The Iron Age 1933-07-27: Vol 132 Iss 4

THE IRON AGE July 27,1933 J. H. VAN DEVENTER Ww. W. MACON A. I. FINDLEY G. L. LACHER Editor Consulting Editor Editor Emeritus Managing Editor Pittsburgh Detroit Boston Cleveland Chicago Washington Cincinnati G. Ea rnxstrom, Jr. F. L. CONTENTS The Acid Test Heat Treatment Steel Gears Sand Structure and Mold Permeability Growth Cast Iron Selling Molding Sands Tests Continuous-Furnace Brazing Corrosion Test for Stainless Steels Speculative Buying Metal-Working Industry What Industry Thinks Industry Control New Equipment Letters the Editor News Personals and Obituaries Washington News Automotive Industry Markets Products Advertised Index Advertisers a THE IRON AGE PUBLISHING COMPANY F. J. FRANK, President G. H. GRIFFITHS, Secretary Cc. 8S. BAUR, General Advertising Manager PUBLICATION OFFICE: Corner Chestnut and 56th Sts., Philadelphia, Pa. EXECUTIVE OFFICES: 239 West 39th New York, Y., Member, Audit Bureau Circulations ADVERTISING STAFF Member, Associated Business Papers Emerson Findley, 311 Union Bldg., Cleveland Herman, 675 Delaware Ave., Buffalo, H. K. Hottenstein, 802 Otis Bldg., Chicago Published every Thursday. Subscription Price: Peirce Lewis, 7338 Woodward Ave., Detroit United States and Possessions. Mexico, Cuba, $6.00; Charles Lundberg, Kent Rd., Upper Darby. Canada, $8.50, including duty; Foreign, $12.00 year. Single Copy 25 Cents . H. Ober, 239 West 39th St., New York B. Robinson, 428 Park Bidg., Pittsburgh ’. C. Sweetser, 239 West 39th St., New York Cable Address, ‘‘Ironage, N. Y."' . C. Warren, P. O. Box 81, Hartford, Conn. SEVENTY-NINTH YEAR SERVICE THE METAL WORKING INDUSTRY nder Act § Construction and Equipment Buying Sone THE IRON AGE......... JULY 27, 1933 AUTOMATICITY State quality being automatic. (Webster’s Automaticity closely allied Flexibility, Tooling, Operation, and Appli- cation Machine Tools. Bullard Single Spindle Automatic Vertical Lathe coordinates these fea- tures design and construction, and, therefore. affords the Metal-Working Industry new means shop Econ- omy. Bullard Automaticity this new lathe provides: Full automatic working cycle per- mitting ideal battery installation single unit operation conjunction with other classes machines. Individual electric button control machine operations. Emer- gency Stop. and Head Advance and Return control. Chuck mo- tion control. Lubricating and Coolant Pump control. Automatic interlocks Main Drive, Rapid Traverse, and Lubri- cating Motors. Automatically controlled clutch for ratio change spindle speeds— three one one three —for slowing down speed- ing during machine work- ing cycle. Automatic, electrical, and clutch control sin- gle motor for rapid ad- vance and return head well power chuck op- eration. Full automatic lubrica- tion all bearings includ- ing slide ways. THE BULLARD COMPANY Bridgeport Connecticut DECIDE equipment purchase SINGLE SPINDLE comparison— AUTOMATIC VERTICAL LATHE Get Bullard ty 4 4 Page ! U L L 1 JULY 27, 1933 Vol. 132, No. The Acid Test ORE than just the future the iron and steel industry hangs upon the action Washington the coming steel code hearings, for this administrative forum will prob- ably determined the fate the open shop America. Against the clauses this code relating employee representation through company unions, organized labor will marshal its strongest polit- ical shock troops. Having failed successfully dictate the case the textile code, the labor lobby will fight its deciding battle with steel. That why industrialists far and wide, every branch industry, will follow the coming struggle with ab- sorbed attention. The result, dictated the admin- istration’s decisions, will determine whether industry will enter fully into the spirit the act, abide the letter the law. Ad * ai ly id ‘ ¢ 4 At : oh te See 3 the great majority American employers believe that the “New Deal” square deal which will not tolerate minority domination, the success the Recovery Act assured. ~~ ‘ Viet, ¥ 4 7 A the Warner Gear Co., selection steel for gears based definite program grain size, which, turn, based upon machineability and impact strength. This group, represent- ing the teeth three different gears, shows the effect grain size hardness, impact value, fracture and static load values. HEN apply the term “heat the operations carburiz- ing, hardening and tempering after the parts are machined. However, the heat treatment gears really begins from the time the scrap, lime and ore are dumped into the open-hearth through the subsequent metal- lurgicai processes casting, ingot heating and roiling, billet heating, and through the forging, nor- malizing and annealing. All these are heat treating operations and all have effect the finished gear. treat all these metallurgical operations is, however, beyond the scope one paper. Hence, will assume that the steel delivered from the mill good uniform quality, satisfactory for gear pur- poses, and confine our attention those metallurgical terior steel mill practice. The material furnished the steel mill the form bars Iron Age, July 27, 1933 slabs. can forge this with little disturbance the flow lines the original bar can orient these direct from the bar segment, can cut off slugs, up-end them and orient the grain board steam hammer. Since gear round shape orientation the fibers radially very desirable. One reason for this that steel will move more heat treatment parallel the fiber than right angles it. explanation for this phenomenon that slip planes have been established the rolling operation and although this par- rangement subsequent heating yet this the plane least resistance should any unusual internal strains ment. Although many good gears have been made from slabs, have also examined number gears made from slabs, such differential ring gears, and found almost invari- Heat Treatment Steel Gears DAVIS Metallurgist, Warner Gear Co., Muncie, Ind. ably the greatest movement was par- allel the fiber. Gear teeth are subject fatigue and impact strains and the resistance these stresses greater right angles the fiber than parallel it. gear made bar stock does not have the impact fatigue value upset gear. series idler gears made bar stock was examined for impact our laboratory com- parison similar number upset idler gears the same kind. The ma- terial was 5150 chrome steel. The oil-hardened gears averaged The same gears up- set stock averaged ft.