The Iron Age 1942-09-17: Vol 150 Iss 12

FORGED HARDENED STEEL WORKING ROLLS FOR COLD MIL “d 7 § 5 | | LS | q { | ; q . Citation for Men War Industry “Op lathe, small tool post grinder feeding the cross slide, the correct LIVE CENTERS RIGHT angle 60° ground. The center Paul Rhinehart has contributed many practical ideas “Blue the Warner Swasey shop bulletin that goes over 30,000 turret lathe opera- tors. now supervisor battery turret lathes the Dallas plant North American Aviation Corp. Some the work requires revolving center support the piece under heavy cuts light cuts run high speed. Although hardened and ground, the center NER SWASEY sometimes becomes worn. The diagram the left shows Mr. Rhinehart’s for redressing centers right the Hundreds good suggestions Warner Swasey, showing sourceful operators are using their and ingenuity increase gold “Victory Pin” sent men, and many their ideas are which sent free the homes lathe operators. Make sure your tors—old-timers and our list get regularly. Write Swasey, Cleveland, Ohio. You CAN TURN BETTER, FASTER, FOR LESS WITH WARNER (©) CROSS SLIDE REVOLVING CENTER the w arches meth ski the SEPTEMBER 17, 1942 VOL. 150, NO. VAN DEVENTER President and Editor BAUR Vice-President and General Manager ° ° Managing Editor, LIPPERT News Markets Editor, ROWAN Technical Editor, OLIVER Associate Editors JAMES Art Editor, WINTERS Editorial Assistants BENEDETTO Resident District Editors Washington Pittsburgh DONALD BROWNE PHAIR Washington Chicago Cleveland Detroit OSGOOD MURDOCK San Francisco Editorial Correspondents Buffalo Cincinnati FRAZAR RAYMOND KAY Boston Los Angeles HUGH SHARP JOHN McCUNE Milwaukee Birmingham SANDERSON Toronto, Ontario BACON Seattle ROY EDMONDS St. Louis ° ° ° DIX, Manager Reader Service ° ° ° Advertising Staff Findley Union Bldg., Cleveland Herman, Chilton Bldg., Philadelphia Hottenstein, 1012 Otis Bldg., Chicago Raymond Kay, 2420 Cheremoya Ave., Los Angeles, Cal. Leonard, 100 East 42nd New York Peirce Lewis, 7310 Woodward Ave., Detroit East 42nd St.; New York Robinson Fitzgerald 428 Park Pittsburgh Warren, Box 81, Hartford, Conn. Johnson, Market Research Mgr. Baur, Typography and Layout. ° ° Member, Audit Bureau Circulations Member, Associated Business Papers Indexed the Industrial Arts Index. Pub- lished every Thursday. Subscription Price North America, South America and Possessions, $8; Foreign, year. Single copy, cents. ° ° ° Owned and Published CHILTON COMPANY Editorial and Advertising Offices Chestnut and Sts. 100 East 42nd St. Philadelphia, Pa. New York, U.S.A. Executive Offices OFFICERS AND DIRECTORS MUSSELMAN, President JOS. HILDRETH, GEORGE GRIFFITHS, EVERIT TERHUNE, VAN DEVENTER, Vice-President BAUR, Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JULIAN CHASE, THOMAS KANE, HARRY DUFFY CHARLES HEALE Vice-President Vice-President Vice-President This Week in... Editorial The Hand That Rocks Technical Articles Physical Properties Helium Shielded Arc Features Assembly Line West Coast News and Markets This Industrial Week Non-Ferrous Metals Scrap Markets Iron and Steel Scrap Finished Steel Prices Warehouse Prices Index Advertisers Cooyrig THE Fatigue Dear ......... News Industry Personals and Obituaries Comparison Prices the Cradle P&W Twin Wasp Spawns Focke-Wulf 190 Motor Spirally Brazed Tubing Carburizing Steels.......... Carboloy Introduces Small Caliber Gun Drills Engineers Discuss Production Innovations Abrasive Cut-Off Wheels—Where and How Use Them ° ° ° ° ° Machine Tool Prices ht. 1942. by Chilton Company (inc.) 231 | 55. i strength with less weight— lower machining cost—elimination pattern expense and scrap—smoother, finer appearance are the rea- sons why many machine tools for war production work are today mounted Welded Machine Bases and Frames. Methods developed Mahon have set new standard the art producing these very essential products all sizes, shapes and weights. When you send your blueprints Mahon you can sure prompt, ac- curate quotations. your service are extensive pro- duction facilities and ultra modern tools the hands skilled craftsmen. Deliveries will made promised. THE MAHON COMPANY DETROIT CHICAGO These twe views from unre- thelr own accuracy 46—THE IRON AGE, September 1942 > “= | { 7 F AGE ° ° SEPT. 17, 1942 ° ° ESTABLISHED 1855 The Hand That Rocks the Cradle too bad miss the boat. American management missed the boat years ago when had exceptional opportunity real public relations job interpretation the American public. course, those days the subject public relations, and with notable exceptions that personnel relations, were minor considera- tions. Management took American industry for granted and assumed that Tom, Dick and Harry, well Jane and Mary, did likewise. are now reaping measure the reward that omission and neglect. Our system enterprise know it, even with the modifications that may come due the present-day impact events, needs more than anything else understanding its functions the public. What not want need glorified and exaggerated picture the impor- tance management's initiative and entrepreneurial functions, but just plain, commonsense, everyday understanding these relationships. say that industry missed the boat during the last war because did not sell itself the millions women who came into industry take the place, least temporarily, the men who went into our armed forces. Students merchandising, well practitioners propaganda, will tell you that influence more cultivated than that the prosaic and taken-for-granted male. had appreciated that fact during the last World War and properly interpreted the functions enterprise many women who temporarily flocked into industry and who later became wives and mothers, believe that industry today would have much better public appreciation. not miss the boat this time. are now inducting into our industries millions women who later will become the wives and mothers American men and boys. Commissioner McNutt has said that one woman out three will engaged war work. one aircraft engine plant, out the expected total 45,000 employees, 15,000 will women. When they leave, many them will after the war, let them leave with good taste their mouths and with understanding what American industry can and does