The Iron Age 1941-08-21: Vol 148 Iss 8

21, 1941 TINNERMAN PRODUCTS, INC, MANUFACTURERS PATENTED SPEED NUTS ¥ i > Turn The Tides War not because its soldiers were braver, but because the North had the machines pro- duce armament. The addition turret the simple metal turning lathe was big factor mass production parts for rifles and shells. After the war, the turret lathe played leading part the industrial ad- vances the ‘eighties. found America with turret lathes capable taking full advantage high speed steels the competitive race for war requisites. productivity swung the scales allied victory. Turret Lathes are playing vital part. Steady improvements WARNER and SWASEY made since 1914 now provide American TURRET LATHE 1941; capacity, manufacturers with power and speed for swing. Built take the metal turning, unsurpassed any nation. heaviest cuts high speed Now, moderntough alloy steels are ances undreamed machined high speeds carbide cutters held chucking and bar tools designed utilize the tremendous power and speed today’s turret lathes. Whether your turret lathe old new, Warner Swasey can help you make more productive. Write TURRET q ~ — 1 TUR- : war AUGUST 21, 1941 VOL. 148, NO. VAN DEVENTER President and Editor BAUR Vice-President and General Manager ° Managing Editor, T. W. LIPPERT News Markets Editor, ROWAN Machine Tool Editor, OLIVER Associate Editors: W. A. PHAIR G. RICCIARDI COSMAN Art Editor, WINTERS Editorial Assistants: Washington MOFFETT JAMES ELLIS Resident District Editors CAMPBELL HERMAN KLEIN Pittsburgh Chicago Cleveland Detroit CHARLES POST San Francisco Editorial Correspondents DEARING Buffalo Cincinnati FRAZAR RAY KAY Boston Los Angeles HUGH SHARP Milwaukee SANDERSON JOHN McCUNE Birmingham ROY EDMONDS Toronto, Ontario St. Louis Newark, Seattle ° DIX, Manager Reader Service ° ° ° Advertising Staff Herman, Chilton Bldg., Hottenstein, 1012 Otis Bldg., Chicago Leonard, 100 East 42nd New York Peirce Lewis, Woodward Ave., Detroit 100 East 42nd New York Robinson Warren, Box 81, Hartford, Conn. Don Harner, 1595 Pacific Avenue, Long Beach, Cal. ° ° Member, Audit Bureau Circulations Member, Associated Business Papers Indexed the Industrial Arts lished every Thursday. Subscription Price United States and Possessions, Mexico, Cuba, $6.00; Canada, $8.50; Foreign, $12.00 year. Single copy, cents. Owned and Published CHILTON COMPANY (Incorporated) Executive Editorial and Office Advertising Offices Chestnut and 100 East 42nd St. Philadelphia, Pa. New York, U.S.A. ° ° ° OFFICERS AND DIRECTORS MUSSELMAN, President JOS. HILDRETH, Vice-President GEORGE GRIFFITHS, Vice-President EVERIT TERHUNE, Vice-President VAN DEVENTER, Vice-President BAUR, Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JULIAN CHASE, THOMAS KANE, HARRY DUFFY CHARLES HEALE ROBERT This Week in... THE IRON AGE Editorial Nothing But Elephants Technical Articles Magnesium Aircraft Castings Conveyors Speed Malleable Casting Oven Expedites Treating Bars Salvaging Porous Pressure Castings Selection Cutting Oils for Threading What's New Motors and Controllers Features Assembly Line Washington Fatigue Cracks News Industry Check Shows 28,482 Republic Workers Hold S.W.O.C. Cards O.P.M. Orders September Pig Iron Set Aside for Pool 232,000 Tons Scrap Estimated Imbedded City Streets Capacity for Finishing Aircraft Steels May Doubled Purvis, Head British Purchasing Commission, Dies Plane Crash Personals and 110 Market Reports Construction Steel Iron and Steel Prices 120 Machine Tool Activity 116 Comparison Prices 121 Non-Ferrous Metals 117 Warehouse 123 Scrap Markets i18 Sales Possibilities Products Advertised Index Advertisers New Dealers Prepare Make Over After the War Copyright, 1941, by Chilton Company (Inc.) L : 36—THE IRON AGE, August the clean cut, slot and circu —— AUGUST 21, 1941 ° ESTABLISHED 1855 Nothing But Elephants NCE upon time, the head man zoological garden determined make market survey determine customer interest. had tabs kept the attendance the elephant house, the monkey house, the bird house and all the other varied departments. conceived big idea. Said he: will double the number elephants and away with the small fry. Then you will see our attendance records leaps and bounds.” was ordered and done and first seemed though the big idea had also been bright one. But shortly attendance began dwindle. People, seemed, grew tired seeing nothing but elephants. Whereupon the head man revised his policy and coined the phrase: “Variety the spice life.” Will come out our defense program with industry composed very largely elephants? Consider what happening the smaller industrial concerns which have not been position get handle defense orders. They are being ground not merely between upper and lower millstone but are being passed through whole succession grinding operations. First, their skin being removed through the operation priorities, which prevents them from getting the materials and tools that they need business. Next, they are being flayed through the establishment price ceilings. These bear down more heavily the small than the large producing units since the latter are usually more efficient and better heeled. Next, they are being penalized the labor market since they have escalator clauses help them keep pace with wage rate rises. And now the new 1941 revenue bill (H.R. 5417)* one finds “joker” Section 204(e) that may easily put the finishing touch upon many small enterprise. This innocuous appearing clause would undo the beneficial provi- sions the Excess Profits Tax Amendments (H.R. 3531), enacted only few months ago, which allowed carryover deficiency earnings one year against the income the following year arriv- ing current excess profits taxes. Unless Section 204(e) struck from the present pending bill, those concerns (and they will principally the smaller ones) which could not take advantage excess profits credit will heavily penal- ized. For they will have pay heavier tax average earnings for 1940 and than will more prosperous concerns which can take full advantage 1940 credit. wonder then that Washington regretfully predicts hardships for the small industrialist and intimates that the coming business casualty lists will include good many them. will too