-lb. Many years ago the Willys Over- land Co. experienced some unexpected breakage the rear axle pinion its Model car. The pinion was highly stressed, but the model was big production, redesign the rear axle was impractical the time. The company’s metallurgist changed from drop-forged pinion up- set pinion and the breakage im- ar Depac Tegte with 4 a > rea. CF in simately #7. f { | 5 normalizing, annealing and carburizing gears are included this part Mr. Davis’ paper, presented the recent meeting the American Gear Manufacturers Association. Radial orientation the fibers the forged blanks very desir- able, and the amount working and the finishing temperature are important. Incorrect normalizing one the principal sources gear noise. Annealing not regarded merely softening the steel prior machining, but means obtaining the par- ticular micro-structure that gives maximum machining results. structure suitable for gear pro- duced Fellows shaper may not best for one produced hobbing, and one suitable for spur gear may not best for helical gear. For carburizing, expected that continuous gas furnaces will predominate. These carburize cost about mills per the chief factor this cost reduction being the elimination carburizing boxes and compound. The other half Mr. Davis’ paper, devoted hardening and cyanid- ing, will included subse- quent issue. mediately stopped. The act distrib- uting the grain was all the difference between success and failure. estimated that steel per cent stronger shear across the fiber than parallel it. Its resiliance toughness also greater, which any- one can determine bending piece sheet steel with the fiber and across it. The temperature forging not important the amount work and the finishing temperature. Steel Effect shearing cold has been given close study the Warner plant. This illustration shows effect shearing cold S.A.E. 5140 steel bar. shows the bar half sheared, half broken; shows the crack that developed after cold shearing. Note that the crack follows the contour the shearing line Cold shearing limited gear steel bars in. less diameter and 255 Brinell hardness. should forged high enough fully plastic order fill out the dies and make sharp cornered forg- ings. obvious that large forgings, such crankshafts, must heated hotter than idler gear forging. The finishing temperatures about 1700 deg. heat piece steel 2300 deg. the grain grows prolonged heating enor- mous size. the steel subsequently worked then the grain reduced not worked any extent then the grain size remains large and the steel degree. obvious, therefore, that the steel not subject much up- setting, such the small end cluster gear for example, should possible. The cluster gear one the most difficult gear forgings make correctly. After forging once coarsened and reduce the grain size materially. Quick heats are better than slow pro- longed heat for the element time also enters into grain coarsening. There great deal difference between pecking piece steel with light hammer and forging with heavy steam hammer press. Using hammers which are too light does not give the grain the fine desirable density but varying grain size which often cause gear distortion. Good working steel improves the machinability and betters hardening properties. gear made bar stock never hardens well one made forging. Incorrect Normalizing Cause Gear Noise After forging, the gear blanks should normalized. Gears annealed but not normalized always show more movement the final hardening operation than gears which are both normalized and annealed. fact, all our researches into the cause gear distortion have shown that lack correct normalizing one the prin- cipal causes gear noise. Normaliz- ing done temperatures from 1700 This gear cracked hardening; the cause was traced cold shearing bars having Brinell about 300. 1850 deg. and consists bring- ing the gears temperature, holding for hr. heat and then cooling fairly fast rate prevent abnormal grain growth. box furnace practice this consists pulling the forgings out the floor and allowing cool the air. continuous fur- nace practice the forgings move out into open air gap. The carburizing grades steel should normalized higher than the carburizing tempera- ture order remove the distortion which would otherwise occur the prolonged temperature 1700 deg. the carburizing boxes. Obviously better remove this metal move- ment before the teeth are cut than have occur afterward. Each Type Steel Annealed Definite Structure Annealing separate operation from normalizing; does not con- sist merely softening the steel developed metallurgical volving all the available knowledge micro constitutents raphy. Each type steel must annealed some definite micro-pat- tern the maximum machining re- sults are obtained. Thus would machine best with lamellar Overheating and insufficient working has this effect the end cluster gear forging. The Iron Age, July 27, 1933—9 eg ’ sd fir Ve. | har = | | pic Macrograph cluster gear showing good upsetting practice. Since gear round shape orientation the fibers radi- ally very desirable. must slightly sorbitic. 4640 will not form lamellar pearlite and will spheroidized pearlite with blocky ferrite. The function the gear metallurgist determine which structure produces the best re- actions gear cutting and then manipulate his furnace until this sistently. furnace cycle thus es- tablished and all subsequent lots steel are run through this cycle. Unfortunately, various heats steel vary characteristics and fre- quently necessary modify the cycle. Hence, the operation requires con- stant attention. Same Structure Not Suitable suitable for gears generated Fellows machine may not the best for hobbed gear, and the structure suitable for spur gear may not the best adapted for helical gear. make cluster gears having both helical and spur gears one forged unit. Our gear department claims that when the spur gears are somewhat rough helical gears are the smoothest and when the spur gears are smooth the helical gears not have desirable finish. determining the correct anneal- ing