The Iron Age 1945-10-11: Vol 156 Iss 15

VAN President Editoriul BAUR Geaeral LEONARD Assistont Manager Advertising Manager JOHNSON, Service and Market CLEARY, Technical Research Promotion Manager Executive Offices Chestnut and Séth and Advertising Regional Business York New York Gast 42nd St. 100 East Cleveland Pittsburgh Philadelphia Chicage RAYMOND KAY Angeles 2420 Cheremoya Owned and Published CHILTON COMPANY OFFICERS AND DIRECTORS MUSSELMAN, JOS. HILORETH, President TERHUNE CHASE WILLIAM BARBER, JOHN BLAIR THOMAS KANE CHARLES ° every Thursday. Subscription Price North America, South America ond $8; Foreign, $15 Single Copy, cents. ° Copyright 1945, by Chitten Company (tae) AGE Vol. 156, No. October 11, 1945 Editorial United Stand, But ° Technical Articles Maximum Carbon Carburized Cases All-Purpose Synthetic Adhesive “70 New Equipment ° Features Assembly West Personals and Obituaries Dear This Industrial Week News Industry News and Markets Construction Machinery Ceilings Increase 110 Assist Soil Pipe 112 Pressed Metal Institute 114 Ceilings Out New 116 Snyder Predicts Million Unemployed 118 Engineer Reports Controls for Germany 122 Electrical Industrial Truck Assn. 128 Unemployment Claims Increasing 128 Special Tools Sold Auction 130 Machine Tool Market Developments 134 Nonferrous Metals News and Prices 136-7 Iron and Steel Scrap News and 138-9 Comparison Prices Week and Year 140 Finished and Semi-Finished Steel Prices 142-3 Warehouse and Steel 144 Iron and Steel Pipe and Tubing Prices 145 Pig Iron and Coke Prices.......... 148 Bolts and Nut 149 Stainless Steel and Ferroalloy 4 4 | | METALS Member, Associated Business ° ° FABRICATED This tremendous Welded Steel Plate appearance that speaks fine work- great wind tunnel manship throughout. Mahon engi- for neers are available for consultation size weight produce strength and economies Steel accurately and with finished Plate Fabrication. Address Steel Plate Division Steel IRON AGE, October 1945 i | | i ri H E R Om A N DETROIT Welded Product Fabricators Machine Bases and Frames and Many Other Welde Products October VAN DEVENTER and Directer BAUR ° Stef ° Associate Editers HIGHT WINTERS JOHN ANTHONY ERNEST SCHIEN Editers Sanderson Pittsburgh 428 Park Bidg. Bidg. Washington National Press Bidg. Guardian Bidg. BRAMS Woodward OSGOOD WORTH HALE Francisco ROBERT McINTOSH Cincinnati Buffalo FRAZAR Boston HUGH SHARP KAY Angeles JOHN McCUNE Birmingham ROY EDMONDS there was ever time history that behooved the United States united, now. For these days international jockeying for position, who going pay attention have respect for.a Disunited States America? And are fast underway earn that title. true that Germany and Japan gambled upon this same spirit disunity this country when they war upon us. But that dec- laration, emphasized particularly the sneak attack Pearl Harbor, did away very largely, but apparently quite temporarily, with those dif- ferences that our enemies calculated would keep inept. The motivation war united sufficiently enable win it. But why win are permit that victory dissolve into defeat the maintenance peace? Today the United States rapidly approaching state civil war. Not armed war which people shoot each other with guns destroy communities with atomic and other bombs, but war between employers and employed which reason discarded, prejudices promoted, antagonisms augmented and holds barred. And over what? Over dispute who shall get what share something that yet does not exist, namely the fruits postwar enterprise. Who knows yet what they will can made be? All know what hope they may all get together make them what think they can be. But any man woman with grain sense, station life, should know what they won’t indulge the expensive game neglecting work fight over possibilities instead getting together work constructively for You cannot build better future from idle plants, idle machines, idle men and women, stagnating business, loss wages and vanished profits. Somebody apparently has dropped atomic bomb squarely upon the forthcoming management-labor peace conference. How much better would have been wait perhaps days see whether formula could evolved that would settle these matters without the deplorable cost internecine warfare. And they could settled reasonable men reasonable way. Any reasonable employer will admit that the best interest business pay the highest possible wages consistent with keeping indus- try and business solvent, providing the money for expansion and paying the cost capital. Any reasonable worker will admit that marking pay envelopes the expense higher price level not only gets him nothing but detracts from what has. For every cent which you cheapen the dollar through this method cent less the value labor’s saving war bonds, cash the bank and insurance. Reasonable men should able get together and agree these things five minutes. Small wonder, the face evidence that cannot get together, that our weight the international conference table nil? For why should nation expect participate reconciling differences abroad when cannot settle those home? | MUNZER TOWNE SPEAR LLOYD Cleveland | JAMES DOUGLAS é 3 4 5 — in “a Nine Operations Prove the Quality Inland Steel Buchanan, the Clark Equipment Co. pro- duces one-piece tubular forged housings great the truck industry, and the proof the uniformity and quality steel from Many thousands these housings are made from Inland plates, which are first rolled into tubes, welded the multi atomic hydrogen welding process, and formed severe working well hot working operations. The housings are then heat treated, developing higher yield point, and higher fatigue properties. These housings have great strength with durability and takes uniform high quality steel make truck housings this modern Clark way. That why Inland steel was chosen—steel that controlled step step, from ore mines finished product, skilled nicians who daily make hundreds tests and inspec- tions. This job checking and rechecking thorough that you can always depend Inland Steel. invite you let our Inland men help you select the right steel for finer, stronger products and more economical fabrication. INLAND STEEL COMPANY, Dearborn Chicago Sales Offices: