large end bell, which has meanwhile been formed punch press, flash welded the outer shell, and small bell end made and fixed the other end similar manner. inner perforated tube, 34% in. long and in. diameter, then inserted close sliding fit through the central hole the small bell, central baffle and large end, and spot welded the small end the big bell, the other end the inner shell being left free expand temperature rises with the exhaust gases. This inner tube has two interior baffles, properly placed and held crimping the tube and spot welding four places. The inlet and outlet pipes are then flash welded the bell ends and the muffler complete. The total weight lb. oz., and the entire job done remarkably short time. Incidentally, because the muffler welded into one piece, there complete absence sympathetic vibration ringing. Precision Work Fan fine piece engineering, welded also, the fan, designed the principle aeroplane propeller, whose pitch, lead, balance and weight are accurately figured that precision job unusual character for such large production the result. The run-out allowed only 0.005 in. The hub flange, the pulley body and (above Fig. gram Fan. One forg- Weld ing and four sheet metal Blades pieces (at Right) Spots roove — Section A-A closed and the handle the side the guard thrown down. This closes the transformer circuit; sec. the current has brought the pieces welding temperature, the automatically throws the correct pressure the top piston, and the upset takes place, forcing out the impure metal and causing the two sections joined the form and manner de- sired. During the first quarter the upset the current cut off. The welding cycle goes automatically completion, opening the air valve the end and re- leasing the clamps. The workman then opens the door, removes the completed part, and reloads the machine. Improvements this machine automatic machine over a former type are: 1. Two men are eliminated—one operator runs the ma- chine. One hundred per cent increase production—two welds made simultaneously pieces per 1742—June 21, 1928, The Iron Age the belt groove, well the two parts the fan itself, are assembled spot seam welding. The fan blade made double layer 3%-in. cold-rolled strip, 16% in. long and 0.0375 in. thick, with minimum elastic limit 45,000 lb. per sq. in. Each strip twisted over its center; one end formed with the correct curve for the face one blade, and the other end into the back the opposite blade. Two these, assembled and seam welded along the edges, give blades aerofoil section, with angles incidence properly modified the tip approached. Assembly shown Fig. Seam welding the ends the blades was illustrated THE April 19, page 1082. Experience with resistance welding would seem indicate that many the old forms assembly will soon abandoned, and, instead building units and bolting them together, they will designed for 7 = | on union flash welding. Instead starting with large block metal and cutting off the excess, the reverse likely occur. Lighter parts will made possible, yet having greater strength. course, there much room for further progress. Special welders will constantly undergoing reconstruction the development work progresses. But, with the coming self-indexing automatic welders, the production welder takes important place among the automatic machine tools the modern factory. Fatigue Resistance Rail Steel Endurance Ranges from 46,000 59,000 Lb. per Square Inch— Rail Steel Responds Understressing and Like Mild Steel Overstressing JOHN RRANGEMENTS were made May, 1926, the Gathmann Engineering Co., Baltimore, for the appointment research associate the United States Bureau Standards study the com- parative properties rails made from rising steel the standard big-end-down ingot molds and rails from fully piping (killed) steel made the big-end-up sink- head ingot molds. total heats made the Carnegie and Algoma steel companies were studied. They were made meet the specification requirements the Baltimore Ohio Railroad and the Canadian Pacific Railway respectively, which are substantially the same the 1925 A.R.E.A. specification. Nine the heats were standard; the other were killed with aluminum and cast Gathmann molds. addition the usual tests, which included drop *Metallurgist Bureau Standards, Washington Pub- lication approved director. FREEMAN, tests, nick and break tests, tensile properties, hardness, impact, and analyses, macro- and microscopic studies, extensive series endurance fatigue tests was made. All test sections were taken the hot saw. The comparative test data from the more usual tests confirmed previous investigations, and indicated that rail steel killed with aluminum can poured free from pipe and excessive segregation sink-head molds the Gathmann type and that the distribution carbon, phosphorus, sulphur and silicon occurs the same man ner such ingots sink-head ingots other types. The tensile properties rails rolled from both types ingots were found essentially the but were appreciably more uniform rails rolled from Gath- mann ingots, especially the rails. Details these findings are given Technologic Paper No. 363 the Bureau Standards, entitled “Endurance and Other Fig. Below.