The Iron Age 1945-04-19: Vol 155 Iss 16

and Advertising VAN DEVENTER President and BAUR Assistant General Manager Advertising Monager JOHNSON, Reader Service and Market CLEARY, Technical Research Gad Manager ¥ Regional Business Managers York New York 42nd St. 100 East 42nd HERM Chilton Bidg. Otis Hertford Cona, RAYMOND KAY Los Angeles Ave. Owned and Published CHILTON COMPANY Executive Offices Chestnut and Sts. OFFICERS AND DIRECTORS MUSSELMAN, HILDRETH Vice-President GRIFFITHS TERHUNE Vice-President Vice-President Vice-President CHARLES HEALE Business the Industrial Arts Index. Pub- lished Thursday. Subscription America, South America and Possessions, $8; year, Single Copy, ° Vol. 155, No. April 19, 1945 Editorial ° ° Technical Articles Metallurgical Control Shaved Aircraft Welding Casting Short-Run Variable Designs.................... Managerial Use Time Study.............. Features ° ° | News and Markets Dayton Avoiding No. Labor Standards Men Correlate Drafting Work................ 120 Midland Steel Reconverting........................... 122 Wage Increase Aetna Ball Bearing................... 124 New Carbine Fires 130 Navy Works Surpluses Back Into 134 Grave Vaults Seen Potential Steel 140 Machine Tool Market Developments.................. 150 Nonferrous Metals News and Prices.................. 152-153 Iron and Steel Scrap News and 154-155 Comparisons Prices Week and 156 Steel Pipe, Tubing, Wire Products, 162-163 Pig Iron and Coke Prices.................... Stainless Steel and Ferroalloy e | + ye | ° STEEL every kind delivered QUICKLY from STOCK The Ryerson organization can rise emer- gency—move heaven and earth when called upon the impossible! But it's day-in, dependability, taking difficult assign- ments stride—that Ryerson Steel-Service stands out. ago the Ohio plant one America’s best known manufacturers was faced with cer- tain shut-down four hundred inch bars cold rolled SAE X1335 could not obtained overnight. The order reached Ryerson plant 4:45 the afternoon; was delivered the next morning. fanfare; just job done, and Ryerson did it. Ryerson gets these calls because Ryerson comes through—not once, now and then, but with regularity. Ryerson stocks, personnel and facilities make jobs like that look easy even, though not. the big difference. For all your steel requirements—simple tough —call Ryerson. The nearest the eleven well- stocked plants can serve you your advantage. Joseph Ryerson Son, Inc., Steel-Service Plants: Chicago, Milwaukee, Detroit, St. Cincinnati, Cleveland, Pittsburgh, Philadelphia, Buffalo, New York, Boston. Presid Editor Technical Commerc +3 x j | : : ESTABLISHED 1855 April 19, 1945 VAN DEVENTER and Editorial Director BAUR Vice-President and General Manager Editorial Staff Technical Editor ......... OLIVER Commercial CAMPBELL ° ° Associate Editors WINTERS JACK HIGHT ALBIN JOHN ANTHONY BARMASEL Assistants SCHIEN DAVIS News and Technical Editors LLOYD Pittsburgh 428 Park Bidg. POST Chicago 1134 Otis Bldg. MOFFETT DONALD BROWNE EUGENE HARDY Washington National Press LLOYD Cleveland 1016 Guardian BRAMS 7310 Woodward Ave. OSGOOD MURDOCK Francisco Market St. Editorial Correspondents ROBERT McINTOSH Cincinnati DEAN Buffalo FRAZAR Boston HUGH SHARP Milwaukee SANDERSON Toronto, Ont. RAYMOND KAY Los Angeles JOHN McCUNE ROY EDMONDS St. Louis JAMES DOUGLAS Seattle Walking the Tight Rope the circus one night last week. was good show although the manpower shortage, evidence here elsewhere, was reflected unusually large proportion women performers. One goes such entertainments forget present day troubles and business. But the circus this time did not that for me. emphasized them. That was not the fault the entertainment but most likely current personal mental quirk. The circus, this occasion, seemed symbolize number things that are industry. One was the black market and labor racketeering; another was the contrast between incentive system and the lack getting work done; still another was reminder management’s present difficulty walking the tight rope. will take these order. The house was about sold out when got there and the only obtain- able the rear the top gallery which close heaven anyone can get Madison Square Garden. very polite usher ex- amined our tickets. can’t see much from there,” said, “but for buck apiece can slip you into some good seats the lower mez- zanine.” saw this enterprising young man repeat this performance least dozen times that evening. Any time that wants recommen- dation for employment Petrillo Lewis, will write him one. was joy watch the trained seals. They went through their act juggling, balancing things their noses and playing tunes musical horns with evident gusto and enjoyment. After each act they would applaud themselves clapping their flippers. And after each act, each would given fish their trainer. The incentive system work. The animal act with the trained cats was diametric opposite. Here was example unwilling workers being driven their tasks under lash and prod and obviously hating their boss. They got meat reward but they clearly would have liked make meal him. The Wallendas, the high wire, gave their usual hair raising per- formance. Two cyclists crossed the high wire with bar extending from one’s shoulder the other’s; another performer, standing chair, bal- anced that bar both himself and woman who was doing handstand his shoulders. net beneath them and foot drop the ground. Enough send cold chills down your back. But the audience respected the difficulty the act. There was ab- solute quiet while was going on, and rocks were thrown them. Quite contrast, thought what management encounters today walking its tight rope. After all, however, the Wallendas have contend with but one law, the law gravity. And management has contend with hundreds laws and thousands regulations. And there net catch its foot slips, and plenty rocks and brickbats fly make things more difficult. Funny, isn’t it, what one can think circus? | | : | agi | | | | | | | | | | ™ | MUNZER O'CONNOR MILLER | § | } | ‘ | | | | in Output cartridge storage container rims, drawn in. deep 8-in. diameter, has been stepped from 400 1200 per day. This increase results partly from die design and die use, and partly from the extremely