Cincinnati, Detroit, Indianapolis, Kansas City, Milwaukee, New York, St. Louis, St. Paul. Principal Products: Sheets, Tin Bars, Plates, Floor Plate, Structurals, Piling. Rails, ‘Track Accessories, Reinforcing Bars. Cal wit nee the tim pos wor pre | | its coat give pro- and. from elded hot heat ength truck step, nspec- select more St., York, Oct. 1945 Magnesium casting design and production now involves the use cast iron inse for bearing faces functional parts. Gray iron inserts are separately cast and magnesium poured around Experimental work progress the use bronze inserts similar man which would greatly broaden the use magnesium parts. Magnesium wheels are duction for major manufacturer heavy duty trucks. Prices magnesium castings continue the steep downgrade slide started the war. Average price magnesium alloy castings produced Chicago foundry $2.50 months ago; $1.70 lb. Aug. 1945; and still dropping. Some sell today for low 55c. lb. Detroit firm has developed auto jack which locks onto the brake drum inside, consisting arm that drops down, which will support two ton weight. the driver has flat tire, simply drops the arm and drives onto Current rumor that Ford will use it. refrigerator people think more plastics will used postwar models the past. Generally they are not sold the use and place quantities steel, although they consider this substitution possibility. One firm has been subjected intensive sales light metals replace steel sheets, but far the cost factor has withheld any action. Boron additions steel are cureall for improper steelmaking practices, Bureau Mines investigation shows. Generally, boron most valuable carbon steels because carbon steels have sufficient innate hardenability and low carbon steels are not intended hardened quenching. Castings aluminum alloys 40E, 195 and 356 having bare, cadmium plated plated cast iron inserts can made resistant with the Alrok treatment without the necessity masking the inserts. Since the Alrok treatment not electrolytic, but chemical dip process, need not masked prevent shorting. The auto workers union has submitted proposal two parts manufacturers tha they grant the pct pay rise, and return the union will waive any claim time premium pay. waive, the union demands guaranteed annual wage, the posal calls for weeks work for employees five more years seniority. This proposal may appeal some parts firms their work often piles into work ‘much overtime, making their labor-costs perennially difficult predict. Jones Laughlin has eased its coal supply problem during the strike purcha sizable quantities government surplus coal from chemical plant. this supply has enabled the firm maintain its operating rate about capacity. Hearings being held this week the NLRB the case supervisory employes coal mines will probably establish pattern for the entire coal industry. Current patent listings for rear engine automobile under the name Well chief engineer Boeing Aircraft give credence rumors that the firm will its product line. The firm insists that will concentrate "primarily aircraf Against the background labor-disputes, General Motors officials are proud their reconversion progress. The first Chevrolet said have been built Kansas City plant within three months the end shell production. The new Buick models show new grille stamped one piece from cold rolled steel. External surfaces are capped with chrome plated stainless steel. new means fabricating cylinder bores includes honed finish after boring coating with manganese phosphate. This permits rapid seating piston rings, and gives protection against scuffing during the early life the engine. "Austerity Peace" the term Britain uses for its present practice exports food and manufactured products the Continent while shortages home| become far tighter than during the war. > | | 7 | | | | | | | | | | i f Maximum Carbon Carburized ° ° SIDNEY BREITBART Senior Metallurgist, Development and Research Section, Standard Steel Spring Co., Madison, Ill. the nucleation theory, that the exces- sive carbon content carburized surface depends the free car- bides the steel during carburization, cussed herein. The ef- ects carburizing me- dium, carburizing poten- tial, and steel chemistry are de- scribed and method control the carburiz- eliminate carburized cases containing exces- sive carbon contents indicated. 50—THE IRON AGE, October 1945 points view, both sup- ported experimental evidence, exist the question maxi- mum carbon carburized cases. One view, advanced Boege- and others, claims that the sur- face carbon content carburized cases can attain very high values normal The other view, advanced claims that McQuaid, Study the Ef- fect the Aluminum Addition the Structures Quenched Carbon Steel,” Transactions ASM 1937, vol. 25, 290. “Carburizing Symposium,” 79. Harris, Metal Progress, April, 1944, 683. the surface carbon content can corre- spond most the saturation value austenite the carburizing tem- perature and that the excessive car- bon built abnormal condition. The apparently contradictory re- sults, which these two views were based, were shown fall into line the basis theory the writer.* Experimental evidence has Metal Progress, June, been presented show that both ex- cessive and normal carbon contents can obtained two sides the same specimen. This was achieved keeping two flat specimens the same steel together for certain time the carburizing medium and then separating them while the carburizing medium and continuing the carburization. The side which was contact with the other specimen before being exposed the carburiz- ing action showed normal carbon content, while the side exposed the action from the very be- ginning showed high carbon contents. was considered that the difference the results the two sides was due the fact that the side con- tact with the other specimen was fully austenized before being exposed the carburizing action. These results, figs and together with analysis data presented other investigators, led the follow- ing theory: The maximum surface carbon con- tent carburized cases depends the microstructure the steel during the process carburization. Exces- sive carbon contents will obtained the case when the steel contains free carbides carbide nuclei