—Endurance Rail from Rising Steel Full line for steel original condition. Dotted line for steel after understressing oe Fig. Rail. Two contigu- ous specimens taken all positions, ex- cept served es- tablish fatigue limits 105 Cucles for Failure Fig Left. of BC Rail from Reje ected Phosphorous (Killed Steel). Full line for steel condi- tion. Dotted lines for steel after overstressing The Iron Age, June 21, 1928—1743 ALS 5 “wan | | N — + * >: i Cycles for Failure y 10 19 Properties Rail Steel,” Dowdell, William Berry and the present author. Nature Transverse Fissures All students transverse fissure failure agree that special case fatigue failure which the crack starts from nucleus inside the head the rail and progresses from the inside the outside, instead from the outside the inside, typical most fatigue failures. Controvery centers about the exist- ence of, nature of; and the causes for the nucleus the fissure and not about the method propagation the failure. was felt that some light would thrown this perplexing problem the endurance properties which has not yet been done, far the writer aware. Endurance tests were therefore made specimens fable I—I ] t of Steel from B Rails Tensile Strenegtl Lit I well AN i B Rail Hard AandCR 20 4 113.5 46 iS 47.800 17.9 125,¢ 1.38 G ) 119,900 0.42 G 7.60 133,200 0.43 4,2 7 880 0.41 19 ) 120 Ce) 0.40 from and rails representing the compara- tive heats. Four the heats were poured according standard practice; the other seven were killed with aluminum and poured the sink-head molds the Gathmann type. The rotating beam type endurance test was used, and all tests were made 25,000,000- basis. The nature endurance testing requires several in- dependent specimens determine the endurance curve. Since there was not sufficient material take them con tiguously along the length the rail, two contiguous specimens were taken from each position indicated Fig. giving specimens from each rail. The specimen marked nearly corresponds the “M” position, where drillings for analysis are taken. might expected contain greater concentration and consequently have inferior fatigue-re- sistant properties, well known fact that in- lusions may exert profound influence the behavior metals when subjected reversed cycles stress. determine the validity this hypothesis the en- durance curves were determined from the specimens her than the specimens. The latter were then run stresses very near the endurance limit. Failure relatively low number cycles indicated rela- tively low fatigue resistance. This was more particu- larly true specimens from sink-head ingots. Figs. and are typical results. The maximum fiber stress plotted ordinate and the number for failure abscissa, the latter logarith- metic scale for convenience. The original endurance urve that designated the figure the open cir- cles and full lines. Endurance limits the rail steel tudied, determined from similar curves, are given Table and II. has been established many investigators that the endurance limit steel more closely correlated with the tensile strength than with any other physical property ordinarily determined. The ratio the en- durance limit the tensile strength commonly called the “endurance ratio.” These values together with the values for tensile strength and Rockwell-B hardness are also given Tables and for the and rails. respectively. When all tests from both and rails rolled from standard ingots are plotted one sheet, the relatively wide “scatter” the individual test results indicates apparently wide variation endurance properties rail steels made meet the same specifi- cation requirements. both standard and Gathmann 21, 1928, The Iron Age ingots the minimum endurance values were found rails. The minimum value obtained rails rolled from standard ingots slightly less than for rails rolled from sink-head ingots. This minimum value ap- proximately 46,000 per sq. in. represents the endur- ance limit steel from 100-lb. section rail rolled from standard ingots. the maximum value repeated stress which the steel the head any rail the section and composition tested this in- vestigation may subjected without danger failure fatigue. The maximum value approximately 53,800 lb. per sq. in. shown similar rail steel indi- cates what might obtained under optimum conditions. The rail steels tested that were rolled from sink- head ingots could not with safety subjected higher repeated stresses service than the rail steels from standard ingots, because low endurance limit shown one the rails. evident, however, that the maximum value approximately 59,000 per sq. in. shown these rail steels considerably higher than was obtained the steels from the standard ingot rails. This indicates that under optimum conditions manufacture killed rail steel cast sink-head ingots might have higher endurance properties than present- day standard rails made the same specification re- quirements. Effect “Overstress” has been shown several investigators that steel specimen subjected number reversals stress above its endurance limit, but not sufficient cause failure, the specimen will then fail fatigue stress considerably below its true endurance limit. The ability the material withstand repeated stress has been decreased; its endurance limit has been low- ered. test was made determine this were true for rail steel and the result given Fig. Two speci- mens were first subjected 25,000 cycles stress stress value approximately 62,000 per sq. in.