The Iron Age 1945-08-16: Vol 156 Iss 7

VAN DEVENTER President and Editorial Director BAUR Vice-President General Manager AGE Vol. 156, No. August 16, 1945 Editorial LEONARD Assistant General Manager HAYES Advertising Manager JOHNSON, Manager Reader Service and Market BAUR, Production Manager Cleary, Technical Research and Promotion Manager ° ° Executive Offices Chestnut and Sts. Philadelphia 39, Pa., U.S.A. Technical Articles Editorial and Advertising Offices Flash Welding All Steel Regional Business Managers Effect Heat Upon Residual 100 East 42nd St. 100 East 42nd St. ROBERT BLAIR GIBBS Cleveland Pittsburgh Precision Founding (Part Determining Surface Resistance Aluminum for Welding 1016 Guardian 428 Park Bidg. New Heat-Resisting Iron 7310 Woodward Ave. Box Los Angeles 2420 Cheremoya Ave. Features j MUSSELMAN, JOS. HILDRETH, President GEORGE News Industry EVERIT TERHUNE Vice-President BAUR Vice-President Vice-President News and Markets JULIAN CHASE Vice-President WILLIAM BARBER, Treasurer Electronic Gaging Device Perfected -Loans Seldom Used Dow Announces New Polystyrene Product.............. 136 Low Tool Priority Delays Nonferrous Metals News and Comparison Prices Week and 156 Finished and Semi-Finished Steel Prices 158-9 Warehouse and Steel 160 Iron and Steel Pipe and Tubing 161 Exceptions Steel Price 162-3 Stainless Steel and Ferroalloy Prices .................. 166-7 | | | | | | | | | | | | | | | | | | | | | | | ¢ | | | | | | | | | | | = | | | | | f | | | | | | | | | q | | Ne. | | a | 46—THE IRON AGE, August 1945 Massive pieces, like this Gear Case Sec- tion, exemplify the ability Mahon handle any size type welded steel plate fabrication for any purpose. COMPLETE SERVICE FROM DESIGN DELIVERY Since Mahon first started fabricating Welded Steel Bases and Frames for the machine tool industry, scores other industries vestigated and adopted the many advantages that Welded Steel Plate Fabrication provides. Lighter—stronger—smoother finished ap- is, most cases, less costly, also. Address Inquiries Reduces scrap and saves machining costs. Our design engineers are prepared long experience thoroughly analyze your product and advise you parts and fittings can pro- duced better and less expense through the use welded steel plate construction. Your inquiries will receive our careful attention. STEEL PLATE DIVISION Machine Bases and Frames Many Other Welded Plote abricotors ESTABLISHED August 16, 1945 ° ° ° VAN DEVENTER President and Editorial Director BAUR Vice-President and General Editorial Commercial CAMPBELL News Edifor ....... JACK HIGHT Editors WINTERS BARMASEL Editorial O'CONNOR MILLER Regional News and Technical Editors LLOYD Pittsburgh 428 Park Bidg. POST Chicago 1134 Otis Bidg. MOFFETT EUGENE HARDY ANSBORO Washington National Press Bidg. LLOYD Cleveland 1016 Guardian Bidg. BRAMS Detroit 7310 Woodward Ave. OSGOOD MURDOCK WORTH HALE San Francisco Market St. Correspondents ROBERT McINTOSH Cincinnati DEAN Buffalo FRAZAR Boston HUGH SHARP Milwaukee SANDERSON Toronto, Ont. RAYMOND KAY Les Angeles JOHN McCUNE Birmingham ROY EDMONDS St. JAMES DOUGLAS Seattle Wonderful EACE—it’s wonderful.” Such the slogan Father Divine and the basis manages dish out the chicken his followers. Perhaps that thought was the mind Senator Vandenberg proposing American industrial peace parley. Certainly internecine does not put chicken the table, money the till cash the pay envelope. War never won anybody anything except headache. are go- ing find that out connection with the defeat Germany and the shortly coming victory over Japan. This last war, will admit, seemed unavoidable, but might not have been unavoidable had developed some other way adjusting differences. And supposing that had, how far ahead and how much better off would all today, both victors and vanquished! The United Nations Conference San Francisco will not solve the problem peace between nations but start that direction. got people together. did the Potsdam meeting. Getting together and knowing each other the first step the necessary many that must take place before any complicated structure, physical, political eco- nomic, can erected. Labor here America stay. And so, hope, for the sake labor management. They are not interchangeable. And necessary both and the future the public capital. Not the capital that spelled with capital “C” but that which represented the savings the millions ordinary people, such ourselves, which indeed today are the principal source investment new and going enterprise. glad that Senator Vandenberg has made his suggestion for employer-employee peace table. matter who settles the bill for the lunch that occasion, and perhaps will Uncle whatever costs will worth lot more than millions that might spent lost strikes and shutdowns. are going need every ounce construc- tive effort give our people what they need and what they want make for the deprivations war, and every hour and day lost from now unnecessary conflict simply another nail our mutual economic coffin. glad that our new Secretary Labor, Mr. Schwellenbach, Johnston, president the Chamber Commerce, Ira Mosher, president the National Association Manufacturers and Green, president the AFL, have already expressed approval this plan writing. Philip Murray has long been record with Eric Johnston such plan. Under such auspices, should get off good start. And start ali that anyone can expect any fundamental movement, ternational domestic. Provided these representative can agree upon certain fundamentals plan and procedure, well objectives, believe that the great majority ordinary citizens will fall line behind them. Peace any price indeed expensive luxury. But peace bought fair price bargain. It’s “wonderful.” 