The Iron Age 1942-08-27: Vol 150 Iss 9

The Germans were getting along first rate World War until confronted this “pitiless energy.” History repeats itself. That energy again the march. Let give unstintingly... keep “ruthless” and “pitiless” NEW BRITAIN-GRIDLEY MACHINE DIVISION AUL AUGUST 27, 1942 trict 18% one and ity, van- Around the Clock—the Months CLEVELAND OWNERS give you the WORM £ —the Years! quieter times, performance was measured hours, months, years. Now, minutes are the unit. Cleveland Worm Gear Speed Reducers make every minute count keeping machines continuous operation. You doubt have been impressed the frequent comment have shutdowns,” others who have bought scores hundreds Clevelands. Many these customers installed their first Cleveland Units years ago applications subject heavy shock loads, yet have had need for replacement maintenance any time. Count Clevelands keep your machines going. The same caliber Engineering ability that has developed standard and special Cleveland Worm Gear Speed Reducers for years, available for applying them your particular equipment. The Cleveland Worm Gear Co., 3252 80th Street, Cleveland, Ohio. Affiliate: The Farval Corporation, Centralized Systems Lubrication Canada: PEACOCK BROTHERS LIMITED THE IRON AGE, published every Thursday the CHILTON CO. (INC.). Entered second class matter November 1932, the Post Office Philadelphia under act March 1879. yearly North America and South America, Foreign $15. Vol. 150, No. AUGUST 27, 1942 ms VAN DEVENTER President and Editor BAUR Vice-President and General Manager Managing Editor, LIPPERT News Markets Editor, ROWAN Technical Editor, OLIVER Associate Editors JAMES Art Editor, WINTERS Editorial Assistants BENEDETTO Resident District Editors Washington Pittsburgh DONALD BROWNE PHAIR Washington Chicago Cleveland Detroit CHARLES POST San Francisco Editorial Correspondents Buffalo Cincinnati FRAZAR RAYMOND KAY Boston Los Angeles HUGH SHARP JOHN McCUNE Milwaukee Birmingham SANDERSON ROY EDMONDS Toronto, Ontario St. Louis BACON Seattle ° ° DIX, Manager Reader Service ° ° Advertising Staff Herman, Chilton Bldg., Philadelphia Hottenstein, Otis Bldg., Chicago Raymond Kay, 2420 Cheremoya Ave., Los Angeles, Cal. Leonard, 100 East 42nd New York Peirce Lewis, 7310 Woodward Ave., Detroit Ober, 100 East 42nd St., New York Warren, Box 81, Hartford, Conn. Johnson, Market Research Hayes, Production Manager. Baur, Typography and Layout. ° ° ° Member, Audit Bureau Circulations Member, Associated Business Papers Indexed the Industrial Arts Index. lished every Thursday. Subscription Price North America, South America and Possessions, $8; Foreign, year. Single copy, cents. ° ° Owned and Published CHILTON COMPANY Executive Editorial and Offices Advertising Offices Chestnut and Sts. 100 East 42nd St. Philadelphia, Pa. New York, U.S.A. U.S.A. OFFICERS AND DIRECTORS MUSSELMAN, President JOS. HILDRETH, Vice-President GEORGE GRIFFITHS, Vice-President EVERIT TERHUNE, Vice-President VAN DEVENTER, Vice-President BAUR, Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR Secretary JULIAN CHASE, THOMAS KANE, HARRY DUFFY CHARLES HEALE This Week in... Editorial Miracle Men Happen Technical Articles Features Assembly Line Washington West Fatigue Cracks Dear News and Markets This Industrial Week News Personals and Obituaries Non-Ferrous Machine Tool Activity Scrap Comparison Prices Finished Steel Prices Warehouse Index Advertisers Iron and Steel Scrap Prices. Cupola Practice with Multiple Subpress Dies for Aircraft Tool Conservation the Navy Drop Hammer Forming Aircraft Induction Heating Brazes 300 Pieces Hour. Carbide Dies for Drawing Metal Copyright. 1942. by Chiltes Company (ine.) 116 from RAW STEEL the BATTLE LINES! But Ryerson Cuts the Corners T’S long way from raw steel finished tools war—from plates, structurals, bars and sheets—to planes, tanks, ships and guns! Helping keep steel moving quickly and smoothly all the thousands that must come ahead final assembly Ryerson’s part the war production job. Ten big Ryerson Steel-Service Plants, conveniently located serve the nation, provide reliable source for emergency steel quickly available keep arteries war production flowing. This the vital function these steel warehouses are performing. And, spite today’s emergencies, when required stocks are not always immediately available, Ryerson engineers, laboratory technicians, and steel-service men usually find way supply industry’s war needs. Time and again, Ryerson stocks and Ryerson ingenuity, have been able supply steel vital the steady flow war production when first seemed impossible. Whatever your steel requirements line with the WPB system—the experience and resources this cen- tury-young steel-service organization are yours com- mand. Phone, wire write the nearest Ryerson plant. You'll get quick action once. Joseph Ryerson Son, Inc., Chicago, Milwaukee, St. Louis, Cincinnati, Detroit, Cleveland, Buffalo, Boston, Philadelphia, Jersey City. | q ° AUGUST 27, 1942 ° ° ESTABLISHED 1855 Miracle Men Don't Happen MERICANS are, whole, enthusiastic, impetuous and impatient. They believe miracles. And miracle men. “Look Henry they say. “There miracle man for you. built one the greatest industrial plants all time from small black- smith shop little more than quarter century.” “Look Charley Schwab. There was another miracle man. organized and built the two largest steel companies the world, and Bethlehem.” “Look Thomas Edison, the great inventor. Miracles were his spe- cialty. waved his wand and out the hat came the phonograph, the incandescent lamp, the motion picture industry and thousand new “Why get miracle men such these Washington take charge our war production program,” people ask. hear any more about shortages and bottlenecks could find such men and put them work for us.” Now there this fact that must recognized about miracle men. They not just happen. They are made. Some them, the real miracle workers whose works endure, are self made. Others are built printers’ ink. Beware the latter you may find you are helping build another ballooning Insull edifice whose foundation sand instead rock. takes time make genuine miracle worker. Time and environ- ment. Ford, Edison and Schwab did not flash