during carburization. Carbon contents called for the A,,, line, modified accord- ing alloy content, will obtained when the steel homogeneous auste- nite during carburization. The carburizing medium, per se, has effect the maximum sur- face carbon content. Excessive car- bon contents may obtained pack, liquid gas carburizing. Pack car- burizing, generally requiring reheat treatment, has the advantage that the event excessive carbon con- tents, the carbon will exist its most desirable form (spheroidal carbides). The same argument would, however, apply liquid gas carburizing, the parts were subjected reheat and quench operation. There one indirect effect which the carburizing medium exercises the question maximum carbon con- tent and this effect related the ability the carburizing load reach the desired temperatures quick- ly. slow rate heating the load will have greater tendency pro- duce excessive carbon contents than rapid rate heating. The reason for this lies the more rapid austen- ization the steel furnaces pro- ducing high rates heating. this respect, liquid carburizing baths have distinct advantage over the other two methods and are less prone produce the undesirable condition. Under general conditions, very rapid rate heating dangerous practice due tendency for distor- tion, but with liquid salt baths, espe- cially the internal heating type, this danger very much minimized, due mainly more uniform heating. The reasons for the more uniform heating are very uniform tempera- tures within the bath and the method heating the stock (conduction). Carburizing Potential While the method carburization (solid, liquid gas) relatively un- important with respect surface car- bon content, the carburizing potential* carburizing potential defined the available carbon for diffusion into the steel and may considered the surface carbon content homogeneous austenite equilibrium with the carbur- izing medium the carburizing temper- ature. the medium exercises very important effect the surface carbon content. general, the small- the carburizing potential the carburizing medium, the less prone the steel contain excessive carbon The type steel under treatment has definite bearing “4 fic sti Cases fas ter rec ral fac que ° ° ° hig this question. steel containing stable should carburized media re- latively low carburizing potentials order prevent excessive carbon “built-up” its surface, since the probability the presence carbide particles nuclei such steel dur- ing the carburizing process indeed high. carburizing medium suf- ficient potential would most certainly cause excessive carbon built-up the surfaces such steels. Thus the question carburizing potential related the steel used—a medium high carburizing potential could satisfactorily used when the steel does not contain sufficient quantities stable carbide formers and medium low carburizing potential used when the steel austenized with difficulty. The next point consider the temperature effect. The higher the temperature carburizing, the less the probability obtaining ab- normally high carbon contents the surface the carburized case. The reason for this found the faster austenization rates higher temperatures. Naturally, not recommended that any carburization conducted above the temperature range 1700° 1725°F due other factors involved, such the tendency for grain growth and distortion upon higher probability better quench and less distortion, better product obtained when the carburized part quenched from lower temperature 2—No coarse carbides present the microstructure the other side the same specimen fig. This side was close contact with another specimen the same steel for before being exposed the gas atmosphere, Etched pet 1G. carbides the microstructure one side SAE 6152 men exposed carburizing gas atmosphere 1725° Etched pct picral (1550°F). for this reason that many heat treaters drop the temper- ature before quenching transfer the stock another furnace held lower temperature. Salt baths are ideally suited for the latter method. Grain Boundary Carbides However, such procedures consti- tute dangerous practice inasmuch grain boundary carbides well abnormal surface carbon contents may obtained. Grain boundary car- bides will develop the temperature lowered, the carburizing poten- tial the higher temperature suf- ficient produce surface carbon content above the saturation value the austenite the temperature from which the load quenched; while the basis the theory, coarse carbides will develop, addition the grain envelopes, the carburizing potential the medium the lower tempera- ture also high. the carburizing potential the secondary medium very low, the carbon content the surface will decrease and the grain envelopes will disappear. this case, however, prolonged immersion this 3—NE 8720 steel carburized carburizing salt bath bath pet and held this bath for before quenching oil. Microstructure contains marten- site, free carbides and grain boundary carbides. Etched THE IRON AGE, October | } — bath will result abnormally low carbon contents the surface. this respect, this method resembles the diffusion cycle commonly employ- ed. the potential the medium the high temperature sufficiently low that carbides will precipitate out upon the transfer the stock the furnace held the lower temper- ature, medium high potential may used this furnace without the danger obtaining ex- cessive carbon built-up surface the stock. The preceding discussion illustrates the complex nature the tionship among carburizing potential, steel chemistry, temperature and burizing process. This complexity is, however, fortunate situation allows numerous methods 8720 steel carburized continuous gas carburizer 1725° for and di- rect quenched oil. tains martensite, re- tained austenite, coarse, free carbides and grain boundary carbides. Etched picral; 500 ing preventing excessive carbon built-ups the surfaces carburized parts. careful examination the process and the microstructure the carburized case will indicate the meth- solution, provided the investi- gator will bear mind that the main point prevent the presence carbide carbide nuclei during car- burizing. immaterial whether this accomplished prior austen- ization (preheat medium low