The Iron Age 1939-05-04: Vol 143 Iss 18

el, FRITZ FRANK President VAN DEVENTER Editor Managing Editor News Editor Emeritus Mechinery Editor Art Bditor Metallurgical Editor Associate Editors Washington Resident District Editors Pittsburgh Chicago Cleveland Detroit Correspondents London, Engiand Cincinnati Boston Hamburg, Germany San Toronto, Ontario Laroy W. ALLISON ASA ROUNTREB, JR. Birmingham Roy Newark, N. J. St. Lowis TURNER, JR. Owned and Published CHILTON COMPANY (Incorporated) Editorial and Executive Offices 239 39th New York, Publication Office Chestnut and 56th Philadelphia, Pa. OFFICERS AND DIRECTORS MUSSELMAN, President FRITZ FRANK, Executive Vice-President FREDERIC C. STEVENS. Vice-President JOSEPH HILDRETH, Vice-President GEORGE H. GRIFFITHS, Vice-President EVERIT B. TERHUNE, Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JOHN VAN DEVENTER, JULIAN CHASE, THOMAS KANE, CHARLES BAUR, BAUR, General Advertising Manuger DIX, Manager Reader Service Member, Audit Bureau Member Associated Business Papers Indexed the Industrial Arts Index. Published every Thursday. Subscrip- tion Price: United States and Pos- sessions, Mexico, Cuba, $6.00; Can- ada, $8.50; Foreign, $12.00 a year. Single 25 Cable Address, ‘Ironage, N. ADVERTISING STAFF Findley, 621 Union Bldg., Cleveland Herman, Chilton Phila. Hottenstein, 1012 Otis Chicago Leonard, 239 39th St., New York Peirce Lewis, 7810 Woodward Ave., Detroit C. H. Ober. 289 W._89th St., New York 428 Park Pitts. D. C. Warren. P. O. Box 81. Hartford, Conn Contents MAY 1939 All Need Little Quiet Carburizing Steels, Treatment Brush Plating Observations High Speed Steel Lead, Old Metal Modernized What's New Short Cycle Annealing Malleable Open Hearth Problems Probed the Assembly Line Washington News THE NEWS BRIEF Statistics Metal Working Activity Weekly Ingot Operating Rate Rate Activity Capital Goods Plant Expansion and Equipment Buying New Industrial Literature Just Between Two Products Advertised Index Advertisers Cepyright 1939 by Chilton Company (tne.) 110 135 139 164 (|- ‘is ps | ill ty. rts er- ter ral ter uc- per the 58,- net the ere | in | | ows red | j | the q 4 The makers Phoenix are engaged solely better better rolls, produce the kind only specialization con Tolls that give account themselves any and ali conditions. PHOENIX MAIN PRODUCTION AND LOWER COSTS IN... Strip Blooming Mills Slabbing Mills Plate Rail Mills Sheet Tin Mills Rod Mills Structural Mills Skelp Merchant Bor ond Billet Mills Pipe Tube Non-Ferrous Mills PITTSBURGH Division PITTSBURGH, | « | ¥ All Need Little Quiet 1855 ... THE IRON AGE ... MAY 1939 Vol. 143, No. FTER seven years and American business, what left it, ought calloused and case hardened and impervious emergencies. One would think that should be, but isn't. During six these seven years manufactured emergency, business was kept worrying about things home. About taxes, depressions, labor troubles, increasing costs and shrinking profits, any. But that did not take enough territory, have recently taken the additional job worrying about things abroad. now the thing that holding business back the Well, probably when that finally releases its hold us, some other fear will take its place. Just one thing after another. too bad that such things can hold business back and particularly business that but afraid stick its neck out. told business executives number lines that every time there are few days official quarters abroad and home, business immediately picks up. But the silence does not last long enough. All that need now for business revival few weeks quiet from the official noise-makers and face-makers the world. won't even insist from Washington. Just give peace and quiet and watch go! reminds the story those big bullfrogs that used keep the inhabitants their neighborhood awake all night, night after night, with their croaking. First one big blustering bull would fill his lungs and explode mighty indicate his supremacy. Then another neighbor his would try outdo him with hefty meaning and me, too, And then from across the pond would come the ear splitting third bull, inquiring yeah, you two and who And went for years and years, with peace and quiet for the neighborhood until one happy night the three bulls exploded from trying outdo each other. After which there was peace, quiet and prosperity! : Xt i ‘ er f a bie } q orn ] 3 Me § : 4 ‘ ‘ be descriptive how Inland seeks serve those who turn for counsel and steel. Serving Inland customer means giving him our usefulness— metallurgical research— personal cooperation—and, course, product suited his needs, delivered when wants it. It’s service highly important our customers because its con- venience and dependability. TIN PLATE BARS PLATES FLOOR PLATES STRUCTURALS PILING RAILS TRACK ACCESSORIES 32—THE IRON AGE, May 1939 REINFORCING BARS | q \ pre = | | SS | | | | | | | South Dearborn Street, CHICAGO District Offices: DETROIT MILWAUKEE ST. PAUL fundamentally simple oper ations case-hardening have been widely used for many years that the process firmly en- trenched modern practice any heat treating method. Such the oldest, and, until recently, the only method producing parts with hard, wear load-resisting surface and interior less hard, tougher And even though obsolescence has been claimed often, “carburizing and hardening” today ever before being demanded tre- mendous variety parts. Increasing application being made induction hardening, and steels shallow hardening that normal heat treating will give sharp hardness dif-. ferential between surface and interior. Furthermore, studies ments recent years have clarified and directed thinking regarding all phases the case hardening process, and its future use appears certain even greater than now. This article intended give general survey case hardening pro- cedure, including selection carburiz- method and performance thereof, steel, and selection hardening treatment. While times long would means this the first section two-part article, the au- thor carburizing procedure today, the equipment used, the various techniques employed, and the and physi- cal characteristics car- burized articles. exhaust the subject, the author’s hope that simple, coherent basis may presented from