— Rails (a) Endurance Rockwell Tensile Endur- Heat Limit, Hardness Strength, ance SS (a) (c) 101.4 . 46.200 G86 132,400 0.35 1G (b) 17,800 99.2 120,400 0.40 G 55 000 101.1 129,750 0.42 Ik G 57.400 98.9 19 G 9,200 134,750 0.44 20 G 52.600 100.3 115.750 0.46 ) In view of the relatively large crop from sink-head gots, one of the manufacturers designated the first rail the rail instead rail These rails have been called ls and classed as A rails heat poured standard ingots »)—G signifies heat poured in sink-head ingots than 50,000 per sq. in. Insufficient material complete the test which was known would eventually cause failure about 60,000 cycles. The specimens were then sub- iected cycles stress stresses below the endur- ance limit, which stress, was known, would never cause failure were the material its original condi- tion. But both specimens failed, proving that the re- peated overstress had caused incipient damage sufficient cause distinct lowering the fatigue resistance. Effect Understress also well known that, specimen sub- jected relatively large number reversals stress value below its endurance limit, the ability that material resist fatigue stresses has been in- creased—its endurance limit raised. This effect also holds for rail steels, illustrated the dotted curve Fig. determining the original endurance limit five the test specimens did not fail 25,000,000 cycles. These five specimens were then considered “new” material, and the endurance limit was redetermined. was found approximately 4300 Ib. per sq. in. greater than before. The creased the fatigue resistance about per cent. Relation Service Stresses These effects overstressing and understressing may offer possible method determining whether (a)—S signifies standard ingot (b) G signifies sink-head ingot c)—Test on B rail rails service are being subjected stresses greater less than their endurance limit, determining their endurance limits before and after service. the en- durance limit has decreased, would indicate that the material has been “overstressed” and, conversely, has increased, would indicate that the material has been “understressed.” There are, course, certain limitations this the- ory, such the effect the total number repeti- tions stress service, the magnitude the and their direction, whether tension compression. with the Baltimore Ohio Railroad and the Canadian Pacific Railway endurance tests are now running specimens from rails that have been service, made from heats whose edurance properties have been previously determined. should remembered that these endurance limits are based tests practically random specimens steel from certain rails and are not necessarily rep- resentation the endurance the rail whole. endurance specimen the rotating-beam type, the volume material that subjected the maximum stress extremely small; rail track, compara- tively large. The neutral axis the test specimen might contain serious flaw which weuld not affect the endurance the small specimen (which fails from stresses the surface), but, existing the rail track, might seriously reduce its life. Internal stresses rail will affect, also, its en- durance properties. When small specimens are cut from rail and machined, internal stresses present may relieved redistributed that the endurance range the steel the specimen may not the same would have been the rail. Nevertheless, reason- able begin the study the endurance properties rails first determining the endurance properties the steel the rails, using the most common type endurance test that comparison may made with available data other types steels. may de- sirable eventually determine the endurance proper- ties rails, making the tests the full section the rail. Before such tests are made, more complete knowledge should had the magnitude and dis- tribution stresses rails under all conditions. Economic Value Safety Work How Pays Direct Savings and Indirect Advantages— Morale Important Factor WENTY years ago Judge Gary, chairman the United States Steel Corporation, called together the casualty managers the larger subsidiary companies that organization. These casualty man- agers were daily contact with all the loss, suffering and sorrow caused industrial accidents. They were thoroughly familiar not only with the direct results industrial accidents but also the indirect results— loss life and limb, loss earning power the bread winner, widows and children left without adequate sup- port. The only thought that meeting was that too many men were being hurt and killed industry and that means must found for preventing, least decreasing, the number accidents. was well understood that such campaign would costly and expensive. But, whatever the cost, was determined that such accidents should prevented far possible. And this has been the spirit the safety campaign from its inception. has been firmly based upon the humanitarian motive. There was thought economic gain advantage until long after safety had been sold thoughtful employers and em- ployees. our plea for safety had been based upon economic grounds might have fallen upon deaf ears might not have received the hearty