make the average person happier and more prosperous. big job for you public relations experts. forget that the hand that rocks the cradle rules the world. ] | | >» | | | | | | | ° ° | | al Miners, entering new raise the Sherwood mine, climb over pile iron ore that soon will made into fighting steel. New Ore Mine Joins the War Production Inland’s new Sherwood mine—the first large buildings—an office building, hoist house, and underground iron ore operation started since combination shop and dry building—all connected Pearl Harbor—joins America’s war production with each other and the main mine shaft against the Axis. This new mine will help assure tunnel. detail has been overlooked making continuous supply vital raw materials for the this model ore producing unit. Inland now service and The entire integrated Inland organization—with new units under construction. its ore and coal mines and limestone quarries, This new Inland development, located the fleet lake freighters, and steel producing plants productive Iron River District the Menominee —is devoting every effort increase the produc- Range, considered outstanding for its operating tion steel that vital our country’s facilities and equipment. There are three main war effort. SHEETS STRIP TIN PLATE BARS PLATES FLOOR PLATE STRUCTURALS PILING RAILS TRACK ACCESSORIES REINFORCING BARS 1 prospect building air- planes “like automobiles” has intrigued the attention laymen, engineers and production experts for many years. often came up, the idea was dis- missed those who thought they knew the answers and was dealt with only cautiously the experts who might have fostered such de- velopment reality. they delved into all, was connection with the use special materials, such stainless steel, and there the difficulties repeatedly floored designers and production men alike, although recent years substantial measure success has come these efforts. Attempts design around the common garden variety mate- rials, such automotive body steels awaited the time when the pressure war and the urge for more and more airplanes and more and more materials were making their effects felt widespread. One the pioneers the devel- opment the use such low-car- bon steel airplanes Vultee Aircraft, Inc., whose manufactur- ing research department more than year and half ago began se- ries experiments that have de- veloped new structural shapes and combinations shapes that readily permit the use such steels airplane primary structures. Peter Altman, director manu- facturing research, engineered the development, association with Kos and Gerlach and with cooperation Gypsum Co., Republic Steel Co. and Car- Steel Corp. Aircraft Fuselage Panels Expanded Steel combining thin gage auto body stock (0.008 in.) with expanded sheet metal mesh backing, Vultee Air- craft has been able produce fuselage panel light aluminum and with the requisite stiffness and strength. This one answer the problem critical material shortages. mere accident research led the selection thin gage, low- carbon steel for these applications aircraft structure. The premise these experiments was simply that steel might used sub- stitute for aluminum period threatened that direction. The basic conception the desirable material was one available quan- tity and low price. This meant that the material itself must low basic cost and should fab- ricated under known, high-rate production methods with low cost. The search was directed toward niques were highly developed, the automotive and allied indus- tries. The types steel considered were those the non-strategic list, especially those that might still availahle because abundance production facilities. This led investigation the use black plate and very thin carbon steel the type employed such garden variety products the automobile body and the tin can. The continuous mill and the tin plate mill capable rolling steel thicknesses low 0.008 in. were looked potential sources supply. For such investigations into ma- terials and fabricating methods, the Vultee manufacturing research department was fortunate its lo- cation close the sources infor- mation, materials and equipment Detroit. For instance, within few hundred miles major sup- pliers steel, forming equipment and welding equipment. fact, this department had been set Detroit through the foresight the Vultee management under- take just such problems research new materials, their applica- tions, manufacturing technique and structures. One the results these ex- periments the utilization ex- panded metal sheet, welded thin skin steel form struc- ture known composite ex- panded steel panel. Fabrication the expanded metal panel standard size being undertaken. The end result possibly will pre- fabricated panels, complete even corrosion-resistant coating, ready for assembly and painting. Other developments fostered this ex- perimental program include sand- wich-like construction which uses expanded metal principally corrugated form means in- creasing the bulk and column stiff- THE IRON AGE, September 1942—49 x q | 7 q | < | 4 4 r ness thin steel. Out these main ideas has been found prac- ticable design and build aircraft that are least strong and light those made from what are commonly known the light ma- terials. Straight Carbon Steels The chemical analysis the ma- terial used that ordinary car- bon ‘steel, which contains none the critical elements like nickel chromium. However, experiments improve physical characteristics changes the chemistry and the processing; the special emphasis was the processing, especially that cold reduction the rolling mill. result these studies, has been found possible obtain straight carbon steels with ulti- mate strength above 100,000 Ib. per sq. in. gages low 0.008 in. The use steel without change the type structure arrange- ment the material would have resulted greater weight than planes, simply because the steel has higher specific gravity than the light materials. the steel was simply used thinner sheets and without any change structure arrangement, there would means stabilizing the steel sheet against buckling and local failure. This difficulty arises because the expanded steel panel installed airplane fuselage. this craft, the panel above