which proper utilization the advantages and su- periorities present practice car- burizing and hardening may follow. accordance with definitions set forth the A.S.M. Metals Handbook, carburization and case hardening are differentiated follows: Carburization ing carbon iron base alloys heat- ing the metal below its melting point contact with carbonaceous solids, liquids, gases. Case hardening—Carburizing, and subsequent hardening suitable heat- treatment, all part the surface portions piece iron base alloy. GORDON WILLIAMS Chief Metallurgist, Cleveland Tractor Co. Why case harden? are two general reasons why hard, bon surface may desired given instance. The first that the high surface hardness may add considerably the normal length life under wear; hardness usually the best means combating abrasive condi- tions and the hardened high-carbon surface will have high mineralogical hardness, i.e., high scratching indentation. The second reason that high hardness here con- notes high tensile strength, and thus improved resistance mechanical loads the surface had. This high surface hardness might at- tained the use high-carbon steels which would harden more less throughout; but, such piece would have poor resistance notch propaga- tion, “brittle,” the sub-surface metal having insufficient ductility permit slight yielding that other- wise destructive stresses might dis- tributed and made harmless. Using steel which after normal treatment would toughen but not develop suffi- cient hardness, the carburizing pro- cedure forms high-carbon zone desired depth the surface and per- mits this case hardened fully while the core, being only toughened, THE IRON AGE, May x 4 Y Rs will give resistance notch propaga- tion, or, simpler words, the piece less brittle than though hard all the way through. The present ever increasing use case hardening may attributed three factors: increasing demands mechanical design, calling for better stress-resisting parts; constant im- provements steels carburized with less distortion and uniformly high properties; and developments accuracy carburizing and control case characteristics. Surface hard- ening localized heating steels which normally treated would hard- fully with concurrent embrittlement and warpage, being successfully carried out two processes, electric high frequency induction heating and flame hardening torches. Important these are, they 1.25 have not yet seriously encroached the field case hardening. borne mind all times that car- burized piece metal, having two critical ranges and differing re- sponses treatment. The selection steel type used, case depth re- quired, and heat treatment provide best properties must made with this mind—all these factors must simultaneously considered, since change one will usually demand compensating change the others. The discussion which follows will ap- proach the subject from four points view, those case depth, heat treatment, and steel selec- tion, but there will necessarily much overlapping and repetition. stated the definition above, the ob- 1.0 0.70 ject carburizing have carbon enter the steel, from the carburizing agent, quantity and manner All carburizing considered the result gas reactions, gardless whether the carbon source gas, liquid, solid, but the latter classifications are useful discussing methods. The actual mechanism carbon combination with iron will not argued, being debatable subject but not present moment. will assumed that carbon present either the necessary gaseous form the metal iron carbide. Since carburizing action almost negligible below 1500 deg., and equip- ment short lived above 1800 these temperatures define the range commonly employed. Characteristics the 045 Approximate carbon content, per cent Surface Apparent Hypereutectoid zone eutectoid Transition (note carbide network) Total depth case Approximate depth case which will show treatment Fig. typical case. 34—THE IRON AGE, 1939 | zone zone | shown Fig. The low-carbon core apparent, the increasing carboa content the surface approached. The “transition zone” from original steel the high carbon, fully harden- able case, the eutectoid zone where neither excess ferrite nor cementite present, and the hypereutectoid zone the surface are designated, well the approximate carbon content. prime importance are the depth hardenable case (usually considered end about 0.50 carbon), the smooth gradation carbon content that each zone well knit with the adjacent ones, and the amount ex- cess cementite the hypereutectoid zone which affects the type heat treatment that must used. This ex- cess carbide is, may seen, the form network the grain boun- daries, and, being brittle, must reformed good case toughness desired. All carburized cases the unhardened condition will resemble Fig. although the hypereutectoid zone may decreased eliminated proper carburizing. There are two simple, important phases carburization, the absorption carbon the steel, and the diffu- sion this absorbed carbon into the steel. Carbon with increasing temperature that greater amount carbon enters the steel higher than lower tempera- tures. The rate diffusion this carbon from the surface inward changes even more markedly with tem- peratures, that, the lower range useful carburizing temperatures, the carbon absorbed will not diffuse and surface carbon content will build surprising degree (well over per cent carbon has been found the extreme surface layer steel carburized 1500 deg. F.), but the case depth attained given time will slight. high temperatures the reverse will found—carbon ab- sorption will high total quantity, but the maximum carbon will lower, perhaps per cent 1800 deg., be- cause the high rate diffusion into the steel; case depth obtained given time will thus large. Carbon absorption, then, depends temperature and available supply active carburizing medium. given there definite maxi- mum value which will not exceeded regardless activity quantity carburizing agent, but absorption less than the maximum may often occur, ‘lue insufficient carburizing medium, this condition being either deliberate- produced lower the maximum retort carburizer dumping night. Photo Silliman Cleveland Tractor Co. with spent compound inadequate gas supply