bad for the future America come out this with nothing left but elephants. “The Joker H.R. page this issue. - 1 rc | : | | | | | | | i | | | | | | | 2 | | | | i 4 = 3 | a | | | 4 | | | | | | | 3 | } | | Shells for Defense Another Example How Inland Steel Used the Preparedness Program Numerous plants throughout the United States are busy manufacturing enormous quantities artillery needed for the defense America. Flowing from the Inland mills steel from which thousands these shells are being forged. Inland has never been producer munitions; nor has made steel for munitions times Inland manufactured steel for war purposes between the close hostilities the First World War and the outbreak the present war. But today, with the same spirit exhibited all American industry, Inland doing its part making steel, whatever form required for our National Defense Program, the limit its manufacturing facilities. This Inland’s No. job! When forging one size field artillery shell, 50-lb. billet heated continuous furnace. The billet quickly descaled and pierced, then follow two fast draiving operations. Above shown shell after the first draw. SHEETS TIN PLATE BARS PLATES FLOOR PLATE PILING STRUCTURALS RAILS TRACK ACCESSORIES REINFORCING BARS Dearborn Street, Louis, Kansas City, Fluxes and temperatures employed, sand characteristics, and molding and handling practices the world’s largest foundry for success the intensive re- search work done recent years magnesium castings the new foundry Wright Aeronau- tical Corp. Fairlawn, Located adjacent the company’s recently opened aluminum foundry, this new plant the world’s larg- est magnesium foundry and the only one devoted solely the pro- duction aircraft engine parts. From dimensional viewpoint this new foundry not massive when compared with other types foundries built recently. However, when judged from view- point the new plant assumes pro- portions unusual magnitude. When full operation, which will probably some time late this year, the foundry will turn out 20,000 lb. castings day, much magnesium eight months was produced all forms the entire magnesium industry the year 1938. The foundry, completed working days, fire-proof build- ing 700 ft. long 200 ft. wide and embraces 113,000 sq. ft. floor area. When working capac- ity, about 650 men will employed. present 350 men are working three shifts day, six days week, and more are being added daily. MONUMENT the practica! Aircraft Magnesium castings (indicated shaded areas) find wide use aircraft engines, this sketch Wright engine shows. Castings Current shipments from the plant are about 50,000 lb. month, with the total rising rapidly. Output the foundry ranges from pieces weighing little (shipping weights; pouring weights would times greater), and covers some 150 different types castings. Chief production items Fairlawn are engine nose sections, oil sumps, supercharger rear covers, PHAIR Associate Editor, THE IRON AGE oil system breathers, supercharger front and rear sections, accessory drive housings and covers, tachom- eter drive housings, pump covers and miscellaneous small plates and covers. Full utilization the favorable weight and strength characteristics magnesium alloys has been re- stricted somewhat the inflam- matory nature molten mag- nesium. The problem Fairlawn was that converting successful laboratory methods into practical plant procedures which, while per- mitting production large scale, also assured safe and efficient oper- ations. While the better understanding magnesium gleaned from exten- sive research work has been suc- cessfully translated into practical control methods this new plant attests, handling molten magnesium still requires technique somewhat akin placating Brahma long horn with sand burr under its thigh. The latest addition the Wright foundries characterized the same design philosophy apparent other plants built recently the company. Briefly, this philosophy THE IRON AGE, August 21, 45 4 } | 3 - : ‘ « = | | | ° ° ° ° ° J Molding the core for supercharger. methods the fullest extent when mechanization more efficient, but not hesitating use hand methods important operations when hand work more efficient. While would seem that this theory plant design should fundamental all plant construc- tion, appears have been over- looked many instances lately where designers have mechanized purely for the sake mechaniza- tion. There more hand work per- formed Wright’s magnesium castings than usual such pro- duction plant, but this use hand work has been made such in- Covering flux applied the metal poured into the mold. 40—THE IRON AGE, August Closing green sand tegral part production scheme and intelligently sup- ported mechanical equipment that doubted whether would possible achieve the same net effect any other way. Probably the chief operating problem any magnesium foundry that preventing oxidation Gates and risers are removed sand mold nose section. Magnesium melted oil-fired crucibles. the metal, which can occur the controls over melting and pouring oxides and nitrides which form slightest provocation (and seems operations. Three fluxes are used when the metal contact with times apparently without provo- Fairlawn; two for melting and the air. The second melting flux cation). one for remelting. addition, contains sulphur and boric acid and inhibiting agent used cores used solely for pouring. The re- Fluxes Important Factor and molding sand. One melting flux melt flux, which Simply stated, prevention fires consists magnesium chloride and sium chloride and magnesium magnesium foundries rests upon calcium fluoride and primarily chloride approximately equal availability good fluxes and rigid covering agent, solvent, for the amounts, acts purifying agent noved from castings band saws. Flexible shaft machines are used for burring and snagging. IRON AGE, August J 4 ag well covering agent. The inhibiting agent consists phur, boric acid and ammonium borofluoride and known commer- cially Dow Chemical agent No. 12. Application the flux the molten metal, the ladles and the gates and risers means shaker similar the type used for sugar dusting bakery. About flux are used each 100 lb. magnesium melted. Melting equipment Fairlawn consists oil-fired