meteor-like upon the Ameri- can horizon overnight. They did not build their businesses their repu- tations overnight. They did not month, year, two years. took them each least years hard and brilliant effort carve their initial niches the hall accomplishment. And are impatient because one year, our men Washington have not completed industrial edifice thousand times larger and more complex than any private industrial undertaking. And takes environment make miracle workers perform. Environ- ment which they can produce their best. which their initiative and abilities have full play, the shackles petty jealousies and partisan politics. could summon Ford, Edison, Schwab and other our past and present miracle workers and send them Washington manage war production, they could not accomplish one whit more than the excellent men who are working for there today. The Washington environment not conducive the production industrial miracles. You cannot good work where there elbow room and where the congestion authority such that people are continually treading upon one toes. Overcentralization always detrimental efficiency. Chicago would better location for the WPB than the Capital, and New York better for the OPA. have real miracle workers now but they cannot produce their best miracles the suffocating hot-bed political intrigue and position jockeying. Get them away from this, and arm them with the authority decide and act, and you will see real miracles made short order. <4 1 Time have war the cen- com- a Gertie’’ Goes War Inland Mine Hoist Makes Scrap for Hungry Furnaces help meet the critical need for scrap, auxiliary some day.” Holding old machinery, stacks, tanks, tools, mine hoist once affectionately known “Gertie,” was jigs, dies, even partly finished parts, for possible taken out retirement one the Inland ore mines future use commendable practice ordinary times. and shipped the company’s mills Indiana Harbor. But this war—total war—and everything made The need for scrap urgent that “Gertie” was cut steel, that not being used produce for war, ought and fed the hungry Inland furnaces the day she scrapped and started its way the steel mills arrived the mill. She was rolled into stee! plates once. and soon will part Liberty ship carrying vital Many steel mill furnaces are down, while millions tons war supplies the fighting fronts. needed scrap remain unreclaimed. The scrap situation typical many pieces equipment critical now and will become more critical winter factories, mines, etc. throughout the country. Replaced approaches, unless management American industry modern electric hoist several years ago, this old gives authority scrap old equipment and materials. mine hoist was stored because inhandy you can’t use it. SHEETS STRIP TIN PLATE BARS PLATES FLOOR PLATE STRUCTURALS PILING RAILS TRACK ACCESSORIES REINFORCING BARS Wor Yy Z yy q bi % fbr, Ur, 7 ‘ j 4 f fe “Gertie” was cut and fed the Inland day ived the the Inland furnaces the day she arrived the | Dearborn Street, Offices: Milwaukee, Detroit, St. Paul, St. Louis, Kansas mills, Practice with Briquettes HAMBLEY and KENNETH GEIST Allis-Chalmers Mfg. Co., Milwaukee With many plants turning cast iron and steel briquettes effort make the deficiency nor- mal scrap supplies, this review cupola practice Allis- Chalmers, where some 1500 tons briquettes are used monthly, especially timely. The authors discuss this, the first two articles, the segregation borings and turnings, the briguetting press room setup, press mainte- nance, briquetting practice, costs, effect oil turn- ings, and making charges. The second article will published succeeding issue The Age. briquetting steel turn- ings and cast iron borings, while not new process, has increased leaps and bounds the last few years. While there were few briquetting machines installed prior 1938, installations since that time have quadrupled several times. The earlier installa- tions were used mainly briquette cast iron chips resulting from ma- chining operations castings. The shortage many types scrap normally used melting has forced many plants turn briquetting source, source which will, the war production effort rises, produce tremendous tonnages borings and turnings. Many opinions have been express- both pro and con the quan- tity briquettes that can used cupola charge. Many claims have been made costs, die re- placement, scrap losses, melting losses what have you. Many fav- orable comments have been heard, well many exaggerated tales, the unsuitability the ma- terial. 1939 the Allis-Chalmers Mfg. Co., after careful consideration the possible savings, installed its first briquetting press. This press was operated continuously three shifts day, and from Nov. 1939, June 1941, 8180 net tons cast iron borings and 6402 net tons steel chips were briquetted. The successful use these materials the cupola charges led the in- stallation second press. Two briquetting presses are operation Allis-Chalmers the present time. One runs continuous- crushed steel chips, while the other alternates cast iron bor- ings and steel chips. There avail- able around 600 tons cast iron borings per month and over 1000 tons steel chips from the ma- chine shops. This amount bri- quetted material has made the com- pany’s foundries independent other sources scrap and has en- abled Allis-Chalmers sell steel plants its accumulations plate and miscellaneous steel scrap. The salvaging cast iron bor- ings from the various machine shops done without any attempt segregate the different classes iron. This done keep the costs tate handling. Since there are machine shops working the great variety products that make equipment for the electrical and heavy industrial fields, any attempt segregation different irons would indeed costly operation. all these machine shops there THE IRON AGE, August 27, 1942—39 S. is n = may seen castings process machining, ranging from high test irons high silicon, low carbon content, silicon-high carbon irons, and including irons with silicon content varying from 0.90 per cent 2.50 per cent. though, when the bor- ings are all mixed, loaded gondo- las magnet cranes and dumped into the hopper the press, the average analysis stant, with the silicon content aver- aging 