the work surface. Diffusion carbon once combined with the iron follows the general laws diffusion; the rate penetration increased with temperature duced carbon gradient the higher carbon zones tending drive carbon toward the lower) de- creases; also affected steel composition, but this relatively lesser effect usually. Thus, reducing useful carbon supply the steel will tend lower the surface carbon and the same time somewhat reduce the rate penetration, and, the con- trary, high-carbon surface layer will continue case depth increase. even though more carbon being added. Frequent advantage taken this latter principle gas carbur- izing, will noted later. Since decreased gradient car- why average rate penetration lower depth case increased; given temperature the rate for the first hour will high, decreasing quickly lower value time pro- ceeds. maximum rate penetration thus seen de- pend maximum absorption given temperature, plus the diffusion which will ensue. Fig. curves developed Schlumpf show case depth found after any given time several temperatures. The case depths were measured fractured hardened specimens. Carburizing formed natural gas (almost pure methane) and the writer’s experi- ence these curves represent about the maximum obtained, since am- ple supply active carburizing agent was always present. Penetrations ap- THE IRON May x h = q t 3 4 | | | a < preciably below those shown are indication weak insufficient ac- tive carburizer, temperature lower than expected. interesting note that replotting these curves log-log coordinates gives series straight parallel lines, indicating conformity basic law. Method Case Depth Measure- quent source confusion; the cases predicted Fig. include the hard portion (above 0.45 carbon) only. general rule this method measure- ment the most useful since the depth the desired case considered. How- ever many ways are used describe specify case depth, and any satis- factory fully understood. Carburizing Methods indicated above, all carburization believed the result gas action. The source and continued activation this gas determines the difference between the three general methods carburizing. Chemical reactions will referred only incidentally here; for more elab- orate discussions the A.S.M. Carburiz- ing Symposium (1937) and the 1939 A.S.M. Metals Handbook should consulted. Solid Compounds: Historically the most important method, carburiz- ing heating steel close contact with solid compounds, still the most widely used. These compounds usu- ally are made charcoal and coke base, impregnated coated with “energizers,” usually barium, calcium, and sodium carbonates, suitably bound together. Charcoal alone very weak the energizers accel- erate the formation actively car- burizing gases, and assist the re- activation spent gases after they have delivered their available carbon the steel surfaces. total energizer content above per cent, maximum activity ordinarily had. Since hand- ling compound causes break into fragments, and the heavy chemicals are loosened, the powder lost screening compound contains much energizer; therefore new car- burizing compound usually made carry about per cent total ener- gizers, and the normal additions new compound replace shrinkage due burning and powdering (usu- ally near per cent) will keep the chemical content the necessary level. the steel parts are packed they are covered with such compound suitable container and heated the selected temperature, carburizing will proceed accordance with Fig. 36—THE IRON AGE, May 1939 But note that carburizing compounds are excellent insulators, and boxes usually are large, that interiors thereof not come heat rapidly might thought from watching external temperature indicator. Thus the rate carburizing com- pound has often been thought less than gas, when the difference actually was time heat. Large irregularities may occur, one box and furnace loads boxes, time coming heat; this means Case depth, inches variety case depths one load, and this occurrence has been im- portant factor stimulating gas car- burizing. course, fundamental requirement uniformity furnace temperature any approach case depth uniformity had; colder portions furnace will result both longer time coming heat and lower penetration rate heat. possible means arriving uni- form furnace and work temperature should ever neglected. Continuous furnaces, which box after box carried through the same heating cycle, give greatly improved uniformity, particularly thin, close- conforming containers are used that lost heat and time due insulat- ing effect compound are held minimum. amazing how little compound needed provide for carburizing. Roush and discussion carburizing container design state that 0.01 compound per sq. in. surface ample. Brief consideration will verify this; case depth 1/16 in. means absorption average 0.50 per cent carbon weight 0.00009 Ib. per sq. in., truly minute amount! Closely con- forming containers dously the time and cost heating, improve the uniformity results, and decrease warpage, but usually require large investment heat resisting Fig. Time- depth penetra- tion chart alloy. Only those plants where large volumes duplicate parts are carburized can economical advantage taken the possibilities such special, individual containers. This also usually true continuous fur- naces, which are not adaptable wide variations size work case depth specifications from hour hour. Although carburizing solid com- pounds the oldest, best known, and most fool-proof method (it can hardly dirty process with handling com- pound start and finish, and ally the most expensive method, be- cause the lost time, heat, and com- pound. Further, modern hardening practice very often direct quenching the end the carburiz- ing cycle; this fairly difficult when the work packed boxes, and the hot compound tends make 0.120 . 