The Iron Age 1943-06-10: Vol 151 Iss 23

JUN 1943 a 10, 1943 | ich | al if 3 ind } it Fine uniforms don’t make fighters ... nor frills and gadgets spell crane performance. why Vic- tory Cranes are built with just what takes the job. Built efficient wartime methods, THE IRON AGE, published every Thursday the CHILTON CO. Philadelphia under act March 1879, vearly North America and South America, Foreign $15. Vol. 151, No. Whiting standards. Sturdy, Whiting Victory Cranes are geared smooth- -running, reliable—Whiting meet today’s needs. They are designed Victory Cranes are guaranteed without gadgets non-essentials, their job. any construction which requires extra cranes are needed increase labor and special, hard-to-get materials. your plant output, get the facts once Although production streamlined Whiting Victory Cranes. Whiting for the quickest possible delivery, every Corporation, 15601 Lathrop Avenue, OVERHEAD TRAVELING CRANE q PORATION other principal adian bsidiary: Corporation (Canada) Toronto and Entered second class matter November 1932, the Post A a \/ { \\\ 4A = ; q | —— VAN DEVENTER President and Editor BAUR Vice-President General Manager Editorial and Advertising Offices Johnson, Market Research Baur, Typography and Regional Business Monagers New York New York 100 East 42nd St. 100 East 42nd ROBERT BLAIR FITZGERALD 1016 Guardian 428 Park Philadelphia Chicago Chilton 1012 Otis PEIRCE LEWIS WARREN Detroit Hartford Conn. 7310 Woodward Ave. Box RAYMOND KAY Los Angeles 2420 Cheremoya Ave. Owned and Published CHILTON COMPANY (Incorporated) Executive Offices Chestnut and Philadelphia 39, Pa., U.S.A. OFFICERS AND DIRECTORS GRIFFITHS Vice-President EVERIT TERHUNE Vice-President VAN DEVENTER Vice-President BAUR Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary CHASE THOMAS KANE Member, Associated Business Papers lished every Thursday. Subscription North. America, South America and $8; Foreign, year. Single Copy, cents. Annucl Number, ° ° ° ° ° Office at 42nd St., New York 17, The IRON AGE Vol. 151, No. Editorial The Enigma Technical Articles Kirksite Die Casting Technique Tool Reclamation Improving Fatigue Strength Machine Parts Testing X-Ray Counting Tubes. Spot Welding Aluminum Clad Steel Reclamation Porous Metals Magnesite Refractories Low Temperature Spraying Metals Steel and the Post-War World ° ° ° Features News Front Assembly Line. Washington West Coast Fatigue Cracks Dear Editor News and Markets This Industrial Week 48-Hr. Week Steel Brings Confusion Coal Strike Forces Shutdown Furnaces Women Play Role Accurate Ore Grading Bars and Plates Top April Steel Output Complacency over Scrap Might Changed Fewer Contracts Rewritten than Expected Additional Data Steel Expansion Procedure Given for Component Scheduling Answers Clarify Component Scheduling Personals and Obituaries Machine Tool News ...... Non-Ferrous Metals News and Developments Non-Ferrous Metals Prices; Scrap Prices Iron and Steel Scrap News and Prices Comparison Prices, Year Finished Iron and Steel Prices. Steel and Warehouse Prices. Stainless Steel, Tool Steel Prices Semi-Finished Iron and Steel Prices Pig Iron Prices Ore and Coke Prices Ferroalloy Prices Index Advertisers June 10, 1943 100 105 108 110 112 117 148 154 155 155 158 159 160 4 thanks WPB directives, ain have warehouse ears the demand has taxed have rehouses. CMP For two for Steel our productive capacity been unable supply our But now anticipation are shipping sub- stantial all branches. inquiries for immedi- ate requirements High-Speed Steels, Tool Steels, Die Steels, and Drill Rod. your telephone. requirements, solicit your 4 ge a wi x 5 ESTABLISHED 1855 ° ° ° VAN DEVENTER President and Editor BAUR and Manager DIX Manager, Reader Service ° ° Markets Editor...D. JAMES ° ° ° Associate Editors MacDONALD BARMASEL BUTZNER BENEDETTO Editorial Assistants SCHIEN WILLIAMS BUTTERS Regional News and Technical Editors CAMPBELL Pittsburgh 428 Park PHAIR Chicago 1012 Otis MOFFETT Washington National Press Bidg. BROWNE Washington National Press Bidg. LLOYD Cleveland Guardian BRAMS Detroit 7310 Woodward Ave. OSGOOD MURDOCK San Francisco 1355 Market St. Editorial Correspondents ROBERT Cincinnati PENLEY Buffalo FRAZAR Boston HUGH SHARP Milwaukee SANDERSON Toronto, Ont. RAYMOND KAY Los Angeles JOHN McCUNE Birmingham ROY EDMONDS St. Louis JAMES DOUGLAS Seattle The Great Enigma editorials are written one week advance publication. Things happen fast nowadays that one likely year be- hind the times ventures publish something that written the day before yesterday. Today going write about John Lewis, the bushy eye- browed commander-in-chief the coal miners. Mr. Lewis has what takes commander-in-chief, not merely word, but fact. has the super ability command obedience not merely spoken orders but unspoken ones. This exceptional talent keeps him out the “hoosegow” while the same time taking his fol- lowers out the mines. Mr. Lewis had actually ordered strike our most essential in- dustry and thus threatened the cause for which 129,500,000 other Americans are fighting, could have been clapped jail cool his heels and read Shakespeare under any number laws relating conspiracy, sabotage what have you. But canny John, like Br’er Rabbit, just sets still and says nothin’. His followers are mind readers. Not that think should clap John jail. That would the final blow the remaining self respect those unfortunates who are already there, many whom have announced their desire permitted fight for, rather than against, their country. Personally, think that there would much better way dispose him, the law permitted. Namely incarcerate him the cage Gargantua the great, Ringling Brothers’ circus, where might quite well feel home, both appearance and disposition. But here again, may doing Gargantua injustice. But let’s get back fundamentals. Let’s grant, Attorney General Biddle has said, that have labor government today the United States. Don’t you believe, do, that labor were free express its con- victions would overwhelmingly favor doing everything pos- sible win this war, regardless the sacrifices entailed? you don’t believe that then your future outlook indeed dismal one for labor constitutes far the larger part our population. not believe