carburizing potential), increase carburizing temperature increase the austenization rate change the carburizing potential, direct quenehing from the carburizing tem- perature. Should any method un- for any reason, and free carbides still persist the diffusion period medi- 8720 steel carburized continuous gas carburizer 1725° for and di- rect quenched oil. tains martensite, large amount re- tained austenite and very fine grain carbides. Etched picral; 500 low carburizing potential (in gas carburizing this may plished the safe furnace) will eli- minate the trouble. Careful control is, however, essential such cases, otherwise consistency the qual- ity the product will obtained. Several examples actual cases will illustrate the above points and will emphasize the desirability con- trol of.the carburizing process metallographic examination. Case No. The coarse, “free” carbides, fig. formed result the undesirable combination ,of suf- ficiently high carburizing potential the bath 1725°F (this caused grain boundary carbides precipitate when the gteel dropped temperature that the bath) and the comparatively high carburizing po- tential the pet This condition was overcome the use direct quenching from the high tem- perature bath, which was simultane- ously lowered 1675°F 1700°F. Case No. The coarse, “free” carbides, fig. are result high carburizing potential (high methane content) while the steel was low temperature the first part the furnace. The grain boundary carbides are result excessive time elapsing prior the steel being quenched, causing drop temperature with consequent precipitation grain boundary carbides. The coarse, free carbides were eliminated lowering the carburizing potential the fur- nace (reduced while the grain boundary carbides were eliminated more rapid im- mersion the steel into the quench- ing oil. The reduction the carburiz- ing potential also contributed the elimination the grain boundary carbides lowering the carbon con- tent the case. Case No. The large amount retained austenite result high potential, which produces carbon content near the saturation value the austenite that temper- Such high carbon contents are undesirable due the high probabili- precipitating fine grain boundary carbides upon the transfer the car- burized stock the quench, addi- tion obtaining large amounts residual austenite with its attendant hardness troubles. This condition was overcome further reduction the carburizing potential. Acknowledgments The writer wishes express his ap- preciation Messrs. Komarn- itsky and Tompos for their valu- able suggestions and criticism. critica the tot Pet ‘ gro sion ing cept ther ners the geth sem] fits has the twee form one and mate comp semb semb 52—THE IRON AGE, October 1945 ATCHING for fit the inner and outer rings bearings selected groups has been found more rapid and accurate than the customary method match- ing single sets. This has been the experience the Gwynedd plant the SKF Industries, Inc., located near Landsdale, Pa. The core the new method consists the operation taking one inner ring from group about ten such rings previously selected measure- ment, and matching its fit with outer ring belonging selected group outers the same dimen- sional range variation the inners. the operator satisfied after mak- ing fit test the sample, she ac- cepts both groups inners and outers properly matched, and associates them together the simple expedient having rod which holds the in- ners slipped into tube which holds the Thus, there assurance that the groups remain intact to- gether when passed the final as- sembly line. The probability poor fits the finished bearing has been greatly reduced even though the job matching divided be- tween three girls place one who formerly matched inner with outer and put them together. Now, one girl measures and groups inners, another girl does the same with outers and third girl fits them for proper matching. The movement bearing components through the selective as- sembly and other sections the as- sembly line continuous and me- chanical the whole. This procedure .of selecting rings being used special rocker arm bearings for aircraft engines which 1400 times per min and are subjected severe radial loads the same li- time. The bearing contains full complement straight cylindrical rollers each end and deep groove ball bearing the center absorb the thrust. The looseness fits the assembled bearings falls within microns about 0.0005 in. Complete temperature and humid- ity held constant through- out the plant, which windowless. Additional electrical filtering air critical areas also maintained. the total manufacturing personnel, are assigned inspecting and checking duties. Process control and quality control stations are located various convenient places throughout the plant. limits some parts are held close mil- lionths inch and surface finish Assembly Bearings Principle This done production basis thousands bearings. Special lint- free garments are supplied inspec- tors and the assemblers. inner rings (races) @ecording from nominal race diam- eter. Determinations are made metric dial indicator reading microns. Each rod holds rings within definite diameter aa 2—Selection outer according inside diameter readings metric dial indicator. fiber tubes numbered according size microns from Note boards which the tubes are mounted. These are shifted conveyor the operator who matches groups inners and outers for proper fit. THE IRON AGE, October “ae , ap- Boron Steel study the properties imparted steels boron addi- tions, undertaken the Bureau Mines (Report Investigations 3816), led the conclusion that the most important effect the proper use boron increase the hardenability steel that used the quenched condition without tempering with only slight tempering. Neither the hardness nor any other property steel materially improved treatment ith boron the steel normalized. abstract this report presented herein. ° ° obtain addi- tion eoncerning the effects boron steel and its method addition, 119 steels and boron bearing addition agents were studied. The steels examined this in- vestigation were made 35-kva high-frequency induction furnace. The basic charge for each heat steel weighed and consisted clean