furnaces, which are crucible fur- naces, are 500-lb. holding units for clean scrap and six are 500-lb. For other detailed data mag- nesium castings see the article “Magnesium Sand Castings,” Briskin, THe Ace, July 10. furnaces for remelting dirty scrap. All dirty scrap melted and pigged before being added new batch. Virgin metal received the in- got form, already alloyed. alloy- ing done the foundry. Because the nature mag- nesium, the percentage returns from gates and risers runs some- what higher than ordinary foun- dry practice. For example, super- charger cover weighs about 168 lb. comes from the mold, but pared down only lb. the time ready for shipping. Actual metal loss the melting op- erations the order per cent. Metal Poured 1450 Deg. starting new batch, the new metal placed the crucible and remelted metal taken from the holding furnaces and added the new ingots the rate ladles remelt material each new in- got. (Each ladle holds This mixture then brought 1600 deg. and held there until ready pour. When ready for pouring, the crucible molten metal removed from the furnace shell and backed down around 1450 deg. F., and then promptly poured. This cooling performed angle iron stands and subject careful supervision means pyrometers. Remelt metal held 1220 deg. the holding fur- naces. All pouring Fairlawn done directly from the crucible and largely hand operation. This 42—THE IRON AGE, August due partly the fact that handling crucible magnesium does not present the same weight problems ladle brass iron; and, too, hand pouring found sub- ject more sensitive control. An- other factor the desire avoid rehandling the metal much possible minimize the surface area exposed the air. The cruci- bles are built high grade boiler plate and have linings. The flux- ing practice Fairlawn quite similar general magnesium foun- dry procedure, far the applica- tion and handling are concerned. The metal now use Fair- lawn the regular Dowmetal grade which averages per cent Al, per cent Zn, 0.2 per cent Mn, 0.5 per cent Si, other impurities 0.3 per balance Mg. Experi- ments are under way with higher zine content step fluidity, but this still the experimental stage. As-cast strength this metal around 27,000 lb. per sq. in., while heat treatment and aging bring this 38,000 Yield strength, after heat treatment and aging the neighborhood 19,- 000 per sq. in. Every heat poured has test bar, and processing heat permitted until the an- alysis the heat returned from the laboratory attesting the qual- ity the metal. Every casting has tag dropped the riser during pouring containing the heat num- ber. After shakeout, this number transferred the casting proper stamping give permanent identification. Sand Closely Controlled Chief feature the sand prac- tice Wright the extremely close control exercised over all phases sand preparation and the 100 per cent reclamation used molding sand. Shakeout and sand prepara- tion departments are located side side one end the plant. Mold- ing sand distributed via overhead conveyor belts, while core sand transported bench hoppers narrow gage dump trucks running benches. Mixing the sands done with intensive mullers. All molding mixtures are based No. Millville silica and Penn- sylvania glass sands. The molding mixture now general use both light and medium work built the following: 900 reclaimed sand silica sand glass sand sulphur ammonium borofluoride inhibiting agent Bentonite 3.6 per cent moisture Green permeability this mix- ture runs between and 70, with dry permeability rated 115 120. Green compression strength between 4.7 and 5.2. facing sand used, the regular mixture pro- viding sufficiently fine surface. General practice ram softly and use very few vents, except exhaust large pockets. Considerable study gating and risering practice has been made Wright’s technicians develop standard practice for both alumi- num and magnesium. From these series standards have been es- tablished summary some the more interesting sections which they apply magnesium work follows: gating, the pouring basin least in. long, whether cored green sand, and only offset basins are used. Sprues are all flat, 5/16 in. thick and in. wide. Sprues are offset when passing through parting. When changing small and medi- magnesium, sprue and gate area increased per cent; converting large castings, the increase per cent. All magnesium castings are gated for external ring runners. Total area all runners twice the sprue area, length between sprue and nearest gate being in. more. major castings the runner least in. from the side the flask, while small castings, least in. from the side. Thickness runners varies from 3/16 5/16 in. Bottom gating used wherever possible and all gates lead from the bottom the runner. Gates are flared into the casting and runner. Fillets are used with radius in. Patterns are built with shrink rule. Chills Are Sprayed Chills are all cast iron, in. wide. For finished surfaces chills are vented central hole with radiating grooves, paral- lel grooves alone. Before using, chills are sprayed with mixture consisting lb. paraffin wax dissolved gal. carbon tetra- chloride. Very little nailing per- mitted. sheet newspaper placed = | — Boy between the cope and drag all molds keep the mold free dirt and destroyed the molten mag- nesium during pouring. Strainers are not used except three four special jobs, and the ultimate aim completely eliminate all such devices. Considerable experimental work was necessary develop the correct gating practice away with straining. Generally speaking, the discarding strainers was pos- sible through the employment very thin gates with heavy headers provide sufficient head pressure. Large work molded over bumper jolt vibrating draw machines and run off onto spring mounted conveyors for core setting and closing. The molding bay ar- ranged with large work along one side and small bench work along the opposing side, with the melting units the center. Two types core and sand mix- tures are used, one for body cores and one for softer interior cores which must collapse. Mixtures these sands are follows: Body Core Mixture per cent silica sand per cent glass sand sulphur Ib. Mogul oil pt. Hyten oil per cent moisture Interior Core