the leading edge the wing metal panel, de- scribed the text and shown Fig. fact that steel 2.8 times heavy aluminum and—on an_ basis with aluminum— would require reduction thick- ness the sheets ratio 2.8 For example, substituting for aluminum sheet 0.032 in. thick, the equivalent steel sheet could only 0.0114 in. thick. fact, since resistance buck- ling and local failure many power the thick- ness higher than unity, straight substitution steel would invari- ably lead increases weight the structure. overcome this, apparent that the designer must make dis- position the material give increase effective thickness 2—Inside view the panel shown Fig. The expanded metal can seen ap- plied the outside sur- face sheet spot weld- ing each the lath. The three stiffening ribs also are spot welded. Note that the edges the panel this case are doubled back finish the panel and add fur- ther stiffening effect. ° ° ° 50—THE IRON AGE, September 17, 1942 ‘ (bulk good word for this) Such attempts the past have been characterized the use low density material like plastic plywood bonded the thin steel. However, this does not give homogeneous structure, and has disadvantages such the diffi- culty joining panels parts made such composite materials. The sdlution sought Vultee was simply the expansion the bulk the steel increase its col- umn resistance the transverse stiffness the sheet, the same time maintaining homogeneous material easy fabricate. Expanded Mesh the Answer the early stages investiga- tion the only materials available begin experiments were stove pipe material 0.008 in. thickness and form stucco expanded mesh. The investigation included perforated metal, stringer reinforcements and many others, including sprayed plas- tics, etc. The eventual decision use expanded mesh was made because its availabil- ity, its strength (actually expanded metal cold worked stretching and thus gains considerably tensile strength), and its ease application. was also determined that the composite sheet was easily formed and Another governing factor the selection expanded metal that there scrap loss any sort since the flat sheet material sim- ply cut then stretched out laterally. was eas- ily determined that the expanded metal could spot welded, seam welded cemented the base ma- terial, depending upon the partic- ular application. Selection the proper gage the expanded metal the basis weight and thickness. the ex- ample already cited, substitution replace 0.032 in. aluminum sheet, the weight the composite RIGHT tests being made racking, eccentric motion imparted the test apparatus twisted and wrinkled the fuselage repeatedly but withstood more than the required number stress reversals. Note the smooth exterior possible with this type assembly. 4 q 3—Stiffness tests have been run wide variety samples. Here, for instance, composite sheet united with plastic cement; specimen with 11.5 in. radius and stiffening rib; flat panel in. wide; in. wide panel with stiffening rib; similar in. panel without rib, and stiffened panel with in. radius. 4—Expanded metal lath without solid sheet has also been aircraft parts. This panel fabric covered, with variety lath sizes used demonstrate possibilities small curved surfaces. THE IRON AGE, September ABOVE test section shown Fig. after buckling failure which resulted from static load tests far beyond the de- sign load the airplane. This shows the hat section ribs which serve join the panels. RIGHT tion being tested Fig. This shows the other side the joints. The flanges the hat-section ribs are the outside. this type structure, the individual panels can joined sub-assemblies make two halves the fuselage, then the halves can joined welding with gun welder from the outside. sheet steel (including expanded metal) cannot exceed the weight represented steel sheet 0.0114 in. thick. Selecting the base mate- rial from the thinnest available the mill, gives base material 0.008 in. thick. then obvious that the weight the expanded metal must held within the weight the differential thickness, which 0.0034 in. obtain the expanded metal material for back- ing this particular sheet, the expanded metal would selected give the proper weight. Ac- tually, since expanded metal has ratio about 1—air space material—the thickness would 52—THE IRON AGE, September 17, 1942 stepped accordingly. this ex- ample the expanded metal could thick 0.034 in., but would picked according commercial specifications. Another way explaining the advantage using expanded metal that the expanded mesh is, effec- tually, sheet from which per cent the weight has been “taken out” without the loss material. When the elements the com- posite panel are joined together acceptable methods such ing, cementing, the panel can rolled and formed considerable degree and adapts itself for use most the shapes common the aircraft industry. Directional Bending Panels The rectangular layout the expanded metal such that the composite sheet more easily bent one direction than the other. This characteristic can con- trolled considerable degree directing the angle which the expanded metal pattern laid the solid sheet varying the pattern the expanded material itself. This bend characteristic advantage forming tubular sections like since the material can wrapped around the longitudinal axis the fuselage quite easily. the form straight column flat sheet, the composite sheet sheet about three times the equivalent weight thickness. the example cited above the composite solid sheet that 0.0125 in. thick, but has comparative strength great free column sheet 0.033 in. thick. the case straight columns flat sheets restrained the edges, fastening stringers and spars, comparative strength two times the equivalent weight solid sheets. For curved panels, the ratio increased materially. 