boiler punchings known analysis plus sufficient wash metal that the carbon could caught com- tester. When the temperature the bath was proper, pct ferrosilicon was added deoxidize the metal and add the silicon necessary ob- tain the desired content. Medium-car- and CORBETT WILLIAMS Junior Metallurgist, Metallurgy Steel Section, Bureau Mines, Pittsburgh ° bon ferromanganese was then added meet the manganese specification. Any slag present was removed, and the boron addi- tion under study was made the bare sur- face molten steel. After the boron addition agent had dissolved, the steel was cast into ingot mold equipped with hot top. After the ingot was separated from its mold, was numbered and cov- ered with sand for slow When number ingots had been collected, they were hammer forged diam bar stock. During forging, liberal portions the top and bottom sections the ingots were hot-cropped for discard. Table lists the composition the boron bearing addition agents used tallur gist, TABLE Composition Commercial Boron, Addition Agents this investigation. All were ob- tained from commercial sources ex- cept the last three (C, and which were prepared experimentally. The hardenability the various boron steels was evaluated appli- cation the Jominy hardenability test accordance with the standard procedure developed the Society Automotive and agreed upon the American Society for Testing and the Steel Standardization Group.’ Committee, SAE Standard Procedure Recommended for Testing Hardenability SAE Journal, January, 1942, pp. 15-20. Committee, Tentative Method End Quench Testing for Steel, Standards, pt. 1942, pp. 1106- Jominy, E., Standardization Hardenability Tests, Metal Progress, December, 1941, pp. 911-914. The austenitic grain size the steel time quench was deter- mined comparing the fracture grain size the martensitic portion the Jominy bar with series P-F grain size standards, whereas the relative cleanliness the steels was established either metallographic- Composition, Pct (Approximate) 54—THE IRON AGE, October 1945 | ‘ | | a Boron Addition Analysis, Pct Added = o SSseses sk Insoluble Total Designation Soluble THE IRON AGE, October > | TABLE 4 | 12 2 | Analysis, Pct TABLE Experimental Data—Continued Boron Additien Agent Boron ooocoooco Pct total boron found chemical analysis Pct added boron was seldom obtained. Pct soluble boron 100. Pct total boron the distance, sixteenths, along side Jomi Heat numbers and were lost. Added Actual ingot weight Efficiency Pet Soluble Grain Size a an 100 because the boron addition was based upon ingot weight which bar from the end-quenched face the position martensite. Multiplying factor due boron found Envelope containing the boron addition agent was plunged into molten bath means iron wire. The boron addition agent was placed the end iron rod that had been drilled for this purpose. The end the rod was then closed iron piug. When this end was into the bath and stirred, dissolved and thus introduced the boron into the Carbon too low for standard Jominy hardenability est. Percentage boron determined the distillation method instead the colorimetric method. Ingot was hot-short; Jominy bar could not forged. ally application the Fitterer electrolytic method for extracting in- clusions from steel which was modi- fied somewhat serve the purpose this investigation. General Observations Chemical analyses, listed table II, were made the fine turnings obtained from the finishing cuts the Jominy test specimens. Carbon, manganese, silicon were determined the usual chemical procedure, whereas the boron content was ob- tained the Quinalizarine method developed the Youngstown Sheet Tube Co. Analyses were made, also, for phosphorus, sulfur, nickel, copper, molybdenum, chromium and vanadium on.a number heats taken random establish the presence and percentage variation these elements residuals often influence the hardenability great extent. addition, the total aluminum, titanium, vanadium and acid-soluble zirconium were determined for those steels which these elements had been introduced various boron bearing addition agents. Making and shaping the boron steels presented particular diffi- fact, boron steels could worked readily steels free 56—THE IRON AGE, October 1945 boron, Although previous reports in- dicated that 0.007 pct boron added steel produced hotshortness, heat containing 0.017 pct total boron was forged without difficulty. However, heat containing 0.024 pct total boron was hotshort, indicating that the change hotshortness occurred some- where between 0.017 and 0.024 pet total boron. Similarly, the observa- tion that boron did not coarsen the grain size the steel contrary that Tisdale and Comstock.* addition, was found that the boron steels were commercial cleanliness, Tisdale, F., “Boron Found Very Beneficial Alloying Element,” Blast Furnace and Steel Plant, January, 1943, pp. 93-94. indicating that none the boron ad- dition agents were detrimental the production quality steel. The boron addition agents listed table were added plain-carbon steel and their efficiencies were calcu- lated. Efficiency here used quantitative measure recovery. equals percent boron recovered ac- cording chemical analysis, divided percent boron added the steel, multiplied 100. Observations the relative effi- ciencies the boron addition agents added melts made the furnace should apply also heats made other types melting fur- naces. Actually the various boron addition agents should show greater efficiencies when they are added open hearth electric furnace melts, because induction furnace melting, contrary the general opinion, oxidizing character. the induc- tion furnace used for these experi- ments the action the electromag- netic forces the molten metal caused rapid stirring the bath; thus fresh metal surface was con- stantly subjected the oxidizing ac- tion the slag and atmosphere. Early the investigation was established that the method add- ing the boron agent the melt was not the bath had been properly killed and cleared slag previous the introduction the boron agent. Therefore, the method used throughout the experimental work, except noted the data table II, was dropping the boron agent the slag free metal surface. Table gives the efficiencies the various boron agents when added steel. For convenience they may listed shown the following page. ing dition | ingot M.F. ‘ 0.63 0.20 0.0006 0.0010 0.0050 15.0 32.0 1.28 0.64 0.27 0.0090 0.0240 FeB 0.0300 13.5 72.1 0.61 0.28 0.0016 0.0042 0.0058 NIB 12.75 98.5 1.33 104......