The Iron Age 1940-04-25: Vol 45 Iss 17

VAN DEVENTER 1S President and Editor c. S. BAUR er Vice-President and General Manager Managing Editor News Editor Editor Emeritua 9.8 6.8 wachinery Editor Art Editor Metallurgical Rditor Associate Editors Washington Editors Resident District Editors Pittsburgh Chicago Olevelana Detroit cor- Editorial Correspondents Buffalo Cincinnati FRAZAR FIDRMUC Boston Hamburg, Germany ram MEYER CHARLES Post ner- Milwaukee San Francisco SANDERSON CLYDE ENNIS ner Toronto, Ontario Birmingham the LEROY ALLISON Roy Newark, N. J St. Louis the lers ter- also DIX, Manager Reader Service the ADVERTISING Emerson Findley Union Cleveland Herman, Chilton Bldg., Phila. H. K. Hottenstein, 1012 Otis Bldg., Chicago war H. E. Leonard, 239 W. 39th St.. New York Peirce Lewis. 7310 Woodward Ave., Detroit nan C. H. Ober. 239 y 39th St., New York W. Robinson 9 > ynal Fitzgerald 428 Park Pitts. D. C. Warren, P. O. Box 81, Hartford, Conn and Don F. Harner. 1595 Pacific Avenue, Long Beach, Cal. will Member, Audit Bureau of Circulations Member, Associated Business Papers Indexed the Industrial Arts Index. ae’ Published every Thursday. Subscrip- will tion Price: United States and Pos- sessions, Mexico, Cuba, $6.00; Can- ada, $8.50; Foreign, $12.00 year. iel Single copy, 25 cents. Annual Num- nie ber $1.00. Cable Address, ‘‘Ironage, na- Be the ‘on, se; 3 Owned and Published by CHILTON COMPANY air (Incorporated) Editorial and Publication Office Executive Offices Chestnut and 56th Sts., 239 West 39th St., ers Philadelphia, Pa., U.S.A. York, U.S.A on. ar- OFFICERS AND DIRECTORS the MUSSELMAN, President JOS. HILDRETH, Vice-President GEORGE GRIFFITHS, Vice-President EVERIT TERHUNE, Vice-President VAN DEVENTER, Vice-President WILLIAM BARBER, Treasurer ter JOHN BLAIR MOFFETT, Secretary JULIAN CHASE, THOMAS KANE, HARRY DUFFY CHARLES HEALE Contents April 25. 1940 Target Practice for University Students Hardenability and Quenching Testing Bond Hardness Abrasives How Alloying Elements Affect High Alloy Steels Facing Brake Pistons Welding Heating Boilers Production Control—How Keep Delivery Promises Architectural Porcelain Enamel What's New Industrial Lighting "Machine Made the Assembly Line Washington News THE NEWS BRIEF Statistics Metal Working Activity Rate Activity Capital Goods Weekly Ingot Operating Plant Expansion and Equipment Buying Free Industrial Literature Products Advertised Just Between Two Index Advertisers Copyright, 1940, Chilton Company 108 112 120 121 146 Ie AS Every pound steel Ryerson stock certi- fied, prime quality. seconds are ever carried. Ryerson has built complete stocks these better steels every classification—steels made narrow, close-range specifications that assure better working For example: Ryerson Hot Rolled Bands will bend flat themselves either with against the grain: Continuous Mill Sheets Ryerson atock are tolled from only the best part the coil make sure flatness, accurate gauge and size; structural shapes and plates meet A.S.T.M. specifications not simply manu- facturers standards; machine and carriage bolts have cut—not rolled—threads, etc. Ryerson Certified Steels cut labor costs. These better steels are free from hard soft spots and can depended upon for uniform working and forming qual- ities. Spoilage and breakage are reduced, proving Ryerson Certified Steels are superior for close-tolerance work, automatic equipment, and production line applications. Ryerson stocks are complete and diversified. You save time, trouble and money concentrating all steel requirements with this one dependable source supply. Stocks include everything stainless from mechanical tubing foundation bolts. Many special analyses and unusual sizes are in- cluded the wide range Certified Steel products stock for Immediate Shipment. The special quality control plan Ryerson Certified Alloy Steels assures uniform heat treatment response and eliminates testing, experimenting and re- heating. Complete chemical and properties. and the exact heat treating characteristics each bar are sent with the steel guide the heat treater quickly securing any desired result. Ryerson Certified Steels cost more. You pay premium for the uniform high quality Ryerson products. Rely Ryerson. are and prompt shipment assured. you not have the Ryerson Stock List the guide Immediate Steel will gladly send copy request. Joseph Ryerson Son, Inc. Plants at: Chicago, Milwaukee, St. Louis. Cincinnati, Detroit, Cleveland, Buffalo, Philadelphia. Jersey City. a Na bi | for Using... | y ESTABLISHED 1855 THE IRON AGE ... APRIL 25, 1940 Vol. 145, No. task! rear the tender thought, teach the young idea how these words, his poem, James Thomson paid tribute his contemporaries, the educators the century. does not say just what the young people were trained shoot at. That left the imagination. Perhaps their aim was directed truth, talent high accomplishment some sort other. What modern youth being taught shoot at? One may well wonder that, you will, when you read the address recently given before gathering hardware merchan- disers and manufacturers Palm Beach the President the University Florida. You will find extracts from his address page this issue. will worth your while read them, you want know what some educators think you and your products mechanization. And presumably when educator holds such views, does not withhold them from those whose tender years have been entrusted his institution for thought formation. Dr. John Tigert doesn't like machines. Nor the machine age, you will see when you read the parts have published from his talk entitled Made accuses causing unemployment, robbery and murder; promoting seduction and war; eradicating personality and talent and breaking violins. Dr. Tigert educator. were, his views would have im- portance. was the first Rhodes Scholar from Tennessee. has held such positions Commissioner Education; chairman the Federal Council Citizenship Train- ing; vice-chairman the Federal Board for Vocational Education. was the president the Association Colleges and Universities Kentucky and member the National Council the Boy Scouts America. Such men have broad opportunity teach young ideas and young minds shoot. And his expressions Palm Beach reflect his philosophy, one wonders whether the tar- get aimed not the American System Enterprise and the Machine. With the intent shooting them full holes! men his position think they about the destructive social effects your work and your products, the slowing down the machine legislative mandate may not remote you think. 