The Iron Age 1945-01-11: Vol 155 Iss 2

Millions dollars VAN DEVENTER President and Director BAUR Vice-President General Manager ° ° and Advertising Offices 100 42nd St.. New York U.S.A. ° ° Johnson, Manager Reader Service and Market Research ° ° Hayes, Production Manager. Baur, Typography and Layout ° ° ° Regional Business Managers New York New York 100 East 42nd St. 100 East 42nd St. ROBERT BLAIR GIBBS Cteveland Pittsburgh 1016 Guardian Park Bidg. Philadelphia Chicago PEIRCE LEWIS WARRE Detroit Hartford Conn. RAYMOND KAY Los Angeles 2420 Cheremoya Ave. ° ° Owned and Published CHILTON COMPANY (Incorporated) Executive Offices Chestnut and Sts. Philadelphia 39, Pa., U.S.A. OFFICERS AND DIRECTORS MUSSELMAN, President JOS. HILDRETH Vice-President GEORGE EVERIT TERHUNE Vice-President VAN DEVENTER Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JULIAN CHASE THOMAS KANE HARRY DUFFY CHARLES HEALE ° ° Member, Audit Bureau Circulations ° ° ° Indexed the Industrial Arts Index. Pub- lished every Thursday. Price North America, South America Possessions, $8; Foreign, $15 year. Single Copy, cents. Copyright 1945, Chilton Company Vol. 155, No. January 11, 1945 Editorial The Avid Aphid and the Conscientious Caterpillar Technical Articles Sandslinger Molding Practice. Sub-Zero Postwar Design Trends Machine Tools. Broaching vs. Milling (Part Pressure Sealing Zipper... Continuous Injection Molding New Features News Front Personals and Obituaries Dear Industrial Week News Industry News and Markets Cleveland Absenteeism, and Curtiss-Wright Postwar Weirton Veterans Program 1944 Naval Building Navy Takes Ordnance Plant Farm Income Exceeds Estimate Steel Using Disabled Men Machine Tool Market Non-Ferrous Metals News and Prices Iron and Steel Scrap News and Comparison Prices Week and Finished Iron and Steel, Steel Prices Warehouse, Semi-Finished, Tool Steel Prices Steel Pipe, Tubing, Wire Products, Prices Pig Iron and Coke Stainless Steel and Ferroalloy Prices Index 144 150 152-153 154-155 158-159 230 with The | 360 3205 c 120 $36,- 3 0 ents over to ders 102 Member, Associated Business Papers Why Ryerson Immediate Steel Ryerson delivers steel time. One reason large, diversified stocks. Another the Ryerson Steel- Service Plants, strategically located quickly serve steel users. Still another experienced personnel— the field, the order desks, warehouses and shipping rooms and the trucks. Even under war’s heavy burdens, steel users gener- ally have learned that Ryerson service enables them hold inventories practical working levels—that anything from single piece several carloads Ryerson service per- sonal, thorough, and, above all, dependable. And Ryerson service goes further. Ryer- son engineers and metallurgists are avail- able for any problem steel selection Cutting and other preparation equipment are un- surpassed. Alloy steels are selected and tested. Data aid heat treatment are reported users. Ryerson Steel-Service based 102 years experi- ence. available for maintenance, inventory fill- ins, regular production, the single, dependable source for all your Company’s steel. Get touch with your nearest Ryerson Plant. Does your Company have the latest Ryerson Stock List?—includes more than 10,000 kinds, shapes and Alloy Steel— Tool Stainless. JOSEPH RYERSON SON, Inc., Steel-Service Plants at: Chicago, Milwaukee, Detroit, St. Cincinnati, Cleveland, Pittsburgh, Philadelphia, Buffalo, New York, Boston | TIFIED \_4ay ESTABLISHED 1855 Jan. 1945 VAN DEVENTER President and Editorial BAUR Vice-President and General Manager ° Staff Technical Editor ........ OLIVER ° ° ° Associate Editors JACK HIGHT WINTERS ALBIN JOHN ANTHONY BARMASEL Editorial Assistants SCHIEN MUNZER O'CONNOR MILLER HANSEN DAVIS Regional News and Technical Editers LLOYD Pittsburgh 428 Park POST Chicago 1134 Otis MOFFETT DONALD BROWNE EUGENE HARDY Washington National Press Bidg. LLOYD Cleveland 1016 Guardian Bldg. BRAMS Detroit 7310 Woodward Ave. OSGOOD MURDOCK San Francisco 1355 Market St. Editorial Correspondents ROBERT Cincinnati DEAN Buffalo FRAZAR Boston HUGH SHARP Milwaukee SANDERSON Toronto, Ont. RAYMOND KAY Los Angeles JOHN Birmingham ROY EDMONDS St. Louis JAMES DOUGLAS Seattle The Avid Aphid and the Conscientious Caterpillar these troubled days mass-murder, arson and rapine, refresh- ing sometimes escape into the past and dwell imagination those ancient times when man could boast being, least, level with the rest the animal kingdom. The outstanding figures those prehistoric days: the lion, the elephant, the owl and the ant have been well preserved and publicized song and story. But yet have heard read mention the avid aphid and the conscientious caterpillar. The horny handed sons and grandsons toil, who turn the pages THE IRON AGE search ideas for making more and better products deliver the Germans and Japs 1945 undoubtedly know well what conscientious caterpillar is. Perhaps not so, however, with aphid. Being myself son toil, without benefit Groton Harvard, must confess that did not know until looked the dictionary. found this repository wordy that avid means “greedy”, and that “aphid” plant louse. “avid aphid” there- fore greedy plant louse. your industrial experience you may have encountered some them. aphid insect that toils not, neither does spin. attaches itself growing plant, proceeds suck the sap out and for time lives “the life Riley”. After awhile, however, the plant dies from loss vitality and the aphid has find another cushy job die with it. The conscientious caterpillar, the form the silkworm, while member the insect family different from the aphid day from night. toiler and spinner “from way back”. Historically, its nature has been give rather than take, and until the advances technology the form rayon and nylon put the shelf, had contributed more the adornment femininity from top bottom than all the garment workers Seventh Avenue New York. way seems too bad that the advances science, expressed technology, could put such willing worker out business. Modern thinking would dictate finding another job for him, least giving ‘him displacement pay for while. Modern thinking out something too about eradicating the avid aphids which are found our industrial plants increasing num- bers