1.75 per cent and the carbon content 3.30 per cent. This check- sentative sample and analyzing it. trouble has ever been encoun- tered from segregation. the pro- portion alloy irons base irons used here small, the possibility trouble from this source mini- mized. Separation Chips Steel chips are salvaged under two broad headings, subdivided in- many finer separations. The first salvaging operation the separat- ing all alloy chips from the non- alloy. The alloy chips are then sep- arated into classes according analysis and sold users who can utilize the alloy contents. The non- alloy chips are separated into two divisions. The extra heavy chips resulting from the heavy cuts taken ma- are kept separate from the lighter chips. The heavy chips are sent directly the foundries where 40—THE IRON AGE, August 27, 1942 +. they are weighed the cupola charges and used is. The lighter chips are taken the stockpile for crushing and briquetting. The lighter. chips which were taken are run through crusher, chip breaker. This machine made the Amer- ican Pulverizer Co., St. Louis, and hour. order obtain high density briquette, these steel chips are run through the breaker twice. The crusher setup shown Fig. The cost this operation in- cluded the total cost quetting steel chips, discussed later this article, and quite low due the capacity the machine. The presses, which are products the Mil- waukee Foundry Equipment Co., Milwaukee, are adjacent the No. foundry. They are located under high track which allows the chips and borings delivered bottom dump gondola cars the hoppers that feed the presses. Each hopper holds about car and half chips. Fig. No. shows the set- No. briquetting machine with its discharge into ring. the foreground can seen pile steel briquettes. The briquettes are handled from the ring crane and are either loaded cars for shipment No. foundry East Side No. foundry, sent the stockpile. The inside briquetting press room with the dust collector Ma- chine used for crushing ‘steel turnings into shorter lengths suitable quetting. setup shown Fig. This col- lector used only cast iron bor- ings which are dry and dusty. When use, screen having 3g-in. openings used catch the tramp iron and prevent from en- tering the dies. The long conveyor seen under the hopper discharges the borings onto this screen placed over the hopper. Careful sorting material the men who collect the borings necessary keep out all tramp iron and foreign material. The press operator must alert see that tramp iron allowed enter the dies, this decreases their life and causes breakage. This par- ticularly true steel chips when the screen re- moved. The borings drop into the dies the press and the ram forces these borings the die against the anvil block with hydraulic pres- sure 1500 lb. per sq. in. the release the ram, the briquettes are discharged from the bottom the die into trough which feeds them onto conveyor. This con- veyor elevates the briquettes and discharges them into ring, the outside, shown Fig. The pressure the ram developed oil and each press has 300 gal. medium heavy oil circulation. Press Maintenance The maintenance the presses very low, with the exception the dies. Dies are hardened steel | bor- usty. the en- eyor rges aced iron ress that nter life par- ting re- dies rces the res- the ttes and the The IG. Bri- quettes from No. briquetting machine dis- charge into the ring shown this illustration. From here they can handled over- head crane. the foreground stockpile steel briquettes. and are in. diameter. They are used interchangeably either cast iron borings steel. The aver- age life the dies around 330,- 000 briquettes and cost around $400. These are forged and hard- ened the company’s forge shop. When operating three shifts day and six days week, the dies are changed every two weeks and whenever possible they and fitted with oversize ram. requires two men four hours each change set dies. Very little trouble ever encoun- tered when briquetting cast iron and possible obtain longer die life this material, but Allis-Chalmers briquettes month’s accumulation these borings nine days, obvious that the press must then take over steel which much harder the dies due the fact that steel chips are larger. Steel chips are also springy, curly, and ductile and the ram comes press them, they tend drag, and work the sides between the die and the ram. This tends slow the stroke that while the press will average strokes per min. cast iron bor- ings, will average only steel chips. When briquetting cast iron bor- ings the dust collector (Fig. quickly set up. requires about one hour connect. the press averages strokes min. this means cast iron briquettes. They are in. diameter and and have density per cent per cent solid piece cast iron the same size. Running three shifts day, each press could turn out from tons. The average operating time for three IG. 3—A bri- quettes from showing the dust collector posi- tion. This collec- tor used only with cast iron borings. ° ° ° lotted for cleaning the machines and delays will average min. While true that the delays will not occur every day, this figure represents the average. The cost briquetting ton cast iron borings approximately — $1.90. This figure has been arrived over the period these presses have been operating and include all applicable charges. The three main items this cost figure are labor, depreciation and repairs. might well mention here that the cast iron briquettes will oxidize rust storage. While this only skin deep, would well consider having the bri- quettes pass through slurry cement, done several manu- facturers briquetted material, the briquettes are stored out- side for any length time. Allis-Chalmers uses all its supply each month, has never considered this necessary. Rusty oxidized borings not affect the operation the press. Even what appear excessively oxidized borings make briquette that metallic and shiny. When briquetting steel chips, the presses are run without the dust collector and the screen. The chips are fed directly into the press hop- per and the operator must watch for tramp iron. these chips are oily, they are dust free. The press squeezes out very high percen- tage this oil, but con- glomeration many