3 ii | JOHN ANTHONY SCHIEN Special duty trucks gather steel samples for the laboratory. truck unloaded mmediately starts mother round trip. samples are unched rough wm, then milled. are sawed, drilled, required. samples un- rgo rigid chemical its. tests impor- for quality con- Operator determining physical properties one the many tensile testing machines the Inland laboratory. Darting from mill building mill building—many times day, and night—are Inland trucks special duty, duty vital interest every user Inland steel. They are the sample trucks which rush samples Inland products the main laboratory where all required tests must completed, reported and checked against specifications before steel shipped. Samples are gathered for the lab- oratory semi-finishing mills—pieces from billets, slabs, etc., that will tested before the steel rolled into final form. Also collected are samples finished products. Depending upon requirements, every piece delivered the Inland laboratory undergoes rigid physical, chemical, and metallurgical tests. Many these tests are special developments Inland—tests that are fast and extremely accurate. Yes, Inland daily tests tons and tons steel assure every customer that his order will measure every requirement. Strip Structurals Tin Plate Track Accessories INLAND STEEL COMPANY — Pp! tz News Front Application alloy steel rings flash welding used extensively the production mild steel rings results not only cutting material costs but materially reducing expensive machining. The welding cycle must carefully adjusted produce sound welds since the presence high carbon and alloy elements necessary for toughness, hardness strength the finished product introduces factors having marked effect welding characteristics. hot forming magnesium alloy sheet, the use electric heating for large, irregular forming tools has been found the most efficient and adaptable method. Experiments heating tools gas and electric have not yet included induction heating. This method seen have definite possibilities and should investigated the near future. Upwards 800,000 passenger vehicles may produced this year, instead the 250,000 quota originally established. The addition trucks this total may swell the volume close 900,000 units. Ford especially fortunate position the production race, and may possibly build more than the original quota figure himself. Production got under way July with 359 cars completed, and plans call for 4,000 August. Changeover new models 1946 may unusually early, most builders will anxious get into production improved cars. The West Coast, affected less the end the European war than were other sections the country, expects more affected With the withdrawal the Steel Corp. from the Geneva mill acquisition race, Colorado Fuel Iron looms the No. contender. formal proposal lease along these lines now being drawn counsel for the Allen group, which controls The Allen syndicate continues blow warmly the idea using Henry Kaiser the Geneva operation, although they disclaim interest the Fontana mill under any terms. Termination hostilities will probably close down Geneva's open hearths and rolling mills fairly promptly. Navy cutbacks already announced will doubtless affect schedules the Utah mill. becomes apparent that the cessation hostilities will find the Red Army occupying strategic portions Manchuria, possibly the richest Chinese province. will enter the peace conference then facing the same impasse this regard did earlier Poland. territory naturally turbulent political history, and some communistic leanings, may see the development some form secession movement for north China provinces. Chicago firm using polystyrene patterns for precision casting obtaining accuracies 0.0002 in. production runs, compared with 0.200 0.003 in. tained from the wax Experiments are now going forward using other styrol resins the styrene group. new firm using polystyrene patterns will start operations Peru, Ind., within the next ninety days. method preserving many types Ordnance equipment cans will require 500,000 tons steel and aluminum sheet and plate. The steel containers, in. thick, are sealed hermetically after the equipment has been placed inside. Braces and frames are used hold the equipment rigid. Sixteen gage sheets will used for the aluminum containers. Since impracticable make aluminum container that airtight, the container equipped with ventilator containing dessicant which balances the pressure and humidifies all air entering the can. This method requires the changing the drying agent, but has the advantage that aluminum does not easily corrode. q J a ~ | supercharger flange rings were flash welded, sized, and finished price about equal the raw material cost under the previous blanking methods. Left: Inlet, in. maj in. min 23/32 in. face 9/32 in. thick, Right: Exhaust, 615/16 in. in. ANY devices are fabricated from, designed around, rings. Due the necessity for high-precision formance and heavy-duty require- ments, many alloy-steel have since the start the war. These demands brought about serious shortage forging ca- pacity for steel rings. Previously, 50—THE IRON AGE, August 16, 1945 Flash Alloy-Steel Rings SCHARF Engineer, Dresser Mfg. Division Bradford, Pa. The flash-welding methods used ex- tensively and satisfactorily the produc- tion mild-steel rings has been applied alloy steel. Herein the products produced and the techniques employed are described most types alloy-steel rings had been made piercing ingot slab, forging mandrel, expanding the desired size series dies; roll working and then splitting into two more short rings before rough machining and heat treating. Many items were punched torch- cut from sheet steel, thus wasting large quantities valuable and special section sub- sequent expensive ma- chining was materially reduced for the super- charger outlet flange rings; in. ODx in. deep, 27/64 in. av- erage thickness. ° ° critical material. result, was inevitable that more rapid and eco- nomical methods production should sought. The possibility apply- ing alloy steel the flash-welding methods used extensively and satisfactorily the production mild-steel rings, was explored and technique mastered. example what was accom- plished, elliptical inlet flange rings and circular exhaust flange rings for aviation supercharger equipment are shown (fig. 1). These rings were formerly blanked from plate ex- tremely high cost and with cor- responding high loss the blanking. These two rings were formed the contours illustrated, flash welded and sized, and delivered the purchaser finished price about equal the raw material costs under the previ- ous blanking methods. Flash welding another aviation ring (fig. not only cut material costs, but due the special