both high and low positions. For unfortunately, the same tech- nology advance that has put the conscientious caterpillar out busi- ness has apparently made easier for his ambitionless cousin. The fact that have succeeded making both mental and physical work much easier has given too many people the idea that can get along without it. After all, there were few hitch hikers before the invention the automobile! ~ on, un- uch eets Higher War Output Results from NLAND LEDLOY -the lead-bearing, faster- Increased production 110%—tool life lengthened 300%—these are the principal results obtained America and England, where Inland Ledloy used for wartime parts production. Inland Ledloy open hearth steel containing small percentage lead, which uniformly dispersed and alloyed with the steel special Inland process. This addition lead greatly improves machineability. Except for its slightly finer grain structure, all physi- cal properties Ledloy—yield strength, ultimate strength, elongation, reduction area, resistance impact, etc.—are the same for open hearth steel analysis. machining, low unit-cost steel Welding qualities are comparable with these ordinary carbon steel. Ledloy easily forged, giving sharp, clean, die impressions. Methods used and results obtained when heat treating and carbu- rizing are the same for steel similar analysis, except for the effects the slightly smaller grain structure. Today, all the Ledloy that Inland can make being used speed war pro- duction. But when peace comes, Ledloy will again available for general manu- facturing speed output, and cut unit cost. Write for further information In- land Ledloy. Limited Cannon Street, London INLAND STEE Dearborn St., Chicago Illinois Sales Offices: Cincinnati Detroit Kansas City New York St. Paul it! qu: News January 1945 The new German secret weapon, socalled "foo fighters", the colored and lowing globes which race along for miles beside Allied airplanes, has all the ewsmen and radio commentators agog. They are guessed agnetic character, capable tremendous speed, and designed interfere ith radio and radar signals. But: The Germans are likely just confounded the secret weapon the Allies. Most undramatically, the probably just St. Elmo's fire, flamelike brush discharge static electricity, which reddish when positive and bluish when negative. The cold winter air and high airplane speed, combined with perhaps new wing dope varnish are ideal conditions for tremendous static charges which could whip off wing tips colored ball form and thence into space form fantastic shapes. Such great static charges would naturally sensitive radio and radar equipment. The Army dollar split follows: 27¢ for Air Forces equipment, 22¢ military pay roll, 20¢ for Ordnance materiel, 10¢ for Quartermaster the remainder for all other supplies and services. Indicative how rich the oil area Arabia that 160 wildcat wells proven reserves great proven reserves the S., the latter quiring 50,000 wildcat wells find. 16,000 English youths picked ballot and directed train for ground coal mining, 143 have been sentenced imprisonment for failing comply. Incentive pay will installed the Ford Motor Co.'s steel mill soon the company and the union work out the details. This will the first in- pay plan appear Ford. Reasons for selecting the steel mill for the trial are twofold: First, such plans are fairly standard steel production, and second, competitive ations make necessary obtain more steel Ford. For its size, total and capacity, the Ford mill has not turned out tonnage comparable best Nearly $18,000,000 will spent the the Chilean government with the financial assistance the Bank for equipment part that country's national industrialization program. Smelters, steel mills and copper working plants will built utilize Chile's yet undeveloped hydroelectric power. And: Corporacion Fomento Produccion which fostering this trialization program has already acquired the 32x72 in. sheet mill the Worth Steel Co., Claymont, Del., reported cost about $5,000,000. average monthly output 375,000,000 caliber 0.30 cartridges will necessary meet current approved Army requirements. For caliber 0.50 ammuni- tion the average monthly output must 250,000,000 rounds and caliber 0.45 and carbine cartridges will require average 175,000,000 rounds per month 1945. United Kingdom steel production for 1943 totaled 13,031,000 tons, statistics recently released reveal. Figures overall war production have now been leased because the improvement England's war position. special purchasing commission the Turkish Government now enroute the United States with plans spend $6,000,000 for ment and intends lay out $40,000,000 program follow. tives, freight and passenger cars, signal equipment and other parts are ordered. Tubular scaffolding used for the protection British beaches being sold, partly for scrap and partly bid farmers for fencing. 3 4 { x : i & ¥ 3 — q | pics: Sandslinger Molding Practice The Sandslinger method ramming mold boxes offers many advantages the jobbing foundry. addition giving more uniform mold surfaces, better permeability for equal mold hardness and improved parting than other methods, the savings manhours the use this mechanical device has been found considerable. British practice the use the Sandslinger, its application specific patterns and evaluation its advantages when com- pared with hand, and squeeze methods ramming are herein described. molding operations require sand into space irregular shape with the object producing uniform degree ramming all surfaces the pattern. This usu- ally necessary also throughout the body the mold itself, although oc- casionally there some attempt produce higher permeability the center rammed masses sand em- ployed molds cores. This im- retically obtained lighter ramming parts away from the mold face, but this usually obtained theory than practice. There methods obtaining the desired re- sults molds and cores: (a) Hand ramming; (b) jolt ramming; (c) squeeze ramming; (d) blowing, and Sandslinger. These methods, par- ticularly the last are discussed Buchanan the 41st annual meet- ing the Institute British Foun- drymen and published Foundry Trade Journal, July 27, 1944, pp. 249 253 and Aug. 1944, pp. 275 