low breakage Inland Hot Rolled Pickled Sheets. the first operation blanked and drawn Container Rim Output 300% Novel die set-up and Inland Sheets increase war part production full depth with shoulder, double acting press. These drawn parts are moved another press which are mounted two dies, one for piercing out the bottom and the other for sizing the bottom, which used later close the container. The two operations are performed each press stroke. The rim then taken third press which are three dies, which pierce locating holes, punch out the start keyways, and trim the 8-in. diameter. rim pleted three press strokes. Final operations consist spot welding three lugs the inner surface the rim, finish piercing the keyways, and swedging the lugs the rim for close fit. The increased speed these cartridge storage container rims example how Inland quality steel helping America the battle production. Sales Offices: Ped INLAND STEEL Dearborn St., Chicago Ill. Three operators trim each prezs stroke. Inland sheets are blanked and drawn 4-in. deep one operation. Each stroke this pierces out the bottom rim and sizes the bottom obtained during the previous stroke. April 17, ierce, punch and charact tion May News FRONT New Army weapons, designed since the overall light metal supply situation last fall, include aluminum bazooka, magnesium cased movie camera, armor vest, aluminum food carrier, well "snake" mine clearing device, rocket powered. modification the General Pershing tank, the T26E4 carries high mm. gun. Using the core shell, the Army claims mpenetration in. armor 300 yds. Current WPB plans will release all and orders soon possible after Restrictions textiles, paper, pulp, chemicals, leather, and tires probably have remain. Though the decline munitions manufacturing will run per cent, the decline total manufacturing will total only around per cent, the increase output civilian goods. hp. aircraft engine weighing only 1640 has been designed the mcontinental Aviation and Engineering Corp., and now limited production. the I-1430, 12-cylinder 60-deg. inverted type. Cylinders are cast individually rather than bloc, intended reduce stresses maximum loads, and permit refinements improve the cooling characteristics. The navy developing airplane, using rocket propulsion similar that the German well twin jet craft using gas turbine powered jets. WMC reducing employment ceilings less essential industries rapidly since hope passing national service act has been abandoned. Cutbacks munitions program working the opposite end the manpower will soon start laying off workers. Pre cuts steel for ammunition will mean reduction 22,000 tons military allotments the second quarter and about 300,000 tons the third This means that the second quarter shell steel rate will continue. Automotive reconversion plans include about $20,000,000 worth machine tools and about $10,000,000 more tooling. Some this work has already begun appear Detroit tool shops, well indeterminate amount die work. Tool men figure three four months will needed clean all retooling programs. Problems the planning departments are manpower Textiles, lead, tin, rubber, lumber and some few chemicals are particular concern. Foremen will probably experience material change their status following their organization into collective bargaining unit, Packard Motor Car Co. and General Motors advised. Following foremen organization, candidates for higher management would then selected and trained for their positions from the start not promoted from the George Christopher, president Packard, said letter Canada anticipates cutback not more than per cent its munitions the cessation European hostilities. For the past year Canadian turned out materials with cost value more than $2,200,000,000. Fisher Body Co. has purchased site near Hamilton, Ohio, for the tion auto body stamping plant, others Cleveland, Grand Rapids, Detroit, and Pontiac, Mich., are contemplated. William Jack, president Jack Heintz, Inc., will leave about May first for overseas assignment. This company will make engine plant just acquired formerly occupied the National Carbon Co., leveland. «ft | Metallurgical Control Shaved Gears sequel the article Charles Pfeffer which appeared last week the mechanical aspects gear shaving practice Wright Aeronautical Corp., Mr. Liebendorfer discusses the heat treatment the gears, with particular emphasis carburizing practice. Since the gear teeth are not touched after hardening, essential that decarburization avoided during hardening. Radically new methods have been devised measure and control the amount decarburization that might take place thin surface layers. INCE the shaved gear placed service with the tooth profile un- touched after heat treatment, small variables the heat treatment have pronounced effect upon the service life the gear. The most troublesome these variables con- trol decarburization. Unfortun- ately, decarburization the worst enemy the shaved tooth surface. Small amounts which may not detected standard hardness testing methods microscopic investiga- tions can mean excessive galling “welding” highly loaded aircraft gears. this decarburization avoided the shaved gear’s freedom from grinding burns and its profile accuracy are largely offset. This not the only metallurgical problem involved gear shaving, however. the highly alloyed carburizing steels the soft retained austenite often en- countered the structure can de- tract considerably from the optimum case hardness obtainable. Depending upon the case depth and the carbon concentration gradient, this soft structure can result two distinct types failures. the case depth not too great, the soft austenite 56—THE IRON AGE, April 19, 1945 Supervisor Heat Treat Control Development Methods, Materials Labo- ratory, Wright Corp. may occur im- mediately the surface and re- sult galling type failure in- from that due decarburization. the case depth greater and the surface carbon concentration exceptionally high, hard alloy carbides appear the surfaces and may prevent the galling type failure. However, the re- tained austenite this instance can cause sharp drop the 0.005-0.010 in. below the surface. With countered some aircraft gears this may result pitting