4 ‘ i | 8—Cellular construction weighing 0.7 per sq. ft. but strong enough bear the weight man (230 This one variety forms which the expanded metal employed get the maximum utility out steel. Other combinations the ex- panded metal and flat sheets have been developed and tested, and are going into production aircraft. These include sandwich-type com- binations and cellular structures with the expanded metal used spacer. example the strength and light weight obtainable cellular structure panel made entirely expanded metal, with- out any flat sheets attached, about in. thickness. This cellular construction will easily take the weight man without crushing, yet weighs only 0.70 per sq. ft. High Fatigue Limit The fatigue life and the uniform resistance vibration failures in- herent steel factor that makes this material highly adapt- able use aircraft structures where fatigue considerations are more and more predominating design. Extensive fatigue tests and vibration tests have been conducted -by Vultee during the months research. sheets composite structure have been put through 30,000,000 reversal cycles without showing failure. Complete aircraft structural sections, including fuse- lages, have been subjected rack- ing vibration tests and have shown that under several times normal load they are able withstand these stresses without failure for longer periods, and through more stress reversals, than are experi- enced the normal life such structures. Actual service data are available from parts installed aircraft substantiate laboratory tests. Vul- tee placing production side panels for trainers which probably will the first low-carbon steel parts actually placed the industry. The change the new material has approval the Army Air Forces. Standard Size Panels The principle fabrication employed the majority cases with the expanded metal make panels standard sizes, the manufacturing done major firms where equipment available, and supply them com- plete with ish, ready for welding into the final structure and giving finishing coat paint. other words, the panels will supplied pre-fab- ricated units, not mill sheets. However, these Vultexmetal fabri- cated panels can cut size conventional equipment and formed conventional means prior as- sembly the aircraft. Extremely simple methods have been developed for attaching com- posite sheets stringers and other structural elements. typi- cal method (illustrated herewith) makes use what are known section” stringers. The flanges the stringer are welded com- posite sheets hold them together. The separate panels and the string- ers that join them lend themselves readily production. possible weld stringers and gether various welding stations sub-assembly points plant and bring them together for final assembly jig and welding into main assembled unit. This panel assembly system changes some- what the prospect jig and fixture design, since the panels lend them- selves assembly with jigs and fixtures built along different lines than those currently used many cases. possible, for instance, semi-circular halves fuselages and then put the whole together one jig and gun weld along the open seams from the outside. Some- what similar assembly methods have already been employed other cases with aluminum riveted with composite panels seemingly are increased. Welding Simple The welding problem is, course, relatively simple with this material, both production and the case necessary field repairs. Con- temporary research spot welding has indicated possibilities dis- tinct improvement over current au- body welding technique, however, and likely that improved weld- ing methods will accompany use steel aircraft production. addition various methods fusion metals welding, further experiments made cooperation with plastic adhesive suppliers who have devel- oped processes which employ plas- tic cement and induction heating form bond between the expanded metal and the steel sheets. the application steel air- craft, good protection metal 9—Sandwich type structure, employing expanded metal and solid sheets steel. Extremely high strength can designed into light sections, employing this principle. ‘ ' & § ° ° 4 THE IRON AGE, September 1942—53 against corrosion paramount importance. Because the size the structure involved almost imperative that the corrosion re- sistant finish put the material before assembly the main struc- ture. The coating must nature that will give protection even the surface scratched deeply. Galvanized Finish method has been worked out which makes use proven elec- tro-galvanizing process which, combination with the usual primers and paints lacquers, shows very satisfactory results under severe conditions. Deeply scratched sam- ples withstand 500 hr. salt spray test with indication the form- ing rust. The electro-galvanizing applied very thin layer di- rectly the sheets which are then bonderized, the purpose the bon- derizing being give satisfac- tory paint base. possible spot weld through this rust resisting finish without harming all. the protecting surface scratched scraped away, even over considerable area, still offers excellent pro- tection the steel underneath be- cause the scratched area quickly filled with oxide that covers the steel completely. Other methods treating ex- panded metal panels have been de- veloped for special purposes. Sound- proofing material can applied cemented the panel form fire wall and insulating panel, all one. The application the expanded metal the sheet steel itself gives sound deadening effect and eliminates drumming ling the skin, both which are objectionable almost all installa- tions, especially aircraft. Other potential applications the expanded metal principal, using variety materials, are under development now. Both aluminum and magnesium sheet, for example, utilized the manner de- scribed, with great weight savings and increases panel stiffness re- sulting. Stainless steel and other metal alloys are similarly adaptable use composite expanded metal panels. Variations the application expanded metal include the use the expanded lath covered with fa- for some aircraft parts. Form- into structural sections, espe- cially closed shapes, these have considerable stiffness. P&W the Focke-Wulf 190 Motor latest threat Allied air domination, the form the new BMW power- plant being used her Focke- Wulf 190, Focke-Wolf Dornier and Blohm Voss planes, has proved, inspection, development from the Pratt Whitney 14-cylinder twin wasp motor being built exten- sively this country. Experts, who have analyzed the motor England, describe being basically orthodox, twin- row radial with ments the cooling system and the cowling