structure, blanking, drilling and broaching must subordinate gear cutting but, course, these produc- tion operations must not difficult perform either. However, varia- tions the rake and clearance are easily made with any tool but the gear cutter, being formed tool, cannot changed clearance and only few degrees the angularity the rake for changed too much will not generate good involutes. When consider that gear cutting the tolerance tooth form variables seldom over 0.0008 error may readily understood 10—The Iron Age, July 27, 1933 Charging end closed-gap combined normalizing and anneal- ing furnace equipped with six thermocouples facilitate con- trol cooling rate and obtaining structure desired. that can little with cutter cor- rections. Carburizing The carburizing operation consists impregnating the surface the steel with carbon for which has affinity when the steel heated. The depth this penetration will vary from 1/64 in., depending upon the time and temperature the car- burizing heat, which usually within the range 1650 1750 deg. certain temperature and definite time the carburizing penetration should proceed fairly uniform rate. does not, regard the steel abnormal. Abnormal steels are oxidized Hence, assume that the carburizing gases, which are usually carbon monoxide, are unbal- anced the necessity attacking the oxygen first and removing and thus upsetting the chemical equilib- rium. thus have peculiar crowding carbide the outer zone and distorted cementite. may compare the damming river with ice for the oxygen prevents the normal flow carburizing gas. Although associate pack harden- ing with solid carburizer the actual phenomenon chemical and done with carbon-bearing gas. packed with solid carburizing ma- terial should regarded gas generator produced burning the carbonaceous material with lim- Front view return counterflow carburizing furnace. Two different units are shown. The boxes enter the furnace one set rails and come out the same doorway the adjoining rails. Front pushers are shown below the level the hearth. | ited oxygen that carbon monoxide produced. does not generate the gas fast enough produce the correct and CO, ratio then may become excessively high which would decarburize. spite gear being surrounded solid car- gear carburizing box be- comes too weak gas generation. Some types depend the dripping hydrocarbon liquids such aniline. The continuous types utilize methane, propane butane mixed correct ratio with flue gas Continuous-Type Furnaces Employed There seldom any change gear during the carburizing opera- tion providing the temperatures are held fairly uniform and the steel has been correctly normalized. However, stationary furnace practice impossible obtain uniform heating rate and uniform temperatures the various boxes one furnace. Some years ago the author made test carburizing furnace loaded with eight boxes work. thermocouple was placed each box and addition the regular furnace thermocouple was used check against the in- terior temperature. Variables high 410 deg. were obtained during the early part the heating period and temperatures varying 120 deg. the termination the carburizing fact, one the eight boxes exceeded the temperature the fur- nace reading deg. F.; this prob- ably caused internal combustion. This condition was recognized num- ber years ago metallurgists and box furnace practice now prac- tically obsolete except small gear Rear end return counterflow furnace showing the side pusher, and the rear pusher, The side pusher connected with the transfer car inside the furnace for moving the carburizing box and tray the exit rails. The rear pusher moves the boxes through the furnace. plants whose production warrant the expenditure for contin- uous furnaces. The continuous furnaces used gear carburizing are the rotary type, the straight through tunnel type, the counterflow and the return counter- flow, sometimes called the boomerang furnace because the work comes out the same door enters. This latter type furnace will carburize cost less than per The gas continuous furnaces will, doubt, supplant these furnaces, for these will carburize cost approximating mills. The chief factor this cost reduction the elimination car- burizing boxes and compound. Vari- ables within 0.010 in. case depth not seemingly affect distortion. Sometimes results the shop in- dicate that these variations are factors distortion, but research does not indicate that important. Grain Sand Structure and Mold Permeability Control and the art mixing different size grains have decided influ- ence permeability, according Harry Dietert and Frank Valtier the Dietert-Detroit Co., Detroit, who presented paper, “Grain Struc- ture Control Insures Mold Permea- bility Control,” the annual conven- tion the American Foundrymen’s well known that the permea- bility production sand mold will decrease rapidly with the slightest decrease fineness, but increase permeability adding coarser sand very slow and requires addi- tions large quantities. Permeability may augmented rapidly reduc- ing the amount fines, for example, shape molding sand grains material retained sieves 200 finer. The behavior sand mixtures may better understood com- paring the relation between grain structure and base permeability place using mold green perme- ability, since base permeability elim- inates variations such may caused moisture clay content. The effect the shapes sand grains permeability problem which often comes up. Various test values for rounded and angular sand grains, when mixed with bonding ma- terial the muller, are given the table. interesting fact, the authors state, that the permeability, whether base, green dry, higher each case least per cent for the rounded grains than for the angular. This entirely natural since rounded grains produce max- imum void space. EFFECT GRAIN SHAPE SAND PROPERTIES Angular Shape Shape A.F.A. average fineness. Approx. surface area, sq. in. per cu. in. sand 10,000 15,000 Base permeability....... 