due failure sub-surface shear. All the heat treatment referred this point consists opera- tions after the shaving has been com- pleted. just important, how- ever, have proper heat treatment for machinability purposes prior shaving, that the shaved surface. not left with ragged tears and gouges which will remain the finished tooth. Controlled heat treat- ment this field much older and not restricted merely .to shaved gears. close control not main- tained over the initial hardness and structure, cutting speeds cannot kept constant grinding practiced, excessive time must expended grinding off heavy burrs from very soft gear teeth. Conse- quently, this becomes quality control, and such has re- ceived considerable attention the past. Forgings Normalized Control metallurgical quality shaved gears starts when the forged gear blank received. Nearly all the carburizing grade gears Wright Aeronautical are fabricated _from AMS 6250 the national emergency substitute AMS One forging from each lot received sent the labratory and AMS harden- ability sections’ cut from it. These sections are normalized and analysis the two steels: AMS 6250 (SAE 3310) AMS 6260 Element Per Cent Per Cent 0.30-0.60 0.70-0.90 0.040 max 0.040 max. 0.040 max. 0.040 max. 0.20-0.35 0.20-0.35 2.00-2.50 0.80-1.10 0.30-0.40 AMS hardenability specimens have sections in. thickness and not greater than sq. in. area, cut represent area half way between the center and outside the bar forging. These sections are ground and copper plated before being hardened. hardness values being recorded after each operation. Since desirable value after nomalizing, neces- sary know whether each lot will reach this hardness without receiv- ing special treatment. The rough forgings are normalized and an- nealed Brinell hardness 223- 255. Most lots AMS 6250 are well above this range after normalizing, contrast SAE 4620 lower alloy grades used more frequently the automotive industry. Occasionally, 625 showi tion | 1700 howev borde: sectio ment hardr that ordin ing abilit optin face time off teeth hard tool ticul hard shav ing chin 4 4 F “4 sf 7 nearly finished gear blank, and metal- lurgical surface carbon control will then determine whether accurately shaved profile will meet the severe re- quirements engine testing. Carburizing Practice The first problem the final heat treatment that insuring optimum carbon concentration the carburized surfaces. Carburizing done Leeds Northrop pit type carburiz- ing furnaces with vaporized and cracked mixture isopropyl alcohol and nitromethane the carburizing agent. Fluid flows the furnace are calibrated advance for given carburizing time and load area. They are set produce case carbon content approximately 0.90 per cent for the first 0.005 in., because sures good depth hardness curve and minimum amount the re- tained austenite. some plants the problem re- tained austenite has been approached through the use refrigeration treatment, the function which cause transformation any retained austenite into the harder martensite constituent. Unfortunately, however, this transformation accompanied per cent increase volume and the amount austenite sufficient, the volume change can pro- duce internal cracks the carburized case. Much more work must done prove that this treatment can used entirely free from such trouble. abortive method, since sanctions improper carbon control carburiz- ing the first place. surface car- 1G. 2—Carburized specimen AMS 6250 steel etched with per cent nital. Sample was furnace cooled after car- burizing. Structure evidently higher carbon than case shown Fig. but contrast not sufficient surface for accurate evaluation 6250 steel etched with per cent nital, showing little evidence decarburiza- tion due removing from furnace 1700 deg. and pit cooling ° ° however, heat AMS 6250 with borderline hardenability will en- countered which accelerated cool- sections enables these heats segregated the production depart- ment for special treatment. the furnace. Small therefore, dilute the gas rapidly and result too low carbon concentra- tion excessive carburizing time. order avoid this trouble, furnace pressure checked before and dur- ing each carburizing load de- Normalizing temperature for the forgings 1700 deg. and the hardness above 223-225 Brinell, that particular lot will annealed, ordinarily 1000 deg. F., but vary- ing with the heat steel. Machin- ability tests have shown that optimum combination tooth sur- face finish and cutting tool life exists this hardness range. the same time less effort expended grinding off burrs formed the edge the bon concentrations are held between 0.90-1.00 per cent and quenching tem- peratures are not excessive, there little need worry about excess re- tained austenite. There one difficulty meeting this requirement fluid carburizing and that the necessity main- taining perfect furnace closures. Low concentrations mean low fluid flows and consequently less gas termine the tightness the furnace. Failure furnace meet pressure requirements before load placed the maintenance department. When necessary, the furnace torn down and rebuilt. this case sealing efficiency checked before the heat turned back on, meter- ing definite amount compressed air the cold retort and requiring teeth during rough cutting, the hardness held above 223 Brinell 3—Depth-hardness curves for: (A) sample cooled 1100 deg. carburizing rather than lower values where furnace and (B) sample removed 1700 deg. and cooled standard pit with tool life might increased. Par- atmosphere protection. ticular freedom had also this hardness from ragged tears the tooth surface which are encountered during the rough cut and which are sufficient severity persist the shaved surface the finished gear. After the normalize-anneal, the gear forging leaves the heat treat- ing department for rough machining, copper plating and semi-finish ma- Micro hardness impression diagonal, Increasing 0.002 0004 0006 0.008 Depth below surface, 0.014 0.016 THE IRON AGE, April 19, 1945—57 nse the ged all nal ent ese tions than area ound fter able iess ces- will eiv- ugh an- ing, wer load Micro hardness impression diagonal, certain pressure buildup before the furnace can released for produc- tion use. poor