different cut- amount oil retained the bri- quette keeps from rusting oxidizing storage and steel bri- quettes have been stored for year without any sign oxidation. The press will average steel briquettes per min. There are length. They run per cent density when compared with piece solid steel. Their weight lb. each. Due the smaller size the briquette, press will average from tons day when running three shifts. The average lost time 150 min. day since longer time alloted cleaning and the average time lost for repairs min. The aver- age cost briquetting steel chips approximately $2.35 per ton, in- cluding the cost crushing. Uses Briquetted Materials Allis-Chalmers has always tried maintain open mind concern- ing the amount briquetted mate- rials generally regarded stand- ard usage. say that any certain mission inability cope with the problems knowing what obtain good metal. Any lim- itations the use briquettes should due the quantity avail- able and the economic factors in- IG. 4—Borings being fed into press hopper. The press operator must catch all tramp iron, etc., here. this ma- terial gets into the press, consid- result. volved, since knowing how han- dle the metal when tapped from the cupola problems the percentages con- tained the mixture. This com- pany uses high per cent the total charge and low per cent. Briquette Charges The cupola operators the three foundries here much prefer use briquettes over any other type material due the uniformity the resulting iron. Since they are given the responsibility see that all charges are weighed and charged correctly and any lack uniformity the analysis chill tests invariably blamed pocr supervision and lack proper charging, makes their tasks that much easier use materials that insure this uniformity. That they prefer briquettes other scrap recommendation itself. Allis-Chalmers makes many ble one paper list them all, but show the uses briquettes have detailed the main mix- tures. There are around 600 tons cast iron briquettes available month and the charges are fig- ured that they are used each month. the present time, the total steel content most mixtures which amounts approximately 800 tons per month. There one slight exception this rule—that the first four five charges the bed contain bri- charges that are put top the bed before the blast turned and are allowed soak. This done only eliminate nuisance caused the oil the bri- quettes. This oil causes dense white smoke for the few minutes before the flame reaches the charg- ing floor can eliminated using two good torches the charging door. soon the temperature the charging door high enough and the flame reaches it, the oil consumed combustion. Rather than create nuisance, chances are taken and the briquettes are left off these few charges. This applies only the steel briquettes and not the cast iron. Ed. Note—The second and concluding article this series will published next issue. | q | a i \ han- the con- com- cent W as hree use are that and chill pocr oper that that they lany all, ‘ttes mix- tons able the ures tely five bri- the ned bri- nse ites rg- the her ces are his tes ing the same way that known that plain carbon steels are water hardening, has been long recognized that they are shal- low hardening, and that alloy ad- ditions increase this depth hardening. But for many purposes the cost alloys not justified, and now course, alloys are not always available. McQuaid and Ehn, early 1921, were really looking for criterion for hardenability when they discovered the relationship between the normal and abnormal hypereutectoid structures and the tendency develop soft spots the surface carburized parts. Out this investigation devel- oped the McQuaid-Ehn test for austenite grain size. Soft spots are simply areas which the cooling rate has been less than the critical and which, therefore, the depth zero. For certain types tools essen- tial that the depth hardening sufficient prevent the devel- opment soft spots and still not great but that soft core left which prevents cracking quenching service. 1926, metallurgist for Ingersoll- Rand, was vitally concerned with the development control test which would assure depth hardening. early rec- ognized, did McQuaid and Ehn, Hardenability Steel ° ° FOCKE Research Metallurgist, Diamond Chain Mfg. Co., Indianapolis ° ° The use large alloy additions means achiev- ing deep hardening must revised and greater atten- tion given controlling hardness depth other means. Tests and procedures for doing this are summarized this, the second series three articles. that plain carbon steels con- trolled chemistry alone was not sufficient provide this assur- ance. For this purpose, Shepherd developed his P-F test, and the publishing his paper this subject 1934° and his presenta- tion this material before many the chapters during his term president the ASM 1935 may considered have marked the start popular interest quan- titative hardenability. Naturally, Shepherd did not work alone this problem. had been actively studied all the tool steel pro- ducers and that connection the work Luerssen the Carpen- ter Steel Co. particularly note- worthy’. Actually, the P-F test has never won wide acceptance, that is, extent that tool steel suppliers would commonly list the P-F char- acteristics their steels their handbooks. Probably this caused part the fact that relatively few users buy tool steels suffi- cient quantities justify detailed specifications and also the nat- ural desire the tool steel sup- pliers keep their customers pur- chasing trade names. Regardless its failure win wide acceptance, the P-F test discussion quantitative harden- ability because takes into con- sideration all the factors which subsequent procedures have had consider. The size the speci- men was kept constant in. round in. long, the cooling rate was established specifying the handling the test piece into water standard vertical jig, the materials normally used were all essentially eutectoid plain car- bon tool steels that the maxi- mum hardness was constant and the effect variations between lots this same material, the same lot varying the pre- treatment hardening tempera- ture could measured noting the distance from the surface which the test piece showed