designed stabilize oil cooling and reduce the air drag the cowling. The design change built around blade fan which ro- tates 3.14 times the propeller aircraft experts examining the first Focke-Wulf 190 brought down English soil. Note the compactness the BMW engine. Two 7.92 mm. machine guns can also seen seated top the engine. speed. gives adequate cooling high speed and with low for- ward speeds. The oil mounted behind the fan the flow, low-velocity cooling. This automatically eliminates the need for separate oil radiator and gives double utility the single fan. The air intake for the motor and cabin heater also through the cowl. Since all air intake through the cowl, controllable gills are needed such normally disturb the air flow behind the nacelle. result these changes, operating efficiency been raised and air drag eliminated the point-where the motor devel- ops 1580 hp. for take-off and 1460 hp. 16,300 ft. Other details interest about the BMW 801A motor include the use fuel injection with the fuel injectors being located the back part the cylinder heads between the two valves and flame-damping exhaust. Each ex- haust utilizes hot-air muff for supplying de-icing and cabin heat- ing needs. Ease control in- dicated the fact that all motor controls are coordinated single box and are operated from single lever which automatically compensates for height and boost opening the throttle. | | 54—THE IRON AGE, September manufacture small tub- ing brazing the edges loose helicoid strip steel being accomplished substantial production scale, amid much eye- brow raising the highly competi- tive tubing industry, the AGA Metal Tube Co. Elizabeth, This tubing. called Agalloyed, be- ing turned out continuous proc- ess, unique brazing technology. The genealogy this tubing runs back the early 20’s, when steel invaded the golf shaft field and not too gently squeezed the hickory shaft out the picture. One the large suppliers these deposed hickory shafts, sensing the inevita- bility the adoption the steel shaft, turned his attention the development steel tubing re- place his lost hickory shaft market. The result this effort, chris- tened long and assiduous re- search, and improving, Agalloyed. The man responsible for its original development Wiley McMinn, president the AGA Metal Tube Co. Aside the characteristics the tubing itself, probably the most interesting aspect the AGA prod- uct the continuous manufactur- ing process that has been developed which makes possible start with length cold rolled strip stock (0.042 0.044 in. thick) one end the plant and literally pull finished tube off the con- veyor the other end. its essentials, Agalloyed piece strip steel with beveled edges, which wound into series spirals and Spirally Brazed Tubing PHAIR Western Editor, IRON AGE ... Steel strip with beveled edges automatically wound into series spirals and then made continuous braz- ing the overlapping adjacent joints the helix. This the first description the process. ° then made continuous brazing the over-lapping adjacent joints the helix. recent years brazing has been finding wider employment means joining metal sections. Consid- information available covering nique, but there are still many phases the resulting joint that are not fully understood. Particu- larly this true the high strengths obtainable with brazed joints. Strength Joints The theory that effective braz- ing procedure creates copper-rich iron alloy the joined area that the joints are not merely phy- sically attached, but rather that the adjacent areas have become inter- woven and knitted together has been put forth reason for the high strengths brazed joints.* Parts Explained,” Webber, Tue Dec. 29, 1938. Ignoring, however, the whys and wherefores the joint strength, both field and laboratory have indicated that the ultimate strengths Agalloyed tubing de- termined not the strength the brazed joint, but the strength ° the parent metal (See Fig. and Table I.) AGA producing tubing the rate thousands pounds week- sizes ranging from 0.625 0.093 in. diameter, with wall thicknesses varying from 0.008 0.042 in. Low and high carbon, Cr-Mo, straight and Monel types are being made, with perhaps the greatest tonnage being accounted for the low carbon grade. sketch the layout one the tubing production lines shown Fig. Steps the production Agalloyed are, briefly: Coils strip are placed reef and fed through broaching machine which bevels two edges the strip. This machine was designed and built AGA specifically for this work. the sketch the movement from the beveling machine the spiral- ing unit shown uninterrupted. actual practice, however, the strip, after beveling, reeled and the reel transferred holder the head the spiraling unit. The speed the beveling operation substantially greater than the brazing operation, hence one bevel- ing machine can feed several braz- ing lines. The edges the strip are given bevel about deg., the area THE IRON AGE, September 1942—55 ‘4 r r ° ; e n O e e a quae \- a n 5 q 4 4 4 half size, typical sizes AGA brazed tubing, after pulling the tensiles tests recorded table below. Note that all cases, the rupture was right angles the axis the tubing and instance does appear have been in- fluenced the brazed seam. This seam can clearly seen the larger samples. TABLE Tensile Strength Brazed Tubing Tensile Strength, Sample SAE No. O.D., In. Wall Thickness, In. Lb. per Sq. In. 1010 (soft) 0.036 59,000 1010 (hard) 0.028 95,500 4155 (soft) 0.018 104,900 1010 (hard) 0.040 85,100 1010 (soft) 0.040 Note: The above data cover samples shown Fig. These stock samples were selected random and the tensiles were pulled independent laboratory. two beveled edges being equal about per cent the width the strip. Looking cross-sec- tion the strip, the edges which are beveled would the top right hand edge and the under left hand edge. The adoption broaching op- eration the beveling rather than grinder other machine the outcome much experimenta- tion. was found that broach- ing provided more effective sur- face for the wetting action neces- sary for good brazing than the other methods tried. Built integral with the broaching cutters are series wipers which remove the cutting fluids from the strip before recoiled. Strip