278. Hand Ramming Hand methods have certain fields application and also certain lim- Hand ramming, when well done, consists the ramming small quantities sand time, using rammer small surface area, which can directed into very re- stricted spaces. The head, that is, the flat rounded area right angle the direction the ramming force, always kept cov- ered with surplus sand during 46—THE IRON AGE, January 1945 the operation, and the rammer progressively lifted incorpo- rate more and more loose sand into the body rammed sand the mold core. Under ideal conditions the results this method should very good, but the main objection hand ram- ming that the results depend en- tirely the diligence the workman and less extent his skill, par- ticularly green sand work. More- over, the work laborious and slow. Then again, the process ramming with metal rammer, matter, how small its ramming surface, tends make series little partings which can actually demonstrated. This turn gives considerable variations degree ramming mold hard- ness from below the rammer face the position the rammer face the last blow. Another defect method ramming that the sand ram- med too near the pattern, this local hardness already described very resulting from hand ramming. Spacing the lines indi- cate the degree densification. fruitful source sand defects, such scabs. one the few definite causes scabs. Similarly, uneven ramming through the rammer being moved too big intervals results swelling the casting due liquid pressure, producing wavy surface which particularly undesirable most types castings left unma- chined. The main advantage that the first cost the ramming machin- ery precisely nil and, course, the equipment readily portable. Hand ramming has long record genera- tions successful application, which cannot lightly set aside any purely technical discussion. Jolt Ramming Jolting consists raising the sand filled mold corebox and allowing fall under the influence gravity, thus obtaining sudden jar impact the lifting table with the solid base the machine. This action produces movement the loose sand towards the surface the base which the impact takes place. When the surface the pattern horizontal, conditions for effective ramming are ideal, and the angle the pattern changes towards the vertical, the effectiveness jolting decreases. Ramming the vertical surface therefore obtained re- sult that property sand known and measured flowability. Re-entrant angles are usually avoid- because the necessity draw- ing the pattern from the sand, but where they have not been blocked out, such projections the cannot rammed without special procedure entailing hand ramming this particular part the box. For molding box having bars the usual vertical shape, the finished top part shows lines softness under each bar. This can prevented only hand ramming either before after jolt- ing. This finishing operation takes more time than the jolting This method ramming tends give greater hardness the flat parting s | tern denc face gree time acco der the also toul som inv: ing der fac the sto the such finite 1even being rface nma- that chin- the Hand nera- vhich any sand base luces the angle the re- nown void- but out, itself For -part isual part each hand jolt- This rting wide horizontal surfaces the pat- tern with gradual reduction the degree ramming from the surface upwards. For this reason flat top parts considerable area are always difficult jolt-ram, owing the ten- dency for large surfaces the mold face drop out. This defect encouraged low green strength, while the same time higher green strength often accompanied poor flowability un- der these conditions. Jolting is, course, very successfully applied flat work, particularly where the boxes are carried off hand and also larger boxes where the con- tour the pattern followed out some extent specially shaped bars. The defect not nearly trouble- some dry sand molds, for these are invariably finished and handled all subsequent with the part- ing upwards. this position the ten- dency softness behind the mold face may assist venting, and is, therefore, very desirable, provided stops short allowing swelling. the same time, the tendency swell- ing causes little difficulty molds which are subsequently dried. Squeezing Squeezing applied relatively small boxes because the high total pressure required. When the force applied from the top the mass sand, the degree packing tends decrease downward direction, re- sulting soft ramming, particularly small: pockets the pattern face. The best results are obtained light castings flat nature, which can made very shallow boxes. The depth the box which can rammed squeezing is, therefore, limited more than in. with plain patterns and even less certain cases. Squeezing machines, because the very simple operation, probably only one movement the piston the making each part, last long time without needing major repairs, contrast jolting machines with their very rapid movements. Squeezing cannot conveniently applied boxes having ribs bars, and considerable strength required the box part itself prevent sides being pushed outwards the force the squeezing action. This results robust design boxes, the LEFT jolting only. RIGHT 3—Distribution ramming density mold made squeezing one direction. same time increasing their weight. combination jolting and squeezing very successfully applied small boxes, particularly where even ramming the mold face ob- tained jolting, and the tendency softness the upper part the mold corrected squeezing after jolting completed. Where the depth the box does not exceed in. fairly uniform degree ramming can obtained throughout the com- plete section. This combination squeezing and jolting cannot applied very large boxes, owing the enormous pres- sure required effect the squeezing, but each box jolted invariably finished flat ramming the top, either hand, some with pneumatic rammers. The piston pres- sure required produce reasonable degree hardness steady squeez- ing evidently much greater than the same energy applied any form blow. Machine operators quickly find this out for themselves, and most squeezing machines are operated like steam hammers. Core Blowing Core blowing, the name implies, applicable cores only