full hardness. This was the part the test. The part dealt with the grain size which was measured com- paring the appearance the frac- tured surface with that set standards which fortunately coin- cide very closely with the ASTM method. This introduction Shepherd lead ASM symposium THE IRON AGE, August 27, 1942—43 — ° ° a | | 4 hardenability the annual meet- ing 1938. this symposium Mehl introduced the subject excellent discussion the “Physics which showed how the effects grain size, rate nucleation, and rate growth controlled har- denability and how physical chemical approach the effects these factors may separated and measured quantitatively. this work which Mehl and his as- sociates have continued and which culminated his brilliant Camp- bell Memorial Lecture last fall which showed for the first time that troostite was definitely finely lamellar pearlite, means the electron miscroscope 30,000X. Burns and presented de- tailed information the harden- ability plain carbon steels using cluded all the elements the P-F test but expanding cover ranges carbon contents from the hypereutectoid less than 0.10 per cent. With this range carbon the maximum hardness was longer constant that Burns had previously” introduced method hardenability measure- ment which the surface hard- ness (S), the average (A) under the hardness penetration and the center hardness (C), measured the Rockwell scale, were used. Burns and Riegel were able . formulas worked out Burns and Riegel are used developing the factor abscissa this chart low, medium, and high carbon steels. show that the analysis the steel (C, Mn, Cr, Ni, and Cu) were known for plain carbon steels, the part their SAC rating could calculated from series empirical formulas. These formulas are follows: For between 0.10-0.35, 2000 500 500 (Cr-0.05) For between 0.30-0.50, For between 0.50-1.00, and the relationship between these (factor) values and the (Rockwell) values shown Fig. this same symposium Quen- eau and Mayo” presented paper “Hardenability and its Desig- nation” which they expanded discussion which they had pre- sented the original Burns, Moore, and Archer which they showed that where the depth hardened case, the radius the round, and the diameter. The straight line which results designated the “hardenability line.” Fig. shows series hardenability lines for steels with various values calculated from the Burns formulas. The value the ordinate and value 0.5 must therefore represent full hardening across the section and usually designated the “critical” size. the abscissa are plotted the values and, for con- venience, the values corre- sponding these ratios are shown also. The work really set the basic principles used this analysis. necessary call attention what meant depth har- dening used these relations, and this can probably done best referring the paper Gross- mann “Relation Hardenabil- ity can shown that round bar steel sufficient harden- ability and length least five times its diameter quenched from the state, the outer sections will martensitic; and the bar diameter great enough, the rate cooling from the surface toward the center will decrease until less than the critical rate and some troostite will form. This troostite increases amount rapidly with only slight most the martensite disappears. the bar cut carefully mid- length and etched HCl. the outer martensitic etch less darkly. The diameter IG. 7—A series hardenability lines for various steels, with various values calculated from the Burns for- mula. 0.500 0.400 0.300 H/D 3-600 HCF 0.200 4-800 MCF 5-1000 LCF “Fine-MC 0.200 H/D 0.100 400 500 600 800 900 040/050 0.80090 1.0 Factor 44—THE IRON AGE, August 27, 1942 | | full and con- own set this tion har- ons, best und len- five hed the tic; reat rom iter han tite ght ntil ars. nid- will of Martensite 50% 50% Pearlite Critical Rockwell hardness 100% Pearlite Distance from surface the unhardened core can meas- ured, more accurately, the area this core can estimated counting squares using transpar- ent cross section paper and the diameter calculated this traverse can made across the piece two diameters. plot these Rockwell readings versus distance from the surface would result curve the type shown Fig. the microstructure associated with these hardnesses were studied, would found that the hardness drops off the amount troostite increases and some point there are approxi- mately equal parts both. The hardness associated with this per cent martensite-50 per cent troostite structure called the “critical hardness.” The choice this point somewhat arbitrary but justified the fact that corresponds that point which the slope the hardness-depth curve maximum. That is, this slope great that wide differ- ences amounts martensite troostite will not greatly change the distance from this point the center; which distance, the critical hardness, one-half the diameter the unhardened zone, Du. Another reason for choosing this point corresponds very closely with the junction between the two types surfaces developed etching. That this critical hardness difficult establish accurately the weakest part the method, although practically and particu- larly, the results are checked both Rockwell traverses and etched areas the accuracy will good enough. The lower dashed line Fig. shows the relationship between critical hardness and carbon con- LEFT IG. across two diameters and plotted against their distance from the surface hardened oO Rockwell hardness Oo steel bar. ° ° ° 30 RIGHT IG. be- tween critical hard- ness and carbon con- tent (after Grossmann). tent for plain carbon steel. The effect alloys raise this value somewhat within the range indicated maximum shown the upper dashed line. Fig. shows diagrammatically the effect varying the diameter rounds the same material quenched from the same tempera- ture into oil and water respec- tively. The cross-hatched areas in- dicated the unhardened zones. might profitable recall here that Grossmann simply modified the Shepherd method include variations diameter and quenching media but keeping the other factors con- stant. possible show the same data the basis the re- sults hardness traverses, diagrams the type Fig. for the oil quench and Fig. for 513 Martensite Plain alloy a 