8, | | = i J OF Yop 4 ~ IRST ship 1938 break through the ice, pass the Soo, and open the upper lakes shipping season was the Inland Steel freighter, Philip Block. Again 1939, navigation was opened the Block, flagship the Inland Fleet, which holds the record for transport- ing the largest single ore cargo 15,778 gross tons. Now 1940, the Inland Fleet moves north into the ice fields bring down raw Freighters First pen 1940 Shipping Season! materials from Inland mines and quarries. The Inland Fleet important unit one America’s largest integrated steel producers, for Inland owns ore mines, quarries, ships. docks and mills —every facility for steel making. From the time the raw materials leave the ground until the last metallurgist makes the final inspection and the steel ready for the customer’s use, Inland maintains continuous unified control every process. SHEETS STRIP TIN PLATE BARS PLATES FLOOR PLATES STRUCTURALS PILING RAILS TRACK ACCESSORIES REINFORCING BARS ; > < i ‘ F HIS article treats the quenching aspect steel simple terms the use charts relate values single standardized quench. this GROSSMANN first section two-part article, hardenability and ASIMOW sented, and explanation Director Research and given for the use the charts. ° ° ° HEN piece steel hard- section being then ground flat and ex- designation. The point that the se- ened quenching, the extent plored for hardness. The data thus ob- verity quench, even when using the which hardens tained are plotted the form same quenching medium, influenced erned (1) the hardenability po- hardness traverse curve, such those markedly the degree circulation tential hardening capacity the piece shown Figs. and Such curves the quenching medium itself about quenched, and (2) the rate show accurately the degree harden- (what amounts the same thing) the which the piece cools, which gov- ing achieved when using the particu- stirring the specimen the quench- erned the size bar and the lar steel the particular bar size, ing bath. The degree this variation manner cooling it. The manner when subjected far greater than commonly taken cooling (circulating brine, quench employed. into account. determines the rate heat ab- With the single exception the se- Now clear that two bars straction from the bar, termed “sever- verity quench, the factors involved steel, entirely alike every respect, both hardenabil- such test are usually known quite are quenched such manner that ity and quenching are involved all adequately. That say, the compo- the severity quench differs, then the actual hardening tests, any attempt sition the steel can determined, bar quenched more evaluate hardenability alone must take can also its grain size, and the bar harden greater degree, and account severity quench. diameter course always stated, fracture etch test will show measuring the hardenability but the severity quench usually greater “depth hardening.” This steel practice, probably the most known only vaguely. While the quench circumstance, while well recognized used test the one which usually described, being stated per- principle, nevertheless not infre- bar quenched, then broken half haps oil quench, quently overlooked practice, simply cut across the cross-section with quench brine quench, this not because not realized that quench- wheel, the any means sufficiently accurate ing severity may show unexpected va- THE IRON AGE, April 25, 1940—25 rey 5 $ q or x Rockwell hardness (left), Fig. (middle), and Fig. traverse curves. each case bar steel has been hardened, Rockwell hardness wn Rockwell hardness then broken half and explored for hardness over the cross-section. riations. stated above, what not generally realized that the severity quench may vary over unexpect- edly wide range due different de- grees stirring, even when the quenching media are practically the same, view these circumstances then, helpful have simple method for measuring severity quench, and par- ticularly were then possible translate results from one severity quench another. Thus for different laboratories for different quench- ing installations, would useful designate severity quench actual numbers. two laboratories and were employing water quench, un- der such scheme might turn out that the severity quench Labora- Laboratory the apparently similar quench would turn out have the greater severity 3.0. Further, sup- posing were found that, quench- ing round, Laboratory found depth hardening 0.10 in. and Lab- oratory-B found depth hardening 0.16 in. The system described here would show that this particular difference hardening was accounted for fully and completely the differ- and H=3.0. Another circumstance that not in- frequently encountered practice difference between laboratory sults and plant production results, when using the same steel and osten- sibly the same quench. Here again 26—THE IRON AGE, April 25, 1940 quench rule out this possible variable. may thus many cases useful, possibly even imperative, ascertain severity quench quantitatively, and described this article. Only then can hardenability results referred single standard quench, and method will described for doing this also. Hardenability, Quenching Charts The accompanying hardenability and quenching chart, the over which rectangular sheet tis- sue paper celluloid (or glass) laid for the calculations. This chart used for measuring severity quench; the points (as low) are plotted the overlying tis- which then moved back and forth until the points match one the col- ored curves. plot the readings when employing celluloid, use “China Pencil” “Cellophane Pencil” (an ordinary colored pencil crayon will not work). good color medium blue green. clean the markings off the celluloid after use, bona, energine any similar cleaning fluid When using the colored chart, Fig. with the rec- tangular tissue paper cover, sure that the lower edge the cover slide coincides with the lower edge the chart