0 | i q Carburizing time heat, hours | | For these reasons prac- tically all recent installations have been gas carburizing equipment. Carbon-supplying activity the compound, and thus maximum carbon the case given temperature, can- not regulated over any range with these solids. With given compound, little control can exerted over the type case produced. Any case depth may achieved compound carburizing, but when very thin cases are sought, difficult pleasant job. eous media. Elimination the solid compound and its insulating effect has given economy time and improve- ment uniformity. Instead boxes which the work packed, the work, suitably supported, necessary trays and fixtures, placed large heated retort muffle into which the carburizing gas introduced and kept isolated from outside air furnace Furnace equipment three funda- mental types use, follows: ro- Activated baths baths case with cyanide and ac- baths Beckwith, Carburiz- Symposium, and Davis, AS.M. Metals Handbook, Davis bath 1650 deg. 0.025 Case know when start counting the short time required, and local variations time heat are very significant. Longer times heat tend make these differences moderate, and this range that compound usually used. When extreme case depths are sought, loss activity due com- pound becoming spent may result such lowered rate maximum car- that cooling and repacking with iresh compound for additional car period may necessary. Gas Carburizing :—Since carburiza- tion depends ultimately gas action, obviously gases may used the original source carbon. Many gases have been found highly effective available carbon, and their modern importance. The large carburizing furnace in- recent years utilize gas- tating retort, fan agitated stationary retort, and non-fan agitated station- ary retort. These may heated any means that will give good tem- perature distribution. When the retort rotated, good uniformity tem- perature assured and all pieces are frequently exposed the fresh car- burizing gas. Tumbling, course, causes some marking work and often not permissible. the other two types, the difference meth- fan used, the gas given turbulence thereby and spent stale gas blown away from the work surfaces. fan not used, several inlets may required, well greater gas flow, provide proper agitation gas. Useful Gases:—A wide variety gases has been successfully used carburizing; practically all current commercial use are hydrocarbons such natural gas, propane, heavier similar compounds which may li- quid room temperature but are readily vaporized the furnace muf- fle. All these contain sufficient car- bon that carburizing the minimum rate may achieved, but this very same over-abundance may cause trou- ble, shown below. Soot Regulation order main- tain maximum activity, the steel sur- faces must kept supplied with effec- tive gas, and the spent gas layer around the parts must removed invigorated. This demands, therefore, certain turbulence rate flow gas past the steel surfaces. Such flow may had use large volume fresh, carburizing gas, forced circulation fan. the latter used, but small additions raw gas are required. If, however, high flow gas must used get sustained activity, then abundance carbon the gas will ordinarily lead heavy deposits carbon soot. the work being tumbled, rotating retort, this cannot ordinarily build any ex- tent the steel surfaces. Otherwise the deposits will often great that the steel effectively blanketed and carburizing action interfered with. Consequently usual today gas carburizing (in the absence tumbling fan agitation) dilute the active gas mixing with the desired proportion relatively in- active gas that high flow rates may used without heavy soot deposits being formed. Air often used free and easily used, but not too effective soot control. Incom- pletely burnt gas prepared auxil- iary unit much used and fairly effective. The same type gas may treated passing through hot charcoal, giving gas very satis- factory properties diluent. Spent gas leaving the carburizing chamber obviously largely broken down and another useful and effective dilu- tion medium. “City gas” sometimes irregularity and insufficient ac- tive portion, but often very useful when the proper “weakness” di- rect carburizer dilution gas. All these are frequent use and their actions are discussed detail the \.S.M. Carburizing Symposium. Regulation Activity:—Since the above gases all provide abundance available carbon, the maximum case produced will have high surface car- bon content, often higher than desired. The dilution employed for soot control may carried further reduce the THE IRON May 1939—37 | baths ‘ e ; carbon-supplying activity the gas that reduced surface carbon content obtained, and the hypereutectoid zone reduced eliminated. This ef- fect probably important reason soot control for dilution current practice. proper dilution pro- duce carburizing gas suitable ac- tivity, the maximum carbon content the case may reduced from, say, 1.30 per cent (at 1700 deg. straight natural gas), 0.95 per cent 1.05 per cent, even lower desired, and with simultaneous improvement cleanliness work. Also, life heat- resisting alloy will lengthened. The writer convinced that excessive soot deposition very important cause premature alloy failure. variation the simple dilution procedure which coming into in- creasing use consists the periodic admission regulated quantities the raw, rich gas, followed periods no-gas admission, during which the carburizing atmosphere gradually be- comes spent. Then the raw gas injec- tion serves reinvigorate this spent gas the desired degree. Thus the spent gas used diluent, de- scribed above. carburizing gears the plant with which the author connected, batch-type horizontal gas carburizers are used. Straight natural gas required flow least cu. ft. per hr. give uniform case, but this led high surface carbon con- tent and heavy soot deposition. Cur- rent practice admit high flow natural gas for approximately one minute, followed several minutes gas injection. The results ob- tained this procedure are very sat- isfactory, soot being very low, maxi- mum carbon about 1.05 per cent, car- burizing gas consumption totaling about cu. ft. per hr. and auxil- iary gas being needed. Such cycles have been used the past variety ways and offer many advantages batch-type gas carburizing operations. Regulation Maximum Carbon This regulation may easily formed, indicated above, reduc- ing the gas activity. Another method, feasible only with gas carburizing, de- pends the continuing inward diffu- sion and leveling tendency the car- bon when further