section supplied, materially reduced expensive machining. But there were many problems in- volved adapting peacetime methods the production alloy-steel rings for war materiel. Demands were con- siderably more exacting. Alloy steels, selected for highly specialized char- acteristics, require closer control all steps processing. The behavior these steels under various procedures had observed, and processing steps adapted the specific charac- teristics involved. assure the desired end results, ste sio res dit hig sal tro fac wit 521 rou tha the abl tho pro exc bea nes ann chit raw material purchases must care- fully controlled, particularly chemical, physical, and dimensional properties. Alloy steels are sub- stantially more difficult process than mild steels. With lower ductility more accuracy and care are required produce specified form and dimen- sions. The alloy steels have greater resistance permanent deformation, this respect being exemplified spring steel, requiring special meth- ods and tooling avoid spoilage. Ad- ditional steps fabrication may cases less work can done any one step. Heat treatment may required one more stages order return the material proper condition for further working. The presence high carbon and alloy elements, neces- sary for toughness, hardness strength the finished product, in- troduces factors having marked effect welding characteristics, and call- ing for careful adjustment the welding cycle produce sound welds. The manner which these diffi- culties have been overcome can illustrated considering the manu- facture roller bearing path ring with approximate inside diameter (fig. This ring made from SAE 52100 steel and held tolerance roundness 1/16 in. and flatness 1/32 in. addition, essential that the finished ring the weld and the weld area should have appreci- able difference properties from those the non-welded material. This steel most difficult alloy process and was formerly considered virtually unweldable, due its exceptionally high carbon content. Early experiments, however, proved that the alloy could successfully welded under properly controlled con- ditions. can seen from table SAE 52100 chromium steel high carbon content, falling within the general classification stainless steel. Steels containing carbon and chromium pct, virtue their hardness and resistance wear, have become the preference bearing manufacturers. These steels have, primarily, deep hardening characteristic, where the actual hard- ness the finished product nearly uniform from surface center. The raw material forms usually used for rolling rings are bars, plates special sections. this case, square rectangular shaped bars are used. grain structure great anneal the bars. They are also ma- chine-straightened insure maximum accuracy. Rigid and detailed inspec- 3—This roller bearing path ring SAE 52100 has been held tolerance roundness in. and the flatness in. This steel difficult alloyed process and was for- merly considered virtually unweld- able due its high content. thick. tion essential, flaws are particu- larly critical this material. Brinell hardness tests are made several points along each bar. the bending rolls, preferably the pyramid type, the bars are rolled the desired curvature until they conform gage. Care must taken make the resulting rings true size and roundness possible order keep subsequent sizing minimum. the ends the bars are overlapped when roll-bending, the ring trimmed calculated inside circumferential length, sufficient ex- cess stock having been allowed for re- moval the straight stub portions each the bars are cut the exact required length before rolling, press used “dicker” shape the straight end portions conform the desired curvature the ring. The welder shown fig. used for sections sq. in. and trol the operation absolutely es- sential the precision required can- not obtained procedures intro- ducing the possibility human varia- tions. Hydraulically operated and elec- tronically controlled welders produced the most suitable results this type steel. The rate upsetting particu- lar importance welding steel this type. The time, heat, and upset cycle must carefully controlled tests made various speeds upset have shown that too slow too rapid up- set produces unsound welds. Metallurgical examination the welded ring may reviewed refer- ring fig. These micrographs were taken 100 diameters, etched nital, the positions indicated. 1G. 4—This welder used for sections from in. in. and rings in. required precision. THE IRON AGE, August reduced one half, were taken positions indicated. Within the heat affected zone, and the temperature during welding was above the critical, the are large and the area very hard and extremely brittle. After proper treatment, grain refining the weld shown and the heat affected zone Spheroidized structure shown “A” the unaffected area. “B” the view directly the line the weld, and “C” the immediate heat affected zone, welded. clearly indicated that the ring, out- side the heat-affected zone, good ma- chinability and workability exist. Within the heat-affected zone, how- ever, the temperature during welding was above the critical, with the re- sult that the are large, the 52—THE August 16, 1945 area being very hard and extremely Hypereutectoid steels such SAE 52100 have been observed having maximum hardness 600 (746 Vickers) extreme cases hardening after welding. produc- tion these rings the normal aver- age tested hardness shown graphi- cally line “A” fig. Under the circumstances neces- sary this point introduce heat treatment condition the weld area for further processing. rapidly the rings are welded and dis- engaged from the welder dies, chip- pers and grinders are used remove all excess material due upset and flashing. This operation completed while the weld still hot and the material relatively soft. The heat treatment usually accorded the ring full anneal the entire ring. The latter has been the most effective method shop practice. temperature recording chart made each furnace run and inspect- before the next operation the manufacture rings attempted. When heat treatment done, grain refinement the weld shown “E,” and the heat- affected zone, shown “F,” fig. ring again the proper metal- lurgical