page, and when moving the slide find the proper curve, sure that these lower edges remain together, otherwise the read- ings are meaningless. For estimating the “ideal critical size,” the figures are read from the other two charts, Figs. and Part Use the Chart following introduction states the exact steps followed determining severity quench; and ideal critical size. The charts may thus used adequately without studying the remain- der the text, which de- scribes detail the underly- ing principles and the manner constructing the charts. The color chart, Fig. used determine severity quench, called When severity quench mined, select single bar steel and prepare from series rounds different diameters (preferably least three sizes). The bar size hardenability should such that all the sizes after quenching have over- lapping hardnesses, other words that particular hardness may se- lected which found some position all the three sizes. y on are suitable, whereas those Fig. are not suitable. Suppose the severity determined. The scheme depends measuring the value called relation the diameter the bar Consider Fig. the hardness level and consider first the di- ameter bar. In. Fig. measure the diameter bounded the Rockwell hardness indicated for ex- ample the distance marked Measurement shows that this distance 0.99 in.; 0.99. Since the bar diameter ho | j 7 Dame 4 | | | | | | | + + + + yp +t THE IRON AGE, April 25, 1940 = Ww 0.99 1.50 case the 2-in. bar, indicated 1.54 in. that this case 0.66. the 2.00 bar, the curve just touches the posi- following the same form there results tains the following table: 1.50 0.66 2.00 0.77 Observe now that, chart Fig. the abscissae the bot- tom are marked HD, and the ordinates the left are marked The points are now plotted the overlying paper celluloid, being care- ful place position previously described. the bottom line the chart find the position marked 1.0, in- dicating that 1.0, and plot the 28—THE IRON AGE, April 25, 1940 Values first point the above table the hottom line, since this the position (shown the left) where Then find the position 1.50 the bottom, namely the appropriate posi- tion between 1.0 and 2.0, and follow this vertical black line perpendicularly upward (disregarding the orange curves); the left find the position 0.60 and 0.70, and follow zontal black line across until inter- sects the previously mentioned vertical line 1.50; this position place the second mark. For the third position find the bottom the page the line upward and make mark the position (judged from the ordinates 0.66, the proper place between 0.77. the left) where Now, slide the transparent cover (with its marks) over the underlying chart, being careful move the cover slide line with the underlying paper previously described. Paying atten- tion now the curved orange colored lines, move the transparent cover until Fic. 5—Relationships among ideal critical size Dy, actual critical size and severity quench all three points marked the cover fall the same orange curve. This will found occur when the bot- tom point the position 5.0, the intermediate point being now the vertical black line 7.5 and the upper- most point the vertical black line The orange colored curves have with the values HD, which the product (severity quench) times (diameter bar). The new position then indicates that, for the l-in. bar (the lowermost point), the product 5.0. then found simple division that 5.0 1.0 The three points all show the same H-value, since for the bar 7.5 that the same way for the 2-in. bar, 10.0 2.0 The severity quench therefore Values a> 4 ‘4 Vv \ 5.0. 1.5 4 D; Values 6—Same Fig. but using different scale. Both graphs copyrighted 1939, Steel Corp. The other charts and Fig. may used refer any actual quench quench. Ideal Critical Size, The “critical has been defined the size which the unhardened core just absent, the size which just “hardened ina fracture etch test, that round the example stated, Fig. note that the ordinates marked the left are marked values, and these refer the actual critical size found the test. The abscissae marked the bottom are called values, indicating the critical size which would have been obtained had the quench been ideal (severest possible the present case, the critical size was 1.0 and the quench was 5.0, find the left the D-value 1.0, follow the horizontal black line until intersects the in- clined black line which (at its upper right-hand end) marked 5.0. From this intersection, follow downward read the value the bottom the page and will found that very slightly less than 1.2, that the ideal critical size would designated designation the hardenability this steel, independent laboratory indicates the size which would just have been “hardened through” (no unhardened core) had this steel been given ideal quench. Explanation The previous paragraphs dicated the manner charts, but because brevity have left many steps unexplained. The lowing discussion offers more com- plete description. Special attention directed the following items: (1) simple way within the bars (time occupied specific point the bar cooling dur ing quenching). particular cooling- time (in specific steel) results particular hardness, hence priety inferring that points which have the same hardness had the same cooling-time (the steel tical) (2) The “unhardened core” (in piece not fully hardened) bounded line where the steel just half- hardened (50 per cent martensite). Thus the “hardened rim” not any means fully hardened throughout 100 per cent martensite, and this stance. The following symbols have been diameter quenched bar. diameter unhardened core arbitrarily selected hardness. (severest possible) severity actual quench. Ed. Note: Next week the authors con- clude this paper with detailed discus- sion the basis for the charts, and the origin and significance the term THE IRON AGE, April 25, 1940—29 ar TESTING FTEN the case that one new development leads an- other originally unforeseen de- velopment. Thus, new method stone grading has been developed outgrowth new process surface finishing. For the past several years, the Foster Machine Co., Elkhart, Ind., has been engaged the manufacture Superfinishing machines. This process involves the removal