301 236 0.20 040 060 080 Carbon, per cent water. Actually, these curves should all symmetrical about the center line, but has become customary show the complete section and such diagrams have companies’ handbooks. Because their character and shape they are commonly designated curves. Grossmann’s main contribution lies his use the diameters the unhardened cores measure the severity the quench. Using either the diameters the unhardened cores Du, obtained from the cross-hatched zones Fig. 10, from the hardness tra- verses recording the diameter less than the critical hardness for each the sizes quenched, se- ries values, such shown Table II, would developed. quench Water quench ing the diameter rounds SAE 3140 quenched from the same temperature into oil and water respectively shown this diagram- matic representation etched cross sections (after Grossmann). Uy pp ALS Yi 695 0 | f ' Y; =. A, Af 3 THE IRON AGE, August 27, 1942—45 Diameter bar Rockwell hardness Distance from center, inches hardness Diameter bar Distance from center, inches IG. distribution curves for SAE 3140 steel quenched oil, another way showing the phenomenon illustrated Fig. (after Grossmann). The Du/D versus values Table may then plotted shown Fig. from which clear that the shape the curve controlled the drasticity the quench. Grossmann and his associates showed some com- plicated mathematics based Newton’s law cooling (which states that the rate heat flow proportion the temperature difference), and the fact that the thermal diffusivity constant— that these values Du/D were plotted against using logarith- mic scale for shown Fig. 14, then the drasticity the quench could determined moving this Fig. over the chart shown Fig. until the curves match. For illustration, this ar- ticle, this procedure was followed but the results plotted their corresponding lines Fig. 15. Each line corresponds constant known for each value Du/D, the drasticity the quench, can readily obtained. For example, from Table III for LEFT IG. Plotting the Du/D versus values 46—THE IRON AGE, August 27, 1942 Table shows graphi- cally that the shape the curve controlled the drasticity the quench. ° ° ° RIGHT IG. Logarithmic values have been sub- stituted for the arithmetic that this curve will the same scale Fig. 15. 0.5 Fig. but for SAE 3140 steel quenched water. 3140 quenched oil, when in. Du/D equals 0.24, and this point the matching curve equals 0.62 and therefore equal 0.5. Similarly, for the water quenched, when in., Du/D 0.35; and this point the curves Figures and are properly matched, the values will 0.5 and for the oil and water quench respectively for any Du/D. these methods was orig- inally shown that the common in. 0.80 methods quenching have val- ues follows: Method Cooling Value motion water... .1.0 High velocity Moderate motion 4.0-6.0 High velocity more Later tests indicate that these values are too high, particularly for the more violent quenches. The figures“ Table are prob- ably more nearly correct. defined above discussing the hardenability lines Fig. the critical size that diam- eter which the unhardened core (that section with hardness less than the critical) just disappeared, and for the 3140 steel used example the diameter the crit- ical size becomes 1.2 in. for oil quench 0.5) 1.8 in. for water quench 0.5) The next problem was obtain measure hardenability inde- pendent the quench. this, Grossman developed the concept the ideal critical size that diameter which the unhardened core would just disappear the piece were quenched myth- ical manner that the would infinite. first glance, would appear that the quench rate were in- finite, any size piece would harden completely; but again, must recalled that all such quench would accomplish would cool the surface instantly but the rate any point the surface would still depend upon the heat conductivity (thermal diffusivity) the steel, which finite value. the same mathematical and basic assumption used previously, Grossmann developed the charts shown Figs. and 17. Knowing the critical size and the values which produced it, the ideal critical size can determined following across horizontally Fig. from this value the curve represent- ing the value which this was obtained and then drop- ping vertically the base line and reading off the value the ideal critical size Theoretically, the samples used for the two quenches illustrated had been identical, the for both the oil and HxD IG. dots this chart indicate where the curves Fig. were superimposed obtain quantitative measure the drasticity the quench (H) (chart after the water quench should the same. Actually, shown Fig. the from the oil quench data 2.45, while from the water only 2.2. This difference becomes relatively insignificant when compared with the range ideal critical size for various SAE anal- yses Table The results Table are re- corded graphically Fig. terms total alloy. The effect small additions molybdenum, particularly when with other alloys, strikingly illus- trated the differences between 9140 (No. and X9140 (No. 11): 3240 (No. 10) and 4340 (No. 13); 5140 (No. and 4140 (No. 9). his latest paper “Hardenabil- ity Calculated from Chemical Com- position” presented February, 1942, before the AIME, Gross- the hardenability per cent accuracy the “com- plete” analysis, dentals (residuals) such chro- mium and nickel and the grain size are known. other words, has simply extended the work Burns and Riegel referred above, but using his concept IG. between ideal critical size critical size D., and severity quench Open scale for steels with low hardenability (Gross- mann, Asimow and Urban). Values THE IRON AGE, August 27, 1942—47 1.2 Values Values Fig. Fig. but for steels with higher hardenability. able determine various multipli- cation factors for each the com- mon chemical elements and for grain size. his paper, his re- sults are shown series charts from which the hardenabil- ity can calculated. From his studies, isolating the effect each element arrived several interesting conclusions, for example: (1) That the first small addition element has much more powerful percentage effect than greater additions, that two elements have equal effect, greater hardenability will result from using equal parts