200 160 per cent moisture, 8.39 per cent clay: Green 150 120 Dry 170 140 Green compression, Ib.. 9.8 11.3 Dry compression, 29.9 39.0 Green tensile, 16.0 16.5 Oil-bonded core, 1-56 ratio tensile strength—lb.. 268.0 185.0 means graphs the authors illustrate the relation between grain size and base permeability; the in- crease decrease permeability (Concluded Page 64) The Iron Age, July 27, ir 1e a- 4 ‘ > a 4 : temperatures above the criti- transformation range east iron, the atmosphere which heating takes place has marked effect upon the extent which growth occurs. The data Table III show the effect oxi- oO Volume Increase, per cent mium being delay the decomposi- tion the combined carbon. Nickel amounts per cent (2335) has little direct influence upon the rate growth cast iron, but the prin- cipal advantage lies the fact that growth-resistant compositions can Growth Cast Hig ture range because its high silicon content. The growth the Ni-Resist iron (2317) practically negligible. The mechanism which growth takes place oxidizing atmospheres 0 | | Fig. cast irons show resistance growth oxidizing atmosphere carbon dioxide 1500 deg. Fig. 7—Dispersed form graphite growth; 500 magnifications. Fig. 6—Unetched structure grown per cent silicon cast iron; 500 magnifications. Fig. flaky form graphite favorable growth; 500 magnifications. dizing atmosphere (carbon dioxide) 1500 deg. (815 deg. C.) upon several cast irons. Curves plotted from these data are shown Fig. will observed these curves that the Ni-Cr cast iron pos- sesses improved growth-resistant properties, the action the chro- made gray and machinable the ad- dition Ni. The “Ni-Tensyl” cast iron (not shown the curves), although hav- ing the graphite flakes desir- able form, was found unsuited growth-resistant material under oxidizing conditions this tempera- Table Cast Oxidizing Atmosphere 1500 Deg (815 Deg. C.) Volume Increase After Indicated Number Heat Analysis Cycles, Per Cent 2361 Plain 3.26 2.02 7.87 15.62 22.08 24.39 2349 Ni-Cr 3.43 1.08 2.33 1.36 3.96 12.59 17.10 2325 Ni 3.82 0.45 3.97 ta a 6.54 5.99 7.62 9.76 2317 Ni- Resist 2.88 1.72 14.31 3.92 5.37 2.17 0.59 1.99 12—The Iron Age, July 27, 1933 photomicrograph the structure plain per cent cast iron which had been heated 1500 deg. and cooled times. will observed that throughout the region the graphite flakes there gray-toned constituent which projects irregularly into the matrix the iron. This gray- toned constituent considered mixture silica and iron oxide, and the result the oxidizing ac- tion the gases which penetrated the iron along the graphite flakes. With the graphite passageways and adjacent areas thus clogged with this oxidizing material, the iron unable contract normally when cooled, and consequently the phenomenon growth observed. > \ «< . THOMAS WOOD Bayonne Laboratory International Nickel Co., Inc. Bayonne, Moreover, the resistance contrac- tion offered the presence the silica and iron oxide sets stresses the iron which result fissures and cracks, which, course, offer new planes attack subse- quent heating. The respiratory “breathing” effect which the iron subjected passing through the critical range, suggested Bene- dicks and Léfquist, may also ap- long, inter-twining graphite flake form conducive growth that affords excellent passageway for the penetration gases. cast iron which contains short and well- dispersed graphite flakes, however, better position resist growth. comparison Figs. and will serve demonstrate the structural advantages which the well-dissemi- nated graphite form offers. connection with the growth tests cast iron under oxidizing condi- tions, scaling tests were also made. The procedure consisted essentially determining the amount scale formed the specimens after definite exposure intervals. The data secured these scaling tests are shown only high temperatures which casting subjected use, but the character the atmosphere surrounding it, have profound effect promoting de- terioration and growth. The author, the light the litera- ture the subject and extended tests the research laboratory the International Nickel Co., brings focus the causes casting growth and finds that ad- ditions nickel will produce strong, growth-resistant, machin- able castings. The accompanying article continued from page THE IRON AGE July 13, where the discussion covered ap- plications castings below 1100 deg. ment resistance scale formation. Small amounts nickel (less than per cent) were found confer Volume cent Cumulative Scale Formed Per Cent Original Weight Specimen Fig. scale formations cast iron (oxidizing atmos- 1500 deg. F.) important applications requiring the transfer heat. Fig. the irons were not affected the same degree illuminating gas 1500 deg. Silicon appeared play important part this type growth. preciated powerful aid fur- thering the penetration the oxidiz- ing gases into the iron. now follows that the size, shape and distribution the graphite flakes are importance cast iron which subjected heat. The Table IV; curves plotted from these data are given Fig. apparent these curves that the Ni-Cr cast iron (2343) definite- more scale-resistant than the plain iron (2361). The iron (2327) shows still further improve- particular advantages with regard the resistance scaling cast iron. The ability iron resist this formation scale considerable importance applications requiring the transfer heat, due the fact that the efficiency the operation Table Cast Oxidizing Atmosphere 1500 Deg. (815 Deg. Heat Num- Analysis 2361 3.2 2.02 2343 3.53 1.97 1.52 2.60 13.17 1.48 Original Grams Scale Cumulative Scale Formed; Weight Formed After Indi- Per Cent Orig. Specimen cated No. Cycles Wt. Specimen Plain 115.49 9.81 29.36 41.24 8.50 25.4 36.6 Ni-Cr 114.13 5.98 18.45 33.61 5.25 16.15 29.5 6.50 Ni-Resist 122.49 1.83 9.22 9.73 1.50 7.56 7.95 While this particular test sample was low silicon, may stated that the standard 1-2 per cent Ni-Resist composition more that requires special foundry mixtures and produces equivalent results. The Iron Age, July 27, 1933—13 emperatures | | | ich age nd 2 rly his ed, appreciably reduced the thermal insulation which scale provides. The growth cast iron il- luminating gas 1500 deg. (815 deg. C.) was also investigated. Under these conditions was ascertained that growth took place rather peculiar process. certain specimens appeared that the illuminating gas had penetrated the irons along the graphite flakes, and had then broken down deposit free