that the great mass American labor likes see little minority that wears the Lewis collar defy and outface the com- mander-in-chief our Army and Navy and President the United States. that came pass would about time call strong man like Joe Stalin who, apparently knows how drive his horses. the time this ppblished, this thing may settled. But unless settled the complete elimination one John Lewis from both labor and political power, more than his ghost will arise again haunt us. q d : 4 | Only four operations are necessary form diameter in. deep cylinder that part shell container used the Navy. the first operation 18-in., 19-gage, blank, cut from Inland deep drawing sheets, formed into cylinder in. diameter in. deep. The sec- ond operation reduces the diameter in. and increases the depth in. the third operation 7-in. 8%-in. cyl- inder placed bottom end over the lower die. The upper die, pressing against Dearborn Street, Chicago Steel Cylinders- Sales Milwaukee, Detroit, St. Cylinders, drawn diameter Drawn from Inland the bottom the 7-in. cylinder, forces into the lower die, turning the cylinder inside out while reducing the diameter in. and increasing the length 12% in. the final operation 6-in. cylinder placed over the upper die which forces through die, drawing the cylinder final size, diameter in. deep. These cylinder forming operations, like many other difficult war jobs, are proof the uniformity and high quality Inland flat rolled steel products—products that are being used 100% for Victory. ,£ turned inside out and reduced to-6 in. diameter. ves The serious and sinister growing race problem Michigan plants believed many factory executives definitely the work Axis agents. Surplus war property, exclusive plants, will amount least $50 billion after hostilities cease, and may $100 billion hot potato. Jockeying has already started the coming ill-defined but bitter conflict between the concepts using the material good advantage and disposing with minimum impact interests any sort. Any conceivable disposition will arouse convincing critical attack. Incidentally, plenty scandals grew the sale only billion surplus after World War Kaiser's pig iron and steel slab ingots are getting almost drug the Pacific Coast. About 900 tons slab ingots have been offered Inland, but sale. This week, the 900-ton Ironton, Utah stack (moved from Joliet, and rebuilt) Steel Corp. blows in, and this will contribute further the temporary western overbalance pig iron, the indicated pig iron surplus being about The Fontana, Cal. plate mill probably won't able take slab ingots until early November. Geneva, Utah, the Steel Corp. can't into plate production until delivery the slabbing mill, which will best Captive mines are exploiting metallurgical coal reserves drastically that quality continues deteriorate. Poorer quality and inability accumulate stocks are also the result widespread development and retreat mining currently taking place. The Navy persists the cushy habit ordering steel marked for particular vessel, with per cent overage. Now some 800,000 tons overage, more than half plates, has overflowed Navy Yard storage facilities. Inventory experts are breaking down the mess. Shortage has turned German industry use Geiger Mueller counting tubes for metal testing. While not good film and fluorescent screen for small defects, the method superior for large area defects, differences wall strength, corrosion under linings, etc. Germans also use test fuses for gunpowder charge defects. Now that the shell program has been cut back per cent sizes other than and mm., several shell and bomb plants are rapidly converting the production steel shell cases sizes from 155 mn. Bomb production off because this country slated supply only the needs the Far East and Pacific theatres. save shipping space, steel rounds and seamless pipe will shipped England increasing pace, and England will make all shipping space likewise has dictated the sending four complete steel drum fabricating plants Africa and the Near East. Flat stock will come from this country. America outselling the British nine one Chile, but still Americans, little jealous, continue moan that Britain sending ship metal goods month that country. The steel industry, two years after Victory, will operate about per cent war time capacity provided million the country's million employables have achieve this degree prosperity, manufacturing, for instance, must per cent more jobs than ever before peace time. Sponge iron again enjoying political favor. North Carolina continues shove ads all the major papers; and are breathing the idea using South Dakota lignite with Minnesota iron oxide produce steel making metallic. The unique wide Rohn cluster mill that has had long experimental run, primarily stainless, the American Steel Wire Co. plant, will soon broken down for reconstruction into conventional cold mill. The Rohn layout was intriguing and gave plenty experience the effect rolling variables, but production unit wasn't hot. i : G | Pes, be | 4 3 : re convey | . shing | | : | abundance potential pitfalls lurks the casting Kirk- site dies. The die can very easily spoiled the melting pour- ing the alloy. The sand mold requires careful preparation. But following the precautions carefully here, extremely rapid die production possible. ULL advantage the rapid die Kirksite “A” can realized only the pattern shop, foundry and ma- chine forming departments work to- gether toward the casting dies produce the best fabricated parts. This requires, the part the plaster pattern maker, complete study the number parts fabricated, the method fabrica- tion, the press hammer operation, metal factors, and the most economi- cal method which the die may cast. Accuracy important the slightest error costly the final assemblies. The working and hand- ling wood patterns well plaster another essential qualifica- tion the plaster pattern maker. With this sort care and co-oper- ation, drawing for simple die can submitted the pattern shop and hr. later this die will producing parts. This course does not apply large dies which sometimes take much hr. solidify and cool sufficiently for handling. the foundry, essential require- ments are floor space which not cramped, and service overhead crane sufficient capacity handle the heaviest die cast. Due the low melting point the alloy (717 deg. F.), the manufacturer kettles pots the gfollowing analysis: per cent carbon ........ 