Mixture 100 per cent silica sand sulphur pt. Hyten oil per cent moisture All cores are sprayed with in- hibitor prevent oxidation the metal during pouring. Baking done continuous oil fired units and requires hr. min. 425 deg. F., followed forced air cooling specially constructed tunnel. After the primary baking, the cores are sprayed with per cent solution Dow No. (am- through another series ovens, drying 325 deg. for min. Removal gates accomplished band saw. Large castings are cleaned blast tables, while small work handled Wheelabrators using steel grit. Immediately fol- lowing cleaning, the castings are tested for leakage. This testing in- cludes soaking for hr. hot water accelerate oxidation around defects for the purpose easy identification. Testing done cold water with air applied the cavities under pressure, bub- bles showing the location the leaks. Burring and snagging done with flexible shaft wheels benches with individual exhausts carry away the highly inflammable mag- nesium dust. Finish machining done plant No. Following the snagging opera- tions, the castings are subjected dichromate dip prevent corro- sion while process. This dip gives the castings corrosion re- sistant surface, somewhat similar anodized treatment. The dip consists first wash bath nitric acid, sodium dichromate and water, followed wash cold water, then hot wash and dip slush oil. Heat treating carried out new continuous, conveyor type elec- tric ovens. Treatment consists hr. 620 deg. F., hr. 650 deg. F., hr. 729 deg. F., and hr. the cooling zone. Aging treatment consists hr. 360 deg. Magnesium dust, not handled molten metal itself. The policy Fairlawn prevent excessive accumulation dry dust keep- ing all exhaust pipes clean and wetting the dust soon hits the accumulators. Conveyors Speed Malleable Casting Cleaning rangement shown the ac- companying sketch utilized Walworth Co., Greensburg, Pa., reduce time required clean its output malleable fittings. Upon leaving the annealing ovens, cast- ings are dumped into vibrating shakeout screen, which turn passes them onto the feeder continuous conveyor. veyor elevates the castings loading hopper located between two in. Wheelabrator Tum- blasts. Castings are fed gravity, un- der manual control, either the two Tumblasts desired. After cleaning, they are dumped through chute onto another conveyor which carries them the mez- zanine. Here they pass into hop- per which feeds onto revolving table where they are inspected and assorted and deposited into con- tainers for trucking shipping room galvanizing department. Usual load for each machine about 1700 assorted sizes. Storage door bearings Cleaning time ranges from min. for large pieces and maxi- mum min. for small castings. No. steel shot used for abrasive. conveyor ‘Conveyor leads mezzanine second sfory mezzanine THE IRON AGE, August : a 3 2 4 > 3 j SS = IGH pressure demands the national defense program have made time losses intol- erable, and the George Porter Steel Treating Co., Cleveland, points out that glaring delays often occur loading and discharging bar heating furnaces, there being also consequent warpage long bars. Production has now been stepped through two-fold program: (1) Semi-automatic loading and unloading; (2) new Lee Wilson bar heating furnace with side doors and protective gas shield the door prevent furnace tempera- ture drop. Through the use side rails, loading and unloading are now sim- ply rolling operations. T-rails the side the furnace are raised per cent angle and the bars, irrespective size weight, are rolled into the furnace. When un- loading, the bars are lowered the proper angle which will ease the bars from the furnace downward the adjacent oil quench. possible for one man load and unload the new furnace, al- though actual practice two three are used. The furnace ft. wide, in. deep the loading hearth, and in. high the door. has gas-fired burners. North American standard burner equipment used, equipped with pilot lights. The protective curtain formed the products combus- tion front the door has greatly reduced heat loss, according George Porter, general manager the company. The furnace can used for hardening, normalizing and tem- pering. Wheelco two-zone control employed. The new furnace has handled much 8880 bars without decking, and generally produces two heats per day. one occasion with three men un- loading, the furnace was emptied min. 44—THE IRON AGE, August 1941 NLOADING bar from new Lee Wilson heating turnace the George Porter Steel Treating Co., Cleveland. Rails between side door furnace and the quenching tank speed production. Gas shield furnace door prevents temperature drop. BELOW View controls and side door new furnace. q | | | rge HERE are two books, one English and another French, which are entirely devoted the technique met- allographic etching. The latest them, Portevin and Bas- tien (1937), lists some 220 etch- ants used various metallogra- phers the study ferrous and non-ferrous metals. Needless say, these authors not recommend any particular reagent nor they discuss the results obtainable, and for these reasons the two books look more like pharmacopoeias cooking rec- ipe books laboriously compiled but very little help the working metallographer. For example, metallographer should just try and select out 100 odd etching solutions for copper alloys one that would give decidedly superior results. The problem getting hold really good etchant for given class work is, theoretically speaking, quite hopeless. There are many reagents that will etch given alloy, many levels ETCHING TECHNIQUE —In which the author submits number interesting observations based many work, sets down the theory etching, and presents informative data the application neutral ferric chloride solutions the etching nickel and its alloys. c ° CORSON Metallurgical Consultant, New York ° temperature, intervals time, possible concentrations and states the polished surface, that systematic investigation cannot even undertaken. Therefore, someone suggests one per cent so- lution picric acid alcohol certain solution chlo- ride and hydrochloric acid water, does not mean all that the author actually compared these reagents with others definitely established the optimum