surface layer material (see THE Sept. 22, Nov. 17, 1938), and has been necessary study number different operating variables. Among the most important these variables has been the selection proper abra- sives “stones.” This selection abrasive stones has often been difficult, and, once made, hard duplicate, because stone manu- facturers apparently not properly and uniformly grade grit bond hard- ness. the purpose this article describe how satisfactory method grading abrasive stones, grinding wheels, and Superfinishing stones, medium and fine grit size, has been developed the Foster metallurgical staff. order clearly demonstrate the difficulties encountered, and how the solutions were reached, seems ad- visable review some the basic principles which are essential suc- cessful Superfinishing. many readers already know, Superfinish new method for the refinement the usual commercial finishes such are produced grind- ing, etc. This fine finish obtained the unusual application fine grit bonded abrasives (320 900 grit) the surface, manner which described. There are several features which contribute the production the extremely smooth surfaces, which are uncovered down base crystalline metal. Among these are the tools pecu- liar the process—fine grit bonded abrasives, usually cup stick shape; the short parted this tool; and the almost total absence heat. After experimentation involving the 30—THE IRON AGE, April 25, 1940 trial several thousand stones every kind bond and grade hard- ness, well size and kind grit, was found that there were compara- tively few uses (especially work ferrous metals) for any but vitrified bonded stones open porous found that grit size 320 600 was advisable—and, just grind- ing, silicon carbide grit was more suc- cessful work cast iron, and alu- minous oxide the finishing steel. These stones, whether they stick cup shape, are applied the rotat- ing work with series rapid short motions (five more ferred) designed prevent accumula- tions loads the working face the stone, and avoid duplication the paths the grits. greater complexity motions the Superfinishing flat work than cylindrical, will serve the present purpose just well, and more easily explained, this discussion confined the action the stick tvpe stones used cylindrical work. So, should instructive set job and see how control pressure, short stroke, low abrasive speed, vis- cosity stone lubricant, hardness the stone can used produce definite quality finish, finish which will automatically duplicated piece after piece work. Suppose shaft bearing taken for example. The first requirements are means for rotating the shaft, and mechanism for the application the stone and its short motions oscillation. Any the conventional methods can used for the shaft rota- tion, such between lathe centers. For the application the stone, and its oscillation, there are several ma- chines available, from simple inex- pensive lathe attachment others capable high production. any them, the stick type stone used ap- proximately per cent the work diameter width, and about the same length the bearing, unless unusually long. The spring pressure, applied hold the stone lengthwise against the work, varies from few ounces not over Ib. per sq. in. stone area contact with the work. the shaft rotates, the stone oscillated right-angles the tion the shaft rotation, speed 350 450 complete cycles per other motion imparted the stone, unless the length the bearing makes necessary traverse the Superfinishing head. Where traverse not necessary, the operation over sec. min. for completion, Nevertheless, during that short period time, the condition the working face the stone must through definite cycle the pre-determined quality finish obtained. The previous finish has probably been pro- duced grinding and the surface composed alternate minute hills and valleys. For some depth, the intense pressure, high speed and resultant heat the grinding wheel the metal this surface mented and amorphous smear-metal state, and, the case hardened steel, annealed condition. the first encounters the peaks the hills, and here the unit pressure high, due the small area contact. Stone metal contact easily attained matter how high the viscosity the lubricant may be. the proper grade bond hardness stone used, will this point break down some extent, presenting new and sharp grits, thus rapidly removing the flow lubricant here has only one purpose—to wash away abraded particles metal and stone. the peaks are removed, and be- come plateaus, the unit pressure the grit points becomes less, because the area contact and metal has increased, and becomes in- creasingly difficult for the points penetrate bite into the work. the points not bite deeply, sufficient leverage not exerted upon them pry out grits and thus dress and keep sharp the stone. the stone becomes duller and duller the area con- j | | My: pre pat OX) £5 (0 bre In ol sto lub nn tac rer ra} pre lab sm pre wil lac wil to wid pol ing ue sur mo thi cor - ine sto ‘ hay pre rea too Su +h We tha clit tar | 1 pressure becomes less. Naturally these dull teeth remove progressively thinner and smaller bits metal, and the belief that these much smaller metal are immediately the black oxide iron (or copper, the case brass bronze), and are deposited the pores the stone face. These deposits aid the stone, and also, filling the stone pores, contribute increase contact area the point where lubricant the proper viscosity will actually prevent further con tact stone and the work, and removal metal ceases. Thus, there automatic cycle rapid stock removal, followed progressive polishing action, control lable any desired degree surface smoothness the correct selection pressure, lubricant, surface footage, and bond hardness stone. Applica tion the stone another rough part will break down the glaze the stone face, and the above described cycle will repeated. rarely necessary dress Superfinishing stones. Incorrect Bond Hardness While possible control the point which the stone stops ing any material all, and thus the quality finish, variation pres sure, lubricant viscosity and surface experience has that bond hardness the stone much more importance. And, unfortunately, this feature has been much harder