3.00 3.50 manganese .... 0.60 0.75 ......... 2.00 2.50 chromium ..... 1.10 1.20 molybdenum ... 0.40 0.60 60—THE IRON AGE, June 10, 1943 Kettles pots this composition should normalized 1200 1400 deg. for hr. and allowed cool slowly for least hr. and prefer- ably hr., room temperature. The inner surface should ground smooth before normalizing. this composition, the maganese, nickel and chromium are present refine the fired Kirksite pot, capac- LEONARD COSTELLO Procedure Control Analyst, North American Aviation, Inc. and reduce the rate solu- bility the iron Kirksite “A,” while the molybdenum toughens the structure that can better resist the heat shock incident the rapid change temperature starting up. Welded steel kettles are attacked very rapidly molten Kirksite “A.” After the kettle cleaned, heated about 200 deg. and iron oxide solution applied least three coats for protection against the solvent action the Kirksite alloy. The kettle emptied after 200 300 hr. operation and the coating renewed. When the melting pot shut down, small heel the Kirksite alloy ° ° ° ° ° ° | ( ron ast the 300 wn, q allowed remain. lifting hook allowed freeze this heel, provid- ing easy way emptying the kettle with crane. The alloy the sides the kettle peeled off and the rest burned out with torch. The kettle then warmed and recoated with the iron oxide solution. This solution will also prolong the life ladles, skimmers and pyrometer pro- tecting tubes. The kettles are shallow bowl shaped, gas, are sufficient size assure plentiful supply Kirksite for the largest die anticipated, and sufficient diameter for the remelting heavy dies. (Fig. Hand ladles should about lb. capacity. The skimmers consist slightly dished disk thick steel, drilled with generous number in. holes. These skimmers can made steel even wrought iron because they are not subjected the continuous and severe service which the kettle must withstand. After the kettle has been warmed and protective coatings applied, few ingots Kirksite “A” are loaded into the kettle, the furnace turned full and soon the melting starts, additional ingots are added until the desired level reached. Just before the melting complete, the burners should turned low cutting the temperature control, keep the temperature from coasting over the safe maximum. this point there little scum dross the surface the metal. has been found that not economi- cal skim the pot until the drosses accumulate form thick blanket, constant skimming exposes the new surfaces oxidation and increases dross losses. small molds when hand ladles are used, the dross layer pushed back and clean metal lifted from the cleared spot. With larger molds, during pouring into the ladle, skimmers are used the spout lip the kettle remove the scum dross (Fig. 2). After the kettle partially emptied, either obsolete dies ingots are add- raise the level cover the thermocouple protecting tube the controller and avoid oxidizing any alloy sticking the sides the ket- tle above the liquid level. When necessary hold the alloy molten state, the tempera- ture control set 800 deg. higher temperatures are held, iron dissolves from the kettle more rapidly and oxidation accelerated. lower 2—Pouring The more slowly the metal poured, the sounder will the casting. The stream molten metal should not more than in. diam- eter. temperatures are held, some segrega- tion copper occurs. The tempera- ture controls are not changed even there pouring night. Under circumstances stirring necessary with accurate temperature control. Because heat shock the kettle, never started with solidified heel metal it. The old heel replaced soon the kettle one- third filled with molten alloy. cut obsolete Kirksite “A” dies, the only satisfactory method disposing sufficient molten alloy always the kettle provide better heat transfer the die. the die remelted too big fit into the kettle safely, can held the crane while first one and then another corner melted away. Remelted dies, not contam- inated, can treated new alloys. Under this condition, needed. For other operating data metal forming, see the following articles THE IRON “Briggs Aids Aircraft Produc- tion,” Jan. 1942. “Drawing Dies for Airframe Stampings,” May 28, 1942. “Stretch Forming Contoured Sheet Metal Aircraft June 1942. “Forming Convex Flanges and Joggles,” June 11, 1942. “Hydro-Press Forming with Rubber June 11, 1942. “Unique Aircraft Construction Methods,” June 25, 1942. “Multiple Subpress Aircraft Fabrication,” Aug. 27, 1942. “Stretch Forming Speeds Aircraft “Plastic Punches Form Aircraft Sheet Metal,” Feb. 18. 1943. “Production Short Cuts,” March 1943. “Coring Kirksite Dies,” April 1943. Kirksite bearings other finely divided scrap are remelted they are added molten alloy 900 deg. F., little time, and sub- merged with stirring rod skim- mer avoid oxidation. least 50-50 mixture salammoniac and zine chloride per ton scrap makes fairly satisfactory flux and used occasionally. special mix- ture salts, prepared the Lead Co., when stirred vigorously into the remelted scrap most effective separating dirt and oxides that they will float the top the melt. The operation creates heavy choking fumes, harmless but offensive. After the flux stirred in, rest period for the heavier dross particles float the top the melt. The drosses are then skimmed off with little disturbance possible. Skimmings from the pot are accu- mulated and intervals treated the same manner scrap. When the dross dark gray color and light little value. The presence bright metal the dross indicates cient fluxing, too short rest period, improper skimming. The reclaimed alloy cast into pigs and used, little time, with new ingots. Contamination The addition aluminum zinc introduces hazard not present many other alloys. The presence lead tin even very small quan- tities extremely detrimental the aging characteristics zinc-alumi- num alloy, making imperative that only the purest obtainable used making Kirksite “A” and that ex- treme care exercised exclude lead and tin from the