carbon. This, course, created condition similar the clogging the graphite passage- ways the oxides previously de- scribed, that the result was growth the iron. The data secured are shown Table while the curves plotted from these data are shown Fig. 10. With respect oxidizing atmos- pheres has been ascertained that growth-resistant compositions may made gray and machinable the ad- dition sufficient amounts nickel. The combination and also useful cast irons for the retarda- tion growth. Unusually good re- Table V—Growth Cast Gas 1500 Deg. (815 Deg. C.) Heat Num- Analysis 2361 Plain 3.26 2.02 2349 Ni-Cr 3.43 1.08 2.33 ‘ 2327 Ni-Resist* 2.60 0.48 13.17 1.48 2317 Ni-Resist 2.88 1.72 14.31 3.9% See footnote Table sistance permanent expansion of- fered the austenitic Ni-Resist iron. For resistance growth car- bonaceous atmospheres necessary have either well-dispersed graph- ite flake formation, such ob- tained the high strength iron, matrix similar that Ni-Resist, which does not tend “crack” the gas form free carbon. third and last part this article will include tabulations recommended cast irons for different general and specific applications.) Selling Molding Sands Tests and Specifications Advocated STRONG plea for the sale all molding sands analysis found paper, “Appli- cation A.F.A. Sand Testing the Producer,” Hardy, presi- dent, Houghland Hardy and Hardy Sand Co., Evansville, Ind., presented the recent annual convention the American Foundrymen’s Associa- tion Chicago. The practice sell- ing molding sand sample and with- out specification and analysis outmoded today the old practice selling pig iron fracture, in- sists the author. Despite the numerous papers and discussions foundry sand, stated that too little has been said about the importance control- ling molding sand its source. Unless sand accurately produced and shipments are uniform, the foun- dry man will have difficulty con- trolling his heaps, and losses are sure take place the foundry. The control heaps with sand known uniformity much simpler than attempt control with unknown, non-uniform product. This control uniformity the sand shipped can secured the producer only analyzing every shipment meability, strength, clay content, grain distribution and moisture. More than one test each car essential; frequent tests for permeability and strengths are necessary show the desired analysis being maintained. Moreover, record all tests should preserved. 14—The Iron Age, July 27, 1933 All deposits molding sand are non-uniform when considered whole, says the author. The clay con- tent, well the strength and per- meability, may vary greatly, although the grain structure may rather uni- form. Other deposits may vary grain structure. the pit ex- tended either farther along the sand structure into it, the deeper the top soil covering the sand, the greater will the clay content the underlying sand itself. Permeability increases and strengths decrease tests pro- ceed farther down the pit. The exact opposite true other deposits. still other deposits the stratum molding sand very shallow and al- most uniform analyses from top bottom any position, but varies with the topography clay content, strengths and permeability. Thus constant testing necessary. With analyses variations de- posits before him, necessary for the producer, says Mr. Hardy, uni- maintained, work out method whereby has pre-determined analysis permeability, clay con- tent, strengths and grain distribution the entire deposit and maintain well-ordered chart. Fortunate the producer who has deposits various light, medium grades which each grade may obtained different clays, permeabili- ties and strengths, together with the natural silicates each sand, all Avg. Volume Increase Content After Indicated No. end Cycles, Per Cent 1.55 5.77 10.06 12.08 13.78 4.60 0.46 343 10.64 14.9 0.83 2.90 4.47 3.32 0.27 0.27 0.63 2.85 within radius enabling him de- liver them one central mill where they may blended. molding sand uniform and produced meet definite specifications, necessary have some very accurate way proportion the different sands and natural silicates bring them together simultaneously the direct ratio each kind bears the whole. “Rule-of-thumb” methods inspec- tion—taking well-chosen, nicely tempered sample sand that has been carefully rubbed through the hands, put container and handed the foundry man who has only the look and feel sand judge by—no longer are used. The appearance molding sand often very deceiv- ing. Answering the query, “What the advantage buying analysis when not have testing equipment our foundry?” Mr. Hardy says: “The terms are the grounds which producer and foundryman meet understandingly. Most foundry men are familiar with the A.F.A. terms permeability, strength, clay con- tent, grain distribution, pan material and moisture content, and their direct relation castings. They know what they want and so, ordering from any producer, their advantage familiar with A.F.A. testing (“Testing and Grading Foundry Sands,” A.F.A. 1931.) turn, they have right expect the producer have com- prehensive understanding these terms and their application mold- ing sand problems. portion Mr. Hardy’s paper devoted discussion tolerances specifications. wide shipping tolerance such specifications should not necessary. The closer ship- ments can held given specifica- tions that have proved successful actual foundry practice, the less grief for the foundry. The author’s discus- sion tolerances covers clay content, shear, compression, permeability con- trol, pan material, grain fineness and fusion point. The number points tolerance each case given. conclusion Mr. Hardy states that, the use the sand the foundry and the production sand its source are improved, the full cooperation between producer and con- sumer paramount, through the medium tests, analyses and specifi- cations. | { New Developments Lower Cost Continuous-Furnace Brazing facturing costs, while the same time increasing the quality finished product, has led during recent years developments the brazing together steel parts heating relatively high temperature atmosphere which will eliminate oxi- dation during such brazing opera- tions. But the cost for the necessary atmosphere protect the parts