support the press. But, based upon humanitarian and sentimental reasons, naturally attracted the attention and sup- port the public. difficult, not impossible, completely sepa- rate the humanitarian from the economic side safety work. The two hand hand. The underlying mo- tive has been and always will the humanitarian side. But experience has taught that many economic ad- vantages inevitably flow from intensive safety work. Considered solely from economic standpoint, the advantages safety work accident prevention industry are both direct and indirect. The direct ad- vantages are obvious and the savings can measured dollars and cents. Every accident prevented means saving just much compensation and necessary medical care and attention. Whether employer carries compen- *Vice-President, Carnegie Steel Co., Pittsburgh This is abstract address before the Pennsylvania Safety Con- gress, Philadelphia, March 21. sation insurance, State insurance, assumes his own risk, the benefits derived from prevention accidents are substantial and immediate. The experience large foundry company with average working force 500 men affords excellent example money sav- ings due entirely intensive safety work. Time lost due accidents 1925 was 62% days for each 100 tons castings shipped. accidents was 66c. out every $100 payroll. 1926 the lost time was days per 100 tons castings shipped; the accident cost being per $100 payroll. 1927 intensive safety campaign was result the time lost was day per 100 tons castings shipped; costing per $100 payroll. Actual reduction total costs, due accident prevention, indicated the following figures: 1925 cost of accidents wa $7,033.03 1926—cost of accidents wa 3,132.88 1927—cost accident 121.50 utility employing average force 1500 men, reducing accidents, cut its compensation costs from 30c. per $100 payroll 1926 1927. large steel works employing 5000 men cut compen- sation costs from $24,378.89 1926 $10,407.45 1927, showing saving $13,971.44. These figures not include savings due decrease medical and hos- pital service. One our largest car and foundry companies spent $1,000,000 for accident prevention years and saved $2,700,000 losses and other costs. said that the United States Steel Corporation spent safety work years and showed actual saving $14,609,920. view these records there can doubt that accident prevention work does pay from purely eco- nomic standpoint. And let not forget that these figures show only the direct savings compensation. They not reflect the many indirect benefits, not only the employees but the large. Safety Work Aid Production When intensive safety work was first begun there was general feeling among industrial leaders that would seriously interfere with and hamper production. Only after many years were safety engineers able The Iron Age, June 21, ’ demonstrate that accident prevention work, far from being hindrance full production, was and aid. For the safety campaign has long since graduated from mere safeguarding dangerous machinery the posi- tion ever increasing and active educational force industry. demands the thought and attention every man the organization. safe plant must clean and orderly plant, and cleanliness and orderliness have been found necessary good production. safe plant must well lighted has been demonstrated time after time that good lighting and have dark and dangerous places eliminated. actual aid—in fact, absolutely essential—to good Absence workers due injuries causes changes personnel requiring the hiring and training new men. The bare cost hiring new man will run from $30 $80. Such accidents disrupt the morale organization. Accident prevention conserves the time, energy and physical fitness employees. produces more stable and contented working force, and a } + ble, contented and highly efficient working force sta WEIGHING MOLTEN IRON Heavy Track Scale for Hot-Metal Cars Large Size section, knife-edge scale for weighing molten-iron cars has recently been completed the plant the Hamilton Coke Iron Co., Hamilton, Ohio. Standard- gage track used and the scale, which has weigh rail ft. long, built two sections. The rail stands are supported steel cross ties. The deck %-in. steel plate covered with firebrick and special type storm guard protects the openings made the rail stand housings. Four primary main levers transmit the load transverse extension lever, which connected the weigh beam. The beam type registering and double slides have been provided the builder, Fairbanks, Morse Co., St. Johnsbury, Vt., that weights can Although this scale was built primarily weigh molten iron, will used also for general service inbound and outbound freight. Pugh-type hot-metal cars are used transport molten iron distance miles open-hearth furnaces Middletown, Ohio. Each has capacity 150 tons and the weight 1746—June 21, 1928, The Iron Age the fondest dream every manager, every department head and every foreman.” recent survey 14,000 industries employing 2,500,000 workers, comparing results 1922 with 1925, shows per cent increase production and per cent decrease accidents. Blast furnaces show in- crease production per cent the last years and per cent decrease accidents. Today accident prevention just much busi- ness proposition production. plant