pressure obtained shaved gears, immediate effort made reseat the top seal. all efforts increase the pressure build- are avail, the load gears held after carburizing for micro- hardness check the laboratory. More will said concerning this check later. Pressure-Tight Furnaces Aside from the factor gas leak- age and the resultant low carbon cases excessive carburizing times, for shaved gears, the most important point that low pressures will re- sult decarburization during cool- ing. explain this statement necessary. review the standard and cooling procedure used with pit type carburizing fur- naces. This consists holding the load the furnace until the required case depth. obtained and then transferring the load brick lined cooling chamber which may may not contain protective atmosphere. During the transfer the hot load carburized parts acts like huge chimney and convection currents air rush through the red hot parts. This causes considerable decarburiza- tion the parts the bottom the load and this decarburization will continue the cooling pit. There are number ways minimizing this type decarburization. Steel “bell blower 58—THE IRON AGE, April 19, 1945 Depth from surface, in. 4—Depth-hardness curve for sample removed from carburizing furnace 1500 deg. and cooled gas filled pit. Slight decarburization still present. 0.016 0.018 jars” can placed over the load dur- ing the transfer curb convection; heavy gas fluid flows can used prior the load that protective blanket soot left each part, protective atmos- phere can placed the cooling pit with pilot flame prevent ex- plosions. All these expedients are used de- crease decarburization, but they are all dependent the human element and all them used together will still not entirely eliminate decarburi- zation. has been generally agreed that impossible remove load parts 1700 deg. from carburizing, furnace without encoun- tering decarburization. This conclu- sion has obviously led furnace cool- ing. However, takes full day cool pit furnace with 20x in. retort temperature which maintenance work can done. production cooling had done this manner, would, course, re- sult excessive expense and three or. four times the normal furnace pacity. addition slow furnace cool- ing causes excessive surface carbon concentrations and poor microstruc- tures. result the problem boils down determining the maximum temperature which parts can removed from the furnace and then finding way speed normal fur- nace cooling save manufac- turing time, expense and quality. Before proceeding further with this discussion necessary that some ° ° ° IG. 5—Sketch car- burizing blower cooling attach- both units would connected one blower and one exhaust stack. clarification made the degree decarburization being discussed. The term not used the sense ferrite being present degree which will show Rockwell hardness differential between the surface and point 0.005 in. be- low the surface. the same token may not even show change the shade the microstructure difference the 15N superficial hardness the surface and 0.005 in. below. Some the decarburization will found successive carbon analyses the cuts are 0.002 in. thick less. Most this decarburization can detected the microhardness tester, readings are taken cross sec- tion within 0.0005 in. the surface. Both these latter means are destruc- tive tests and the former case, are quite time consuming. Therefore, they should used means setting foolproof process rather than means routine inspection each part load parts. Ex- amples the minuteness decarburization and the difficulty detecting are shown the follow- ing series hardness values taken test pieces from the bottom pot standard carburizing loads which have been pit cooled: Standard Practice Furnace Cooled 15-N 15-N 63 92 62 92 62 92 62 91 62.5 Since the specifications for case hardness the 15-N scale, there reason suppose that the standard pieces are decarburized. difference the photomicrographs sample each group shown Figs. and However, from the microhardness curve shown Fig. for these same two samples will noted that the furnace cooled sample holds its hardness right the surface while the standard sample shows decided drop, starting about 0.004 in. under the surface. The scale used this and succeed- ing charts needs some explanation. While readings were made with Vickers diamond pyramid hardness was not possible use standard loads ranging from kg., be- cause the indentation would have been too large when measuring the from the edge the section. Instead for this particular analysis, 150 gm. load was used and the microhardness recorded terms the length the diagonal the impression inches haust furnace when scope. smalle hardn the VHN hardn parat carbu gree the motiv ing fore take same num gear then ing ever still FY //7/ 477, stack Exhaust Exhaust Exhaust 6—Actual ex- haust fan cooled corresponding Fig. when viewed under 375 micro- scope. Hence, this scale, the smaller the diagonal, the higher the hardness. (Standard Vickers hardness numbers involve the reciprocal the square the diagonal millimeters). attempt has been made convert the values recorded the charts into VHN standard diamond pyramid hardness numbers. The values given should regarded purely com- parative for this particular class steels. With decarburization this de- gree mind can now continue the discussion cooling subsequent carburizing. number auto- motive gear manufacturers are cool- ing critical parts 1500 deg. be- fore pulling the load. Since may take hr. cool this temperature represents almost practical limit such cooling furnace capacity held within existing limits. the same time, however, felt number these manufacturers that gears cooled this temperature and then transferred gas filled cool- ing pit are decarburization free. How- ever, microhardness curve for sample treated this method, Fig. still indicates appreciable decarburiza- tion. The important item that free- dom from decarburization entirely dependent upon the operator and the speed with which effects the trans- fer. Forced Furnace Cooling With this mind and the knowl- edge that 1100 deg. was safe temperature for removing the load (See Fig. 3), forced cooling sys- tem was designed conjunction with the furnace