Spiralled Leaving the beveling machine, the strip moves the spiraling unit where, addition the spiraling operation, ribbon copper laid between the beveled edges the strip. After the spiral- ing, the two beveled edges are 56—THE IRON AGE, September 1942 now face face, forming over- lapping joint, with the brazing ma- terial between them. flux used brazing. Passing from the spiraler, the tubing feeds into high frequency induction brazing furnace, designed AGA and built Ajax Electro- thermic Corp. The furnace held over 2000 deg. with automatic controls and anhydrous am- monia atmosphere maintained the furnace prevent oxidation the tubing. When brazing joints high carbon and which later must heat treated for high physicals, the possibility decarburization harmful grain growth presents serious problem. has been found that with the AGA brazing process, decarburiza- tion grain growth practically non-existent, due primarily the extremely short period time the tubing the high heat zone the furnace. total about sec. required bring the tubing brazing temperature and bring down again past the decarburizing and oxidizing range. The tubing itself the maximum temperature for only sec. During this brazing operation, some excess copper collects the inside and outside the tube along the joint the form small ridge. effort made remove this copper ridge from the tube blank for has been found that this serves excellent lubricant during the drawing operation. the finished tubing this ridge reduced the point where about 0.001 in. high. This has important effect upon the efficiency the tubing. the photograph (Fig. tubing sizes difficult, almost impossible, detect the joint, al- though the blank and some the larger finished sizes readily distinguished. The tubing, leaves the fur- nace chamber, red heat and immediately passes into cooling unit where reducing atmosphere also maintained. This cooling unit consists streams water flooding over tubular chamber through which the tubing passes. Thus the tubing does not come into direct contact with the water. the time the tubing leaves this chamber has been brought down about 200 deg. Tension Unit Incorporated into this cooling chamber what might well called the heart the entire proc- ess. This tension device, which sets pressure the spirals back the spiraler. From even cursory observation the process, obvious that the success the brazing opera- tion dependent upon the two beveled edges being intimate contact with one another, with neither too much nor too little This condition controlled this patented tension device. Too little pressure the spirals leads loose contact quently bad joints, while inversely, too much pressure causes buckling excessive overlap, both which will cause displacement the relative position the brazing ma- terial, misalinement the edges and ensuing bad joint. this must added the fact that while brazing temperature, the tubing malleable condition and quite susceptible distortion. 7 4 ul H = m ! Ol Ve CE el 07 F strip Beveling That these problems trollable this tension unit attested the steady flow sound tubing off the draw benches. After leaving the cooling chamber, the tubing run onto series roll- ers and cut stock lengths with acetylene torch. That, briefly, the method now being employed AGA produce tubing. The idea brazing single thickness strip steel make tube has been played with number individuals and companies, but present AGA the only company actively turning out such tubing successfully. Blank Size Production operations AGA, far the brazing lines are con- cerned, concentrated stock blank averaging about ft. long size determined handling con- venience and ments), with diameter 0.78 in. and wall 0.044 in. From these blanks wide variety finished tubing produced drawing size with accepted pro- cedures. For this drawing opera- tion, the usual draw shop equip- ment used swaggers, draw benches, cut-off machines, straight- eners, electric and gas annealing ovens, inspection table, in- stalled the production line Fig. device Cut off torch (Approx. 2—Layout equipment used produce Agalloyed tubing. The production sequence starts the beveling machine. Auxiliary standard equipment, such swag- ers, furnaces, etc., are not shown. ° ° ° The treatment accorded each type tube is, course, predicated upon its ultimate use. Some com- posite tubing has been made with monel and copper linings. The manufacturing practice AGA with composite tubing similar that other shops, with the inner alloy tubing being used man- drel drawing. When drawing the regular AGA tubing, reductions per cent are routine. The ability the brazed joint withstand such re- ductions, which are near the break- ing point many types steel, probably good test the strength the joint may devised. Significantly, this opera- tion the point where the bulk defective tubing spotted. Wall tolerances AGA tubing are held regularly 0.002 in. The finish drawn and annealed tubing appears quite comparable that cold drawn bar. 3—This view the AGA plant shows the draw benches (to the left), the furnaces, swaging ma- chines and other processing equip- ment. The Age Present applications for this tub- ing are many and varied, including number war uses. Commer- cial applications have included golf shafts, aerials, condensers, lighting fixtures and many mechanical ap- plications, such conveying fluids hydraulic braking systems. One especially interesting appli- cation the use brazed tubing for refrigerating unit condenser. The fins this condenser are brazed after the tubing has been formed shape. This operation requires that the tubing again brought the brazing tempera- ture where would expected that the original material the tubing come liquid again and possibly leave the joint. This, however, does not result. Hydraulic tests for leaks after the fins are attached ac- tually showed smaller percentage leaks than was previously experi- enced with other types tubing. This behavior taken tending substantiate the theory previous- mentioned the alloying the joint, rather than simply mechanical joining. While war applications restrict discussion the type fabrica- tion this tubing standing, can stated that this material being regularly bent, coiled, threaded and