blocks oil sand used for relatively small molds, although there theoreti- cal reasons why boxes cannot ram- med this way nceessary. The use air under pressure the carrier for the sand tends give very uni- form degree ramming, free from close packed layers any particular zone. Although some foundrymen are the opinion that the act core blowing, the large grains the center and smaller material the surface, thus giving enhanced per- meability the center—so much de- sired core making practice. All the energy used the ramming this case employed moving the sand only, and thus the power required will compare very favorably with such methods jolting, particularly ram- ming the larger molds. Sandslinger The Sandslinger method ram- ming resembles the action throw- ing small handful loam into the mold, loam molding. The force the thrust very great, and ram- ming obtained the impact the sand itself moving very high velocity. The mechanism consists rotating. impeller having only one cup-shaped blade vane throwing delivering sand the mold core. The stream bonded molding sand fed into the path the cup travel- ing very high speed, where handful once each revolution, and expelled from the rammer head downward direction into the mold. The velocity this small handful sand such that impact with the 4—Mold hardness shown by: The Sandslinger; (2) jolting; (3) and (5) squeezing, and (4) ill-adjusted Sandslinger. Top number ‘THE IRON AGE, January Fig. 5—Relative mold hardnesses determined the wire penetration test. sand already the box actually pene- trates and packs on, and builds mass uniformly rammed sand. This probably the nearest thing individually placing grains sand mold, and should easily equal hand ramming, when done prop- erly. The obvious advantages this method ramming that all the power expended packing the grains, and that the moving parts the machine itself are very small. This particularly noticeable when trying ram boxes ft. long jolting. The mass materials lifted each jolt consisting box parts, table piston, and large mass sand 48—THE IRON AGE, January 1945 amounts to, say, tons. This ad- vantage applies lesser extent smaller boxes. One important advantage the Sandslinger ramming the aeration which goes during the process. This has very beneficial effect any molding sand, more particularly the primary preparation not what should be. This, turn, tends give much more uniform mold sur- faces and better permeability for equal mold hardness than the case molds made other methods. For example, making green sand castings with flat surfaces the drag the jolt-squeeze method has been 6—Test box and mold hardness results obtained from the ramming. found necessary avoid jolting ‘drags prevent formation scabs. This means that the drags referred are squeezed only, and are relatively soft the mold face. Using the same sand which largely Erith loam and ramming with the Sandslinger, which turn rams much harder, trouble experienced with scabs. has been said that the general purposes machine myth. This usually taken axiom well-in- formed founders, and applies without doubt all machines coming under the previous categories. Most ma- chines are eminently suitable for the type and size castings box for which they were designed. The truth this axiom becomes painfully obvious foundrymen who have one time another tried demonstrate their own satisfaction that there are some exceptions. Thus, the jolt roll-over machine intended for 30-in. square patterns not properly employed making boxes either bigger smaller. the one hand, the machine overloaded and tends wear out rap- idly, while, the other, the effort re- quired the mechanical operation out proportion the results ob- tained. For example, turnover boards made fit 30-in. boxes are both too big and too heavy for any smaller sizes boxes, and the manual effort has discouraging effect time- workers. The Sandslinger can, however, called machine, since will ram molds cores within range practically covering all foun- drywork. can, course, work conjunction with any size type stripping machine provided there are high projections which interfere with the travel the rammed head over the molding box. Fig. illustrates the hardness which results from hand ramming. The spacing the line indicates the degree densification. With this method ramming, the pattern vari- ations are theoretically unlimited, al- though, course, obvious from everyday experience that good salable castings can made from molds which are well removed from being perfectly uniform rammed. well known that there use- ful range ramming, and that radi- cal variations from this range are easily detected placing the finger tips against the face the mold—the most elementary and commonest method judging hardness de- gree ramming, may better described test for soft spots. Fig. shows distribution hard- ness molds cores rammed jolting only. order obtain the ideal ramming illustrated here, that is, horizontal straight lines equal hardness “Isofirms” they may called, the molding sand would have introuced into the box evenly, for example, through fine riddle well-aerated condition, and also means suitable sand frame keep good head surplus sand above the top the box itself. Fig. shows diagrammatically the distribution ramming density tio cal | h Bottom | fr the for comes who Thus, for operly bigger rap- ort re- tion ob- boards too maller effort time- rer, achine, within foun- ork ype are terfere head from the top. The hardness tests were ardness mming. tes the this vari- ted, al- from salable molds being use- radi- are finger de- better spots. hard- ned ain the that equal may would box fine and sand surplus itself. ally the ina mold made squeezing one direc- tion. The depth the sand, which can rammed squeezing lim- first all the total pressure available and also the surface area the box. For instance, the box becomes narrower, the friction the sides tends increase, although this factor only appears when the depth greater than the width—a condition which unlikely occur the mak- ing molds, except when deep pat- terns are molded very small boxes. Thus the pattern close the side the box. Experimental Data These theories have habit breaking down practice. Therefore, check these