| 0.61 0.28 0.0003 0.0016 0.0019 0.0040 15.5 49.2 1.52 0.63 0.24 0.0004 0.0027 0.0031 CrB 0.0050 15.5 64.0 106......| 0.60 0.28 0.0003 0.0037 0.0080 15.5 44.0 1.38 108......| 0.52 0.22 0.0004 0.0003 0.0007 0.002 16.5 38.4 1.63 0.61 0.0002 0.0015 0.0017 Bortam 14.75 1.39 0.85 0.0003 0.0007 0.0010 0.0030 13.5 1,30 the con | not con for the rela Car whi elen othe the iner cept pet pet pet dents the effect alum oxida and and abilit titani thus harde May Addition Agent No. Heats Range Efficiencies Average Manganese boron alloy 66.2to 87.7 73.0 addition agent with respect boron content. The spread between the maximum and minimum recoveries for par- ticular boron agent was too great warrant classifying the agents ac- their relative efficiencies. The reason for this spread was that the various addition agents were not homogeneous with respect chemical composition; furthermore, the amount addition per heat was small. From the above, important note that Sileaz and Silvaz, which contain elements other than boron for the express purpose protecting the boron from oxidation while these agents dissolve the steel, have relatively high efficiencies. However, Carbortam and especially Bortam, which also contain such protecting elements show low efficiencies. has been observed that elements other than boron present most the boron bearing agents will not increase hardenability measurably. However, Silvaz and are ex- ceptions. For instance, when 0.005 pet boron added Silvaz, 0.10 pet titanium, 0.10 pet vanadium, 0.06 pet zirconium, 0.06 aluminum and pet silicon are added coinci- dentally. This silicon supplies part total silicon required, and its effect the hardenability, therefore, taken into account. Most the aluminum and zirconium lost oxidation, but some the titanium and vanadium will alloy with the steel and exert influence the harden- ability. Although the effects titanium and vanadium harden- ability have not been definitely estab- lished, believed that the vanadium thus introduced will increase the hardenability, whereas the titanium may decrease it. The same reason- ing may applied the Sileaz ad- dition, except that vanadium not present. Because Silvaz and Borosil contain approximately pct silicon, whereas Bortam contains pct, the final silicon analysis the melt likely higher than desired, un- less this fact taken into account the melter. was excellent source boron, giving the best overall re- sults. Additions chromium boride boron carbide did not cause any machining difficulties the steels investigated this work. Boron car- bide, however, tended produce explosive reaction when was added the molten steel. Furthermore, also tended give poor ingot sur- face. Titanium boride had greater tendency cause the retention austenite than other sources boron. also caused excessive pipe the ingot. Manganese boron and nickel boron alloys, commonly used de- oxidize nonferrous alloys and im- prove their physical properties, were found satisfactory sources boron for steel. Additions Silvaz and well titanium boride lessor extent, appeared dis- solve with difficulty the molten steel. spite information the con- trary, both pyrobor (dehydrated borax with formula and fused boron trioxide glass which are inex- pensive, proved good sources boron for steel. was found that would add 0.005 pct (total) boron the steel (15 ingot), were necessary obtain the equiva- lent boron content. addition, the quantity boron obtainable from these two agents did not seem limited. For example, one heat, 10.9 the boron-trioxide glass added pct total boron the steel. Although the results tained experimental laboratory work small induction furnace heats steel and have not yet been applied commercial practice, believed that they are applicable commercial size heats. Boron should regarded any other element added steel in- crease the hardenability, and its use should not expected cure- all for improper steelmaking prac- tice. Generally, boron most valu- able medium-carbon steels because high-carbon steels have sufficient in- nate hardenability, whereas low-car- bon steels are not intended hardened quenching. Contrary general belief, boron may used produce fine-grained The boron steels examined had goo hardenability low alloy content were ob- and were uniform structure consistent in. behavior, tion steel, boron has specific effect words, certain percentage boron steel increases the fixed amount. The multiplying other factor for the hardenability conferred boron steel was determined and the boron content maximum value 1.58 0.003 pct total boron. With further increase boron con- tent above pet, the factor decreased. Minute amounts boron will in- crease the hardenability steel parable that produced much larger additions other more com- mon alloying elements. For instance, was shown that 0.003 pet boron steel has effect the tent 0.87 pct, nickel content 0.79 pet, content 0.27 pet, manganese content 0.12 pct However, should not construed that the use boron will eliminate the usefulness the more common alloying elements the increase hardenability due the addition boron limited; furthermore, proper- ties other than hardenability must necessity supplied formerly elements other than boron. | its ter its, ng, eri- ac- was add- was been the ental rface. added may owing i | Twin-Motor Drives maximum torque that can developed rpm with motors reasonable size was closely approached with the 8000-hp, drive installed the blooming mill Homestead, Pa., 1925, yet was apparent still greater power mill drives was needed. Problems pinion design increased with the size the motor, and higher speeds with shorter re- versal perieds were required in- crease capacities, particularly connection with blooming mills. creasing demands for power pres- sented problem the slabbing mill. When new installation con- sidered for South Works, Carnegie- Illinois Steel Corp. engineers co- operation with those the motor manufacturer developed, 1928, the first twin-motor