can truthfully said sound business basis until safety much matter daily consideration and practice quantity and quality production. And the average mill worker today can buy life insurance the same rate premium the office worker other preferred risk. Before had accident prevention, was com- pelled pay much higher rate. fact, undoubtedly true today that, whether look accident prevention from the humanitarian standpoint from the economic side, can safely say that pays; that worth while, and that worth much more than the effort and energy expended the dollars and cents invested. and its full load 343 tons. This load carried wheelbase ft. in., with maximum axle Each car built with two eight- addition providing transportation for hot metal, these cars also furnish hot-metal storage capacity. load 85,600 Ib. wheel trucks. Lever Construc- tion (Above) Unusually Heavy. This scale the section, type The Deck This Scale (Left) Overlaid with Firebrick. The molten-metal car with full load weighs 343 tons 4 Ways Improve Gray Iron Castings High Strength Super-Heat Irons Points Recapture Lost Markets—-High Malleability Attainable Also DR. RICHARD ECENT achievements the improvement cast iron, brought out more particularly German metallurgists, least partially explain why marked increases strength are obtained without seri- ous reductions the carbon content cast irons. The explanation based upon the influence temperature the physical condition the graphite precipitated during the change the iron from the molten the solid phase. must patent that the slower the cooling—or the interval time between the liquid and the solid state—the larger the crystals formed solution given material sufficiently concentrated contain nuclei that material starting points such crystals. And, per contra, the faster the cooling rate, the shorter the interval time setting, the smaller the crystals the resulting solidified mass. Graphite forms exception the rule, for, under ordinary conditions melting, with slow cooling the molten carbon-iron solution when poured into dried even heated molds low heat-conducting power such sand—the crystals formed will very coarse; whereas, the same iron poured into molds high heat-conducting power—such not contain any precipitated graphite fine crystals. Superheating Destroys Graphite Nuclei Naturally, obtain any graphite crystals there must present, formed, graphite nuclei starting points for crystals the liquid metal either before during the period setting. The size the crystals will depend upon how much time elapses between the commencement crystal growth, out the nuclei graphite, and solidification. The impor- tance the recent research developments lies there having been located gray cast iron, melted under ordinary conditions melting and superheating, abundance microscopically small graphite nuclei nuclei which serve the starting points coarse crystal growth when the metal freezes and give weak cast iron. Further, superheating the metal extremely high temperatures the graphite nuclei disappear completely solution the iron, and the subsequent cooling the growth large graphite crystals cannot take place with nuclei present. Only when considerably cooled—in fact, actually supercooled below normal freezing ranges—will graphite nuclei form again that could serve for the growth large crystals, were there time allow this before the metal solid. matter fact, when the graphite nuclei form such super-cooled mol- ten iron, the temperature will have dropped close the freezing point that there time only for the formation very fine crystals, and strong metal results. Hence iron melted under conditions superheat, far beyond the ranges ordinary practice, may give castings perhaps twice strong the same iron melted with the ordinary degree superheat. The above statement may proved melting charge gray cast iron crucible resistance *Watchung, Abstract paper presented the European Foundrymen’s Congress, Barcelona, Spain, April. electric furnace. When just liquid, test piece poured with one end against chill. Photomicrographs made the hard and the soft ends the casting will show the graphite nuclei the white portion the metal, and the large graphite crystals the gray. If, now, the remainder the charge successively heated hundred more degrees Fahrenheit, cooled down the first pouring temperature, and corresponding test pieces and photomicrographs are made, the graphite nuclei the chilled portions will found gradually disappear the high temperature ranges are reached, whereas the soft portions, similarly, the crystals graphite will have become smaller and smaller. enough metal used permit the making tensile test specimens sand molds each case, the strengths will found the degree superheat rises. There doubtless additional explanation for the strength increase incident melting under conditions which give high superheat. temperatures equal those molten steel, iron containing over 2.50 per cent total carbon and possibly much silicon, with manganese per cent, can hardly tolerate the presence dissolved iron oxide. This will certainly reduced, just when adding ferromanganese “blow” Bessemer steel deoxidize it; and tho- roughly deoxidized cast iron will gain correspondingly quality. Even ordinary foundry practice, known