control, due the variations testing methods employed the abrasive stone This brings the question: What happens when the proves harder softer than there reason believe? When stone supported grits are not removed, and the cutting action slows down sooner than desired. Further, the large par metal that may removed the first few passes the grit often them and become permanent particle this size will out the grit the stone correct grade, and both the grit and metal will washed away the lubricant. These loads, retained the too rigidly held grits, immediately start tearing deep scratches the work surface, and will ruin the stone not removed. condition is, this case, never reached where particles metal are removed which are thin enough oxidize, and assist When the stone use has too little bond strength hardness, its applica HIS new method grad- ing bonded abrasives em- ploys ordinary Rockwell hardness tester. The results have been extremely helpful selecting proper stones for Superfinishing work, and the method could easily adapted other operations wherein bonded abrasives are used. tion the hill peaks results extremely rapid removal metal, the stone breaks down very fast. Un- fortunately, after the hills have become plateaus, the bond still does not have sufficient strength retain the grit under the reduced leverage pressure, and the stone keeps right cutting rapidly, removing particles metal too large oxidize and con- tribute polishing burnishing tendency The continuously sharp grit points will penetrate lubricant any viscosity, and there will obtain neither polished surface nor cycle any respect. Oddly enough, possible for stone have little bond strength and the grits loosely held that they not possess rigidity enough any real amount cutting, and very large stock removing capacity, may very little work all. possible, the visual exam- ination stone determine whether HEMINGWAY Chief Metallurgist, Foster Machine Co., Elkhart, Ind. has produced satisiactory piece Superfinished work. One that correct bond strength will always discolored its working face the accumulation oxide. None this blackening means that the stone there bright metallic particles firmly fixed the face the stone, is, almost invariably, evi- dence that the stone too hard. too soft. Such are the effects produced the use stones too great, too little bond strength hardness. pos- sible compensate for these condi- tions some extent, variation lubricant viscosity, pressure stone, surface footage the work. Suppuse, however, that high pro- duction machine has been designed for the finishing parts uniform size, the greatest possible efficiency. such machine is, more often than not, much easier change set stones than change tank full lubricant, several sets pressure springs, the speed rotation several spindles. When, such case, the stone first selected happens simple matter one little means available accurately pre- determine these qualities. the experimental laboratory has been necessary superfinish hundreds sample parts sent prospective purchasers equipment. Naturally, very little experimental work deter- mining the proper grade stone could done single sample sent in, because could easily much re- duced size stone too soft, too deeply scratched too hard, loaded stone, that the impression made the sender would decidedly un- favorable. So, again, readily ap- parent that some accurate means pre-determining the bond strength, cutting capacity stones was not only desirable, but almost absolutely neces- sary. The above described sample work was first undertaken November, 1938. Until September, 1939, this work was continual source culty. Unless stone, that had actu- ally been work tested, was available, THE IRON AGE, April 25, i 3 3 | * | 5, | } ~ | “mee 3 e e it 0 | was never known what results could expected. was the rule rather than the exception that from two six, more, stones tried before one was found that would job. New Stone Testing Method One handicap was surely, there was adequate meth- stone testing would have been discovered long ago, and put into use. Finally, Whitmeyer suggested that the Brinell method hardness testing tried. The writer had held the opinion that the diamond would found the only practical testing tool material. was felt that other would hard enough get consistent results reasonable number tests, under such abrasive conditions. also seemed obvious that the pres- sure obtained with the Brinell surely break many stones. While later work proved that the use diamond was not necessary, was natural, under the circumstances, turn the Rockwell method. For the information those not acquainted with these two hardness testers, both these machines are used find the hardness materials, usu- ally metals, the indentation method, under fixed load. the Brinell method, hardened steel ball, 2/5 in. diameter, pressed into the mate- rial, under load either 500 3000 kg., depending upon its hardness. The impression made the ball then measured for width, and the wider is, the softer the material considered be. The heavy load necessary press large ball into the tested material would break, injure the average sized stone used Superfin- ishing. The Rockwell uses the ciple identation under fixed load, but instead measuring the width the impression, its depth measured directly needle and dial. The penetrator used hard materials cone shaped diamond 120 deg. included angle, and with rounded tip. With the usual load 150 kg., its penetration only few thousandths inch hard metals. When testing soft materials, 1/16 in. diameter round steel ball used 100 kg. weight instead the 150 kg. The dial divided into 100 points, and one complete circuit the needle represents penetration 0.008 in. Two these 100-point scales are provided, one with black and one with red numbers, with zero points points apart. This desirable when using 32—THE IRON AGE, April 25, 1940 different combinations penetrators and load weights, the range hard- ness certain material may show some minus numbers one dial, but not the other. the use both the Brinell and Rockwell machines, the higher the hardness the material tested, the higher will the Rockwell number. Several changes have been made the makers the Rockwell machine the method