drive used the steel rolling industry, applying §000-hp motor each roll two- high, 54-in. blooming mill. This in- stallation shown fig. These are motors operating Hot Reducing Steel Corp. has been using twin-motor driven rolls blooming, slabbing, and reversing plate mills with consider- able success and considering today the installation such equip- ment cold-reducing mills. description the development these mills contained herein. FRANK CRAMER Electrical Engineer, Carnegie-Illinois Steel Corp. maximum torque rating 3,940,000 lb-ft for both rolls, shown fig. Since then has in- stalled four similar twin-motor drives listed the table. One the most interesting these applications the 160-in. four-high reversing plate mill the Homestead works where wide range widths and gages both alloys and carbon steels have been suc- cessfully rolled (see fig. 3). using large twin-motor drives can installed for about the same overall cost the single-motor drive with pinion stand. These twin-motor drives not need pinion stands and have several ad- vantages over the single motor with pinion, among which much lower inertia the rotating parts that greatly facilitates both acceleration and deceleration. The relatively low inertia the twin motors permits the control designed for un- usually fast field response without causing high acceleration currents and high reverse power currents thus greatly decreasing maintenance prob- lems. The rapid response the mo- tors not only makes possible in- crease the entering speed and the rolling speed, but also permits the operator keep the piece nearer the stand. The combination these fac- Twin-Motor Drives for Hot-Reducing Mills Date Installed Size and Type Edger Main Motor, 54-in. blooming 2500 2500 44-in. slabbing 3000 3000 160-in. rev. plate All sets are units. 100-in. diameter doubie armature. 120-in. diameter single armature. IRON AGE, October 1945 Voltage Motor Generator Equipmentt Generator Units, Motor, 700 3-3000 600 700 700 700 6500 Induction 6500 Induction 7500 Induction 7500 9000 Induction { 4 100 drive Sout | tors that can the load this and will mot The backg two erator Speed, twinen close- view shows the twin-motor blooming mill South Works, Car- negie Corp. tors increases the percentage time that metal the rolls. Speed reversal not problem, the piece can entered smoothly low speed, the power being ample permit ac- celeration while the piece being rolled. Any tendency either motor take more than its share the load strengthens its field and weak- ens the field the other, thereby quickly restoring equilibrium. One the problems encountered this type design arises from the length connecting spindles required and the maximum angle which they will transmit the required torque. 2—This the motor room the blooming mill South Works. The mill drive the background consists two 5000-hp, dou- ble-armature, 80-rpm reversing mo- tors. The 9000-kw motor gen- erator the fore- This the installation drive, built 1928. With twin-motor drive, the spindle angle smallest when the rolls are about the mid-position, which nor- mally represents the condition for maximum rolling loads. Each the 5000-hp motors (40 rpm) the 160-in. plate Homestead mill has maximum torque 1,800,000 the South Chicago mills the torque 1,970,000 Fig. shows the maximum spindle angles and other principal dimensions for the twin- motor drives that have been installed Steel Corp. plants. the initial applications South Chicago double armatures were used hold the spindle angles mini- mum. From experience was learned, however, that minor changes the spindle angle offered serious prob- lems. the other three installa- tions, therefore, single armature motors have been used. The overall effi- ciency both the single and double armature units about the same. The gain WR’ the double arma- ture units large extent offset their series operation and end con- nection losses. Fig. shows the schematic diagram connections for twin-motor drive applied the two-high reversing ; — q its slabbing mill Homestead. This ar- rangement includes 3000-hp motor the edging rolls which must controlled such manner that when rolling and edging are done si- multaneously neither drive will push pull the other. Electrical connec- tions between the two main drive mo- tors are laid out balance the loads rather than the speeds. This allows different diameters used for the top and bottom rolls and still divide the load satisfactorily between the two drive motors. This type layout uses two pilot series exciters and two load balancing series exciters indicated the diagram. Typical the motor room setups the twin-motor drives for the vari- ous hot-reducing mills that the 45-in. universal slabbing mill Homestead. The two large driving units are Westinghouse 5000-hp mo- tors the main mill stand. four- unit, 10,500-kw main flywheel motor- generator set (three 5000-kw genera- tors and one 7500-hp driving motor) provides the power, controlled 440-v distribution switchgear. There variable voltage control board for the two 5000-hp twin-drive motors; the three 3500-kw generators; and the 3000-hp edger motor. Control the 1500-kw generator and feeders that furnish power for the motors oper- ating the auxiliary drives centered 250-v constant voltage switch- board. Precipitron installed the make-up air duct the ventilating system. Fresh air brought into the system through two ducts. Cooled re- 4—The relation the motors and spindles the various twin-motor drive mills can observed from this illustration and the data shown. The spindle angle smallest when the rolls are about mid-position, which normally represents the condi- tion for maximum rolling loads. 