manufacturer. This so- sketched Fig. and photograph one the units shown Fig. The principle, will noted, simply that sucking column cooling air down between the retort and the brick lining and exhausting the hot air through auxiliary stack. suction unit placed each side the retort and the blower exhaust from both units sent out through one stack. With such ar- rangement furnace can cooled with full load from 1700 1100 will now understood why furnace pressure during the carburiz- ing cycle and the resultant seal effi- ciency important. The suction ac- 7—Depth-hardness curves for samples annealed after carburizing: (A) with 0.0003 in. copper plate, (B) with copper plate protection. Micro hardness impression 0.002 0.004 0.006 0.008 0.010 0.02 0.014 0.016 0.018 Depth below surface, in. THE IRON AGE, April 19, 1945—59 2 n 0 e a 0.85 0.90 Depth below surface, in. 8—Depth-hardness curves for samples hardened from conveyor furnace (side door for die quenching) with lean atmosphere (A) with 0.0003 in. copper plate protection, (B) with copper plate protection. ° tion this air column conjunction with the diminishing gas volume the retort during cooling enough air into the retort decar- burize the gears while still the furnace. The fluid pump not shut off until just before the load re- moved that enough gas formed the furnace keep this pressure differential low possible. This method cooling from carburizing considered milestone the road metallurgical surface control and will outmoded only when satis- factory bell-type carburizing furnace put the market. Following carburizing, the gears can divided into two classes—those which are annealed permit addi- tional machining before hardening and those which are not annealed. Each these types can further subdivided into simple gears which there apt little distortion and are free quenched and those which are apt have large amount distortion and must die quenched. Again the primary point im- portance the shaved gear pro- tection from decarburization and each operation will discussed separately with this mind. Anneal The anneal following carburizing so-called cycle isothermal an- ° ° neal. Parts are heated 1380 deg. F., held for hr., and then cooled rap- idly possible 1100 deg. F., where they are held for hr. before remov- ing from the furnace. Since these peratures are the dangerous range for using protective atmospheres high enough (and the accompanying prevent decarburization the case, mechanical protection used instead. All shaved parts which must annealed after carburizing are given 0.0003 in. copper plate prior the anneal. Fig. shows the microhardness curves hardened parts which had an- without such pro- tection. This annealing treatment leaves the core hardness about and the case between and Re, depending upon the size the annealing load and its resultant cool- ing rate between 1380 deg and 1100 deg. Gears which have been annealed leave the heat treating de- partment once more for such drilling milling operations are necessary and return when they are ready for hardening. Gears uniform heavy sections which distort very little during car- burizing are hardened pusher type, complete muffle furnaces which the parts directly from the protective atmosphere into the quenching oil without contacting the air. Gears 9—Depth-hardness curve for samples hardened from complete muffle, continuous type under pusher furnace: (A) with atmosphere 0.90 per cent carbon potential, (B) with atmosphere 0.20 per cent carbon potential. Micro hardness impression diagonal inches xand gram load 0.002 0.004 0,006 60—THE IRON AGE, April 19, 1945 0.008 Depth below thin and complicated cross-sections are hardened from conveyor type fur- naces with side doors from which they may pulled off the conveyor and die quenched. the first type furnace where the direct quench used for small uniform gears, protective atmos- phere partially combusted city gas used which essentially neutral the carburized surfaces. However, the conveyor type furnace not amen- able this type protection because the difficulties connected with build- ing purging chamber the side door which will permit moving the gears off the conveyor into the cham- ber, perpendicular the conveyor motion for die quenching. re- sult, when the side door opened the protective atmosphere diluted the inrush air and considerably lowers the carbon content which can stabilized this protective atmos- phere. avoid the dangers mak- ing freedom from decarburization de- pendent upon the length time the side door held open, shaved gears which must die quenched are also protected mechanically 0.0003 in. copper plate. Fig. shows the micro- hardness curve for faces hardened conveyor furnace with and without this copper plate protection. the case the de- occurring during cool- ing from carburizing, removal 0.004 in. stock grinding will com- pletely remove this decarburization ground gear andmakeunnecessary these extra precautions which are used the shaved gear. Testing Carbon Potential For gears which are hardened from the pusher furnaces and protected carburized areas only atmos- phere, the determination the car- bon potential that atmosphere be- comes quite important. already noted the microstructure not sensitive enough indication de- carburization. While the micro-hard- ness curve gives information enough, too laborious routine test and involves either destructive inspection part the smaller mass effect test piece. simple test has been devised determine the actual carbon potential the protective at- mosphere, and the air-gas ratio the atmosphere generator then ad- justed maintain carbon potential between 0.75-1.00 per cent (safety above eutectoid for AMS 6250 steel). devise used this test small carbon combustion furnace with silica Samples steel chips, one machined from case and the other from placed the perature phere passed arrived which The im] Fig. ness cent cent notéd only fo: where Even tance where Hemph within al: flats. Inte after dem ing line rolls also any lined zonta adjus contr fricti steel justa nate press toa posit hous are mak ~ 0.85 0.90 from core areas AMS 6250 are placed combustion boat, inserted the muffle standard hardening tem- perature and the protective atmos- phere from the