carburizing agent present. Thus, simply shutting off the supply active gas, the case penetration continues very nearly the same rate for long time, the sur- face carbon being steadily decreased. This method carbon content con- trol widely used; the procedure periodic injection active gas, de- 38—THE IRON AGE, May 1939 scribed above, really form al- ternate carburizing and diffusion. the “head” carbon lowered, course, the rate penetration must decrease, but during diffusion period which the surface carbon re- duced only slightly, from 1.25 1.00 per cent, the case depth will con- tinue increase nearly the normal rate. Direct Quenching From Gas Car- burizers:—Such quenching easily performed, packing material being present. Soot must controlled, else heavy deposits will interfere with quenching. However, the ease quenching direct has led increasing use gas carburizing prior such treatment. important phase this lies the ever-growing use car- burizing atmosphere furnaces used for heating automobile gears for hardening, thin extremely hard surface layer being formed standard oil-hardening materials. This will referred again connection with selection case depth. Liquid Bath Carburizing :—The use molten baths for surface hardening sense new process, but de- velopments recent years have caused such treatment gain rapidly im- portance. Cyanides have long been used for the production thin, very hard cases, but attempts produce depths more than few thousandths inch leads rapid deteriora- tion the bath (high temperatures rate) plus serious embrittlement due high nitrogen content the case. The modern liquid carburizing media consist principally inactive carrier salts plus cyanides, but also include special materials added accelerate the production available carbon. reduce nitrogen absorption, and retard bath deterioration. such molten carburizing bath, case depths 0.030 in. are readily produced and very satisfactory type case obtained. Since uniformity temperature usually quite good molten salt bath, good uniformity case depth expected. Penetration rates appear follow the curve Fig. Fig. are shown curves for case depth, taken from the paper Beck- with the Carburizing Sym- These curves seem cover all types carburizing baths full activity, since there maximum which cannot exceeded. The time the work comes heat easily esti- mated, that desired case depth may rather precisely controlled. for this reason especially that use such carburizing baths Small, thin parts requiring hard face and good closely controlled case depth and type, and these demands are nicely met the molten media. Work direct-quenched from the pot into water oil almost universal- ly. was formerly difficult clean quenching, due the base salts used, but recent years many baths have been developed which wash freely clean surface after oil quenching. This done largely reduction elimina- tion the insoluble portion the constituents. Water quenching offers difficulties any event, the adher- ent salt being “exploded” off the quench. Stability bath activity has been improved the currently available liquid carburizers, that discarding spent salt not often required, the normal drag-out replacement sufficing maintain high carburizing activity. When long heats with little drag-out are employed, may periodically bail out portion the bath, permit addition sufficient fresh salt. For such operations cer- tain makers offer concentrated ener- gizer, the bath thus consisting base salt plus separate energizer, while most baths are sold single com- ponent containing the required propor- tion active agent. latter type, baths greater less ratio energizer are usually offered meet varying conditions, the active content regulating the price the salt supplied. The liquid carburizing baths find their greatest employment the pro- duction case depths around 0.010 in, 0.015 in., but, mentioned pre- viously, are useful 0.030 in. even more some instances. Work almost invariably direct quenched, followed tempering treatment necessary. oil quench being used for very thin pieces, when factory hardening will occur, for steels, while water even caustic brine solutions are used for heavier parts carbon steel. The uniformity heating and case depth, plus the simplicity treatment, will result low distortion. Note:—The second and last section this article will appeat shortly, and will deal with the ized and the selection the depth used. q | | | | | | | i | | find pro- pre- for even for The case ment, pear the -hur- case Current, amperes AWS ime minutes SURFACE treatment and finish ing metals, either decora- tive protective plating, are accomplished practically and efficiently the portable brush electroplating process, according makers the equipment, Portable Plating Equip- ment Co., 1000 South Michigan Ave- nue, Chicago. said that over 500 these in- stallations are now use. Brush plat- ing developed this company said comparable the principle the tank immersion method with the exception that the solution, made plastic form, applied with special type brush and anode. Plating takes place only where the brush directed and the longer the brush applied with sufficient solution, the thicker the deposit becomes. increasing the size the anode the brush, greater current effi- more rapid deposition metal. sizes pure metal anodes are available. The plastic plating solu- not deteriorate with age. They are always ready for use and can salvaged and used again. The plating efficiency the brush Process said remarkably high due the proximity the anode the brush the base metal and the simple control and continual agitation Solution Cadmium Copper Lead Nickel Silver Tin V.) Zine Copper (Sul.) ELECTRODEPOSITION CHART Time for brush plating area 100 sq. in. with thickness .00025 thousandth) in. Approximate Amperes Drawn Various Anodes Using Volts— Spiral Anode Anode Anode Anode Brass and Bronze: same Cyanide Copper. Take amperage (left side) read down (bottom) minutes: Example: in. anode will deposit from the metalline solution tin 0.00025 in. over area 100 sq. in. approx. With in. anode, 100 sq. in. sq. in. min. Double divide for thicker thinner deposits. Calculated use brush per cent total time. BRUSH PLATING the plating compound during the brushing. This