melting kettles. little 0.01 per cent lead will cause losses physical properties aging, 0.5 per cent will cause loss one-third the tensile strength THE IRON AGE, June 10, lu- the ist . pid up. A. ls q 3 1 7 f q q and per cent the impact strength and expansion the dies in. per ft., one year normal indoor aging. The effect tin contamina- tion are least serious those lead. Once either these elements allowed get into the alloy, noth- ing can done remove it. The original properties are restored re- melting, but the aging losses again begin soon the recast casting cools. The presence iron quantities greater than 0.25 per cent also harmful and care must taken protect the kettles and all iron tools from direct contact with the molten alloy. The rate solution iron Kirksite “A” increases rapidly with increases temperature. The melt must kept below 900 deg. all times. Excess iron will produce, all ver- tical walls the castings, deeply etched defects resembling borings insect, giving rise the descrip- tive term, “dural-bug-marks.” [ron will float iron-aluminum compound, when the melt held quietly for about hr. 775 deg., and can skimmed off. Molding The necessity using sturdy flasks various sizes, high quality molding sand, and adequate tools cannot over-emphasized. The flasks are made heavy lumber mortized the joints and strengthened through bolts across the ends. The use trunnions the centers the ends the flasks simplifies the task rolling the flasks over, and reduces the danger the sand mold. remove very heavy from the sand smoothly and with minimum rapping, pair lifting bars and clamps (Fig. found great value. The ends the bars, which are long enough extend the width the widest flask, bear blocks resting the side the flask. The blocks, drilled the outside diameter the bars, have threaded end hooks engage eyes set the pattern. Two men with very little rap- ping can lift the largest mold from flask using these lifting tools. The open mold method has proved satisfactory (Fig. 4). the alloy solidifies, molten metal drawn from the heavier sections the lighter, and unless there ample supply molten metal, the forces set the solidification are great enough pull portions the frozen surface inward, causing draws, draw molten particles out partly solidi- fied section, causing porosity. At- 62—THE IRON AGE, June 10, 1943 patterns tempts produce castings having heavy sections closed mold have proved unsuccessful, even though heavy risers were supplied. pro- ducing castings with light walls, the closed mold can used, but even then difficult obtain perfect ABOVE Lifting clamps for remov- ing heavy patterns from the sand with minimum rap- ping. RIGHT Open mold. produc- ing castings with light walls, the closed mold can used, but even then tain perfect cast- ing. The open mold method has proved satisfactory for cast- ings with either light heavy sec- tions. casting. The drag, bottom, surface usually better than the top, cope, side. For open mold casting, flat rein- forced platform having the same di- mensions the exterior the flask used, placed the floor. The pattern laid this platform with the contours the die punch fac- ing up. The flask then placed the platform form fence around the pattern. There should least in. space between the pattern and the nearest point the flask, prevent metal runouts. Sand with low moisture con- tent possible then sifted over the pattern. After the pattern covered, additional sand shoveled and tamped down firmly. provision for venting need made except with very deep dies, which case 1/16 in. vent wires are run down through the sand after the mold turned over, but before the pattern has been removed. The vent wires enter the sand near the flask and are pushed down plank until they touch the pattern. fumes are pro- duced the alloy, but steam from the sand may cause rough spots the bottom die not vented. After the mold has been completely rammed up, the sand scraped off level with the top the flask and cover, called “follow board,” which duplicate the platform which the pattern rests, laid top the flask. Clamps are used fasten platform, flask and follow board firmly together and the mold then turned over crane. Having removed clamps and plat- forms, the flask leveled both directions means wooden wedges under cover cleats, and any loose sand brushed off the exposed bottom the pattern. With stick, the sand adjacent the pattern compacted and smoothed slight level. The pattern then rapped lightly free ne ar ail | su ne all ve off me pil in; = which firmly urned plat- both redges sand sand pacted The free from the sand and withdraw nearly vertically possible lifting bars. Any necessary patching then done the mold and particles sand are removed blowing with the air suction pump previously described. The mold then coated with tale skin dry before the pouring begins. Gating the Casting The casting gated one point only, except when there are two deep sections the mold which are not connected channel through which the metal can flow equalize the levels. Two gates are used such case and levels metal kept approxi- mately equal both sections. Pouring directly into the cavity considered hazardous because washing the sand likely occur and splashes the molten alloy may adhere the surface the mold and freeze. this the rising level the molten alloy apt float these splashes, lifting sand with them and causing bump the casting; float around them without remelting them, causing still more serious sur- face defects. The use various kinds inserts entirely practical Kirksite “A” dies. Chills can where. trouble experienced with draw marks, al- though this rarely necessary. Cast iron steel draw ring beads can anchored place improve wear re- sistance local points the die. Nuts bolts can cast proper position line fastening holes the press platens through the use spiders templates. Handling and Pouring the principal handling method, which has proved satisfactory, baked sand cones form lifting pin holes into which bolts are cast inserts. Holes are cut the outer walls the molds means tubing and lugs the alloy receive the lifting chains. Lifting the dies wrapping chain around them very danger- ous because the hardness and oili- ness the casting. With sand molds