concen- trations. Most likely every re- agent proposed forms the result pleased its originator. And, such the main reason why 220 odd etchants are listed the book Prof. Portevin. The prerequisites good etch- ant: might desirable con- sider what requirements good etching medium must satisfy. Needless say must reveal structure that pleasing the eye—this the first and almost only way approaching etched surface. The picture which the met- allographer intends examine ° must clear, clean, contrasting, and great extent should show exactly what intends see. Be- sides must obtained fairly rapidly. Etchants that fulfill quirements are well known for the majority industrial metals and alloys. Excellent pictures can secured pearlitic martensitic steels using picral almost any concentration. Just are the pictures obtainable other etchants for brasses, tin bronzes, aluminum alloys, etc. the other hand, most the etchants suffer from the defect being uncontrol- lable. short dip followed good washing and drying produces good etch skillfully executed. However, the metal etched for fraction minute longer the section must repolished, because the features become blurred and many cases pitted well. course, most the pits are not pits all, but small pyramids which re- mained because they tected gas bubbles while the metal around was being etched THE IRON AGE, August i ° a } Ate | | | | — + ig. ters. Cathode 500 di- Cathode iame Same ig. kel cold rolled ameters. ° 100 diameters. but 500 annealing 800 deg. BELOW Fig. nickel which recrystallized ABOVE—Fig CENTER nic 1941 Shows the ters. August 21, inder the Note the continuation Cathode nickel, crystalline features from the first 100 diameters. the second. nealed 125 diame gn boundary between sheet and the rema BELOW—Fig. Cathode nickel, cold rolled per cent and an- cathode. 46—THE IRON AGE ABOVE—Fig ABOVE—Fig. Cathode nickel annealed 800 deg. and cold rolled per cent 100 diam- eters. CENTER—Fig. Cathode nickel, annealed 800 deg. C., cold rolled per cent and annealed again 800 deg. 125 di- ameters. BELOW—Fig. 10. Same sample Fig. but unetched. Shows that the black dots correspond something that was the metal and certainly are not etching pits. ABOVE—Fig. Same Fig. but 500 diameters. BELOW Fig. Commercial nickel; in. rod, annealed. The grain size well defined, spite numerous black dots. 100 diameters. THE IRON AGE, August 1941—47 mium alloy containing some carbon diam- eters. Annealed 950 deg. away. Besides, the beautiful pic- ture which seen after skillful but short etch rarely telling the whole story. Sharp and clear is, does not reveal number features which require long etch. And the majority etchants, espe- cially those containing hydrogen ions, not permit etching all. Three types etchants: gen- eral the existing etching reagents can subdivided into three groups, namely: (1) Those where the etching effect due primarily their con- tent hydrogen ions. (2) Those where the etching de- pends upon the ion. (3) Reagents producing dif- ferential staining effect, the chem- ical nature which still most obscure. this group belong the picrates used darken iron carbide steels, the ferricyanides used differentiate between various carbides, etc. The reagents the first two groups might expected pro- duce pictures consisting strictly sharp lines, i.e. grain boundaries, twinning trace lines, outlines 48—THE IRON AGE, August secondary constituents, sions. Sometimes they actually just that; however, the majority cases they produce staining effect addition. The metallog- rapher inclined describe the troostite, bainite, steels; or, when the beautiful stain- ing effect obtained brasses, aluminum bronze, silicon bronzes, the visible grains are called etching were capable bringing out each gran- ule its outer surfaces, not merely cross-sections. The fact that all these beauti- ful shadings, etc., are merely stains properly placed the etchant upon the surface the sample. slight repolishing velvet, using dilute solution soap with abrasive all eliminates these stains en- tirely, leaving behind mere outlines. Again, the case copper-base alloys the alpha type, etching with ammonium tions produces only outlines, while etching with acid ferric chloride chromic acid will immediately pro- duce these staining effects are undesir- region the longitudinal section. Shows stringers chromium carbide. able. For, matter what the esthetic effect, every staining the specific character the region stained. Even stain produced due disturbed metal important, because reveals the latter’s presence. And, stain continues reappear after many repolishings, mechanical trolytical, points out definitely some local discontinuity, and should studied thoroughly instead being discarded for its ugliness and lack agreement with preconcep- tions regarding the nature the structure looked for. logical choice the etchant: might too presumptious try and offer ideas leading some uni- versal etching solution. Such hard- worth while reduce the huge number etchants published just few, chosen the basis chemical logics, not mere “cut and try,” “hit and miss,” “lucky idea. This what the writ- Among all the etchants possible there great number that should called “violent.” fact most them are violent. Even alcoholic solution picric acid violent and > 4 the tain the tain lany itely ould and cep- the ant try uni- ard- “cut icky vrit- sible ould and And FR The grains are clearly defined. diameters. will produce black hydrochloric acid will etch steel well enough acting for frac- tion second, otherwise will pit the sample badly call for re-grinding paper No. etc., etc. non-violent etchant one whose action not accompanied any development gases. This implies reaction straight transfer between the etchant and the metal. And such reactions de- pend exclusively upon the lowering valency some element present the etching solution. Reagents this kind are never highly ionized, and the ionization even further reduced using proper solvent. Therefore, their action slow and can easily controlled. certain cases the etching action may allowed for hours and even days, con- tinuously revealing new structural new phases, merely more delicate features phases already known. Ferric ion solutions: The most