form for further processing. attempt made here heat treat rings for the final physical character- istics, however. The treatment given one restricted hypereutectoid steels and usually applied the steel previous final hardening order assure uniformity the hardness ‘as later developed from final heat treatments. Hardness curve after this anneal shown graphically fig. line “B.” The desired physical effect ac- complished this heat treatment, wherein the carbide globular small nodule condition. The hard- ness brought down the weld and the heat-affected zone that the original bar. The desired elongation characteristics are restored and brit- tleness thereby removed. The sizing operation the next step the line production. One several methods may used. The ring may expanded circumferential- press, tire-set shrunk, uniformly expanded expanding machine. The latter method was used the rings under consideration. Special dies were used insure that the rings, when expanded, would round and substantially flat. Inspection gages and face plates are used check the Rings are checked completed ring. Phosphorus Sut (max).... Nickel (max) for length before turnec tested weld turne fract curre tance The The other show and tabul prope cess weldi are resid form. ! £ a | / | TABLE Chemical Pet Pet 0.030 0.030 0.030 0.20 | for inside diameter, circumferential length inside, flatness and sectional dimensions. Specimen bars SAE 52100 steel before and after flash welding were turned in. diam. and tensile tested. the welded specimen, the weld was the middle portion the > H Brinell hardness numbers turned specimen. all cases properly heat-treated bars, tensile fracture the welded specimen oc- curred the parent metal dis- tance well removed from the weld. The breaks the “as welded” and the “annealed” bars were characteristical- ly, cup-shaped, illustrated fig. The average tensile strength and other physical characteristics are shown table specimens Nos. and Specimens Nos. and are tabulated for comparison and their interpretation shows how critical the proper heat treatment the suc- cess this process. the process described the welding stresses the resulting ring are irreducible minimum. The residual stresses the ring after ex- panding are minimum and very equally displaced around the ring form. Symmetrical stresses alone BELOW average tested hard- ness after welding. Line indicates the ‘tested hardness af- ter heat treatment. No. Psi ABOVE 7—The breaks the and the bars are charac- teristically cup-shaped. Above, an- nealed. Below, welded. not reduce the strength the weld. the manufacture finished bear- ing races roller paths, the final finish given the surfaces the steel has greater influence its fatigue strength than any characteristic at- tributable the weld. Flash welding alloy steels not only practical but advantageous. Re- sults are uniformly more accurate than those resulting from previous methods, the amount necessary sub- sequent machining being greatly re- duced and even eliminated many in- stances. The savings scrap mate- rials are appreciable, point partic- ular importance the case high- cost alloys. Most rings can made cold, thus eliminating cost furnace heating. Tool and die maintenance generally less than with other proc- esses. Production line operation facilitated. Inches TABLE Physical Properties Welded SAE 52100 Steel Area, Hardness Bar Elonga- tion Remarks Parent bar heat treated 285 Bhn, broke approximately the the machined length, cup break. 112,000 bar broke weld, cup break, inadequate heat treatment. Welded and heat treated Bhn, broke inadequate heat treatment. Parent bar heat treated 175 broke approximately the middie machined length, cup break. bar broke outside weld, cup break. Fig. Welded and heat treated 175 outside weld, cup break, correct heat treatment indi- cated. Fig. THE IRON AGE, August 16, x ® 500 Brazing Heat-Treated Parts Shear test integral component shows silver brazing satisfactory method for joining heat-treated parts and meet definite tensile strength requirements. unusual production problem in- the joining two heat- treated parts and the same time have the integral part meet definite tensile strength requirement, was faced the Western Gear Works, Seattle, the result change design. Because the particular steel specified, this require- ment had met heat treating. Considering the steel and the tensile strength requirements, silver brazing appeared the only logical method joining these parts. Shear tests the brazed unit (fig substantiated the method selected. The original specifications called for the use SAE 4130 steel with LEFT Exploded view coupling assembly for bomb door drive. Part the partially ma- chined sections, ring low tem- perature, free flow- ing brazing and the completely chined section with were fabricated. 280,000 per 160,000 Tensile strength 400 500 600 800 900 1100 Drawing temperature, °F. IRON AGE, August 16, 1945 maximum tensile strength 160,000 psi and minimum tensile strength 130,000 psi. With this type steel specified, was necessary termine its response heat treat- ment. was then necessary select brazing alloy which would meet all tensile requirements and, the same time, have melting point which would not exceed the maximum draw temperature the two heat-treated parts. was also required that the brazing alloy meet the Army Specification No. The parts two sample couplings were accord- ingly machined from steel the following chemical analysis: 0.30 pet 0.50 Mn, 0.019 0.019 0.27 Si, 1.05 Cr, 0.20 Mo. These parts were heat treated give the curves shown fig study these curves indicates that the tensile requirements could met drawing the water-quenched pieces between the temperature 1000° and 1170° while the draw tempera- ture for the oil-quenched parts would searching for low-temperature, free-flowing brazing alloy which would meet tensile requirements the braze and also the above mentioned specifications, Handy Harman Co.’s Easy-Flo was found satisfac- tory. Since was known that the melt- ing point the brazing alloy was the experimental parts were cleaned, fluxed and assembled with ring brazing alloy and fur- nace brazed temperature 1200° (see fig 3). The slightly higher furnace temperature helped keep the