prepared, the responsibility for good casting depends upon the man charge melting and the man who pours the alloy. can spoil the casting very easily. The temperature the offset temperature drop metal transferred from the melting kettle the pouring ladle. Increase 900 deg. will also eliminate the danger the metal temperature drop- ping deg. during pour- ing. Holding the alloy below deg. causes segregation copper- 5—Female Kirksite die being heated about 300 deg. F., prior pouring lead punch. rich compounds the bottom the kettle and consequent loss physical properties the casting. Pouring the foundry 800 deg. the ladle gives very satisfactory castings. also important pour very slowly, with stream molten metal not more than in. diameter. This rate pouring permits production two-ton dies free from cold shots folds. The more slowly the metal poured, the sounder will the cast- ing and the less will distortion due inequalities rates cooling (Fig. 2). Gating the mold the lowest pos- sible point, and pouring slowly within approximately in. the top, gives the mold fairly flat bottom. Distortion minimized covering the flask after the pouring with sheet in. asbestos board keep the surface from freezing and set- ting strains tending bow the casting. light cut the planer gives sufficient bearing surface after the mold has been removed from the flask and allowed cool. The finished casting will have least in. the alloy above the high- est point the cavity and the. die the lead the Kirksite die distributed the whole area the die. d a § 4 q q 1 a THE IRON AGE, June 10, has very heavy side walls, may necessary keep the metal the thinnest portion the casting molten state with torch until the side walls have solidified. this not done, migration molten par- ticles from the partially solidified light section will cause porosity that point. Punches All that has been written mold- applies equally punches, dies and stand for fairly long runs light gage metal parts. produce these lead alloy punches, the die surface fitted templates and polished with emery disk flexible shaft grinder. heated approximately 300 deg. F., which will expand the die the metal thickness required (Fig. 5). fence boards built around the die, ex- tended sufficient distance above the cop the die give ample clear- ance between the die and the upper 7—Completed lead punch and die. pressure rings binders, provided each has separate pattern from which sand mold can made. is, however, often the practice cast only the die the punch from pat- tern and produce the mating mem- bers the die-set from this casting. the die female casting chosen the master, the punch can made only material which sufficiently ductile flow under pres- sure the press, fill the space between and the die caused its solidification shrinkage. Antimonial lead has proved sufficiently ductile for the purpose and yet hard enough platen head the press, and braced clamps resist the pressure the molten metal. Fillets made fire clay mixed with three parts lard oil and one part kero- sene are applied all interior cor- ners prevent run outs. After being sprayed with solution iron oxide and water prevent the punch from sticking the die, the cavity filled with molten antimonial lead tem- perature about 800 deg. Pouring not concentrated one spot, but distributed over the whole area the die (Fig. 6). After the pouring finished, bolts held spider are set place provide fastening facili- ties. Fig. shows the completed punch and die. attempting take full advan- tage the beneficial effects anti- mony, the danger point brittleness may reached. Sections the flange the punch even the punch itself may break away under the re- peated impact stresses, and injure the operator the hammer. Much the beneficial effect an- timony achieved per cent addition, giving maximum tility measured elongation. actual practice the foundry North American has achieved the best re- sults using per cent antimony. For use forming presses which not deliver such sudden blow, safe use harder punches. Since the lead punch proves too soft and ductile for satisfactory use with the heavier gage aluminum al- loys and for steel and Inconel, necessary produce punches Kirk- site “A”. With sufficient amount protective coating over the die and the proper pouring technique, satis- factory results have been achieved through the same method used for casting lead punches. Finishing the Dies the pattern and foundry work has been done well, little fitting necessary match the punch the die and pressure ring. produce perfect parts, has been found ad- visable polish the dies with fine abrasive disk flexible shaft. What little work necessary the dies can best performed with set scrapers and various shaped burrs, bits and abrasive disks flex- ible shaft grinder. necessary, Kirk- site may sawed, drilled, milled and planed very rapidly. preparing the dies for try out, all emery dust, steel chips and dirt must removed from the die set be- fore the first stamping.is made. such material remains the dies, the pressure the press imbeds the surface the dies and causes scratch- ing the sheet metal. Tool Reclamation—A Correction the article “Tool Engineers Show Draws Big Crowd,” appear- ing THE IRON April 61, was stated that the No. alloy the Euctectic Welding Alloys Co. has melting point 1300 deg. This incorrect. The “binding tempera- ture” the alloy 1300 deg. F., while the melting point around 1775 deg. binding temperature meant 64—THE IRON AGE, June 10, 1943 the temperature which the parent metal (in this case tool) heated, locally cause the alloy (melted down with torch) flow and bind the heated surface. The higher melting point the alloy little importance torch work since the tool itself heated only the binding temperature. the report also stated that the alloy can used for brazing tools which are subsequently heat treated 2300 deg. The actual statement the speaker was that with its ability withstand higher tempera- tures, the No. alloy has also been successfully used brazing and hardening high speed steel simul- taneously 2300 deg. This must done furnace with reducing atmosphere. ne 3 a | inch anti- ness ange the al- Kirk- and satis- d for work the fine with haped Kirk- milled out, dirt le. the the