accessible reagents which act changing their valency are the fer- ric salts iron. There are the IG. Fig. but 500 diameters. The grain boundaries are heavy and the grains some- what mottled account the presence undissolved hardener (probably chloride, bromide, iodide oride the first line; nitrate and sulfate the second. The first four are quite soluble water, alcohol, glycol, glycerol, even ether, and their action very sim- ple: one quite mobile ion halo- gene taken away the metal ions are much less mobile and their action therefore much slower even too slow. The ferric salts are capable attacking the great majority the existing metals, and proper temperature they etch even platinum. might said that ferric etchant. That true. However, has been used mainly for cop- per-base alloys. And, here the use straight ferric chloride solu- tion out question, because insoluble precipitate fine crystals cuprous chloride forms hap- hazard manner and obstructs the view. For this reason the ferric chloride reagents always carry some acid and this immedi- ately puts them the class violent etchants, used skillfully and rapidly, without any chance ob- taining more information pro- longed etching. What the writer proposes the use ferric salts any concentration but various solvents the complete absence ionized acid. And, instead using these etchants copper alloys proposed use them only metals which cannot form insoluble subchlorides chlorides. This eliminates copper, silver, gold, mercury, lead, and nickel, cobalt, aluminum magnesi- um, tin, antimony. all the latter properly chosen solution some ferric salt can applied etchant, although certain cases protecting film present the surface the sample must eliminated first etch-polishing electro-polishing. The etching nickel alloys: well known that the etching nickel and its alloys considered difficult task. Scores reagents were offered and some seem have given good results skillfully used specific cases. Here propose consider how nickel acts under the etching attack ferric chlo- ride dissolved water. concentration the reagent will indicated. Any one can used from that having merely THE IRON AGE, August xial RIGHT IG. rod Z-nickel (an alloy con- taining small amounts magnesium, carbon and titanium, and hardened the precipitation car- bides, magnesium preventing the formation graphite). Grain size quite clear. Dark areas corre- spond excessive precipitation the hardener. 100 diameters. visible yellow tinge one that car- ries deep orange color. All will work even when cold, and slight heating will expedite the process need be. This writer prefers quite dilute cold solutions, but mere- personal preference. Consider, then, The sample examined had extremely high mechanical characteristics. With tensile strength 85,000 Ib. per sq. in. and hardness 180 Brinell combined ductility per cent elongation in. and impact resistance over ft.-lb. Izod. Figs. and show the structure this cathode 100 and 500 diam- eters. The black streak the boundary between the starting sheet and the heavier part the cathode. Attention must drawn the precise duplication and continua- tion the crystalline outlines across the gap. This cathode nickel rolled per cent into strips; Fig. shows the resulting structure 500 diameters. The cold rolled cathode was next annealed 800 deg. C., and Fig. shows 100 diameters the structure the an- nealed metal and outside the starting sheet. another experiment the cath- ode was annnealed the same temperature without cold rolling. 50—THE IRON AGE, August 194! LEFT IG. Monel after anneal 1250 deg. molten water quenched. 100 diameters. Perfectly analo- gous alpha brass. Grain boundaries sharp because hard- ener present and excessive chemical action eliminated. shown Figs. and 100 and 500 diameters respectively. also quite obvious that spite being separated wide gap hundreds thousands interatomic distances, the crystals the start- ing sheet and their continuations recrystallized single grains nothing did separate them. The recrystallized cathode was also cold rolled per cent. Fig. shows the structure the distort- metal 100 diameters. Finally Fig. shows the structure the previous sample after was an- nealed 800 deg. much for the cathode nickel, which probably pure pos- sibly could except for the pres- ence cobalt and hydrogen—the latter form which made the metal extremely strong, quite hard, but did not embrittle the pres- ence hydrogen does usually under different conditions. Consider next what results can obtained with commercial nickel that was melted from cathodes, in- goted, hot rolled and cold drawn before being turned over customer. Fig. shows 100 diameters the structure rod commercial nickel which con- tained carbon and was magnesium treated. evident that the pic- ture allows for good determina- tion the grain size. the other hand, contains great number fine black spots the grains and along their boundaries. How- ever, this was not the fault the reagent, for, examine Fig. which shows the unetched structure the same sample. full the same black spots and carries two grayish inclusions besides. Some the black spots (probably graphite magnesium oxide both) certainly became enlarged etching with but this cannot avoided except controlling the time etching. How about nickel base alloys? Figs. and show 100 and 500 diameters the structure heat-hardenable Ni-Be taining carbon and chromium. The possibility making reliable grain count obvious and the pres- ence stringers chromium carbide rather distinct. Figs. and show 100 and 500 diameters respectively the structure commercial rod K-Monel. The sample was slightly overetched and the grain boundaries are somewhat thick. However, this alloy, quenched from 1050 deg. contains some aluminide thrown out che grain boundaries—there- fore, the excessive etch along them. Fig. shows the same alloy quenched from 1250 deg. The grains are obviously too large; however, all aluminide was dissolved and therefore the bound- aries are fine spite 5-min. etch. Figs. and show the struc- ture commercial Z-nickel (an alloy which the presence mag- nesium and titanium permits the hardening the metal carbide precipitation 320 Brinell). also was quenched from 1050 deg. while not all the carbide was