application the load the penetrator. the early machines the load was applied through leverage system, which later events proved subject some frictional losses, when using the lighter kg. weight. models apply the load through much simpler system, which results almost dead weight appli- cation, with practically friction. Preliminary tests were the use one the old models. First trials testing stones, with the dia- mond and the load 150 kg., imme- diately proved that considerably less pressure was necessary. The diamond penetrated the stone far greater depth than did when testing steel, and the indicator needle made two three circuits the dial. After fur ther experiment, was found that the 60-kg. load was the most tory one available, giving penetration averaging in. stones hard- ness suitable for Superfinishing. However, the “C” black scale, usually used with the diamond, gave great many minus readings, the red scale was used instead. Ap- proximately per cent the stones used Superfinishing will thus show plus number. seemed desirable alter the setup that all readings would plus, but that would necessi- tate the use non-standard weights, alteration the machine. Conse- quently the idea was, that time, abandoned. After thus working out the combina- tion load and scale used, there followed systematic testing stones. Fortunately, those first tested were unusual uniformity the individual stone. Had some that were found later been originally tested, the results would not have been encouraging. each one the first lot tested within one three points uniform- ity, from end end. Trial another lot different marked grading showed quite different Rockwell hardness, yet all stones this second lot were nearly identical hardness. Eleven separate lots stones were hand this time, all from the same points difference any one lot, and points from the hardest the softest lot. other lots had appar- ently been mixed before being marked for grade, one-half each tested and the other half 32. Two more small lots 800 and 900 grit showed tively. Having thus seen that lot two dozen stones would test uniformly, and that different lots checked rea- sonable number points apart, seemed that the investigation was pro- gressing satisfactorily. Each lot was now listed the order the increase Rockwell hardness, and compared with the manufacturers’ alphabetical grading. was immediately apparent that the Rockwell sequence increase hardness was not accordance with that the maker the stones. This again was encouraging, because seemed reasonable that here was the cause the erratic results obtained actual Superfinishing. example this sort condition had just recently occurred. Twelve large pilot bars were received Super- finish, and unsuccessful new type- ot-bond stone was being used, and the job was taking hr. for each, when should have been done min. When about half through, lot six, square, 1000U, and one six, square, 1000U stones came in. was felt that these were too fine grit for such work, but was decided try them, apparently they could worse. Surprisingly, the first bar was Superfinished min., and beautiful job obtained. But, trying the square, such speed was possible. After the method stones was developed, this job was recalled, and was suggested that hardness test might explain this difference cutting quality. The hardness test these two stones identical manufac- turer’s grading, received the same time, showed the 34-in. stone check siderable decrease cutting capacity. During the next month, approxi- mately 300 Superfinishing tests were made the original lots stones. All them indicated that the Rockwell test was consistent with the cutting characteristics these stones could possibly desired. The troubles finishing customers’ ately began diminish. order fill plant needs and > > i | provide wider diversity for test pur- poses, large number stones were ordered from two different manutac- turers. Every bond hardness usable Superfinishing work included. Upon receipt these stones, approxi- mately 1500 separate hardness tests were made upon 402 them. was These 402 were separate items, averaging about stones per grade. the lots, only were found satisfactory uniformity. Only four these were estimated anywhere near correct grading. Eight ELATIONSHIP for selecting vitre- dicate the proper hardness stone use finishing any given hardness steel. Another purpose was locate, accurately possible, the correct hardness limits each the two manufacturer’s gradings. all these tests case was found where this new method hardness testing was not proved consistent with the actual finishing qualities the stones. The sample Superfinishing, which had difficult, easier and easier the relation be- been became tween steel and stone came more familiar. Data were care- ous bonded alumi- nous oxide stone for the cylindrical Super- finishing steels > ul > Carborundum Co's. grading — | | The data thus collected also made possible the graph desired. All this work was done with the diamond penetrator and the kg. load the old style machine. While the results had proved very satisfactory, was felt that they should checked the use new instrument the dead weight frictionless model, before mak- ing this new information available those interested this abrasive prob- lem. Recheck Rockwell Data During the latter part this work, the writer was correspondence with hardness shown. The finishing conditions are follows: oscil- lation, grit, 500 600; sur- face feet 60; per sq. in. pres- sure; profilometer micro-in.; and per hardness, Rockwell Compound No. points Rockwell each. Most lots which had wide spread hardness were also lacking uniformity in- dividual stones, often much points one stone. This, was felt, undoubtedly accounted for the uneven wear often observed. After these hard ness tests were completed, the stones were arranged cupboard classified according the Rockwell numbers, en- tirely disregarding the manufacturers’ marked gradings. Proving the Rockwell Test During the next three months some 700 Superfinishing tests were made further ascertain whether the cutting characteristics these stones were actually consistent with the Rockwell hardness numbers. was the inten- tion, too, this proved the preliminary work have been the