has been high, and therefore application the process has been more less limited. With the recent develop- ment the Electric Furnace Co., Salem, Ohio, inexpensive gas atmosphere, together with the neces- sary furnace equipment, the field economic application has, however, materially widened. now possible numerous cases replace present joining methods economically, and also bring down the production cost many parts which are now made single piece making them two more pieces, followed con- tinuous brazing. necessity for lowering manu- This joining steel products such stampings, forgings and screw machine parts brazing accom- plished electric furnaces with con- trolled reducing gas atmosphere temperatures ranging from 1400 2100 deg. Primarily, furnace brazing operation consists heating furnace-brazed successfully include the tennis racquet frame, pulley, filter, float, condenser, muffler and golf shaft shown this illustration. No. piece 1045 steel which brazed strip manganese bronze. The parts were assembled with ribbon silver solder between them, heated 1500 deg. reducing atmosphere, and quenched water. WEST Research Engineer Electric Furnace Co., Salem, Ohio low cost reducing atmos- phere, together with the necessary furnace equipment, expected that the continuous-furnace braz- ing steel assemblies will much more widely applied than heretofore. Being cheaper, the new reducing gas may used more extravagantly, and this, stated, permits use furnaces more simple design, with econo- mies operation and mainte- nance. Data different brazing materials and the fitting and preparation the parts joined, well the operation and scope furnace brazing, are given this article. any assembly parts the melting point the brazing medium used reducing atmosphere and cooling the parts the same atmosphere temperature which the parts will not oxidize air upon removal from the cooling chamber. Brazing Materials Used Brazing materials utilized include silver solders, brass alloys and copper. Silver solders, because their com- paratively low melting temperature 1400 1600 deg. F., are used where higher temperatures would detri- mental the parts forming the brazed assembly. The silver solders form very strong bond between steel and other metallic parts. The mate- rial furnished wire thin rib- bon form cost approximately lb.; because the high cost, its use frequently avoided where cheaper alloys can employed satis- factorily. Brass wire and brass powder are used extensively where very strong bond between the parts the assem- bly the prime consideration. Braz- ing with brass wire accomplished most cases, and the resulting joints have the normal strength mild steel. Where brass powder used the braz- ing temperature closely approaches 2000 deg. due the rapid volatil- ization free zinc from the powder elevated temperatures, with result- and bronze strip were brazed tightly that was impossible separate the parts without cutting The Iron Age, July 27, 1933—15 The steel was hardened and the steel 4 ie 0 l- ie : ant increase the melting temper- ature the residue the copper- zinc mixture when the steel parts finally reach the brazing temperature. The brass alloys are cheap, being obtainable for all general purposes approximately 15c. prepared for use. They are not always satisfactory, however, for refrigerator parts which contain gases liquids and are subjected relatively high pressures. Tests are usually from 600 1000 Failure this respect probably due the fact that such brass alloys continue give off zinc during the entire brazing cycle, the time solidification, and mi- nute pores are sometimes found the film alloy left the joints after brazing. These failures are not nec- essarily frequent, but they cannot oc- cur the manufacture refriger- ator parts and other mechanisms where high pressures are encountered. For this reason commercially pure copper used the brazing such parts. Copper the pure state offers the most perfect brazing medium where the strongest and tightest bonding steel parts essential. used wire, ribbon and powdered form, and free from alloying agents, the melting temperature very con- sistent any form. The disadvan- tage using copper brazing medium that the operation car- ried out the high temperature 2100 deg. F., which naturally tends increase the maintenance cost furnace alloys over that encountered temperatures 1740 deg. and lower. Fitting and Preparation Parts Brazed The parts which are form brazed assembly should fabricated such manner that the joints fit closely together. Light press fits are very desirable, and extremely tight fits will aid perfect flow the brazing material into the joint. Capil- lary attraction plays important part the brazing operation and hence the tighter the joint, the farther the molten metal will flow. the other hand, void spots gaps any assembly are always difficult and many times impossible seal due the dependence capillary attraction for drawing the molten metal into the joints. The parts should clean ef- fective brazing expected. The reducing action the gas atmosphere used these furnaces will normally clean the parts light oxides oil and soot films. scale oil deposits should removed from the parts before assembly. heavy scale, even thoroughly reduced, would leave film very absorbent iron the surface, and the possibility the molten copper penetrating through this film and bonding with the solid steel doubtful. Where such union 16—The Iron Age, July 27, 1933 may possible with excessive amounts copper, the result would not always dependable. Heavy oil, grease soot deposits are likely leave deposit carbon upon the surface the metal which detri- mental good brazing. Simpler Furnace Used With New Reducing Atmosphere Furnaces relatively simple design have been installed for brazing the parts referred this article. For brazing operations 1800 deg. this test the furnace-brazed joint proved even stronger than the original parts, the steel pulley having failed while the brazed joint held securely. electric furnace utilizing conveyor heat-resisting alloy commonly used for heating and con- veying the work. When the brazing temperatures are high 2100 deg. F., simple pusher-type furnaces are usually employed, which the work conveyed through