time the furnace minimum. From this procedure the parts assembled brazing were com- pletely drawn 1200° the final brazing operation. After braz- ing the water-quenched parts 1200° responds with tensile strength 128,000 psi. This tensile strength corresponds the expected hardness the show below sary speci tions. the could With there using speci the 000 leng 1.05 ing coup that Tens Shes Key the This ing betv ine par shown curve No. fig for the 1200° draw. When this test showed that tensile strength dropped below the 130,000 psi, was neces- sary ask for change tensile specifications material specifica- tions. Accordingly, stress analysis the assembled parts was made the customer; The test revealed that the minimum tensile requirement could safely lowered 115,000 psi. With this new and lower specification there was difficulty encountered using the material originally specified, Shear Test final test, special fixture was constructed for the purpose shear- ing some the completed couplings destruction. The test revealed that the shearing point was between 34,- 000 and 35,000 The brazed area has diameter 0.660 in. and length 0.5 in. This area 1.05 in. which represents aver- age shear strength 32,800 psi. Us- ing shear value 25,000 psi this coupling good for torque load of: 25,000 1.05 0.660/2 8662 Comparing this with the torque load that two keys will develop, where: Tensile strength 96,000 psi Shear (96,000) psi Key size in. square Key length 0.573 in. Shaft diam 0.500 in. Shaft radius 0.250 in. Comparing these figures, the silver brazing has factor safety 8662/2586 3.5 over the strength the two keys. The variation tensile strength with joint thickness shown fig This index gives the reason for hav- ing the joint thickness 0.0015 in. between the parts. Effect Production investigation the properties iron powder products made from powders produced various processes was conducted Dawihl and Schmidt and reported Stahl und Vol. 65, Jan. 1945, pp. 14, Porosity and structure were exam- ined micrographs high magnifi- cation and microhardness tests were made. was found that the effects the manufacturing process were still quite marked, even after sinter- ing 2642 deg. The pores parts made from iron powders that had been melted are uniformly dis- FIG. 3—Showing preparation parts before furnace brazing. BELOW 4—Relation joint thickness tensile strength compiled from Handy per Tensile stren thousand 0,003 0009 Harman Co. data Easy-Flo brazing alloy. Thickness joint, inches the Properties Powder Compacts tributed, while the distribution not uniform the iron had not been melt- ed, sponge iron powders for exam- ple. Subjecting powders severe de- formation, when made the cold stamping sheet iron, was observed have detrimental effect the sintering properties and the growth the ferite. Microhardness readings indicated that the fusion crystals gave rise additional stresses called sintering stresses. These stresses sug- gested were probably the cause the variations micrahardness with the varying methods producing the powder. Additional time and power con- sumption making the powder can some cases compensated the finishing proc- esses. example this cited the case compact being made from powder produced directing two streams particles one against the other. Sintering then required only produce soft and easily deformed part. With powders made other methods, forging and re- crystallization are necessary pro- duce the same deformability. THE IRON AGE, August 4 140 120 J | > | ‘ Hot Forming Magnesium Alloy Sheet Hot forming magnesium alloy sheet using electrically heated tools showing particular efficiency. Herein, data are presented temperatures, heating methods, types forming, gage material, and most satisfactory lubricants. WEST Development Engineer, Aluminum Co. America, Jobbing increased demands air- craft designers weight parts have led more and more applications for magnesium alloy sheet. result, its form- ability has become the utmost im- portance fabricators, who intend translate such experience into post- war products. Although many forming operations can performed magnesium sheet room temperature, severe forming can best accomplished elevated temperatures. Since light gage sheet Die temperature, °F. 56—THE IRON AGE, August 16, 1945 will not retain sufficient heat during forming operations, the forming tools must heated some way, and ac- curate temperature control desir- able. The hot forming magnesium al- loy sheet generally brings forth two objections from fabricators. First the extra cost heating; and second are the difficulties involved heating and operating large dies, particularly those used double-action draw presses. The answer the first ob- jection depends upon the part 1G. draw- reduction graph for light-gage mag- nesium alloy sheets the basis all magnesium sheet drawing. formed. many cases, the additional cost heating offset the fact that intricate shapes can formed magnesium sheet with fewer opera- tions and fewer sets tools than are required when forming other ma- terials. For other data the drawing mag- nesium alloys, see IRON issues July 1945; May 10, 1945; Nov. 30, 1944; and July 27, 1944. The solution the second problem requires additional investigation be- fore final decision can reached. Considerable progress has already been made, however, and Alcoa engi- neers have arrived several conclu- sions, These are: (1) following standard prac- tices the design magnesium parts regarding such details radii and draw reductions, severe forming magnesium sheet prod- ucts, when done the temperature range 400° 700° F., can par with the more common sheet materials. The information contained herein, determined investiga- tion, may used govern the choice temperature, heating methods, type forming, gage material and lubricant. (2) Electric heating has been found the most efficient and adaptable method for heating large, irregular forming tools. The vari- ety electric-heating units avail- able—tubular, ring, cartridge, and strip—permits the application electric heat any type tool. Ring strip heaters should used whenever possible and tubular heaters only emergencies. (3) The detailed .wiring dia- grams, description equipment used, and heat requirements for the