ratch- tools reated tement its mpera- been and simul- must ducing THE IRON AGE, June 10, 1943—63 Improving Fatigue Machine Parts ALMEN Research Laboratories Division, General Motors Corp., Detroit HILE great strides have been made most phases engi- neering and metallurgy, dynamically loaded parts, more net work being obtained from metals today than was obtainable generation ago. New fabrication techniques have made pos- sible many design improvements, bet- ter bearing materials are available, lubricants have been improved, but the basic useful strength structural materials remains unaltered. Although super-strength alloys have been discovered and such dis- coveries seem imminent, there much that can done increase materially the fatigue strength many machine parts made from ordi- nary structural materials. This fa- tigue strengthening does not require changes design material, and fact does not require processes that are fundamentally new un- tried. merely the extension processes that, the whole, have long and honorable histories and the avoid- ance processes and practices that are now known reduce fatigue strength. The significance these processes has only recently become clear through the introduction new concepts fatigue phenomena which new avenues reasoning are opened us. These new concepts are: Fatigue failures result only compressive stresses, and any surface, matter how smoothly finished, stress raiser. Fully per cent all fatigue failures service dur- ing laboratory and road tests are traceable design and production de- fects and only the remaining per cent are primarily the responsibility the metallurgist defects ma- terial, material specification, heat treatment. While this ratio not measure the quality workman- Dramatic increase fatigue strength pre-stressing com- pression thin layer machine part through peen hammering, swaging, shot blasting tumbling, pressure operations balls rollers has long been realized, but improved technique and theory have lately excited the industry. The author this paper, presented fortnight ago before the American Gear Manufacturers Association, prominent proponent this method ex- tending the life machine elements, and herein brings theory and technique this subject date. ship contributed each department, there can doubt that the metal- lurgist has better appreciation his responsibility for fatigue failures than has the designer, the engineer, the man the production depart- ment. Fatigue Vulnerability The surface repeatedly stressed specimens, matter how perfectly they are finished, are much more vul- nerable fatigue than the deeper layers. has long been appreciated that the vulnerability fatigue in- creases the surface roughness particularly the rough- ness consists sharp notches and more particularly the notches are oriented right angles the prin- cipal stress. The practice carefully finishing fatigue test specimens and engine parts is, course, recognition this vulnerability insofar marks scratches are concerned even down assuring that the final polishing marks are parallel the direction the applied stress. These precautions are known effective increasing the fatigue strength the specimens and specimens finished this manner have, therefore, come known “par” bars. This name implies that fatigue specimens and machine parts approaching perfection finish give the highest possible fa- tigue endurance for any particular material and that they accurately measure the ultimate fatigue proper- ties that material. can shown, however, that the so-called “par” bars are not the best specimens but that influences akin notches, far fatigue vulner- ability concerned, are retained the specimens. seems that the specimen surface highly vulner- able simply because surface; that there extra hazard the surface layer not shared the deeper layers. This extra surface hazard may due notch effects the fact that the sur- face discontinuity since the outer crystals are not supported their outer faces. Whatever the reason for surface vulnerability, the evidence its existence strong. Fatigue Life Increased The fatigue strength the most carefully prepared specimen will increased thin layer the speci- peening operation such peen hammering, swaging, shot blasting tumbling pressure operations balls rollers. This increase fatigue strength resulting from the surface layer being stressed com- pression clearly shown the S-N curves, Fig. which compare nor- mally finished railway THE IRON AGE, June 10, 1943—65 an- cent duc- too use 100 These S-N way axles that have been normally finished with axles have been subjected rolling operation. From this graph, can Cycles failure axles that had been subjected rolling This and other tests show compressive stressed surface effective in- creasing the fatigue strength whether appiied highly finished specimens specimens having rough surfaces. The bar chart, Fig. records the increased fatigue durability resulting from shot peening few typical machine parts. will seen that the fatigue durability increased whether the parts are hard, such carburized gears soft steer- ing gear parts;. and whether the stress completely reversed, crankshafts; the stress range small, preloaded springs. should noted that the fatigue durability peened axle shafts was not increased much most the other specimens. The work these shafts was conducted number years ago before the technique peening machine parts had been de- veloped and the relatively small in- crease was probably due insuffi- sults have been ebtained from large variety machine parts and from aluminum specimens and there are reasons expect that the treatment equally effective for all metals. Fig. shows the fatigue durability 1000 seen that compres- sive stressed surface effective fatique strength. increase per cent gain above the durability the same machine part before peening. Actually, durability comparisons cannot made per- centage basis alone apparent when examining the improvement fatigue due rolling shown Fig. If, this chart, the durability comparison made load equal per cent the ultimate strength, the percentage improvement zero; the durability comparison made load corresponding per cent the ultimate strength, the percent- age improvement infinite and, intermediate