both rather than one only, (2) Total alloy, per cent 48—THE IRON AGE, August 27, 1942 that manganese actually powerful hardening agent molybdenum, and (3) that even medium carbon steels with carbide forming elements such chro- mium, with without molyb- denum vanadium, sufficient un- dissolved carbides may remain after common heat treating re- per cent the hardenability. Perhaps the most useful contrib- ution Grossmann has made his concept the that shows that simply increasing the dras- ticitv the quench will not pro- vide complete hardening the sec- tion exceeds certain well-defined limits. LEFT illustration the results Table RIGHT IG. ship between ideal critical thick- ness critical thick- ness and severity quench Open scale for steels with low hardenability. (Grossmann, Thickness his paper “Hardening Char- acteristics Various Grossmann demonstrated how these concepts could applied shapes other than rounds. Using the same fundamental assump- tions before, developed the charts shown Figs. 19, and 21. From these the data obtained for rounds may calculated flats this manner: Measure Du/D for enough samples establish and then De. From Fig. 17. The ideal plate thickness in. the critical thickness for the values desired. From Fig. determine the thickness the unhardened core for this value and and plate thickness actually used. Obviously, plate data were known and those for rounds de- sired, the operation would re- versed. For illustration this: Using the 3140 steel before for which the was ratio the unhardened core full plate thickness in. would be: (Since steps and are 3.0 L. — 1.4 4.2 set off base, follow curve intersection with vertical repre- senting actual plate 3.0 6.0 caiculate D,, using Ideal critical thickness how Jsing ump- the and 1ined ough then ising mine the core and were de- the are 0.65 hardened core. From practical standpoint, any method quenching various rounds laborious and difficult, particularly the hardenability increases when the number pieces prepared, quenched, sectioned and traversed becomes large and, because many rounds sufficient diameters are not readily available. Part these objections were eliminated Greene and Post" for shallow hardening steels using conical specimen shown Fig. 22. They showed that for any quenching medium, the crit- ical size for the steels tested was equal the diameter the cone that point which the critical hardness occurred along the cone axis, provided that the hardenabil- ity the material was such that for this quench this point occurred not more than ins. from the tip. The writer has found that using these cones made from lot SAE 1045 for which the ideal critical size (D,) had been deter- mined other methods, the value his laboratory and pro- duction oil and water quenches could measured and compared quantitatively. For example, as- suming that the value for this sample 1045 was 1.50 and that when Greene and Post cone this material was quenched the laboratory oil bath and sectioned, the critical hardness Rockwell was found in. from the tip; then from geometry di- rect measurement, the diameter the cone that point would in., and from the intersections the dotted lines Fig. this would show that the value the laboratory oil quench was about 0.3. This method has also proved very useful determining the value special quenching oils compounds. Also was really eliminate many the difficulties encoun- tered quenching various sized rounds that Jominy developed the method, sample such shown water one end only. Since its introduction Jominy the ASM Hardenability Symposium 1938, has been subjected va- rious modifications and critical which only last January, Thickness Ideal critical thickness 20—Same Fig. but for steels with higher hardenability. (Gross- mann, IG. for estimating severity quench plates. (Grossmann, With Figs. 19, 20, and 21, hardenability data obtained from rounds may transposed into equivalent figures for flats vice versa. Fig. 22—Conical specimen for shallow hardening steels. Greene and Post. 1942, resulted its acceptance the SAE its proposed standard procedure for hardenability test- This standard procedure re- quires that the piece normal- ized before quenching, mits modifications mutually agreed upon. The writer feels that while desirable normalize first when comparing steels for general information, for practical applications the pretreatment should more less than that which the part will receive THE IRON AGE, August 27, 1942—49 ° ° ° | urve ° ° production. For the standard specimen the orifice in., the free water height in. and the With these fixed, the quench rate fixed the water-cooled end and therefore the rate cooling all points along the bar estab- lished. When Jominy test watched for the first time, the slow rate which the tempera- ture back from the water-cooled drops below the visible red striking. After cooling this way for ten minutes, two flats 180 deg. apart and 0.015 in. deep are ground the entire length the sample and Rockwell hardness readings taken 1/16 in. intervals. The results are then plotted shown Fig. 24. The shape and position these Rockwell hardness-end distance curves alone are sufficient estab- lish the relative hardenabilities different steels, but not pos- sible apply these data directly the solution practical prob- lems. However, again, using the same concepts cooling rate described above, possible correlate Jominy data with ideal TABLE Effect Variations Diameter and Quenching Media Critical Hardness SAE 3140 Steel Diameter Unhardened Cores, (Du) In. Du, In. Diameter Bar, (D) In. Oil Quench Water Quench Oil Quench Water Quench 2.0 0.7 1.00 0.35 1.6 0.64 1.9 0.69 2.2 0.73 3.3 0.82 TABLE 0.24 0.86 0.97 1.00 Calculation Values Superimposing the Curve Fig. Oil Quench That Shown Fig. 15, SAE 3140 Steel Water Quench 134 0.5 7.5 0.5 8.8 0.5 1.0 0.5 Distance from quenched end, sixteenths inch IRON AGE, August 27, 1942 0.53 0.69 8.4 0.82 12.0 TABLE Revised Table Values for Various Quenches Method Cooling Oil Water Brine Mild circulation 0.30-0.35 1.0-1.1 2-2.2 Moderate circulation................. 0.35-0.40 1.2-1.3 Good 0.40-0.50 1.4-1.5 Strong circulation................ 