finished spray and manual painting. THE IRON AGE, September 1942—57 4 t O Is VO purpose conserving the now scarce alloys such nickel, chro- mium and vanadium the produc- tion alloy steels. Manganese and molybdenum the time the de- National Emergency steels were developed for the PERCENT TOTAL ELONGATION STRENGTH YIELD POINT POUNDS PER SQ. QUEN Steel Alloy Symbol Class Min. Max 4023 0.20 0.25 4024 4028 0.25 4032 0.30 0.35 8024 Manganese 0.22 0.28 8124 Molybdenum 0.22 0.28 8620 Nickel 0.18 8724 Chromium 0.22 8817 Molybdenum 0.15 0.20 58—THE IRON AGE, September 1942 HING IG. tensile properties 4620 steel. Standard 0.505- in. round specimens were heated the temperatures indicated, held for min., quenched water and tempered 325 deg. for hr. Austenitic grain size was deg. F., T-32 test. Average composition was: 0.20; Mn., 0.56; Si., Ni., 1.73; and Mo., 0.24. Min. Max 0.90 JAMESON Works Metallurgisi, International Harvester Co., Chicago PERCENT REDUCTION OF AREA velopment these steels, were considered less scarce. These alloy steel composi- tions were sponsored the War Production Board and published the American Iron Steel Insti- tute and the Society Automotive Engineers the early part 1942. (THE IRON AGE, April 66). this group are included the plain molybdenum and manganese- molybdenum steels. These had been previously used extensively the Chrysler Corp. under the general name Amola steels. The nickel- chromium-molybdenum alloy com- bination not entirely new the SAE 4300 series has been gen- eral application for number but should noted that the nickel content the 4300 series higher than that the steels. list the steels consid- ered the carburizing type and their chemical compositions are given Table These composi- tions have been suggested emer- gency alternates for the standard alloy compositions Table II. the following discussion, the properties the steels shown Table are compared with the standard alloy analyses “phys- ical properties,” term itself that needs clarification what factors should included. Table |—Composition Carburizing Steels Component Elements, Per Cent Min. Max. Min. Max. Min. Max 0.20 0.30 0.20 0.30 0.30 0.10 0.20 0.40 0.60 0.40 0.60 0.15 0.25 0.40 0.60 0.20 0.30 0.40 0.60 0.40 0.40 | a Min. Max. Max. Min. 0.040 0.035 0.055 0.040 0.040 0.040 0.035 0.055 0.040 0.040 0.040 0.040 0.040 ere Var sti- the een the Kel- om- the ren- hat ries sid- and are ner- lard the the hys- self & WM WD WW Www Carburizing Steels.. attempting arrive some common measure comparison between the steels and the al- ready existing standard composi- tions, tension tests, hardenability and carburizing tests were selected being appropriate. The method test briefly described and the reason for the selection the method explained herein. All the steels tested were fine grained 1700 deg. Tension Tests The tension test probably the most easily made test that gives the most information the prop- erties steel. Considering the use the car- burizing which are used the production parts with high carbon case and the original low carbon core, properties for the steel the carburized and uncarburized condition are interest. obtain tensile values that would represent the steel the uncarburized con- dition the core carburized part, the steels were heat treated ASTM 0.505-in. test bar size quenching water (70-80 deg. F.) from temperatures 1450 1650 deg. deg. intervals and tempering 325 deg. The object for selecting the particular bar size and the particular heat treatment was produce uniform micro- structural condition throughout and facilitate the selection the quenching temperature which optimum properties would ob- tained. The type information obtained for each steel from these tests illustrated Fig. which the average several heats AISI E-4620 steel. The optimum tensile properties for the steels stand- ard compositions and for the steels shown composition the line shows the yield strength the elongation value. estimating the relative de- sirability the various steel com- positions represented Fig. Acorrelation and comparison the standard car- burizing steels and their alternates based tensile, hard- enability and carburizing tests. CARBON 22 23 20 23 28 33 .20 20 23 19 22 30 23 6 260000 240000 220000 200000 180000 YP ANOTS PS! AiSiNO < z 2 < QUENCHING TEMPS *F 1500 1S00 1950 1500 1550 ISSO 1550 1600 1500 1500 1550-1550 1550 HARONESS RC 43 468 40 44 46 48 Si 42 46 43 45 44 43 47 43 5! 43 43 2—Tensile properties 0.505-in. ASTM test bars quenched water temperatures from 1450 1550 deg. Table Emergency Alternates for Standard Alternate Steels Standard Series Manganese Designation Molybdenum Molybdenum Nickel-Chromium-Molybdenum 1320 4027 8024 2317 4027 8024 8620 2515 4027 8817 3120 4027 8024 8620 4119 4027 8024 4120 4027 8024 4320 8124 8724 4620 4027 8024 8620 4820 8124 8724 5120 4027 8024 6120 4027 8024 8620 From American Iron & Steel Institute THE IRON AGE, September 1942—59 / 5 120000 oz se sr sr ve av er % NOBYYD zeor v uv ee + + + o9 00000! z 5 4 | “W33LS JO JIISNIL g OL 40 0000S! = | oO z | 000 022 000 0SZ s¢ % | 7 | 7 { | ROCKWELL “C” HARDNESS ze€or Sziv vi € S3HOIN!I ONZ FJONVLSIO Zi N3WID30dS Qu -N3ND DNITOOD Sv zeor SZiv 6liy Gise Lice ‘ON oz oz sr 42° av - Oo er % ‘ON ee =« se ve z 4 j ° | ° | o | | | | ‘ | | | | | | N INCH)TO 55 > DISTANCE FROM END OFA REHEATING TEMPERATURE quench tests were used prepare this chart the effect reheating temperature the hardenability rating. Heat treatment con- sisted carburizing 1700 deg. and quenching oil, followed reheating the indicated tem- perature and end quench water. CARBON CUNTENT PERCENT 120 120 10 100 m m 40 40 oo ° 00 DISTANCE FROM SURFACE IG. 13—This chart the carburizing properties va- rious steels shows carbon concentration and gradient. Specimens were carburized for hr. 1700 deg. est tensile values indicate the most desirable steel. The elongation and reduction area values shown below the base line should con- sidered making any such esti- mates they represent ductility should not considered that high- roughness, which impor- tant property. There recognized standard for rating steels the basis tensile test data. Certain comments can however made regarding the steel compositions covered Fig. IG. bar graph carburizing