yet dissolved. Some the grain bound- aries are quite distinct, showing that those spots the hardener went fully solution. other spots the boundaries are due the presence carbides LEFT IG. sample Fig. but 500 diameters. The presence the undissolved hard- ener the grain boundaries causes the latter quite dif- fuse. which caused accelerated action. Many spots are darkish due the spontaneous precipitation the carbides. The presence grain- lets the latter distinct 500 diameters, mainly the graip boundaries. The same sample was also an- nealed molten barium chloride 1250 deg. and oil quenched. Again the grains became quite large and rather precisely defined boundaries, Fig. shows. The latter reveal well that the granules carbides still remained ABOVE 18—Same metal Fig. but annealed barium chloride 1250 deg. Practically all hardener dissolved coalesced (white Grain boundaries quite sharp and the structure looks like that alpha brass. 100 diameters. undissolved and fact grew size comparison the 1050 deg. treatment (Fig. 16). much for the etching nickel and its alloys. The author believes have furnished enough proof that neutral FeCl, aqueous solutions forms good etchant for this class work. must added that the same not true for Nichromes except their cast state. The wrought Nichromes refuse com- pletely etched FeCl, except etch-polishing, which will dis- cussed later. Salvaging Porous Pressure Castings RESSURE castings which are unable meet required pres- sure tests due excessive porosity can salvaged impregnation with newly developed phenolic resin, according Durez Plastics Chemicals, Inc. Citing specific example such salvage possibili- ties, the company reports pump casting which was required withstand water test 500 but which leaked 100 pressure due porosity. After impregna- tion with this new material, called Durez 7347A, the casting withstood pressure test 800 Ib. leakage. Impregnation with Durez 7347A accomplished forcing the resin into the pores the casting under pressure between and 100 per sq. in. This may done either pressure tank sealing the casting outlets and pumping the resin into the casting under pressure. This pressure treatment followed application heat polymerize the resin. The heat may applied either baking oven for several heurs 250 275 deg. F., pressure pressure for two hours, followed 100 lb. pressure for another two hours. Resin treated this manner described practically impervious water, solvents, mild alkalies and acids. The Navy Department has approved resin impregnation castings for certain types pump castings. THE IRON AGE, August Basic Open Hearth last this series three articles refractories used below the sill plate level discusses the construction, materials, causes failure, and lines im- provements checkers, checker chambers, gas and air valves, and flues. The Checkers distinctive feature the Siemens Martin open hearth furnace the regen- erative system. The preheating the gas and air before they enter the furnace enables much higher *Diagram illustrating nomenclature parts marked appeared THE IRON AGE, May 22, 1941, 41. Chemical analysis: SiO. Fe.O, ; TiO. ... MgO Loss ignition, per cent Melting point, deg. Cold crushing strength, per sq. Porosity, per cent Bt.u. C.g.s. units Specific heat, c.g.s. units (from 1382 deg. Heat capacity specific heat bulk density thermal conductivity Diffusivity factor bulk density sp. heat garding the relative efficiencies chamber, freedom TABLE Properties Checker Bricks Semi-Silica (1) (2) (3) Fireclay Silica 88.7 92.3 88.0 53.8 95.8 9.1 5.8 7.9 39.2 0.8 1.0 0.5 1.2 0.9 0.4 0.7 0.7 1.6 0.0 0.2 trace 0.4 0.3 1.6 0.3 0.2 trace 0.7 0.3 0.4 0.5 0.8 1.4 0.5 over 2912 over 2912 over 2912 2840 3074 1480 over 8030 1250 2350 4680 23.6 27.7 26.3 26.8 1.93 1.90 1.85 1.96 1.70 5.6 7.1 5.6 6.2 0.0019 0.0024 0.0019 0.0021 0.0026 0.26 0.245 0.27 0.25 0.255 0.50 0.47 0.50 0.49 0.43 0.49 0.49 0.43 3.8 5.1 3.8 6.0 _ ~- = 4.2 4.3 6.0 Average 52—THE IRON AGE, August 1941 Bulk density, gm. per Thermal conductivity (hot face, 1292 deg. temperature and hence melting rate obtained, and the same time increases the fuel efficiency the furnace. study open hearth furnace checkers number steelworks shows that the current practice both gards materials and the type setting employed, varies over wide range. Comparatively little infor- mation is, however, CHESTERS Central Research Department, United Steel Companies, Ltd., Sheffield, England these different arrangements. This not surprising, since the carry- ing out heat balance open hearth furnace exceedingly difficult task, while any comparison similar furnaces having differ- ent types checkers open the objection that other variables, such the melting program, have prej- udiced the result. (A) CONSTRUCTION: large number complicated checker designs are manufactured and advantages claimed for their use, among which may mentioned bigger surface area, maintenance high gas ve- locity the lower part the q ~ t q t ° ° ° < and greater rigidity. type employed the result bound compromise between the weight checker filling per unit volume and the heating surface ex- Whichever posed the gases. Thus, the fol- lowing figures show typical com- parative data for special shape similar design the Moll checker and settings made from standard squares. will seen that the special shape offers much greater vertical heating surface, but impossible say with any certainty whether this more than compensated for the lower weight brickwork per cubic yard. true that formulas exist for the calculation checker efficien- cies, but the number assumptions and approximations made may well lead errors greater order than the actual differences between the efficiencies the types con- sidered. Types Checker Settings Type Flue Area in. sq. Special shape, in. thickness. Complex +Assuming bulk density 118 per cu. Thus checker may have high through the ideal manner, but actual practice may contain serious amount “dead” space. one set checker chambers was filled with standard squares, and the other with special shapes, any difference efficiency would ap- parent, but the experiment might prove expensive one the fur- nace worked out balance. Valu- able data might obtained using small scale checkers baby open