production furnace passed through the silica muffle. hr. both samples chips have arrived the same carbon content which beyond doubt the carbon potential the protective atmosphere. The importance maintaining this potential above eutectoid shown Fig. which shows the microhard- ness curve for carburized samples hardened atmosphere 0.20 per cent carbon potential and 0.90 per cent carbon. Here again will notéd that the amounts decarbur- being discussed are important only for shaved finish cut gears where further stock removed. Even this type gear the impor- tance further limited those gears where unit loading very high. Air- craft gears engine whose weight has been reduced less. than per hp. fall largely this class. Following the hardening operation all gears are tempered for hr. 250 deg. minimum and_ checked the Rockwell and 15-N superficial scales for case hardness. there any doubt about carburiz- ing furnace pressure hardening at- mosphere carbon potential, gear from that particular load may sec- tioned and microhardness curve run the polished cross-section. most cases careful control the processes can avoid this extra operation and the finished gear can guaranteed possess surface maximum hard- ness. Cleaning methods after each treat- ment are limited very light grit blasting and stripping any residual -copper chronic acid bath. The heat treating methods described above may appear involved and ex- pensive the smaller manufacturer having highly skilled personnel and several reliable salt baths. granted that there much said for salt bath heat treatment for few file hard parts, but for the mass production highly loaded aircraft engine gears the outlined procedures offer the following advantages over salt bath heat treating the quality manufacturer: Freedom from corrosion due salt remaining recesses in- tricate gears. Quality control the process opposed batch control for each small lot. Ability die quench compli- gears which distort during previous carburizing. Responsibility for metallurgi- quality fixed with supervision, the laboratory and automatic in- struments rather than vidual worker. Mill Rolls Accurate Rounds LARGE percentage the prod- uct the new type vertical precision mill built Mackintosh- Hemphill Co., Pittsburgh, can rolled within cold drawn tolerances. designed roll accurate rounds from in. diameter. The machine also set edge shapes and flats. Intended located immediately after the finishing stand the tan- dem mill train, the roll stand consist- ing pair vertical rolls, can moved horizontally line the pass line with any pass the horizontal rolls the finishing stand. The rolls also can adjusted vertically, that any pass the vertical rolls can lined with any pass the hori- zontal rolls the tandem mill. Roll housings the precision mill are also adjustable with respect each roll control the size the product. The rolls are in. diameter in. long and are supported anti- friction roll neck bearings cast steel carrier. The carrier ad- justable vertically cast steel housing and locked place elimi- nate any movement due rolling pressures. This housing connected similar housing, holding the op- posite roll, means four heavy columns. Distance between the roll housings adjustable nuts both sides one housing. Vernier scales are provided all adjustments make possible accurate control the size the roll pass and hence the rod. The stand mounted ways heavy base, and adjustable hori- zontally means screw jack, which operated electric motor and worm gear drive. The mill driven 100 hp. d.c. mill type variable speed motor through indi- vidual mill spindles and bevel gear drives. allow for horizontal move- ment the roll housings, the pinion stand ends the mill spindles are provided with splines which slide the hollow pinions. The bottom ends the roll spindles are also splined that they can slide down the bevel gears allow for vertical ad- justment the rolls. The rolls may removed disconnecting the coupling box and lifting out the com- plete roll carrier through the top the mill stand. MACKINTOSH-HEMPHILL vertical mill which rolls rounds ranging diameter from in. THE IRON AGE, April 19. 1945—61 i Identifying the Constituents rod coatings insufficient for the identification their com- ponents usually radicals only are estimated, and accurate correlation the analytical results with the proper- ties electrodes almost im- possibility. Mineralogical examina- tion the coating constituents must, therefore, resorted to, and this combined with the results chemi- analysis can give information extreme interest. facilitate examination elec- trode coatings, the author has com- piled scheme utilizing the min- eralogical and chemical attributes the most common components. applied with the usual precautions analysis welding and care, this methods gives results fairly close the truth. The method can only applied the ferrous type welding rod, the com- ponents nonferrous electrodes are such reactivity, both with them- selves and with the reagents employed preclude any all embracing scheme. has been found, moreover, that the majority cases, the coating positions nonferrous electrodes are relatively simple compared with their ferrous counterparts and chemical analysis usually suffices give all the information required. Identified Apart from the binding agents, sodium and potassium silicate, the coatings of. ferrous electrodes the TABLE Physical Properties Common Constituents Electrode Coatings Substance Property Enstatite Hausmannite Ferrotitaniumt Chromium powder................. Ferrochromiumt Ferro Nickel Tungsten Index Refraction Density . . —_— Ne anwo- = The figures for the ferro-alloys are for those containing 60% Si, 65% Ti, 60% 75% Cr, 85% Mn, and 70% respectively. 