continual movement, wiping away any accumulated film oc- casioned the chemical and physical characteristics the base metal, acts insure unusual bond between the two metals, resulting very dense, uniform and nonporous deposit. The essential requirements for satis- factory results with brush electroplat- ing are personal efficiency the oper- ator and attention instructions. average workman said able learn the correct method plating few hours. The time required plate definite thickness any the more common metals, with various anodes and various current values, shown the accompanying tion. The portability the unit de- finite convenience. permits plating articles and equipment without dis- mantling and reassembling. The equip- ment complete consists specially designed and constructed power sup- ply unit, correct cleaning agents, plastic plating solutions, special type brushes and anodes. The power unit operates wherever there a.c. out- let, d.c. outlets through the use converter. examples the use ‘this equipment, note that utility companies find valuable for applying silver de- posits bus bars and switch gear all kinds eliminate copper corrosion and for higher electrical conductivity. Manufacturing companies use for applying zinc over welded seams where the protective coatings have been burned off for all types anti- corrosive deposits vats, tanks and other surfaces. Railroads use for decorative plating equipment and fixtures without dismantling; corrosive deposits metal surfaces, especially cadmium locomotive driving rods. Users press steel dies use for applying hard nickel cobalt deposits large small surfaces. Automobile service stations have in- numerable uses for Towns and cities find valuable, where tank plating facilities are available. Industrial art schools find valuable for practical work and in- struction, and service companies use the equipment for replating metal window strips, signs, and store fronts. THE IRON AGE, May ace the ers the een ble ing ary the ient hile om- por- neet OLD SHORTNESS: Cold shortness the term applied steel which brittle when cold. the several cases follow, the term cold short will refer specifically several heats 18-4-1 high speed steel which when stamped with steel roller stamps under hydraulic press devel- oped cracks the roots the letters —such very practical example cold brittleness cold shortness. This method stamping quite uniform regards the pressure applied, and the steel not subjected sharp blow. With the exception the steel made from the two showed cold brittleness, the develop- ment cracks this method stamping practically unknown. 40—THE IRON AGE, May 1939 The analyses two heats steel dicated are shown Table With respect the steels shown, heat was mildly cold short, the number cracked blanks being few. Heat was abnormally cold short, per cent the blanks processed being cracked. shortness, which rarely found high speed steel, attributed arsenic arsenic and phosphorus, the latter being additive with arsenic. Arsenic the extent per cent considered sufficient make high speed steel The combined arsenic and phosphorus Cross-section annealed in. high speed steel. Heat (Right) As- quenched high speed steel. Heat Both etched with per cent Nital, and shown 1000 diameters. heat equals 0.036 per cent and heat the arsenic total 0.06 per cent. Material from heat showed normal response heat treatment and normal annealed and treated structures. Material from heat was definitely sluggish response heat treatment and showed poor microstructures both the an- nealed and heat (left) taken 1000 diame- ters, shows the mill annealed structure cross-section midway between the outside and middle bar from heat There are number relatively large carbide masses. The tially due the structural abnormal- ity, although more likely that the arsenic and phosphorus tended em- the matrix. The micrographs material from heat will dis- cussed under the heading “Hard- enability,” since this heat addition showed low hardenability index. high speed steel here considered arbitrary index the capacity ° ° | | . | re) ) | | | the steel produce same conditions regards sample size and heat treatment) hardness equiv- alent that usually found normal steel, higher lower hardness than normal. Such test would whatever the individual might choose make it; for obvious that variations furnace equipment and furnace atmospheres would ence heating rates that sample sizes and time-temperature cycles established under one set conditions—in electrically heated controlled atmos- phere furnace—could not uniform- duplicated gas oil-fired furnaces. any test for harden- ability the analysis the high speed steel must taken into account. One would not compare the hardenability 0.70 carbon high speed steel with one containing 0.60 carbon. When the tungsten about 18.5 per cent, the steel tends react somewhat slug- gishly response heat treatment compared one containing 17.50 per cent. Increasing the vanadium content from 1.00 1.25 per cent tends decrease, but only slightly, ~ HIS the conclusion two-part article, the section which appeared the April issue. that time the author described the effect trace elements, and gave detailed information sweating. Herein, other heat characteristics are studied, such cold shortness, hardenability, susceptibility decarburizo- tion, etc. the hardness obtained under the set conditions described. One the tests used gage the hardenability 0.68 0.71 carbon Cross-section annealed in. high speed steel heat (Right) As- quenched high speed steel heat Both etched with per cent Nital and shown 1000 diameters. ° ° MORRISON Metallurgist, Landis Machine Co., Waynesboro, Pa. ° ° ° material consists sample approxi- mating in. There particular reason for using this size sample except for the fact that has been convenient. Samples pared that slightly more than the specified maximum decarburization removed from each side the bar. Samples are heated light heat re- sisting trays together with control samples. (Samples more heats, the hardenability index which known.) Samples are preheated 1550 deg. for total time the furnace. One tray transferred the high temperature furnace 2350 deg. and held there for min. sec. and quenched Another duplicate tray