the heating and cooling chambers light shoes trays heat-resisting alloy. any case the equipment consists heating chamber which the work heated tothe desired brazing temper- ature, with cooling chamber attached through which the work passes after leaving the furnace proper. The cool- ing chamber usually double steel shell construction, the inner chamber being filled with the gas atmosphere, and water circulated between the inner and outer shells means forcing the cooling the satisfactory discharging tempera- ture the shortest possible time. Until recently hydrogen gas was used almost exclusively for the re- ducing atmosphere electric brazing furnaces. This type gas has satis- factory reducing qualities, but serious decarburizer steels ele- vated temperatures. cannot used the presence steels where de- carburization important factor except with special preparation the parts, such electroplating the sur- faces the product before processing the hydrogen atmosphere. Hydro- gen gas costs from $10 1000 cu. ft., depending upon the method production and the quantities used. small furnace installation may require from 300 500 cu. ft. hour with the result that the furnace design, with regard entrance and exit open- ings, may become quite complicated order use the gas sparingly possible. low cost reducing atmosphere, which produced the brazing fur- nace location, utilizing gas producer size suit each installation, has been developed the Electric Fur- nace Co. Its cost produced the company may vary from 20c. 30c. 1000 cu. ft., depending upon the cost electric energy and base materials the locality where the gas pro- duced. Such cheap gas atmosphere can used somewhat more extrav- agantly than more expensive gases, and furnace equipment can sim- ple character, resulting lower first cost and lowered operating and main- tenance cost such equipment. Brazing Operation Explained illustrate the operation, with the brazing hub and pulley assembly such used automobile fans, continuous belt-conveyor type electric furnace with reducing gas atmosphere might assumed. The parts are as- sembled with light press fit and single strand ring brass wire, 1/32 in. diameter, placed around the hub point adjacent the steel pulley. The pulley assembly placed upon the moving conveyor belt and carried into the furnace, which fourths the distance through the furnace the steel parts reach the fur- nace temperature and the brass alloy then very liquid state. Capil- lary attraction and force now come into play, and the molten metal drawn through the joint between the pulley and the hub and further forced out under the flange, thus wetting the entire surface contact, while the surplus forms fillet each end the joint. The work then moves out the furnace and into the cooling hood, during which time the film iron and copper alloy the joint solidifies. The work then cooled approximately 250 deg. its passage through the cooling hood and the job complete. Joint Exceeds Strength Requirements was found that the strength the brazed joint this case many times exceeded the requirements. automobile that “in torsion test load 5160 was applied and the weld still held, the in. diameter shaft failing. The pulley was then held outside hub and load 7190 ap- plied. The weld again held, the bolts the driver shearing. The test was discontinued, being the opinion that the weld had satisfactory safety factor under the actual working load.” (Concluded Page 66) a = L | { | 4 he Indiscriminate Use Corrosion Test for Stainless Steels Harmful BROWNE Vice-President Charge Research, ALLEGHENY STEEL CO. accelerated corrosion test has universal application, and that applies any such offered for stainless steels, but, says the author, each has its value when intelligently applied. Differences behavior metals under test and actual service may due, suggests, different electrolytic actions owing turn different potentials the electro- chemical series according the electrolyte present. particular the accompanying article discusses the corrosion stain- less steels, especially the region welds. The use columbium the alloy advanced retarder intercrystalline precipitation, the phenomenon that regarded the cause corrosion failures. general accelerated corro- sion test measure what will occur service was exemplified the case the sulphuric acid test which was used some years ago forecast the possible life steel un- der all conditions service. The re- sults this test definitely indicated that very poor grade steel would outlast the finest Swedish irons many, many times—a_ conclusion which was obviously ridiculous. Similarly, the salt spray test which was primarily designed for testing the continuity galvanized coating, functioned admirably for this pur- pose, but when applied ac- celerated test determine the re- sistance corrosion for general pur- poses, failed miserably. However, when this test used specifically, the Navy uses it, measure the resistance metal the cor- rosion ocean water, the results can accepted fairly accurate meas- ure the life material under such conditions. Engineers and metallurgists have searched diligently for some single accelerated test which might used fairly accurate measure de- folly accepting the results wv termine the relative sistance various metals under normal commercial service, but safe say that far test has been worked out which can used for such purpose. One must con- clude that each accelerated test indi- cates nothing more than what likely occur service with the same medium and under identical condi- tions. Even slight change these conditions, for example, tempera- ture concentration, likely give entirely different result. Satisfactory Accelerated Corrosion Test HEN have deal with metals high resistance corrosion the problem becomes more and more difficult. The chrome steels and the chrome-nickel steels, which gen- eral consent have all been classified under the common nomenclature stainless steels, are exceedingly re- sistant the ordinary corrosive media encountered service, and accelerated test has yet been devised which will forecast what will happen, except when the conditions the service are identical with the condi- tions which exist the test, when the results the test have been