104-0" 3—These two 5000-hp main roll drive motors com- prise the first twin- motor drive the Westinghouse reversing motors are installed the mo- tor room the 160- in. four-high, revers- ing plate mill Homestead works but operated air brought into the motor room through several large floor ducts. Electrostatic air clean- ing reduces fire hazard from thick layers dust, reduces wear the commutators, improves commutation, and insures efficient operation deli- cate control mechanisms. Several advantages are derived from the twin motor type drive. They are: (1) There practically ten- dency for the mill chatter when the steel enters the rolls and the piece can entered higher speed than with drive. Chatter marks the plates, caused worn gears, are absent. (2) With twin motor drive the phase positions the rolls can shift independently, thus permitting rapid adjustment the steel. (3) The rate acceleration and deceleration faster, because the lower inertia the motors. (4) Higher rolling speeds can maintained with resultant higher tonnages being obtained from the mills. (5) Backlash eliminated. (6) Cost gear maintenance reduced. The twin-motor type drive wide hot and cold strip mills offers another advantage that elimi- nates the necessity accurately matching the work rolls. either hot cold mills equipped with sin- gle motor and pinion stand, unless the roll diameters are accurately matched, extremely high stresses are set pinions. With twin-motor drives the motor speeds easily and quickly ad- set. load the | The erat amp ing ener pass wou! be r TWIN MOTOR DRIVE DATA just themselves that each roll has the same surface speed. There was some question first whether twin motors would syn- 6600v. for the twin- motor drives shown here are applied the two-high reversing slabbing mill Homestead. 3000 kw. generator. chronize closely enough avoid curl- ing plate thin 3/16 in., but ex- sult tests made Homestead, ynotor which the motor loads had been va- each other, showed that plates could curling. Plate straightness was found in. has been rolled without diffi- Edger motor The four-high, 160-in. reversing plate mill Homestead handles fin- potential ished product ranging size from excitation and control in. 144 in. width and in. 720 in. length, and thick- motor nesses from 3/16 in. in. Slabs shunt excifer vary from tons with present ingot weights. Fig. shows power ehart for this mill showing the power required for the flywheel-generator set. The continuous curve shows the loads the two 5000-hp motors ick the main drive. Plate 0.812 248 the in. was rolled passes from slabs on, 105 in. during this test run. 5000 eli- The larger motor the motor-gen- erator set was provided assure ved ample power full speeds when roll- ive. ing long plates inasmuch flywheel 5000 hp. lower energy would consumed before the motor pass was completed reversal hen would occur before the energy could the restored. the curve the power curve can developed from test taken w o- passes. THE IRON AGE, October ad- Precision Founding Part VIII this series articles (part appeared Aug. 23) precision casting concludes the discussion coring problems previously described. The author analyzes the use refractory materials several types molds suitable for steel castings, and the operating factors involved centrifugal casting. ° FRANCIS DITTMAR Engineer, Buffalo cores for either plaster-base dry sand molds should have somewhat more permeability than that the mold itself. the same time plaster-base cores the binder (plaster content) must great enough afford the core the neces- sary strength order insure firm anchorage the prints. This firm anchorage essential preventing the core from shifting under the cen- trifugal force and under the impact the metal. Fig. shows simple coring prob- lem where, for the sake clarifying the subject cores and gating, each casting made separately. Under mass production such cast- ing would not made single flasks. The molds would lie tiers, the patterns arranged horizontal plane around central sprue, manner similar the example shown fig. 33, which procedure will dis- cussed presently. Meanwhile, the flask here consists two rectangular frames dowelled and locked together form square shell around the investment. this instance the seam which forms the casting disregarded. However, where such seam would objectionable the cast- ing would have made via the run-out wax process; this also will gone into later. The mold and its core may plaster-base one one dry sand; for that matter could also sand mold bonded with cement. Since the present case the core too small permit pouring fun- nel inserted, single castings ordinary sand castings the 62—THE IRON AGE, October 1945 could poured the manner shown fig. 36. Whether the metal aluminum copper alloy iron immaterial; the coring, venting and gating would the same any long the seam left the casting unimportant the metal pat- tern would split one, with gates and sprue attached. Attention called the concealed, masked, venting; note also the two vents leading from the hollow core the surface the mold. the case fig. (Part XV) pro- visions must made locate the pattern halves the exact center the frames; the locating “bridges” shown fig. effect such centraliza- tion. Wax Pattern Procedure The wax pattern would cast separate matrix, with their sprue another. The reason for making two units that single matrix would difficult fill owing the small diameter and lengthy gates through which the wax would have flow. The gates, assembly with the pattern, would fused onto the latter. See fig. 37. The core made first and poured its split box around cen- tral, slightly tapered and vaseline- coated rod either brass steel. This rod projects beyond the prints shown fig. that the pro- jecting ends may first serve cen- tralize the pattern the matrix and later also the flask. When the in- vestment the flask has set, the rod withdrawn, thus leaving central vent the core. The core placed the matrix while still wet that the hot wax poured around cannot soak into its soft structure. Whatever wax infu- sion may occur later when the wax pattern melts out the investment and the core partly dry will negligible. The pouring the wax pattern effected means the four gates shown fig. 37, these then being cut off, and the seam left the pattern obliterated when the wax has hardened. Cutters made fit the curvatures the cylindrical parts the pattern well its globular section would insure re- tention the correct shape and di- ameters the casting. The wax run out the mold via the four holes through which was poured, these holes also serving vents. further venting would necessary except inserting wire the still wet investment produce the vents leading from the core vent the top the mold was done the example shown fig. 36. While there reason why the ru