ples held the high temperature side for min sec., appoxi- mately min. more than would required normal hardening. The same controlled temperature furnaces and the same furnace atmospheres are always used for this test. Normal steel given these two treat- ments will show “as quenched” Rockwell hardness 67, pro- THE IRON AGE, May rus led its ved an- ure the bar lity red city @ vided the surfaces for Rockwell test- ing are carefully prepared. the surface prepared grinding, and the surface temperature the test surface perchance raised 700 deg. 900 deg. F., the hardness test may show low Rockwell Asa general rule, 18-4-1 steel containing 0.70 per cent carbon which shows true “as quenched” Rockwell will usually show high degree red hardness. steel showing true Rockwell may may not show high degree red hardness. The “as quenched” hardness 18-4-1 steel be- cause the thermal instability the steel this state not considered very reliable criterion hardenability. The hardened samples may nicked half and examined under the miero- scope for comparison austenitic grain sizes when given usual, longer than usual, time the high temperature furnace, and compared with normal steel treated under the The quenched test samples are drawn 1050 deg. for hr. and then tested. normal steel will show approximately 65.5 Rockwell depending time test tempera- ture. The samples are then redrawn 1100 deg. for hr. Two steels held 2350 deg. for min. sec. may show the same hardness when drawn 1050 deg. When re-drawn 1100 deg. one the steels may show lower hardness than the other. Steels the 0.68 0.71 carbon range which show higher hardenability in- dex than normal are exceptional, and where this condition found, rule based fractional Rockwell value which not very conclusive. 42—THE IRON AGE, May 1939 high speed steel heat Etched with per cent Nital and shown 1000 diameters. (In the 0.58 0.62 carbon range, spe- cifically 0.61 car- bon material, high hardenability index less exceptional than the case the 0.68 0.71 car- bon range.) Material made from some heats 18-4-1 steel exhibit unmistakably low hardenability index. Table shows the analyses three heats high speed steel which showed low degrees hardenability. Two heats steel have been previously listed heat Table (in first section article) and heat Table Excessive Aluminum Undesirable Heats and both showed the same degree hardenability, producing the test sample after the 1050 deg. after the 1100 deg. re-draw Rockwell 60.5 61.5. Numerous tests were run sample material from these two heats, and the low hardenability was always prevailing. Both these heats steel show ad- dition other abnormalities analy- sis excessive amounts aluminum. Aluminum high speed steel has been termed “bad exces- sive amounts appears act deterrent the hardening the steel. bon high speed steel which contained only trace aluminum yet showed low degree hardenability. the carbon 18-4-1 steel raised from 0.75 per cent, there slight but noticeable change sponse heat treatment. tively, the 0.75 carbon steel slightly less active response heat ment than the 0.70 carbon. quently, testing this type material slightly longer time given the high temperature furnace. Samples heat ordinarily tested should produce Rockwell hardness approximately 64.5 after 1100 deg. draw. However, the case this steel the samples consistently showed Low hardenability high steel sometimes attributed over- annealing, which causes the carbides masses with subsequent diminution solution during hardening. The mill records heat indicated that this heat was not scopic examination the and treated structures indicated slight- larger carbide size particles than found normal material. the microstructures did not give evr dence that the structural difference was sufficiently great account for the difference hardenability. While aluminum probably tends act inhibitor affecting would appear likely that other hibitors may exist. clusive are comparison the nealed and “as material heat and material from two relatively normal heats steel. ‘ey | | 7 62. ver- ides mill this ght- than ver, evi- ence for shows annealed and hardened structures heat Fig. shows the annealed and hardened structures the hardened structure heat Micrographs shown the right Figs. and and Fig. illustrate the “as quenched” structures the same size samples from three different heats steel which were treated the same time the same tray 2350 deg. The usual analyses heats and are follow: Heat 0.029 Si, 4.00 Cr, 17.92 1.01 and 0.06 Ni. Heat 0.70 0.22 Mn, 0.016 trace 0.26 Si, 3.97 Cr, 17.80 0.98 and 0.08 Ni. Fig. (left) shows the structure cross-section mill-annealed bar in. taken midway between the outside and center bar. Fig. (right) the same sample micro- graphed the same relative position after heating 2350 deg. for min. and then quenching oil. This steel showed good response heat treatment, considerable resistance grain growth during heating for hard- ening, and hardenability index only slightly lower than average. 7—(Left) tool near the cutting edge, compared with companion normal tool (right) near the cutting edge. Both etched per cent Nital and shown 500 diameters. tool in. beneath the cutting edge, compared with companion normal (right) tool in. beneath the cutting edge. per cent Nital, and micrographs are shown 500 diameters. Fig. (left) shows the mill annealed structure in. bar steel from heat taken the same relative location that Fig. (left), heat The micrograph shows ab- normally large masses carbide. Fig. (right) the “as quenched” structure sample heat The grain size this sample consider- ably larger than that heat Fig. (right). The micrograph shows the presence large carbide tween the grains and large carbide particles inside the grains. Steel showed hardenability index consid- erably below normal. ture heat This sample showed good response heat treatment, size only somewhat smaller than that heat Fig. (right), although fewer and smaller large car- masses between the grains, well fewer and inside the grains. Susceptibility Decarburization from some heats 18-4-1 steel decarburize during heat treatment well known. Often this tendency decarburize may traced excessive amounts cobalt, cobalt and nickel. Some heats 18-4-1 steel may