standardized with some given service. For example, the Brearley copper- sulphate test, designed test stain- less cutlery, and used Brearley definition the word stainless, only indicates that this steel were hard- ened, tempered and polished and does not become plated with copper when immersed this solution, rea- sonably safe assume that the ar- ticle cutlery can used for domes- tic service and specifically resist the action fruit juices and vinegar. does not, however, indicate that the material stainless, defined the dictionary, and matter fact stainless which conforms all the requirements cutlery tests will, under many conditions service, stain and rust very badly. all the stainless steels the most resistant corrosion the austenitic chrome-nickel steel containing ap- proximately per cent chrome and per cent nickel. When this steel was developed and commercial proc- esses worked out for its manufacture and fabrication, was hoped that would solve more our corrosion problems, because its properties, which more nearly approach, from the standpoint corrosion those the noble metals. was practically untarnishable under ordi- nary service, and was only soluble certain mineral acids, and some their compounds. developed, however, that this metal was susceptible disease which under certain conditions im- paired its resistance corrosion. The effect this disease was somewhat analogous season cracking yel- low brass, and was brought about when the material was used temperature range from 800 1500 deg. and subjected active corrosive agent. Even The Iron Age, July 27, e, 1e S- e e- is nd ill 7% 4 metal was merely heated tem- perature within this range and after- ward subjected corrosive conditions when cold, would affected point where failure frequently oc- curred. The Disease Inter-Crystalline Embrittlement change which occurs this particular steel heated within the above temperature range struc- tural one, and perhaps will apropos describe briefly this par- ticular phenomenon, for the benefit readers who are not familiar with it. Austenite, named after its discoverer, Prof. Austen, solid solution iron and carbon. non-magnetic and unstable low-carbon steels ex- cept temperatures above 1750 deg. exists only when the steel maintained high temperatures, and soon cooling takes place this constituent breaks dissociates into two constituents, iron carbide and ferrite. When certain elements are added the iron and carbon alloy, the stability this constituent considerably in- creased. For example, when chromium and nickel are added the extent and per cent respectively, the re- enough that cooled rapidly the austenite persists ordinary temper- atures, but cooled slowly heated temperature within the range 800 1500 deg. dissociation will take place, and the carbide will precipitated, usually the grain boundaries. When this takes Place subsequent heating temper- ature above the dissociation tempera- ture followed rapid cooling will again render the alloy completely austenitic. this dissociation austenite into ferrite and carbide that causes the disease mentioned above. The ex- tent which dissociation occurs governed the time and temperature heating, and limited extent the composition. The influence modifications the composition only affects the time element retarding the process dissociation, and there- fore, such modifications have dis- tinctly restricted value. Irrespective composition, this material when heated for sufficient length time within the above range will dissociate and the disease will de- velop the metal contact with corrosive agent sufficiently active produce it. This disease has been embrittle- ment, and manifests itself either the formation cracks along the crystal boundaries the metal, severe cases complete disintegra- tion, which the intergranular con- stituent destroyed dissolved and the crystals fall apart the form powder. This disease rarely occurs unless the material heated within 18—The Iron Age, July 27, 1933 the range mentioned, cooled slowly from above the range. Disease Prevention Factor Welding NFORTUNATELY the fabrica- tion many articles from this metal, not only necessary but highly desirable weld, which in- volves heating the area contiguous the weld, temperatures within this range. Equipment fabricated will develop this disease when the service such that the metal contact with active corrosive medium. tween the grain boundaries does not necessarily mean that the disease will develop all cases. matter fact this phenomenon increases the tensile strength the metal, and only slightly decreases its ductility and impact value. many forms com- mercial application the materials with which the metal contact are not sufficiently corrosive, sufficiently concentrated produce the disease, and therefore, such phenomenon can disregarded. How- ever, when the service which the highly corrosive, where experience has indicated that this disease will occur, necessary anneal the welded equipment, this impossible take advantage the limited value which modifica- tion the composition will give. suitably modifying the composi- tion this alloy the dissociation the austenite will retarded that the short period occupied the cycle the welding operation, there will not sufficient time permit carbide precipitation the extent which would produce inter-crystalline corrosion. Keeping Down the Carbon Not the Cure was logical that the first attempt modify the composition this alloy would reduce the carbon content. This was done the Krupp works Germany, and based tain laboratory tests was first recommended that order prevent the occurrence this disease, espe- cially welded equipment which could not annealed after welding, was simply necessary keep the carbon content the alloy below 0.07 per cent. Subsequent laboratory tests and the results service showed, however, that even with the carbon content below 0.07, this alloy was still susceptible carbide precipitation held sufficiently long the dissocia- tion temperature range, and was also found that the chromium and nickel content were low the alloy was susceptible the carbon con- tent were considerably higher with normal percentages chromium and nickel. Further research number metallurgists indicated this phenomenon cou