that melting very hot means less sulphur picked from fuel, less chances for blow-holes and generally better castings. fact, the rule pour hot the sand will stand it. Again, foundrymen know that the hotter the metal, the deeper the chill—especially when running low-silicon irons. Doubtless the disap- pearance the graphite nuclei under conditions extremely hot melting helps retard the formation large graphite crystals, and therefore the metal can chill deeper. gratifying have last expla- nation the phenomenon higher combined carbon results from hotter iron, not only the case chilling irons, but general foundry practice. Hold Superheated Metal Before Pouring does not follow, however, that cupola melting, when operating under low degrees superheat, soft iron will result because the ready growth large crystals graphite from the nuclei present the molten metal. Melting cold may result from unduly low fuel bed, and this causes oxidation the iron. This, turn, results higher freezing point, reduc- ing the normal interval time for crystalline graphite growth before the metal solidifies. Hence hard iron. the case furnace melting, however, cold molten iron does mean softer metal, for malleable castings practice, with air furnace melting, iron with about 0.75 per cent silicon can give white cast iron when dipped from the hot surface the bath, and gray iron when tapped out from the colder bottom. This occurs the samples are taken just before the entire bath hot enough for tapping out, and the test pieces are large enough cross-section. further point practical importance learned The Iron Age, June 21, 1928—1747 _S SSS SS SS q from the researches under consideration. Melting under conditions extreme superheat the part the metal produced necessitates that held, before pour- ing into the molds, until can cool the desired pour- ing temperature. the metal were poured into the molds once, allowing the sand body absorb and dissipate the surplus heat, not only would the sand surfaces suffer, but the added heat cared for the sand would retard the freezing the iron that large crystals could grow from the nuclei finally formed during the cooling, even the entire graphite the is, including the residual graphite been dissolved the high-temperature melting. Hence this intensely superheated molten iron should allowed dissipate into the air all heat above regular pouring temperatures before being poured off into molds. ordinary foundry practice, the molder, when receives molten iron and thinks too hot use, instead holding cool, often adds piece some the gates sprues. This saves him time. noted, however, that the theory crystal growth from graphite nuclei correct, the molder, be- sides cooling his metal, will have goodly quantity graphite nuclei from the cold gray iron scrap added, which his now colder iron not able dissolve. The result will that has reduced the quality his dearly won extremely superheated iron that ordinary melt. Composition High-Test Irons The foundryman, hearing the wonderful strengths and other qualities cast iron obtained the result the recent researches, naturally wishes approach, not actually duplicate, them his own establishment. first looks the compositions these high-test cast irons and finds them high silicon, the upper ordinary manganese limit, low sulphur phorus but with the total carbon quite low far or- dinary means obtaining this concerned, 2.80 per cent total carbon for cast iron not being easily obtained from the cupola. can just done the air furnace, using the maximum percentage soft steel scrap about per cent. The open-hearth and the electric furnace can handle the situation readily. Most foundrymen, however, have only the cupola melt with, and when recalled that steel melted the cupola absorbs about 2.75 per cent carbon from the fuel, get the desired 2.80 per cent total carbon the castings would mean practically 100 per cent steel mixture. Since, however, with the aid ferro- alloys, particularly the cement briquetted form there are also other ways protect the descending ferroalloys, such mixing with clay and vitrifying, mixing with cast borings and inclosing steel con- tainers—there reason why every foundryman should not least improve his work using high steel scrap mixtures, using steel altogether for his very special castings. With high steel percentages, necessary have enough silicon and manganese available while melting, as, under the very high tem- peratures involved, there chance oxidation from the carbon dioxide the cupola gases and, without the deoxidizing action the two elements question, sorry metal would come out over the spout. get somewhat closer the melting details, the first question consider how obtain from the cupola the very high temperatures desired for the molten metal. This involves sacrifice fuel, and per- haps the best example actual operation found making large radiators, for which the molten iron required must snow-white, avoid heavy losses through “cold-shuts” thin class pressure cast- ings. Here, melting has done with moderate blast volume—say that giving about three-quarters the normal hourly tonnage capacity. The fuel bed must high enough allow time interval 1748—June 21, 1928, The Iron Age min. between putting the blast and observing the molten metal