more susceptible absorbing carbon the steel surfaces during heat treatment. Susceptibility de- carburization, carburization dur- ing heat treatment will discussed very general sort way, since any consideration these two would re- quire their correlation with furnace equipment, furnace atmospheres and the combination these two with the THE IRON AGE, May se- ‘ial the uld eg. his shape and mass the part treated. Furnace atmospheres with the hardening high speed steel are ever topic for inconclusive discussion. Controlled atmosphere fur- naces have been tremendous value the tool manufacturer and great strides are being made, and will con- tinue made improve the prop- erties the furnace atmospheres. Much the present day progress connection with the development atmospheres with the aim finding atmosphere which neutral the steel surface regards carbon content the surface. Furnace atmospheres used today are actually compro- mises related the steel part parts being treated. Let supposed that found that treating cer- tain class tools that slightly oxi- dizing atmosphere for preheating 1550 deg. and strongly reducing atmosphere about per cent the high heat furnace 2350 deg. produces the most desirable tool, least, what opinion and experi- ence indicates the best. slightly oxidizing condition were cor- rect for preheating the tool 1550 deg. F., might asked what atmos- phere should surround the surface this tool, when, after transferring the high heat furnace the surface passing from 1550 deg. 1800 deg. mosphere correct 1550 deg. per cent atmosphere would not appear correct the time the surface the tool was passing through the temperature range 1550 deg. 1800 deg. Again, the 2350 deg. heat, due any lack uniformity section, some areas projections tool may lose some little surface car- bon, while other areas may gain much points carbon for depth several thousandths inch. Neutral furnace the heat treatment steel are frequently spoken of. at- mosphere may almost ideally neu- tral the regards loss metal. regards atmospheres being neutral the surface the steel the relation carbon content the first few thousandths inch, very probable that such atmos- phere were commercially available, the point neutrality would such hair-line nature that could not commercially maintained. 18-4-1 steel “glutton” for ab- sorbing carbon the surface. one packs high speed steel carburizing spots sometimes found near the surface nealed high speed compound and heats 2150 deg. the surface time will much carbon that the edges will melt fuse due the lowering the melting point. high speed steel hardened strongly reducing pheres the steel will tend, within rea- sonable time limits, absorb some carbon for the first few thousandths aninch. very probable that controlled atmosphere furnaces, where reducing atmospheres are used the high temperature side, that more car- bon generally added the steel surfaces than taken away. The ad- dition carbon the first few thou- sandths inch high speed steel surface rather than being objec- tionable may even desirable, pro- vided excessive over-heating does not accompany the increased surface car- bon. the other hand, even the loss some surface carbon, within reason- able limits, may desirable some areas some tools, which because design are particularly fragile. Truly ideal furnace atmosphere condition relation the design certain tools might require the ence two different atmospheres the same furnace the same time—a ridiculous consideration. Perhaps possible avenue approach this matter furnace atmosphere would 0.68 0.18 0.012 trace 0.69 0.29 0.028 0.012 TABLE Two Heats Steel Exhibiting Cold Brittleness 0.30 4.53 17.40 1.06 0.15 0.07 17.60 1.08 0.10 0.12 TABLE 0.025 0.023 0.12 trace 0.04 0.032 Three Heats Steel Showing Low Degrees Hardenability HeatT..... 0.74 0.018 trace HeatZ..... 0.69 0.25 0.020 0.019 0.69 0.29 0.012 0.39 3.99 17.68 0.08 0.30 4.05 18.56 1.01 0.09 0.31 0.21 17.60 1.08 0.10 0.12 0.54 0.10 0.022 trace trace 44—THE IRON AGE, May 1939 >= : | | | | | | | | | | an have ever changing atmos- phere the high temperature side. After the high speed steel would transferred the high temperature side the atmosphere the furnace which surrounds the steel would change the changing temperature the high speed steel surface. However, this put print. Again, heavy-bodied tool with small projection would have different rates heating the Decarburization the case hardened high speed steel would appear terms having quite definite meanings. Both terms, however, may used, and are used, describe the condition partial loss, partial absorption the maximum saturation amount car- bon, opposed respectively total decarburization nearly complete loss surface carbon; total car- burization when the surface has ab- sorbed the maximum amount nearly the maximum amount possible under the existing conditions equilibrium. 0.80 carbon 18-4-1 steel were hardened under such conditions that the surface were lose points carbon the first 0.002 in. sur- face (or the first 0.002 in. surface would analyze 0.65 carbon) this sur- face would very probably absolutely practical standpoint the steel surface not decarburized; for does not show absolutely hard the testing the analytical standpoint the steel has indeed been partially served that little known quan- TABLE Analysis Superior Heat and Several Normal Heats 4.04 17.80 0.98 0.078 4.01 17.84 0.99 0.070 4.00 17.92 1.00 0.075 titative way the hardness steel surfaces. the present time, quantitative measurement the hard- ness extremely hard steel surfaces, been available, which gives test value, general, more accurate than that good testing file. Quantita tive here used restricted practical sense. For example, suppose low carbon steel were heated commercial cyanide-chloride bath for such time obtain 0.001 in. case, after which quenched water. How could the hardness num- ber this 0.001 in. case deter- mined terms one the present day hardness testing One the severest handicaps inves- tigators surface hardness have had contend with the lack method for evaluating the the first one thousandth inch less surface thickness terms comprehensible system. That the fore- 10—(Left) Cross-section hard spot near surface an- nealed high speed steel sample s