conclusions, series experiments were carried out. box, in. square and in. deep, closed top and bottom, was used. For ram- ming, the top was removed. was replaced after ramming and the side taken away, allow hardness testing regular measured intervals from top bottom the mass rammed sand. Rows tests were made 1-in. intervals, that is, commencing 1-in. from the bottom and finishing 1-in. taken Dietert’s surface hardness tester, measuring indentation hard- ness thousandths inch and the author’s wire penetration ram- ming test. The average each row six hardness tests was used rep- resent the hardness these levels. One size box was used limit the extent these experiments, al- though the size chosen equally suitable for all types ram- ming, for example, the Sandslinger does not show its best because the area presented smaller than usual, and the box rams fast that the operator has liftle time for maneu- vering the rammer head. the other hand, practically ideal for ram- ming jolting. The results illustrated Fig. show series hardness tests, each graph giving the average hardness varying levels from top bottom the box rammed various means. The heavy black lines indicate the average each group—thus graph No. the Sandslinger, indicates that the degree hardness improves slightly towards the top, giving rea- sonable uniformly hard rammed mold. Graph No. the average the group test molds rammed ing only, and this indicates very rapid falling off hardness towards the top, that is, from “hard” the bottom “soft” the top. Graph No. the average the group test molds rammed squeezing only, and this indicates corresponding falling off hardness from top bottom, that is, “soft rammed” molds “very soft,” con- dition which quite useless for any form molding. That the box much deeper than can handled responsible for the poor showing the squeezing machine. If, however, the box refilled and the squeeze operation repeated, three times all, the hardness the mold raised the hard rammed zone, shown graph No. LEFT 8—A tray casting requiring manhours for making hand and manhours the Sand- slinger. RIGHT 9—This drum hous- ing required man- hours for hand ramming and the Sandslinger method. ° ° ° F's. 7—Type Sand- slinger used the foun- dry John Lang Sons, England. The hardnes zones marked out the bottom the graph Fig. are quoted from Dietert thus: Condition Molds Very soft rammed.......... Medium rammed Very hard rammed.......... This point stressed here because there times tendency for foun- drymen interpret these figures in- dividually. Reference has been made paper* the Institute British *“Foundry Trade Vol. XLVIII, pp. 171 seq., 191 seq. Foundrymen 1933, the wire pene- tration method measuring hard- ness devised the author, not alternative the one developed Dietert, but because known method was available the author the time. outlined series tests carried out examine these rammed sands, was found that Dietert’s system measures skin (CONTINUED PAGE 122) THE IRON AGE, January 1945—49 Le chromium tool steel. They are hard- ened Rockwell tempered for hr. boiling water, and are brought Rockwell sub-zero treatment —100 deg. several articles have been writ- ten the improved properties and performance brought about sub-zero cooling steel parts, par- ticularly tools. Claims several hundred per cent improvement life, while probably exaggerated, are not uncommon. other cases, the treatment was partial cure for im- proper initial heat treatment. Nevertheless, the value the process unquestioned. likely become routine part normal heat treating practices and sufficient authoritative information already evidence warrant vigorous program actual exploitation the shop and further study the labora- tory. appears, therefore, that presentation the fundamentals cooling hardened steels tempera- tures considerably below room tem- perature properly correlated with the ARGE numbers reports and For other articles sub-zero treat- ment steels, see THE IRON issues April 13, 1944 52; March 23, 1944, 52; and Oct. 29, 1942, 55. 50—THE IRON AGE, January 1945 Sub-Zero Treatment Steel The fundamentals cooling hardened steels temperatures considerably below room temperature, properly correlated with the basic treatment cycle and related structural changes. AMTSBERG Westinghouse Electric Mfg. Co., East Pittsburgh basic treatment cycle related structural changes, order. When steel heated its harden- ing temperature, the structure con- sists solid solution carbon iron, known austenite, with without alloying elements solution, and with without free iron alloy carbides, depending the com- position and temperature. Austenite relatively soft, tough, and ductile, even room temperature. The car- bides are very hard compounds carbon and iron alloying elements such chromium, tungsten, molyb- denum, and vanadium. When harden- ing such steel cooling some suitable medium, the austenite trans- forms martensite, hard strong constituent that aggre- gate finely dispersed carbides iron. This aggregate bears one similarity suspensions such col- loidal graphite water except that the particle size the former much finer. explained greater detail later, ideal hardening operation would one which all the austenite was transformed marten- site upon reaching room temperature. This true even the final hard- ness desired much lower than would result from this ideal hardening, for well known that the best physical properties are obtained quenching (i.e. water, oil, air) maximum hardness, then tempering the TABLE Tempering High Speed Steel 1050 Deg. Hardness, Tempering Double Tempering Hot hardness measured 1000 deg. Transverse, Lb. Per Sq. In. Hot Torsion Impact, Ft.