parts which Alcoa experimented, may serve guide for future de- signs, but should not considered criterion design. (4) Although considerable work has been done gas and electrical heating, experiments have not yet ties fabr Pilo menta shows eratio the graph minin draw: clear: tools well | | | a. . and forr ope’ hea pre pro gas use tar ize ap’ arm ing q | fo included induction heating. This method may have definite possibili- ties and should investigated fabricators the near future. Pilot production jobs and experi- mental work provided the data used making the graph, fig. which shows the maximum reduction per op- eration practicable for temperatures the range 70° 700° This graph served the basis for deter- mining the number operations (or draws) required and the temperatures which the draw must performed. Factors such die radii, punch radii, clearance between punch and die, die material, blank size, and type draw tools and equipment, were determined past experience with aluminum well Gas Heating For Small Parts Heating tools was first confined manual torch heating small ex- tools and the fitting natural gas ring burners small and medium sized standard designed tools. Fig. and illustrate gas burner installa- tions double-action toggle presses. Such applications were successful production basis for small parts which required only relatively slight forming. For severe forming, such that encountered deep drawing operation approximately pct reduction, the fluctuations heat and its effect blankholder pressures, plus the expansion the tools and moving parts, made this method heating unsuitable production basis. Attempts use gas heating several deep-draw dies used form parts aircraft oil tanks proved that could not util- ized for larger tools, since the area application the heat amount heat available the work- ing surfaces were not satisfactory provide the required temperature. Gas heating, however, was favored for the initial work hot forming magnesium because its economy both time and money. relatively small number parts was needed and gas burners were inexpensive and easy install, shown figs. and Electrically Heated Tools The need for different source heat order make further techni- cal advancements the field severe magnesium forming, led inves- tigation electricity. The results ob- tained have proved very encouraging. Commercial electrical heating units adaptable the type tooling under consideration were available suffi- ciently wide range types, sizes, and \ Burner Knockout not shown wattage capacities accommodate anything from small embossing tools large deep drawing tools. Further- more, this type heating offered ab- solute temperature control, eliminated the hazards fire and overheating presses, and created safer working conditions. Electrical heating was first at- tempted small tools. Initial experi- ments were carried out existing single-action embossing tools, which instant tubular heating units 500 600w capacity were wrapped and securely fastened the outside diam- eter the tool. Since the range ABOVE 2—The in- stallation gas burners mag- nesium drawing operation. RIGHT duction installa- tion burners the same that shown schematically Fig. clamp Part working temperature for this type operation was wide, lack control introduced serious problems, In- adequate surface contact between the tubular type unit and the tool, how- ever, resulted inefficient heating and short heater life. Insulation these applications consisted asbes- tos packing around the outside the heaters, and asbestos shingles placed between the tools and the press. Solid round oval outside contour can maintained this manner tem- peratures around 600° The first tool specifically designed | : _ | Area- pipe Atmospheric mixer 4—In determining the size and port area gas ring burners, the cross-section area the pipe should equal greater than one and one-half times the total port area half (180°) the ring. The mixer connection should the same size larger than the burner ring. Gas should 0.57 specific gravity, 1030 pendent upon the volume material heated. general, for dies in. diameter less, use in. dies in. in. diameter, use in. and dies in. in. diameter, use in. not advisable attempt gas heat tools greater than in. diameter. Zero hose Ring burner (Die) air-zero gas) 5—This schematic drawing illustrates the ring burner and mixing unit for gas heating draw and stamping fools. hose line was the dimpling tool illustrated fig. this case ring heaters, with practically 100 pct heating surface contact, were installed with excellent results. Since the largest commercial unit now the market only in. outside diameter, ring heaters can- not used large tools. Wherever applicable, however, the ring heater should used source heat. Since tubular heaters were found inefficient and difficult install accommodate electric unit heaters 58—THE IRON AGE, August 16, 1945 properly, small embossing tool the type previously described was fit- ted with cartridge heaters. These were inserted close fitting holes which were bored from the bottom face the tool within 0.25 in. the area heated. This setup re- sulted more uniform heat and of- fered neater and more permanent job. The next step electrical heating was its application set draw tools designed form 5-in. diam- eter hopper tube two operations, shown fig. this application the first operation draw tools were heated using cartridge heaters described. The formed part represents total reduction pct. required first draw die and blankholder in. diameter with punch diameter in., and started with circu- lar blank 0.051 in. in. diameter. The tools used the sec- ond operation were die (which had outside diameter only in.), and inside blankholder and punch 51/16 in. diameter. this par- LEFT ring heated dimp- ling RIGHT Fis. hopper tube drawn final shape from circular flat two draws. ticular instance, ring heaters are suited for the die and cartridge heat- ers for the blankholder. Heat calcu- lations for this draw are shown table II. With parts having proportions sim- ilar that shown fig. only the die and blankholder are heated. For the second draw the punch was de- liberately cooled with water. the punch were heated, the area the part first formed would, the ele- vated