62—THE IRON AGE, April 19, 1945 constituents most commonly found are: Rutile Asbestos Powdered metals Magnetite Mica Quartz Hematite Witherite Feldspars Pyrolusite Enstatite Kaolin Hausmannite Cryolite Calcite Siderite Graphite Dolomite Iron powder Magnesite Fluorspar Ferro-alloys Alumina Tale Organic matter these might added several materials which are claimed patent specifications, but which are isolated instances little importance, such powdered glass, carborundum, braunite, rhodocrosite, etc. The essential properties the more common these compounds are given Table will seen from Table that possible segregate the various substances differences magnetic susceptibility, into three groups, each which further subdivided density determinations, while the observation refractive index chemical reactions will usually sufficient enable the individual con- stituents identified. The follow- ing scheme may employed: Scheme Separation Initial Treatment—After being detached piecemeal from the core wire, the coatings three electrodes from batch (four they are only in. length) are boiled for min. with 200 ml. distilled water order dissolve the sodium and potassium silicates usually employed binding agents. The solution ob- tained should examined chemically, otherwise, for radicals other than and which would in- dicate the existence the coating water-soluble materials other than waterglass—probably inorganic salts, but should not omitted test for such binding dextrine, starch, etc. After this boiling, may usually assumed that the binding silicates have been dissolved and the grains the coating constituents freed. The suspension filtered hot through Whatman No. paper, and washed thrice with boiling water, the filtrates being subjected, indicated above, tests for radicals other than those and silicates—in actual prac- tice for ani The coating the bonate One during the served lished tween silicate matior fore, saf are Whe injure sieve, amour the residu the morta: the mater day 100 the ous tur compo grain varies for 2.16 2.32 2.62 2.75 59, 1.59 Sodium 2.79 2.86 -63, 1.63 2.98 3.17 2.7 3.19 3.20 3.70 3.70 3.80 Siderito 3.88 1.63 4.32 4.75 5.05 5.10 3.22, 2.94 5.69 8.68 powde chalk. 7.49 8.9 prelin 9.5 autho magn Welding Electrode Coatings Vickery, Ph.D., tice this confined initially tests for anions other than Si---- The filter carrying the disintegrated coating dried hot air oven higher temperatures these are inadvisable owing the possible decomposition car- bonates organic matter. One point which might noticed during this preliminary treatment, the odor present while the suspension being boiled, has been ob- June 1934, pub- lished Foote Mineral Co., Phila- tween ferromanganese and sodium- silicate solution resulting the for- mation nascent hydrogen and acetylene with several other volatile, odoriferous hydrocarbons. If, there- fore, such odor noticed may safely. concluded that ferroalloys are present. When dry and removed carefully from the filter (taking care not injure the paper) the fimely divided mixture passed through 100-mesh sieve. possible that certain amount material will retained the gauze first, but unless this residue shows evidenec being par- ticularly different from the bulk the coating crushed agate mortar until all passed through the sieve. There are relatively few materials employed electrodes to- day which are much larger than 90- 100 mesh, and when large amount the former size usually homogene- ous and may easily identified, such tungsten carbide. far the identification the components concerned, however, sieve-analysis little value the grain size powdered minerals varies greatly some manufacturers, for instance, employing calcium car- bonate rather coarse marble powder while others use air-floated chalk. Preliminary Examination—As preliminary actual separation, usually advisable examine the powdered coating microscopically un- der direct lighting. Although the author employs binocular microscope magnifying 60X, quite good observa- Since there practically published information arc weld- ing electrode coating compositions, necessary examine the coatings existing electrodes when attempting comprehensive re- search the subject. Since chemical analysis little avail, the author has formulated scheme involving magnetic and gravita- tional separation that gives surprisingly accurate results. The material originally appeared the British journal, Metallurgia. ° tions may made with magnifica- tions low diameters. This micro-examination essentially for the identification organic materials and asbestos, but will also give experienced worker useful indica- tion what substances may an- ticipated the separations. The organic material met with this stage nearly every case form cellulose, usually wood some description. Fig. illustrates the microscopical appearances some the different types cellulose encountered well the micro- scopical appearance powder. Magnetic Separation—The micro- scopical identification minerals direct vision only, without the aid polarized light, one can only attain effi- ciency practice, and well experienced worker can occasionally dispense with any further examina- tion. With the recent ad- vances the manufacture welding electrodes, however, the complexity the coating composi- tions renders direct visual identification matter increasing difficulty, es- pecially IG. ap- the differ- ent types cellulose en- countered, well as- bestos powder. Wheat flour x30 Wood flour ° amounts different ferro-alloys are used. After the preliminary microscopical examination, therefore, the mixture extracted with bar magnet over paper; this will remove iron powder, magnetite, and little the ferro- molybdenum and ferrochrome. Elec- tromagnet separation then carried out the residue the usual petro- logical manner. The electromagnet employed the author similar that described The Methods and Calcu- lations,” London, 1921. essentials its construction are, core soft iron some in. long, bent U-shaped with curve in. Cotton fibres x30 Asbestos powder Rice THE IRON AGE, April 19, 1945—63 n h n- ae ns ve, TABLE Solutions and Mixtures for Density Separation Components Per Cent Methylene lodide Methylene Methylene lodide Thallium mercurous nitrate internal diameter give arms about in. long which are bound opposite directions with seven layers turns each S.W.G. wire. The two movable poles piece are in. wide and in. thick. Using the source current 8-volt cell the moderately magnetic substances are attracted poles in. apart and feebly magnetic materials poles in. apart. The orthodox technique its use, however, considered some- what tedious that the current has switched off enable the grains adhering the poles removed with camel’s hair brush. avoid such tedious