-Lb. Strength, hr. 65.0 408 ,000 58.0 plus hr. - vith gre- one col- that atail tion the ard- ould for sical num the strength versus ductility and tough- many steels, however, the trans- formation the soft high-tempera- ture constituent austenite the hard constituent martensite does not al- words, after the steel has been cooled room temperature some austenite has still been retained. This illus- trated Fig. showing isothermal time high speed steel de- ably due the greater degree thermal stress the latter. further believed that the same phe- nomenon exists higher alloy steels when air and oil quenched, respective- ly. impossible state specific rule, but may generally said, that the higher the carbon and alloy content and the higher the hardening temperature, the greater will the tendency retain austenite. Thus, apparent that mixed structures this nature may present fre- quently “as quenched” steel. tained austenite, that is, reduces its reluctance transform. many plain carbon and low alloy steels, either medium high carbon (in- cluding such cooling sufficient virtually complete all transformation. other steels, par- ticularly the highly alloyed die steels, several such operations may neces- sary with intermediate tempering between each sub-zero treatment. In- deed, high speed steel must tem- pered the conventional manner 1400 1600 carbide 1200 transformation curve for high speed steel. termined Gordon, Cohen, and and air hardening die steel Payson and Klein’ which cool- ing curves for standard treatments have been superimposed. Fig. seen that oil quenching 18-4-1 high speed steel room temperature transforms only about per cent the structure martensite while per cent remains untransformed austenite. Fig. shows that about per cent austenite remains the chromium air-hardening after air room temperature. Many other steels retain austenite similar manner provided the cool- ing sufficiently rapid prevent transformation high temperature relatively soft product—pearlite. The cooling rates the steels Fig. could reversed and the amount austenite retained each case would approximately the same. Furthermore, Honda and have shown that more aus- tenite may retained oil quench- ing than water quenching, prob- Retained austenite can made few steels, which the amounts retained austenite are relatively small, sufficient length time (sometimes months years) room temperature will change all nearly course, frequently disadvantageous particularly for dies and gages be- cause full hardness and dimensional stability are not obtained once. This explains the inability many gages maintain shape and size accurately over long period time. all steels, the austenite can transformed tempering, but fre- quently such high temperatures are required lose hardness the martensite and cause transformation the austenite softer produce, obvious that this purpose may accomplished simply continuing cooling the steel considerably below room temperature. Gordon and Cohen* have shown how such treat- ment reduces the stability the re- transformation curve for per cent chromium air hardening steel. least once during the heat treatment cycle order obtain transforma- tion all the austenite. Now that has been determined how austenite-free structure may all this trouble? well-known that, from the mechanical property standpoint, the amounts retained austenite and untempered martensite should be-at absolute minimum the final product. Repeated tests Cohen and his co-workers have in- dicated higher strength and toughness without appreciable loss hardness when all the austenite has been trans- treatment, especially the latter, and this particularly when the com- pletely transformed structure fol- lowed final temper for stress- relief. Scott and Gray* have shown (see Fig. more than 200 per cent increase transverse bend strength over Metallurgical Section Engineer and Consulting Metallurgical Steff respective- ly, Westinghouse Research Laboratories. THE IRON AGE, January range hardness cyclic treat- ment after hardening. This consisted alternately tempering boiling water and cooling —100 deg. three times followed the final tem- per the desired hardness. Evidence has been offered for high speed steel, showing that all the austenite may transformed tempering one more times the usual temperature (1050 deg. F.) with cooling room temperature following each such heat- ing. The amount austenite that will transform dependent the time the tempering temperature, and the effect the properties the progressively reduced amounts result- ing thereof, shown Table (from The effect these improved prop- erties has been substantiated actual shop results where reduced breakage- and edge chipping, longer cutting life, and more blanks per grind have all been obtained. previously pointed out, usually desirable have the trans- formation take place relatively low temperatures (under 300 deg. F.). This necessitates note caution, since steels containing considerable proportions austenite are provided “cushion” high plasticity for accommodation considerable stress. this “cushion” removed, particularly very low temperatures where plasticity general quite low, stresses resulting from natural dimensional changes occur which con- notes serious cracking hazard. With these facts mind then, approach treatments can made. For carbon moderately alloyed steels medium carbon content such SAE 1045, 4140, 4340 and equivalents, the practical value sub-zero cooling questionable be- cause the amounts retained aus- 3—Cycles for water and oil hardening tool steels, alloy carburizing steels, SAE Rockwell hardness 900 850 800 750 650 600 Diamond pyramid hardness 2—Effect cyclic treatment the bend strength per cent per cent Cr, per cent Mo, air harden- ing steel. tenite are either nil relatively small. Furthermore, most engi- neering applications steels this type, tempering temperatures are fairly high and hardness considerably reduced, wherein the conversion the austenite would objectionable. Bainite, untempered tempered, known have excel- lent properties for applications not requiring maximum hardness. water and oil hardening tool steels, alloy carburizing steels, and other low alloy high carbon steels such SAE 52100, the treatment has been found frequently beneficial. Typical cycles are illustrated Fig. general, cycle (a) satisfac- tory for virtually all alloy carburiz- ing steels and, some cases, the other steels well. Cycles (b) and 52100. 