right track, collect the data necessary the con- Stone hardness, Rockwell collected order locate the correct Rockwell hardness numbers for each the two manufacturers’ true gradings, well construct the steel hardness graph. After the work was completed, grading limits versus stone hardness three months additional were satisfactorily established. Having located these gradings, was interest- ing reconsider the gradings the last 402 stones plus those originally tested, total 529 different lots. Out these lots, correct stones grading. Thirteen lots averaged points averaged from true grading, approximately letters the Bay State Abrasive system, nearly seven grades the Carborundum Co.’s. From this, obvious why the Rockwell hard- ness numbers were substituted for all stone grading. the Chrysler Corp., and with the Wil- son Mechanical Instrument Co., maker the Rockwell tester. The encourage- ment Wallace, the Chrysler Corp., hereby gratefully acknowl- edged. Also, through the kindness Mr. Wilson, new and latest model Rockwell was made available for con- tinuance the tests, with the recom- mendation that the possibilities the use the steel ball fully in- vestigated. was Mr. Wilson’s belief that, owing their small cost, their use might prove advisable. Accordingly, upon receipt the new instrument, approximately one thou- sand tests were made order de- termine the dependability the steel balls. These were made upon both relatively fine and coarse grits, and upon both hard and soft bonds. The conclusion was reached that approxi- mately tests could made without danger appreciable error. THE IRON AGE, April 25, of ar- ed ly, Vas Ca 65 the Bay State Cos. grading to | ar | | | 4 vas on- } : ity | ies ere ing uld : While there will that ball will occasionally used after too badly worn, has been adopted the standard for the test, and the use the diamond discontin- ued. Another fact that contributed this decision was that better range hardness numbers, with Super- finishing stones giving minus ones, was obtained with the ball and kg. load, than with any the other several combinations penetrator and loads which were tried. Che task still remained correlate the results obtained with the old setup and that the new. set stones varied bond hardnesses, and the greatest uniformity were selected for this comparison. Ten tests were made each stone, with each instrument, obtain good average, and the results plotted. range minus five plus 45, tained the original manner, became plus plus use the new method. The plotted results were quite parallel, except the soft stone where the results friction the old instrument seemed have some effect. After thus translating the original data into terms, numbers the newly adopted the revised graph was put into use all sample and experimental work. this writing, has been use for several weeks, with the same highly satisfactory results. fact, work with soft stones hard steels, even more dependable, because the greater accuracy and sensitivity the new instrument. Stone Testing Procedure already related, the use the newer more frictionless type Rock- well recommended. However, and are satisfactory. The combina- tion diameter steel ball and the kg. load, which designated the makers the machine the must used. The speed drop the weight arm should adjusted the elapsed time from its release until meets the stop from sec. The stone placed the anvil, and the test proceeds just testing part made The weight arm raised immediately after comes stop, and the Rockwell number the stone read the “B” red scale. Owing the possibility that stone may vary hardness, well test three points, both ends and the center. Many times stones will vary from face face well. Most lots stones have been 34—THE IRON AGE, April 25, 1940 found either satisfactory uni show the same pattern variation each individual stone the lot. Hard stones usually are more uniform than soft grades. Use the Graph will noted the accompany- ing graph that limits are shown for each grade stone, used Super- finishing, made the Bay State Abrasive Co., and the Carborundum Co. Each alphabetical grade Bay State system further divided into three numerical grades, for in- stance, 1H, 2H, and 3H. Once the proper Rockwell hardness stone has been determined trial Superfinish- ing, the manufacturer’s grading can found from the Incoming ship- ments can also inspected for correct ferred that other makes stones, than the two mentioned, are not recom mended. Time has not been found for trial all them. The curved line the graph in- tended guide the selection vitreous bonded aluminous oxide stones for the cylindrical Superfinishing steels. determine the proper hard- ness stone use, find the Rockwell “C” hardness the steel the ver- tical column numbers the left edge the graph. Follow the line passing horizontally through this steel number the right, until the curved line met. Now follow the vertical line, intersecting the horizontal that point, downward the stone hardness number the horizontal column the bottom the graph. This graph, together with may obtained from the Foster Ma- chine Co. While experience has proved this graph accurate under the Super- finishing conditions noted, any changes these variables will also change the selection stones small extent. If, for instance, the surface footage the work increased above the ft. per min. shown, few points softer stone must used obtain the same micro-in. Profilometer reading. the percentage International Compound No. 155 decreased, slightly harder stone order, be- cause decreasing the viscosity causes stone cut faster, act softer. Variation grit size will not usu- ally affect the bond hardness chosen the graph, but the Profilometer reading obtained will less, when using finer grits, than the 500 600 shown, and slightly higher with the use coarser grits. All these effects are small, and are readily compensated for, after reasonable amount ex- perience Superfinishing. ing operation about surface and after removal the ground finish, increase this speed close 100 ft. This method, developed ented the Foster company, does not affect the selection the stone accord ing the graph. compared the results obtained the single speed the stone will act softer during the slow