running from the open tap-hole over the spout and into the receiving ladle forehearth. Fur- thermore, even with the best coke, the ratio metal fuel between charges should not more than and, with high ash cokes which are rather friable, this may have drop metal charges must small enough hold the intermediate coke charges down layer about in. thick, and charging must done carefully get level layers. If, after the cupola has been fully filled, this can let stand for hour more, warm well, the first iron will hot enough use, and, very shortly after starting, the molten metal will come out extremely Results Alloy Additions Until the recent developments “high-test” cast iron, the only apparent avenue betterment gray iron castings seemed lie the addition such metals nickel, chromium, vanadium, the production alloy cast irons. These could pro- duced either direct addition the ladle cupola, preferably component elements the pig irons charged, The quality the castings was thus unques- tionably improved either for strength wearing quali- ties. However, the amount and condition the graphite cast iron will always have the most powerful effect upon its physical qualities, and giving this more weight when judging erratic alloy, addition results will ex- plain them more satisfactoril Some the actual figures involved will inter- est. For very “high-test” cast iron, tensile strengths hovering around 60,000 lb. per sq. in. have been regu- larly attained. Transverse strengths almost double the normal, with more than double the are common. The addition nickel, chromium, has added another notch these values, 65,000 and even more being reputably reported. would appear, then, that, with our present knowledge, cast iron can made enough recapture much the market lost the steel and the malleable casting, and the producer iron castings shou!d lose time doing so. Development Which Has Promise But there still another development cast iron which should prove valuable the considerable reduction the silicon and manganese content cast irons, leaving the total carbon, sulphur and phosphorus given the previous typical iron, to- gether with the extremely high degrees superheat given melting, when poured into castings, gives class cast iron not quite strong those previ- mentioned, but peculiarly amenable anneal- ing process which converts the comparatively higher combined carbon contained the temper-carbon variety without special interference the finely crystalline graphite present. Thus, fine-grained gray cast iron can sent partly the way the malleable casting, and light castings with around 1.50 per cent silicon, over half their carbon fine graphite and with low manganese can readily twisted. other words, the material has malleability and can elongated. Large and heavy castings practically anneal themselves, since only few hours 1550 deg. Fahr. are required accomplish the combined carbon conversion. Thus another avenue opened the gray iron founder retrieve his losses. Advances Summarized Reviewing the achievements the scientific control cast iron for the last three decades, for they fall within practically that period, would almost seem that the most important advances have been made only recently, and scientists rather than men active operation The search for cast iron which will not “grow” under alternating heat applica- tions, and other problems similar nature, gave the necessary impetus which brought the highly important developments. This argument for more extended and, the same time, cooperative research cast iron its various branches, and the several move- ments going the present time number highly industrial countries should encouraged and financed. the same time, some method informa- tion exchange should arranged for which would limit duplication effort and extend the usefulness the discoveries that are certain made. Safe Loads for Steels Working High Temperatures Bureau Standards Publication Gives Data Whereby Superheated Steam Chemical Equipment May Designed generally understood that the tensile strength steels determined the ordinary way room temperature gives little information the ability the metal withstand stress elevated tempera- tures. There has consequently been much study given the tensile properties from 600 1400 deg. Fahr., view the decided trend the power and chemical in- dustries toward higher working pressures and tempera- tures. Two general types tests have been per- formed. one, the load applied step step rap- idly the corresponding extension can measured the hot specimen; the other, quiescent load left indefinitely, and observations are made daily inter- vals see whether gradual extension “creep” occurring. Much work, done principally the former plan, Peterson the United States Bureau Standards Technologic Paper No. 362. Their equipment (described Technologic Paper No. 296) was capable main- taining the tension specimen uniform and sta- tionary temperature within plus minus deg. Fahr., and extensions were read four millionths Extreme accuracy necessary for this work, be- cause variation deg. Fahr. will cause measure- able changes over gage length. Furthermore. since the elastic limit low high temperatures (on the order 1000 lb. per square inch), the total de- HOT ROLLED STEEL HIGH STEEL, QUENCHED