temperature, have insufficient strength pull the balance the material under the blankholder into the die cavity. The ratio punch area blank area which the punch should cooled rather than heated has not yet been established. matter judgment and trial rather than calculation. Drawing Oil Tanks Main engine aircraft oil tanks 40-gal. capacity furnished the prob- lem using electrically heated tools for deep drawing large, light gage sheet parts production basis for A the f ticul heat gal. skin size stre hea hea | the first time. The design this par- ticular tank required different and more existing techniques heating, heat control, and tool design than that any job previously attempted. Because this 40-gal. tank had fit the space formerly used 28- gal. tank, had numerous deforma- tions consisting bumps and inden- tations for clearance purposes. result, two pieces were used for the skin; and two drawn shells unusual size, depth and shape were used for the heads. was decided that the bottom skin should formed stretcher press using hollow, cast aluminum male die heated with strip heaters, and that the right and left heads and the top skin should TABLE Temperature Settings Heated Tool Parts Temperature, Left-Hand Head, (Fig. 12) Right-Hand Head, (Fig. 11) Preheat drawn double-action toggle presses 275-ton capacity. air-cushion knockout, two draw operations for the right and left-hand heads, and hol- low cast-iron dies, blankholders and punches heated with strip heaters were employed. The severity the forming operations required pro- duce these parts dictated the use optimum temperatures. addition, the large size, irregular shape and heat capacity the necessary tools seemed preclude any possibility heating the methods torch gas, tubular, ring cartridge electric heaters. obtain some degree heating efficiency, hollow tools, rather than the usual solid type, were designed operate with minimum heat input and allow placing the heating elements close possible the working faces. Hollow tools ap- proximately in. wall thickness are satisfactory, since hot drawing magnesium does not require the strength solid tools. This ex- plained the fact that hot working requires only the pressure needed for room-temperature work- ing. The top half one these dies FIG. installation electrically heated strip heaters. shown fig. which also illustrates the installation setup used for the strip heaters. Their selection for this type tool was governed the available contact area and their adaptability contours. The various parts, formed the presses, are shown fig. The tolerance and production rate require- ments justified almost complete tool- ing. Complete thermostatic control all heated operations was required, and the temperature settings shown table were determined from ac- tual production. When using the heaters shown fig. 11. was difficult maintain die and blankholder temperatures for more than hour steady tion. This resulted partly from insuffi- cient heaters but mainly from heat losses into the press and the work. For satisfactory shells, was neces- sary operate 550° This was also found the maximum tem- perature that could obtained with the setup shown fig. 14. Future designs should provide for greater heat losses. the initial investiga- tion transite board asbestos 9—The four parts comprising the 40-gal aircraft engine oil tank. The botton skin, formed stretcher press using hollow, cast aluminum male die heated with strip heaters. The right and left heads, and respectively and the top skin, are drawn double-action toggle presses 275-ton capacity. THE IRON AGE, August 16, 1945—59 | 450 550 700 700 é 4 4 slide Punch ram Part FIG. 10—Strip heater installations the top skin the 40-gal oil tank. shingles were placed between the tools and the press for insulation. the case tubular and ring heaters, as- bestos packing was placed around the outside the tool. the larger size tools, blankholder pressure con- tinually changes the tools are set transite asbestos, because the pressures crush the insulation mate- rial and acts cushion rather than positive base. From experience thus far, has been found that the only insulation strength for severe draw work thickness in. more 0.020 in. 0.032 in. polished stainless steel sheets, each which pierced with irregularly spaced holes form dead air spaces. addition, the outside the die and blankholder should fit- ted with insulating material mini- mize heat losses well protect the press operators. The general tool design and wiring setup final draw tools for the left- 440 hand heads are shown figs. and 11. addition the development proper blank size, radii and general operating procedure, tryout tial production this part brought forth the associated problems heat distribution the tools, lubricants, insulation, die pickup, blankholder pressure variations, and preheating the blanks they affected production rates and the quality the shells. The rough dimensions this fin- ished shell are 17% 23% in. deep. The original blank was in., alloy For rea- sons blankholder this blank was increased in. Furthermore, the blank was left rec- tangular shape, contrary the normal practice developing ir- regular blank for irregular shapes order keep the blankholder pres- sure uniform over the die face. The maximum thickness the shell the approximate center the deep Thermocouple relays BLANKHOLDER FIG. diagram—Left-hand head tools. 