operation the author inverts the magnet and places tray kraft paper over the poles shown Fig. The sides the tray are reinforced with thin and the corners one the long ends left unsecured form hinged side which will turn down and facilitate removal the contents the tray. The inner sur- face the tray marked with two lines, thus producing three visual divisions which are marked con- secutively A(m); B(+); and C(—). The material under examination placed the portion the tray marked C(—) and the magnet ac- tivated electric current. After passing the mineral mixture over the poles the magnet moving the container backwards and forwards, etc., the tray moved sideways that compartment above the Density poles. The more highly susceptible materials remain above the poles while the tray moved and are de- posited section The process repeated until further grains fol- low the magnet into compartment’ strip card then placed along the line separating the sections and Employing shorter distance be- tween the poles, the sideway move- ment the tray repeated and the less attractive particles are deposited compartment Thus the original mixture divided into four portions corresponding the sus- ceptibilities its ingredients: Highly magnetic (extracted the bar mag- net); moderately magnetic (m) weak- magnetic (+), and non-magnetic (—). constituents commercial electrode coating, that one more these sections will represented apparently homogeneous powder; this homogeneity confirmed microscopical examination, further separations need carried out upon that portion the material which may then identified the con- firmatory tests indicated Section Where the material each com- partment heterogeneous, however, suspension liquids varying den- sities, described below. One further point must borne mind, i.e., the possibility impurities substances rendering them more amenable TABLE Ill Electrode Coating Constituents Classified Magnetic Property and Densities Group 1.—Highly magnetic: Magnetite, iron powder. Group 2.—Moderately magnetic: Ferromolybdenum, ferrochromium. Group 3.—Weakly magnetic: ferrovanadium, hematite, hausmannite, pyrolusite. Group 4.—Non-magnetic—D 2.45: flour, bentonite, graphite, asbestos, gypsum, Group 5.—Non-magnetic—D 2.45, 2.69: Bauxite, feldspar, kaolin, Group 6.—Non-magnetic—D 2.69, 2.90: 64—THE IRON AGE, April 19, 1945 talc, sodium flouride, dolomite, wolla- Group 7.—Non-magnetic—D 2.90, 3.10: Cryolite, biotite, Group 8.—Non-magnetic—D 3.10, 3.30: Carborundum, enstatite. Group 3.30, 5.3: Lime, magnesia, alumina, siderite, rutile, Group 10.—Non-magnetic—D 5.3, 13.5: Ferrotitanium, chromium, ferromanganese, nickel. Tungsten powder. magnetic separation than would the pure material, for example, the inclusion asbestos fibers small amounts magnetite, etc., would lead the occurrence asbestos com- further, the case carborundum, the methods its manufacture are iron the finished product, which might lead the finding this ma- terial also theoretically incorrect division. Density process necessary employ liquids varying specific gravity. densities 2.9 bromoform/benzol mixtures may employed, the em- pirical values for some these mix- tures being shown Fig. From 2.8 3.8 admixtures methylene iodide with benzol are used, the nom- inal densities attained trated Fig. will seen from Table that these liquids are applicable only the non-magnetic materials and that one-third these have densities higher than 3.3. view this fact the author reverses the usual separa- tion procedure that employs methylene iodide those bromoform. The operation separation these liquids well known; for those not familiar with the technique, however, reference may made the works Holmes’, and Raeburn‘. Petrography,” 3rd Ed., London, 1940. Prospecting,” London, 1927. After the “sink” and “float” process has been carried out with methylene iodide mixtures, the heavy minerals are separated via tap funnel, filtered off and washed the usual way with benzol. Further separation the heavier material may then carried out the use thallium mercurous which the fused state has density 5.3. the materials heavier than this, tungsten powder may separated the use mer- After removal filtration the solids suspended the separating media, the filters and their contents are dried sand bath. The benzol, bromoform and methylene iodide em- ployed are subsequently recovered distillation, and employed for further separations. use solutions the composi- tions indicated Table II, pos- sible subdivide the non-magnetic substances into eight sections, that the employment magnetic and density separations groups the coating materials are obtained (Table Ultimate Identification—Group plete soluble thus state. density identifi the pos iron and/or mind the wide the this advant put entiati two mium the tests Gro tween Detect specifi either are upon micro: hausn black black, steel. actior Per Cent The fused fus substar and the the The two members this group may separated with ease the use fused thallium fusion mixture the three substances, magnetite, iron powder and the thallium salt, will found cooling that possible cut the melt two, thus attaining com- plete separation. Since the salt soluble water, the powders may thus obtained the disintegrated state. Apart from the detection the thiocyanate reaction, the density separation sufficient for the identification this group, although the possibility contamination the iron powder ferromolybdenum and/or ferrochrome must borne mind and the heavier fraction from the melt separately tested for and given the following section. Group Although there fairly wide difference between the densities the two ferro-alloys constituting this not possible take advantage and reliance must put upon chemical tests only. Differ- entiation may made between the two alloys identification chro- mium and/or molybdenum the use the benzidine and a-benzoin-oxine tests Group The main difficulty this section lies the differentiation be- tween hausmannite and pyrolusite. Detection manganese the group the bismuthate method will not specifically indicate the presence either them, and their densities are relatively close, one must rely upon visual identification under the microscope; this comparatively simple, for under direc