loads, the percentage gain will, course, somewhere between these limits. Why Peening Effective The most plausible explanation the effectiveness surface compres- sion that when load applied such specimens the tension stress the surface layer less the amount the compression pre- stress and since fatigue failure starts from tension stress the fatigue dura- bility the weak surface layer increased. Although the tension stress the material below the pre-stressed layer not reduced but may actu- ally increased, the fatigue strength the specimen increased. fol- 900 + Q oO 2—The increased fatigue durability re- | Life improvement, per cen a 200— x 5 100 @ 66—THE IRON AGE, June 10, 1943 sulting from shot peen- ing few machine illustrated. Fatigue dur- ability increased whether the parts are hard soft. gears U-Joint crosses lows, therefore, that the lower layer inherently stronger than the sur- face layer. shows that the fracture rolled specimens does not originate the surface but the material below the pre-stressed layer would expected the surface sufficiently pre-stressed compression. Similar sub-surface fatigue failures usually called fissures and attributed faulty material have long been known occur railroad rail which the surface stressed compression result the cold work heavily loaded locomotive and car wheels. Stress Patterns Fig. represents the residual stress pattern unloaded beam that has been rolled peened, has been described, which C:P and rep- resent the magnitude compressive pre-stresses and represents the magnitude the tension pre-stress balance the compressed stresses the surface. After this beam has been loaded from either side through one stress cycle reversed fatigue test the compression pre-stress will reduced the applied load raises the total compression stress above the yield point. The stress diagram for such pre-stressed beam supporting external load shown Fig. which the effective tension stress the surface may less than the stress below the surface which case failure would start below the surface noted Foeppl. Note also that the neutral axis displaced from the geometric center the beam and that the tension stress below the surface greater than the beam that had not been pre-stressed shown the dotted lines. The magnitude the sub-surface tension stress loaded beam hav- ing pre-stressed surfaces will vary with the amount compression pre- stress and with the depth the pre- stressed layer. The sub-surface ten- sion stress may greater for deeply pre-stressed layer than for layer lesser depth. seems evident that the improve- ment fatigue strength compres- sive pre-stress due the reduction tension stress when loaded the vulnerable surface layer and that the increased compressive stress specimen stressed from zero maximum either direction does harm, probably because adjust- ment compression stress the pre- stressed layer through yield. Further evidence the extra vul- nerability the surface layer found the behavior specimens s essed rface hav- vary pre- ten- for iction the the djust- pre- vul- having increased thin surface layer thinly carburized cyanided specimens thinly nitrided specimens. Fatigue failures such specimens also start below the surface and show greater fatigue strength than the same material the unclad state. nitrided specimen probably the other forms hard cladding because, addition the higher physical prop- erties the surface layer this layer state compression and has, therefore, less notch sensitivity. While the subject beneficial internal stresses, mention should made surface compressive stress obtainable heat treatment. rapid quench possible, through thermal contraction alone, trap compressive stress the surface and corresponding tension stress the core, but this method, although show- ing some benefit fatigue, not effective the other methods that have been discussed. This subject will discussed later this paper. Cold working metals increases the hardness most metals including steel least the range low hardness. usually results in- ternal stresses Varying degrees and patterns, alters the physical prop- erties and sometimes fractures the material. With the known sensitivity that the problem controlling cold work must solved just has been done the control heat treatment order benefit the good effects and overcome the evil. Cold working can good bad, depending upon how done and for what purpose. Several instances are known which the strength machine parts and specimens have been decreased too intense surface peening. The fatigue strength increased the intensity peening rolling in- creased until maximum improve- ment obtained. peening, With more intense rolling, the fatigue strength rapidly decreases below the original strength and the part will damaged due excessive internal tension stresses. would, therefore, seem important control the compression stressed layer stress magnitude and depth with considerable accuracy proper selection the curvature the rolling peening instruments and the pressure that applied. The precise amount surface com- pressive stress that required for optimum fatigue strength known 3—Residual stress pattern loaded beam that has been rolled and peened. and sent the magnitude the stresses and stands Compression for the magnitude the tension pre-stress balance the compressed for few specimens only. will vary with the shape and section thickness the machine part, with the hard- ness and with the kind metal being treated. For the present, neces- sary frequently rely upon the not too accurate sense proportion that developed experience indicate the treatment that should applied any given machine part. When the layer stressed com- pression (by applying sufficient pres- sure the work rollers peening) degree exceeding the yield strength the metal com- pression, the amount residual stress presumably least equal this yield strength. The depth the stressed layer probably roughly proportional the instantaneous area over which the pressure applied, and the pres- sure intensity. The depth the com- pression stressed layer railroad should greater than the depth the compression stressed layer the same material small rollers the same pressure intensity were used instead large car wheels. Under these circumstances, the