60—THE IRON AGE, August 16, 1945 PUNCH side (fig. 9C) and averages 0.102 in., while the minimum thickness the deep corner (fig. 9C) and averages 0.060 in. The original gage was de- liberately made 0.072 in. order take care such thinning. All the radii the shell are in., while the draw radius (radius the die) in. 5T. Although too small radius would have caused fractures during the drawing opera- tions, the radius had kept minimum prevent the formation wrinkles the sides and bottom the shell. The correct balance these two factors was determined during the actual tryout the tools. Usual Lubricants Unsatisfactory temperatures the 600° range, lubrication becomes real problem, not only from the stand- point allowing the blank slip readily between blankholder and die, but also from the standpoint pre- venting scratching, galling and pick- during the drawing operation. Mutton tallow and paraffin, the lubri- usually employed the most severe aluminum draws, break down completely. Ordinary laundry soap, which frequently used for mag- nesium spinning and drawing, un- satisfactory above 400° Normal heavy lubricating oils flash various temperatures but always below 600° Although graphite, with with- out vehicle, fair from draw- ing standpoint, difficult re- move completely, and, allowed remain the part for any length time the presence moisture, cor- rosion will ocur. mixture Tube Draw and Mica was found satisfac- tory for the parts discussion. Cyltal also brought good results. The spirits used with Tube Draw main- tain viscosity which can han- dled, will flash occa- sionally but the lu- bricant quickly burns off and leaves Rapid application Tube Draw requires preheating the blanks which, inci- dentally, should preheated any event. minimize the lubri- cant the punch and knockout, lu- bricant was desired ical bat cally used Die Die base plate enco iron shee mor out ing sho oil ina siu L$ x= DIE the center the blank the afore- mentioned job. Consequently, the log- ical setup preheating the blanks bath the lubricant dipping the lubricant after preheat could not employed. Therefore, electri- cally heated batch type furnace was used for preheating. Even with Tube Draw, excessive pickup and consequent deep scratch- ing the sidewalls the shell were encountered. Nor did the use cast- iron tools help this condition. Contrary normal practice, all magnesium sheet that processed within months after its delivery used with- out the standard chrome pickle coat- ing principally because this coating increases pickup troubles draw work. Sheet obtained from the mills should, however, ordered with oil coating. Solution the problem pickup was further aided elim- inating the normal amount magne- sium oxide that rolled into the sur- face the sheet during final cold rolling. This oxide was removed immersing the as-rolled material pet solution citric acid for min. room temperature. The resultant very finely etched surface also helped hold the lubricant the metal moved over the die face and radii. TABLE For Determining the Necessary Heat Input Operate the First-draw Hopper- (1) Weight die 259 watt-hour absorption per temperature rise required kw-hr input equals (600) (9) 1000 input (0.12) er Heat losses from uninsulated surface Uninsulated surface area 2.5 loss per 800 (for stee!) (800) (2.5) 1000 5.45 Kw-hr required attain die temperature 675° and operate 675° (2) 5.4 (3) 2.0 7.4 insulating some the (3) Selecting suitable heaters: Die design dictates cartridge heaters ap- heaters 4.75 in. 0.933 in. Use brass sheathing with maximum safe operating temperature 750° FIG. tools. 4 Control Power input Variations little 25° the temperature any the tools suffi- ciently altered the blankholder pres- sures and the lubricating effect produce wrinkled shells with de- creased blankholder pressures and fractured shells with increased pres- sures. This proved the necessity having accurate temperature control. The tools for both the right and left-hand heads were originally de- signed for two draw operations ac- cordance with standard aluminum practice. During the tryouts, how- ever, was found unnecessary use the first operation tools and both parts were made one draw. The stretcher press operation the part shown fig. was per- formed over hollow, cast-aluminum form, which was fitted with strip heaters, diagrammed fig. 15, maintain temperature 600° Since the sheet material has almost point contact with the tool for about the first pct the operation, addi- tional’ heat was applied gas burner the area the severest stretch. This was brought the work after the sheet had been clamped place the jaws the press. more efficient method might lay electric heating pad over the during the operation. The long offset the center one side the shell was set the block with air ham- mer after stretching but during the time that the shell was still held tension the press. Heat calculations for determining the heat input oper- ate the cast-aluminum stretcher die 675° are shown table III. Cyltal was applied the radii the tool over which the sheet was stretched but none was applied the sheet itself. Pickup, particularly with cast block, was even more lem here than drawing. There some hope, however, that this condi- through the development heat-re- sistant rubber sheeting which could placed between the tool and the part. TABLE For Determining Necessary Heat Operate Cast Aluminum Stretcher Die (1) Weight cast aluminum die 177.6 (2) required raise 177.6 alumi- num a—Aluminum watt-hour absorption per For (change temperature) input equals: (600) (12) input equals: (weight die) (specific heat (AT) (177.8) (0.22) (600) (3) Heat losses from surface areas: f ) 1000 (4) required attain die temperature (2) 7.2 9.65 For safe operating margin add pct 9.85 (1.10) 10.6 (5) Selecting suitable heaters: Die design dictates heaters approxi- mately in. long 1.5 in. wide, Choosing 18.25-in. heaters with (1000) Use sheathing with maximum safe operating temperature 1200° THE IRON AGE, August 16, 5.4 1000 : Effect Upon Residual Stresses Simple analyses are presented illustrate the actions ex- pansion, contraction, and elastic and plastic deformations resulting from the heating and cooling mild steel; also illustrate the effects these actions upon residual stresses and distortion. These actions and effects are significance connection with such processes welding, local stress relieving any method involv- ing heating, straightening" remove buckles other dis- tortion, preheating, postheating, local heating for bending flang- ing, and any other operations involving local heating, particularly continuous, progressive nature. ° ° MOTTE GROVER Welding Engineer, Air Reduction Sales Co., New York steel temperature sub- stantially greater than 200° (about 400° F.) shown result residual stress yield point intensity, all continuous welds have longitudinal residual stresses such intensity. Research has confirmed this fact repeatedly during the last years more. However, expe- rience well research indicate that these localized stresses not re- duce the safe load capacity structural pla