properties dozen steels, cating the percentage carbon points 0.010 in. below the surface. AIS.1. NO. 2317 31S 4027 4032 4120 4620 5120 6120 8024 8124 8724 8817 140 140 130 130 120 120 110 110 100 100 62—THE IRON AGE, September 17, 1942 For instance would appear that AISI 4815 very desirable steel, for the tensile strength value relatively high and this value not obtained the expense the elongation and reduction area values. Whereas the instance AISI 4032, the high tensile value obtained the expense elongation and reduction area values. Naturally, regardless the alloy composition, the carbon content the greatest factor determining the hardness obtained given heat treatment. And further, the higher the hardness, the higher the tensile strength value will and the lower will the elongation and reduction area values. Fig. shows how the tensile values given Fig. fitted into some other pertinent data and also allows for estimate the microstructural content the test bars. This curve, Fig. shows that the heat treated test bars the steels are close being fully martensitic. general, the steels seem fall into the picture normal way. order investigate the nor- mality the behavior the steels, they are set Fig. with the standard compositions against another set published data. Again their behavior seen normal. might considered interest- } 26 i ing have record the tensile properties after quenching from 1650 deg. which would represent the values obtained from the cores carburized parts direct quenched from the heat. Perhaps might said this data that tensile properties after what re- ferred preferable. However, there objection this method bring out the grain growth char- acteristics particular heat steel rather than representative the alloy composition. Fig. shows the tensile properties ob- tained after quenching from 1650 deg. and tempering 325 deg. These values not differ any marked extent those shown Fig. except for tendency slightly lower and more erratic. Hardenability Tests The extent which the previous tensile data could applied prac- tical applications would depend the relative hardenability the alloy compositions. Tensile values good for particular section almost wholly martensitic structure ob- tained after relatively severe quench, such water quenching, would not hold true for larger sec- tions sections more slowly cooled, resulting the production other this field that the alloy contents the steels would show their great- est effect making possible obtain the tensile properties larger sections shown Fig. Fig. gives the relative harden- ability the steels taken from end-quench tests treated follows: normalized 1650 deg. and re- heated and quenched deg. water. Using data from Howard Scott, the tensile properties shown Fig. should approximately good for the steels shown Fig. for bar sizes shown Table III. much for consideration the steels the uncarburized condi- tion. The behavior the steel the carburized condition and dur- ing carburization covered below. Hardenability Figs. and show the relative hardenability the various steels. The former indicates relative hard- enability after carburizing for hr. 1700 deg. F., and end quench- ing water. From Fig. certain conclusions can drawn. First, 045 040 AAS.ANO. 2317 31S 4027 4032 4120 4620 $120 6120 8024 8124 8724 8817 IG. 15—This bar graph shows case depth 0.50 per cent The specimens were cylinders, carburized for hr. 1700 can stated that NE8124, 8620, 8724 and 8817 have hardenability rating direct quenching compar- able 4815 and that the 4000 series and have relative- low hardenability. The data Fig. are for end- quench specimens carburized 1700 deg. for hr., quenched oil and reheated 1480 deg. and quenched water. This treat- ment would simulate treatment parts which are reheat- after direct quenching. The hardenability the 4000 series the lowest and compar- able with A5120. These data for A5120 are for heats averaging about 0.50 per cent manganese compared with minimum manga- nese 0.70 per cent now specified AISI A5120. the use the data Fig. must understood that the various alloy combinations exhibit different behavior depending the holding time before quenching and also the reheating tempera- ture used. For example, see Fig. which shows the effect various reheating temperatures the which shows little change hard- enability when reheated temper- atures from 1450 deg. 1650 deg. Table Rates for Oil and Water Quenched Bars Approximate Cooling Rate Steel deg. per sec. Symbol 1300 deg. 2317 3115 4023 200 4027 150 4119 4125 4620 100 4815 6120 100 8024 100 8124 8724 8817 Approximate maximum bar size (in.) which tensile property data Fig. would applicable. Water Oil THE IRON AGE, September 1942—63 | | > ’ , ‘ comparing Fig. with Fig. which shows the effect the reheating temperature A4120 steel, will noted that higher reheating the hardenability this steel siderably. Most steels are not affected the holding within the normal variations used practice. How- ever, least one steel, A4620, quite easily changed variation the holding time. (Fig. 11). Fig. composite graph showing the effect the reheating temperature for number steels. will noted NE8124, 8724 and 8817 increase sharply harden- ability about 1550 deg. and this respect compare with 4120. Steels A3115, A5120 and A6120 ex- hibit the same characteristic lesser degree. 4620, 2317 and the 4000 series tend de- crease hardenability when the temperature reaches 1550 deg. general may said that steels containing chromium crease hardenability the tem- perature raised. Molybdenum appears decrease the harden- ability the temperature raised. The steels carburize normal manner. Fig. shows the carbon gradients for the number other standard com- positions. These results were ob- tained from cylinders carbur- ized for hr. per cent BaCO: energized compound. The only alloy compositions which ex- hibit tendency build high carbon content the surface are the A4120 and steels, though this true lesser degree the A5120 composition. Fig. was drawn from the data given Fig. 13. The carbon con- tent 0.010 in. below the surface shown Fig. 14. certain alloys increase the rate carburization and others decrease the rate, important know the relative rates carbur- ization. Fig. shows