2400 200 Time, hours 52—THE IRON AGE, January 1945 (c) offer considerably reduced danger cracking, particularly where sharp corners edges are present where the part has hardened throughout the advantageous for gages since offers the greatest degree stabilization. all cases, the final temper the last operation and this true all subsequent treatments The curves indicate actual steel tempera- ture. While the time relationships are not intended exact (except where specifically stated), signifi- cant note that not deemed necessary hold the steel the sub- zero temperature for any appreciable length time. important, how- ever, that the steel reach the tempera- ture given. Treatments for the highly die steels, shown Fig. are very similar except that two and sometimes more immersions the sub-zero cooling medium sary obtain optimum properties since the austenite considerably more sluggish (that is, resistant transformation). Somewhat inferior properties result from cycle (b) against cycle (a) due “aging” (subsequently explained the dis- cussion high speed steel). Cycle (b) does, however, offer greater free- dom from the cracking hazard. Since steels that have been sub- zero treated have considerably great- strength given hardness they may used higher hardness than with ordinary heat treating practice. the same token, breakage service had been serious problem previously, tempering the same hardness used with conventional treatment will produce much greater toughness. Fig. illustrates several cycles for high speed steel. The regular salt bath technique may also employed, the only difference being the air cool from the customary quench into salt bath held temperature approximately 1100 deg. High speed steel, however, because some anomalous behaviors, requires addi- tional explanation. Cycles (a) and (b) are equal effectiveness and would seem most likely produce the best results performance all the heat treatments given. should pointed out, though, that this not definitely established. Ber- lien® and have obtained op- posing results independently con- ducted service tests. reported, however, that beneficial results have been obtained sub-zero treating finished tools, which seems indicate “X” effect factor that has, yet, not been explained. will Cycle (c) especially 800 quen Cohe 500 lowe: Cohe coolea 100 ners ertie point ment meal ment ‘for tenit that one ther: appr omm aust the Spec for noted that even when the cooling less continuous from the quench the sub-zero temperature, double tempering recommended. has shown this because the first cool still leaves approximate- per cent the austenite untrans- formed and amount time lower temperature will appreciably alter this condition. According Cohen and is, therefore, necessary “condition” the remain- ing austenite the first temper, that will transform cooling room temperature. course, desirable stress-relieve this last formed martensite for best properties, hence, the second temper. appreciated that many tools, particularly large ones complicated and/or containing sharp cor- ners edges, would prone cracking given either treatment (a) (b). the treatments shown cycles (c) and (d) are offered. These may not produce prop- erties equal cycles (a) (b), pointed out above, but the improve- ment over conventional practice considerable and they provide means treating shapes that would certain distort crack sub- zero cooled directly. carrying out any the treat- ments illustrated, the steel should not held near room temperature for any appreciable length time before sub-zero cooling, since the aus- tenite becomes stabilized through “aging” phenomenon, and thereby be- comes increasingly difficult decom- pose. Gordon and have shown that holding for short time one hour has detrimental effect and hr. reduces the efficiency the sub-zero treatment per cent. Fur- thermore, arresting the quench above approximately 225 deg. not rec- ommended since majority the austenite would then not trans- formed until the steel cooled from the tempering temperature with even greater hazard cracking. Specific tempering times are given for high speed steel because they are 1600 high speed steels. 600 2400 2200 hours 4—Cycles for Cr-Mo, Mn-Cr-Mo, and high-carbon high-chromium air hardening tool steels. considerable importance. Accord- ing the first temper less than hr. 1050 deg. will not permit sufficient precipitation car- bides the tempering temperature allow for complete transformation the retained austenite cooling, while more than three hours causes some loss both room temperature and hot hardness, strength, and toughness. add some further precautions that have been dictated actual experi- ence. Since the distortion and crack- ing hazard ever present when transforming austenite martensite such low temperatures, de- sirable that the temperature the prevent additional thermal stresses. Many users the process have, con- sequently, employed the practice surrounding the part with one more layers heavy wrapping asbestos paper before insertion the cooling medium slow the cool- ing somewhat. Users are also cau- tioned avoid making hardness tests, particularly with heavy indenters, until the part has been tempered. 012345618 012345678 Time, hours BIBLIOGRAPHY Gordon, Morris Cohen, and Rob- ert Rose, “The Kinetics Austenite Decomposition High Steel,” Transactions, A.S.M., vol. 161-197. Payson and Klein, “The Hardening Tool Steels,” Transactions, A.S.M., vol. 31, 1943, 218-244. Davenport, “Isothermal Transformation Steels,” Transactions, A.S.M., vol. 27, 1939, “Kinetics the Austenite Martensite Transformation Steel,” Transactions, A.S.M., vol. 28, 1940, 537-574. 5K. Honda and Iwase, “On the Transformation. into Martensite Stress,” Transactions, American Society for Steel Treating, vol. 11, 1927, 399-412. Gordon and Morris Cohen, “The Transformation Retained into High Speed Steel Sub-Atmos- pheric Temperatures,” Transactions, A.S.M., vol. 30, 1942, 569-591. 