hearth furnace the type avail- able certain American labora- tories, though here again difficulty would experienced simulating the slagging and choking the checkers experienced large scale practice. (B) MATERIALS: (1) Fireclay Brick: Most open hearth furnaces Great Britain employ either medium alumina semi-silica (sand-clay) brick for the checker work, with the exception the top five ten courses, which are usu- ally silica high alumina fire- clay brick* The results num- *High Britain generally means per cent. ber tests semi-silica and fire- clay brick similar those now used checkers are summarized Table IV. The fireclay material examined was the form special shape while the semi-silica brick were in.). Porosity and Bulk Density: view the fact that the object the checker work recover heat from the outgoing gases, the heat capacity which direct function bulk density clearly important. Checker bricks have been tested with porosities low 13.0 per cent and bulk densities Specific Heat: Refractory ma- terials appear vary less their specific heats than almost any other property, the value obtained for checker bricks being monoton- ously close 0.25. Thermal Conductivity: The con- ductivity each the test brick was determined over range temperatures using apparatus Blakeley and Cobb (J. Chem. Ind., 1932, 51, 83T). will seen that the thermal conduc- tivity the fireclay brick tested, like the specific heat, falls within the range values given the semi-silica brick. high 2.27 gm. per but general the porosity checker brick lies between and per cent. According Keller, however, Heat Capacity and Diffusivity: The heat capacity checker brick, assuming have attained uniform temperature throughout, simply function the bulk density and the specific heat. will seen from the table that the product these terms when cal- Weightt Vertical Heating culated for the range 1380 deg. Checker Brick Surface Around the room temperature close 0.50 PerCu.Yd. Area, for both the fireclay and brick. The rate which the heat 1440 diffuses into the brick will depend both the thermal conductivity and the heat capacity. The dif- fusivity factor thermal conduc- tivity bulk density specific heat) will seen much the same for both types brick. The above comparisons involve number assumptions and are the thermal conductivity, which function porosity, has surpris- ingly little influence the effi- ciency the checker. TABLE V—Used Versus Unused Checker Bricks Used Gas Brick Used Air Brick Unused Melting point, deg. 2840 2642 Cold crushing per 2350 3310 4960 Bulk density, gm. per 1.96 2.04 1.92 2.09 1.93 Average 1.98 2.01 Thermal conductivity (hot face, 1292 deg. F.). Specific heat (from 1382 deg. 0.25 0.25 0.25 0.25 THE IRON AGE, August 21, | based the examination lim- ited number samples. They rep- resent over simplification checker conditions, but least serve show that there little difference between typical fireclay and brick regards heat capacity the rate which heat absorbed. Other Properties: The melting points the bricks are not partic- ularly high, but there little like- lihood fusion occurring, since the maximum checker temperature rarely exceeds 2462 deg. (2) SILICA BRICKS: The high temperature and the corrosive dust found the top the checkers necessitate the use silica high alumina fireclay brick. some plants silica bricks are used throughout. The results TEST1 Unused brick 900 Temperature, deg. min. Time 8—Heat penetration tests used and unused air checker brick. given Table suggest that for this silica brick, which has un- usually low bulk density, the heat capacity would less than for that the fireclay semi-silica brick, but this would compen- sated least some extent higher diffusivity. (3) ALUMINA FIRECLAY BRICKS: Both the United States and Great Britain fireclay brick 54—THE IRON AGE, August Sample Thermocouples Sample used for the comparison heat penetration Temperature, deg. 400 800 700 Temperature, deg. checker brick. TEST Unused brick Used brick brick Time per cent alumina and over have been successfully employed the top section the checkers. Such brick now available high bulk den- sity, good volume stability and un- usually high refractoriness under load, while their slag resistance definitely superior that the low alumina quality. (C) LIFE AND CAUSES FAILURE: Checker brick, particularly the top the setting, subject severe corrosion basic dust con- sisting mainly iron oxide and lime, but containing also consider- able quantities such materials lead, zinc and alkalies. general, the top section quite unfit for use after campaign say weeks, but brick lower the setting where the temperature not great, although coated with dust not severely slagged. some steel plants most the used checker brick are thrown away, whilst others large proportion the brick cleaned and re-used. one works was the practice re-use the air checker brick, which similar color the unused brick, but throw away the red- colored gas checker brick, which was alleged weak, likely crack heating, and “natureless,” that is, unable absorb and give out the required amount heat. study was made such brick with view finding whether this procedure was justified. Samples chipped from the skins the used bricks gave analyses similar those the unused brick (See Table V), the only marked change being increase the alkali content the gas checker Unused brick Used brick (as received) So 20min. a 600 heatin perat Tem Time 9—Heat penetration tests used and unused gas checker brick, both received (left) and glazed refiring (right). ° ° 800 600 Time brick. The red color the latter does not, usually assumed, imply high iron content, but merely different state oxida- tion. This borne out the fact that such brick reheating oxidizing atmosphere assumes similar color that the unused material. Melting Point: The determina- tion the melting point and chem- RIGHT IS. 10—Silica brick removed from the air checker shown Fig. 14. BELOW IG. brick removed from the lowest ical analysis the skin checker brick complicated the fact that the amount im- purity decreases with the depth penetration. the present tests the cone cut from the gas checker brick thick skin) melted suddenly 2300 deg. F., while that from the air checker brick although fused