AND TEMPERED 40 4 ©00 800 1000 1200 1400 formation over 2-in. gage length only 0.00002 in. The limit proportionality between the observed stress such low strain can determined only when the limit error each determination very small. Five steels were studied: 0.24 per cent carbon boiler plate, quenched and tempered chromium- molybdenum steel, annealed low-tungsten high-speed steel, quenched and tempered per cent chromium steel and annealed austenitic nickel-chromium steel. Results for four these are shown the diagrams. will observed that each diagram has curves two different families, one showing performance rela- tively low temperatures (where the cold work done the bar stretching past the elastic limit strain- hardens the steel and automatically raises its strength sufficiently carry the imposed load indefinitely) and the other indicating the relationship between time and the loads which cause continuing creep. For instance, the proportional limit boiler plate about 12,500 lb. per square inch 500 deg. Fahr. Any load below that will carried indefinitely that temperature and will not cause permanent set. boiler steel under heat 500 deg. stressed 17,500 per sq. in., the curves show will acquire permanent set 0.1 per cent, but still stable structure. 800 deg. Fahr., however, this steel must stressed considerably below 10,000 lb. per square inch remain service indefinitely; carries load 22,500 Ib. per ORTIONAL 200 400 600 TEMPERATURE, DEGREES F. Loads Required Cause Either Permanent Sets Continuing Creep Steels Elevated Temperature The Iron Age, June 21, 1928—1749 000 12090 14090 4 i Cr-Mo STEEL, QUENCHED AND TEMPERED | 10 re) 200 400 600 800 1000 1200 .e) z00 400 600 800 1000 1200 square inch that temperature, will stretch per cent 1000 hr. The authors recommend that ample margins safety used for figures taken from these curves be- cause the experimental work underlying them none too extensive, and the high-temperature portions are based the unproved assumption that creep de- termined relatively short time intervals continues indefinitely the same rate. But the values are con- servative when compared with results other gators. Cox, the Midvale Steel Co., has recom- mended that per cent these figures used for de- sign values allow for unavoidable variations qual- ity metal and accuracy machine work. also thinks that container which exhibits creep should replaced when acquires permanent extension per cent. (See IRON Dec. 15, 1927, page 1662.) Railroads Spent $432,604,000 for Iron and Steel Nearly One-Fourth Went for Rails 1927—Locomotives and Cars Cost $30,000,000 First Quarter WASHINGTON, June 16.—Class railroads the United States 1927 directly expended $432,604,000 for iron and steel products, according annual statement issued the Bureau Railway Economics. This outlay was per cent total expenditures these railroads last year for materials and supplies all kinds. Only the case fuel were expenditures for iron and steel exceeded, the total for coal and fuel oil being $438,821,000, 31.4 per cent the total outlay $1,395,928,000. The fuel purchased consisted 130,190,000 net tons bituminous coal, 3,199,000 net tons anthracite and 2,765,259,000 gal. fuel oil. Expenditures for iron and steel last year, however, the case other lines, were not great they were 1926, when, out total $1.559,032,000, purchases iron and steel amounted $507,302,000. 1925, iron and steel purchases aggregated $419,255,- 000; 1924, they were $365,610,000; 1923, they amounted $464,955,000. Detailed railroad expendi- tures for iron and steel 1927 were follows: Per Cent all purchases Steel rails (new and second-hand, $101, Wheels, axles and tires........ 47, Frogs, switches, crossings, track fastenings and bolts, spikes, tie plates, rail anchors, etc....... 72,032,000 5.16 Iron bridges, turntables, struc- tural steel, bar iron and steel, forgings, fabricated fabricated shapes and pressed and tubes for locomotives and stationary boilers ....... 8,191,000 0.59 Telegraph and locking and signal material... Bolts, nuts, washers, rivets, Locomotive and beams, couplers, frames and Machinery, boilers, repair parts and all other iron 567,000 7.2 435,000 3.40 51,267,000 3.67 25,300,000 1.81 19,064,000 1.37 62,294,000 4.46 45,454,000 3.25 Total steel $432,604,000 30.99 The bureau quoted the estimate THE IRON AGE (Jan. issue) that the railroads 1927 absorbed 6,125,000 tons steel, amounting per cent the total. Rail purchases the carriers 1927, the Bureau statement said, amounted gross tons, 86.7 per cent this class distribution. With the exception 1926, the 1927 rail purchases were greater than any recent year, and were nearly per cent the steel tonnage bought the Growth Heavier Rails After quoting THE IRON AGE, showing taken the railroads 1927 each form steel distributed, the bureau statement pointed out that dur- ing recent years heavier steel rails have been coming more and more into use meet conditions improved heavier and denser traffic. Rails 100-lb. section and over rolled 1927, the statement explained, were 68.8 per cent the year’s production. 1926 the corre- sponding proportion was 61.12 per cent; 1925, 58.76 per cent; 50.47 per cent. Recognizing the growing importance extra heavy rail sections, was pointed out, the American Iron