7Paul Gordon, Morris Cohen, and Rob- ert Rose, “Effect Quenching-Bath Temperature the Tempering High Speed Steel,” Transactions, A.S.M., vol. 33, 1944, p. 411-454. “Internal Changes During the Heat Treatment High Speed Steel,” talk presented the regular monthly meeting, Pittsburgh Chapter, A.S.M., April 13, 1944, Dr. Morris Cohen, Asso- ciate Professor Metallurgy, Massachu- setts Institute Berlien, “Sub-zero Hardening Cycles,” Steel, Jan. 10, 1944, 86-90. DePoy, “Sub-zero Treat- ment High Speed IRON April 13, 1944, 52-55. Cohen and Koh, “The Tempering High Speed Steel,” Trans- actions, A.S.M., vol. 27, 1939, 1015- 1051. THE IRON AGE, January e -20 is- at- ce. me nal ter for alt ed, igh yme and and uce 2200 hat op- ted, cate Postwar Design Trends Machine Tools Recent announcements the builders indicate that greater automaticity without sacrifice flexibility will feature models the future. Trends machine shop practice are also covered this review 1944 activity. For market trends, the reader the year drew close, few announcements machine tool builders gave some clues postwar design trends. these few are typical, can expected that the new models will feature greater au- tomaticity, without, however, sacri- fice flexibility changeover from one job another. The Bullard Man- Au-Trol, for example, described predetermined method for providing the sequence and functioning ma- chining operations, designed that setup time little more than for manually operated machine. With this device, the machine can thrown from automatic operation piece complete manual opera- tion the same piece en- tirely different piece. set job, the operation run through manually and the automatic settings made the termination each cut. production runs, Man-Au-Trol equipped machines are said work from three four times faster than manually operated machines because tools cut almost continuously. The system was first applied vertical turret lathe but adapt- able many other types machines. vertical turret lathe, simultane- ous cutting multi-tooled main and side heads possible. Microme- ter electric stops and switches con- trol work size within 0.001 in. Mi- croswitch control also being used control head travel and automatic another type turret lathe yet formally announced. Use two-speed reversing motor permits simplified belt drive which takes ing tapping with reversal twice the threading speed. Microswitch devices are also em- ployed give automatic sizing new “postwar” honing machine re- announced Micromatic Hone Corp. the hone sticks are expanded bringing the hole size, IRON AGE, January 1945 referred last week's annual review machine plastic tabs projecting from their ends ultimately make friction contact with ring gage below the work and turn slight arc, actuating microswitch which with- drawal the hone. Multiple spindle setups make possible production hon- ing work high production basis. three spindle machine, rough honing, semi-finish and finish honing can performed with the aid indexing fixture. Costs are considerably reduced, with savings per cent reported one job. For larger work, Micromatic has developed system pressure fluid gaging akin air gaging, using the cutting oil the pressure medium. The cutting oil flows against the cylinder wall, the distance between the two elements being suffi- ciently close build substantial pressure the line. the diame- ter enlarges, the pressure drops and when predetermined pressure, ob- tained experimentally, reached, the operator withdraws the hone. This so-called Hydrosizing method can made automatic through the use pressure switch. Just revealed this week meth- roughing out gears which the cutting time measured seconds rather than minutes. The new Michigan “Shear-Speed” unit cuts all teeth small gears simultaneously with radially fed form-tool blades having shear cutting action. 51-tooth gear, in. diameter in. face, for instance, can cut less than minute. All the operator has place the gear the work holder. Chucking part the automatic work cycle initiated push button. This cycle includes lowering the multi-blade cutter head and reciprocating the work within the stationary head. the begin- ning each upstroke all blades are fed into the work equal amount; the return stroke, the blades are retracted slightly provide clear- ance the tools. Sizing the work automatically controlled and ad- justable. Helical well straight spur gears can cut the machine, both plain and shoulder types. present the machine limited gears in. diameter and in. face. The Shear-Speed unit designed teamed with shaving type finishing machine one-to-one basis. Heretofore, one-gear shav- ing machine has been capable han- dling the output number con- ventional shapers and hobbers. this connection, the wider extension the shaving process finishing aircraft gears has been noted the past year. Deliberate mismachining the involute profile take care controlled distortion heat treat- ment essential element this process compared with finish grinding hardened gears still done large scale. Much the suc- cess the process depends upon close metallurgical control aircraft quality gears the mill. Carbide Hobbing Carbide hobbing large marine drive pinions was tried out experi- mentally the Joshua Henry Iron Works last summer with the Bureau Ships, Navy. While the results were suc- cessful from the quality point view, the economic factors leave much desired. High first cost the cutters, largely attributed the novelty the application will major deterrent the wider ex- tension carbide tipped hobs for the immediate present, although the de- velopment one that hob makers, machine builders and gear cutters cannot afford ignore. Time hob large marine drive pinion was re- duced from hr. hr. this test, low carbon steel pinions were cut peripheral speed 150 ft. per hob fou spe fini loo! rat ter pla dia he: bei re’ sti per min.—the fastest available with in. diameter hob and existing hobbing equipment. This about four times fast standard high speed steel hobs are run.. Use climb cut was believed have con- tributed considerably the excellent finish obtained the teeth, which looked they had been shaved rather than hobbed. Absence chat- ter vibration this speed was ex- plained the fact that in. diameter arbor about double the standard size. Faster and heavier hobbing machines are now being built carry further tests cutting speeds 270 ft. per min. feeds high 0.090 in. per rev. the in. diameter blank. Although more cemented carbide tools are being applied generally, especially shell turning, there still much learnéd about the carbides both turning and mill- ing steel, particularly with negative angle tools. least two large manufacturers, not suppliers ce- mented carbides, are the process setting elaborate equipment for making large scale under laboratory tions. One investigation will concern itself largely with determining the optimum tool angles and setting