speed, and more quickly re- move the roughness the part. Then, high speed, the stone acts harder than normal, and produces smooth surface high polish than the single speed. Conclusion addition the information shown the graph for the Superfinishing steels, certain that the Rockwell method testing bond hardnesses will prove invaluable assistance pose such work is being done upon a part made cast iron. Application stone will quickly indicate whether too soft too hard, and other stones are hand different and known, not guessed hardness, the cor- rect selection comparatively easy. The application the Rockwell method has been thoroughly tried the Superfinishing process that there selection stones for that purpose. further believed that will prove equally valuable the determination cutting capacities grinding abra- sives, within the range grit sizes which can applied. Grits 320 1000 mesh have cessfully tested routine manner. not certain how much coarser grades can checked with the ball, but believed that the use larger ball, with correspondingly larger load would test grits any size. The difficulties met the Super- finishing prospective customers’ samples, and the setup machines ready for delivery have been practically eliminated, but was felt that only small part the possible benefit had been accomplished. The major purpose make this informa- tion available the purchasers equipment. also believed that every user fine grit bonded abra- sives, matter what their application may be, will now have his disposal accurate means predetermining the cutting characteristics. ~ > i ay i = ARIOUS elements have definite and predictable effects high alloy steels, and the author herein de- scribes what these effects are and how various ele- ments may added give steels definite service char- acteristics. Last week the functions alloy additions were described, and detailed data given for manganese, nickel and cobalt steels. Herein, conclusion, the author describes tungsten and molybdenum steels and chromium steels. UNGSTEN MOLYB- DENUM STEELS: the very early high alloy steels was Mushet’s steel. This was high carbon manganese tungsten steel which was air hardening, and was very satisfactory tool steel. About years ago, Taylor and White, experimenting with modification steel, discovered the marked advantage high heat treatment, followed tempering, which produced tools which would retain good cutting edge even when the tools were run such high speeds that the nose the tool was ° ° ° PETER PAYSON Chief Metallurgist, Crucible Steel Co. America, Eastern Research Laboratory, Harrison, actually red heat because the energy developed. This was the origin high speed steel, and the best the modern steels was evolved when Dr. Mathews added vanadium the tungsten-chromium steel then being used. This steel, the 0.70 per cent carbon, per cent tungsten, per cent chro- mium, per cent vanadium type, known 18-4-1, has been the standard all- purpose high speed steel for very many There are, sure, many other types, with different proportions tungsten and vanadium, and with additions cobalt. recent years, several steels have been marketed which molybdenum has been used substitute for all, some the tung sten. all these high speed steels the carbon 0.65 per cent higher. Associated with these are group lower carbon steels containing tung- sten, vanadium, molybdenum and chromium which are known hot work steels. These may heat treated that they will retain hardness 375 450 Brinell after being tem- pered 1100 deg. F., higher. This makes them useful for dies, punches, mandrels, ete., for severe hot forging and hot extruding jobs, because they not soften readily when they are contact with the hot metals which are being worked. The high speed and hot work steels are all heated tem peratures between 1800 deg. and deg. the hardening operation. these steels, the alloy additions have the functional effects slowing the transformation rate the austenite, formation products are formed during cooling, and forming high alloy carbides. The high temperature aus- tenitizing treatments given these steels are for the purpose allowing the alloy carbides dissolve the austen- ite and also serve help retard the transformation. Then, when the mar- tensite these steels tempered, these alloy carbides precipitate tem- peratures about 1100 deg. F., and because this precipitation the steel resists softening during tempering, and some cases actually shows re- hardening, secondary hardening. this respect, vanadium, tungsten, molybdenum, and chromium have specific effects raising the tempera- ture which rapid softening takes place tempering. Other effects these elements high speed steel are the formation tough martensite, and complex carbides which contribute the excellent cut- ting properties the martensite. list some high speed and hot work steels given Table II. the most interesting the al- loying elements chromium, first, be- cause has the specific effect THE IRON AGE, April 25, 1940—35 e- ell ler ler ied ere ra- ser nes felt na- hat ing 5.7 steel, air cooled from deg. 36. Hydrochloric-picral etch, and 1000 diameters. increasing the resistance steel corrosion and and second, be- cause steels containing high amounts chromium can made run the gamut phase changes with delight- ful simplicity. The first the series high alloy chromium steels the low carbon per cent chromium steel which almost always contains 0.50 per cent molybdenum addition. This steel widely used for still tubes leum refineries preference plain carbon steel, because corrosion resistance and better resist- ance deformation under load high temperatures, i.e., ance. completely austenitic temperatures over 1550 deg. F., and although this austenite will transform only martensite during the air cool- ing pieces with fairly heavy sec- tions, will transform high tem- cooling and can therefore annealed very low hardnesses. This air hardening property rather annoying under conditions where weld- ing has done the field, because 36—THE IRON AGE, April 25, 1940 the martensite which forms when the steel cools down after the welding operation causes the part brittle. overcome this quality, additions ferrite forming elements made this steel. These prevent the formation m