0.50-0.80 1.6-2.0 ° ° LEFT IG. Re- sults Jominy and quench tests SAE 1045 and SAE 3140 steels. critical size and thus obtain prac- tical usefulness. Editor’s note: This the second series three articles. The conclusion, next week, correlates the test data, giv- ing practical application the substi- tution SAE 1045 for SAE 3140 steel gear blank. Bibliography Hardenability Charac- teristics Tool Steel,” Shep- herd, Transactions, A.S.S.T., Vol. 17, 1930, 90. “The P-F Characteristics Shepherd, Transactions, A.S.M., Vol. 22, 1934, 979. Notes Behaviour Car- bon Tool Steel Quenching,” Luerssen, Transactions, A.S.S.T., Vol. 17, 161. “Discussion Paper P-F Char- and Greene, Transactions, A.S.M., Vol. 22, 1934, 979. Physics Hardenability,” Mehl, Hardenability Alloy Steels, A.S.M., 1939, Hardenability,” Archer, Transactions, A.S.M., Vol. 26, 1938, and Its Designa- tion,” Queneau and Mayo, Hardenability Alloy Steels, A.S.M., 1939, 237. ““Some Problems Quenching Steel Cylinders,” Scott, Transac- tions, A.S.M., Vol. 22, 1934, 68-94. Calculated from Chem- ical Composition,” Grossmann, Publication No. 1437, A.I.M.E., February, 1942. Characteristics Various Shapes,” Asimow and A.S.M., Vol. 28, 1940, 949. “Standardization Sought Deter- Steels”; Symposium including papers Werfel, Asimow, Craig, Jominy. Transactions, Jour- nal, Vol. 49, No. 266, July, 1941. “Standardization Hardenabil- ity Tests,” Jominy, Metal Prog- ress, December, 1941. Standard Procedure Rec- ommended for Testing Hardenability Steel,” Journal, Vol. 50, No. January, 1942, 15. Preferred test specimen forged Depth Tap Depth in. Optional specimen IG. Jom- iny end quench test specimens. TABLE Set screws Optional specimen Representative Hardenabilities Cent Carbon Steels Steel Description X9140 1040 T1340 5140 3140 6140 9140 2340 4140 3240 3340 4340 Total Average Alloy None 1.16 (0.9-1.3) 0.2 1.6 (1.3-1.9) 1.0 2.0 (1.7-2.3) 1.0 2.5 (2.2-2.9) 1.9 (2.3-3.0) 1.1 2.8 (2.4-3.1) 3.5(3.0-4.0) 2.8 3.8 1.7 5.0 7.0 (7.0-9.0) 2.9 7.0 THE IRON AGE, August 27, = OS a“ ° ° ° = = = — ——- 0.15-0.25 1.60-1.90 0.15 0.80-1.10 0.10-0.20 1.25-1.75 rac- 0.70-0.90 1ep- 0.20-0.30 17, | Multiple Subpress Dies ECAUSE the fact that air- craft designs have not been frozen and frequent modifica- tions therefore have made subpress type hole punching dies has throughout the aircraft industry. These dies are being used multi- ple perform series in-line out-of-line rivet operations press brakes and both hole punching and notching opera- GEORGE WALES President, Strippit Corp., Buffalo punching equipment attached the reciprocating ram the machine which they are used, press brake stamping press. The ram merely strikes the top the punches and depresses them through the material. the up- stroke, the floating stripping guide, Fig. shows cutaway view type Wales subpress die designed for use punch press. general, Wales dies may set three ways: templates, T-slotted plates and the rails press brakes. Where runs are large repeated frequently, punch- ing and notching dies may mounted steel templates in. thick, Fig. the desired points where the holes are punched, in. holes are drilled accommo- date pilot pins the bottom the holders. The holders are fastened regular shapes punch presses. strips the punch from the work. BELOW 2—This sketch shows group hole punching and corner notch- ing dies mounted the same template. The two long rails extend several inches ahead the dies and form ledge which the sheet placed before being fed into the dies. tooling accommodate changes design, the use interchangeable tions are being performed which descends with the punch, ABOVE mounted adapters press brake. This disassembled and cut-away view shows the simplicity construction these units. Punches, and springs may removed from the stantly. Lower die has light press fit the cast iron holder. Guide button slip fit the upper arm. These Wales dies were invented 1932 and found ready acceptance the aircraft industry long before war was ever thought of. The prin- ciple all these dies, which cov- ered patents construction and method using, that they are self-contained units having the punching elements carried indi- vidual holders which also carry the die elements. unnecessary, therefore, for any part the 52—THE IRON AGE, August 27, 1942 | For Aircraft Fabrication signed rails are in. points nched, the stened notch- extend sheet Rails which support and guide the work into the throat the holders are also fastened the template with countersunk screws from the bottom side. Usually, the rest bars and gages are left place and stored with the template suitable racks, Fig. while the units are current work. The accuracy these dies depends upon the accu- racy with which the templates are but once the templates are drilled, the production duplicate parts assured. The same dies may used with- out mounting template at- taching them T-slotted plate, platen. Location the dies achieved means pilot plugs in- serted place the punching units that engage holes one the pilot blanks thin template the part perforated. Fig. shows series airframe bulkhead notching dies being lo- cated T-slotted plate means template. Since the notching punches are uniform cross-sec- Frequency design changes aircraft sheet metal parts makes highly desirable use low cost die sets for punching rivet holes. The interchangeable subpress type hole punching dies are widely used the industry because the arrangement the dies can changed suit various rivet pitches matter minutes. They are also suitable for notching operations bulkheads and the like. tion throughout their length the template may laid against the tops the dies where the punches protrude against stripping spring pressure. Note the use guide rails for supporting the stock the die level. Assemblages large numbers these dies can made and slid onto the bed press, ready operate without any further adjust- ment tryout. Fig. shows set- hole punching dies mounted T-slotted plate perform operations three different blanks each stroke the press. The same dies may also used 3—Simple racks made welded structural steel and pipe for storage special templates with rails, but without units place. These may attached with screws few minutes when needed. This procedure permits maximum utilization tools. press brakes attaching them mounted standard press brake