initial point fracture should appear corre- sponding depths. Such evidence available indicates this true. Overdose Nitriding Although the usual experience with nitriding that greatly improves 4—Stress diagram for beam supporting ex- ternal load which the effective tension stress the surface may less than the stress below the surface. Tension pre-stress fatigue strength, possible over- overdo surface stressing peening and rolling. The high compressive surface stress that results from nitriding must, course, balanced internal tension stress equal total value. When deep nitriding applied light sections the unit in- ternal tension stress dangerous proportions. known that internally nitrided cylinder barrels are more prone fail cracking than cylinder barrels that are not nitrided, since the stress due nitriding added the stress from gas pressure. Care must there- fore used nitriding thin sections gage the depth the nitrided layer proportion thickness the section being nitrided. The carburized layer car- burized part stressed compres- sion graphically shown Fig. Two opposite faces this half-inch square specimen while the ofher two faces were pro- tected copper plating. The speci- men was quenched and tempered the usual manner after which was split with saw shown Fig. The parts are curved convex the outer faces indicating compressive stress these faces. interest here the magnitude the compres- sive stress the carburized layer and the reduced compressive stress, pos- sibly even tension stress, thin surface layer. When carburized parts Compression lar the vily ress has een rep- sive the ress one igue will for ting than elow Note Neutral axis, . component THE IRON AGE, June 10, 1943—67 such bearing races, wrist pins and gear teeth are ground may ex- pected that the surface will the dotted lines shown the right Fig. The residual stress crankshafts and other parts hardened induction heating and probably also flame hardened parts resembles the residual With internal stresses the mag- readily why carburized parts are prone warp during heat treatment especially the design not symmetrical with respect the internal stresses. stresses due quenching from relatively low temperatures may reach considerable magnitudes and may harmful helpful fatigue durability depending upon whether the trapped stresses augment diminish the tension stresses from the applied loads. Corrosion Promotes Fatigue Fatigue failures many machine parts are traceable corrosion several kinds other forms surface damage that occur service. normal machine parts even slight corrosion bruising very potent encouraging fatigue fractures be- cause each pit interrupts the con- tinuity the surface and increases the local stress. The damaging ef- fect corrosion bruising pre- vented the surfaces that are ade- quately protected compressive pre- stress because the local tension stress cannot become dangerously high until the pits bruises have progressed sufficiently penetrate the compres- sively stressed layer. This was force- fully demonstrated fatigue tests machine part that failed alternately badly formed fillet the re- gion clamp remote from the fillet where fretting corrosion occurred. The durability the part could not increased improving the fillet because this would merely transfer all failures the fretted area about the same durability. After peening, however, the fatigue dura- bility was found have increased several hundred per cent and large additional gains were then possible improving the form the fillet without failure the corroded area. The peening did not prevent corrosion but did prevent the ill effect corrosion promoting fatigue. Similar protection against the ef- fects corrosion and surface bruises afforded nitriding,’ car- burizing and other treatments that 68—THE IRON AGE, June 10, 1943 5—The upper and lower faces this port are carburized and hardened, and are stressed compression The specimen was split with saw. The parts are curved convex the outer face, indicat- ing these faces. produce compressively faces. The working face gear tooth may severely pitted, creating fatigue hazard, but the bending fatigue strength may not impaired because the carburized layer com- pressively stressed and the surface compressively stressed the cold work mating teeth. Efforts improve products im- proving surface finish may sometimes have the opposite effect. Highly finished surfaces and fillets may lead false sense security if, the result machining straightening operations, the parts have high in- ternal stresses the wrong kind. When machine polishing done the use abrasive paper cloth wheels, sufficient heat often gen- erated induce serious surface ten- sion stresses and thus promote in- stead prevent fatigue failures. ground surfaces such shafts, wrist pins, and gear teeth, the grind- ing operations may introduce high surface tension stresses that from the standpoint fatigue strength, often more harm than good. The surface tension stresses from grinding are often great produce visible whether detectable not, surface tension frequently very serious. Internal stresses the wrong kind are perhaps the most insidious all fatigue hazards because difficult learn their magnitude the pat- tern which they are distributed within the material whether they are alike for all commercially identi- cal machine parts. Internal stresses may the result operating condi- tions such occur brake drums, clutch plates, sur- faces where the instantaneous tem- perature thin layer great that, under thermal expansion, the surface layer stressed beyond the yield point compression. When the source heat removed, the heated surface layer quenched the ad- jacent cool metal and, under thermal contraction, severely stressed tension that fractures often occur. B—After Splitting This is, course, the same thing that happens machine polishing and grinding unless great care used. Internal stresses often result from the cooling castings and forgings from the vigorous heat transfer heat treating. Many parts, such crankshafts, axle shafts and cam- shafts require straightening during processing. Since the straightening operation usually done room temperature and since the part rarely stress relieved after straighten- ing, the result stres