The Iron Age 1933-06-08: Vol 131 Iss 23

of steam-turbine ven pumps. the manufacture } process is made ed by the A. M. itled “The New Iron.” Il lustra- tual scenes taken picture of the ket are available ..THE IRON AGE.. cago, has issued ge bulletin show- f automatic air- ir-painting ma- tes le Creek, Mich., industrial trac- inted Harold B. w York, branch n interests. Mr. npany 12 years, en in charge of problems and has decided to larger quarters. st Lake Street, le the nd fixtures are former da line it together with new ised in connee- aught beer. A ut June | ark, Mass., has “om 1506 Park Iding. H. A. re. ntly organized ant, has taken Iding, Dayton, aircraft acces- ved from its ‘ourth Street, i South Sixty- The present November as y Co., to con- yley lines. n City, Ind., schke & Frey f the Cooler ection Cooler h Afri- n., Ltd. signed ‘ructed , Ltd., leering it Pre- udes a art of sht of ESTABLISHED 1855 JUNE 8, 1933 Vol. 131, No. 23 Unusual Applications of Stainless IGHTEEN - EIGHT - stainless H; steel, because of its low elastic limit and very high ductility, lends itself very readily to severe drawing work. This applies not only to cold forming, but to hot forming as well. It is true that 18-8 hardens rapidly when cold worked, which char- acteristic decreases somewhat its ease of fabrication and which results, in some cases, in considerable wear of dies unless special alloy tool steels and specially selected drawing lubri- cants are employed. Even then satis- factory results will not be obtained if the material being drawn is not of maximum softness and small grain size, Small grain size is important, as it will avoid granulation or “orange peel” in the drawn object, which, if present, results in increased polishing time and costs. Tests have also shown that the small grained 18-8 really draws better than the large grained structure. With controlled and super- vised annealing and the proper selec- tion of analysis, small grained 18-8 having a Rockwell hardness of 80 maximum is available for extra deep drawing work. For ordinary draw- ing work material of 85 B maximum is more or less standard. There are many articles which would be of superior quality, appear- ance and utility if made of stainless steel. Some of these articles are per- haps of intricate shape and design, and after one or two unsuccessful at- tempts to make them from stainless steel the idea would be discarded. Often there are grounds for such action, as the extra costs involved, could the ar- ticle be made successfully, would re- sult in an exorbitant price as com- pared to other satisfactory materials. In other cases, after careful analysis of the problems involved and the ap- plication of the proper quality of metal, the various obstacles have been Alloys By C. C. SNYDER Alloy Steel Division Republic Steel Corpn. surmounted and a really worth while product has been the result. Forming a Wheel of 18-8 Alloy An example of this is shown in the photographs of the spider for the au- tomotive air wheel which was made by the Cleveland Welding Co., Cleve- land. This is shown before and after assembling into the completed wheel. The hub cap is of chrome plate. The ao ma & AT the author empha- sizes is that apparently difficult manufacturing proc- esses are too often regarded as barring the use of the 18-and-8 and other chromium-nickel steels. Instead a careful analysis of fab- ricating problems will frequently disclose the feasibility of adopt- ing the stainless alloys and result in the production of articles of truly economic value. Examples are detailed to illustrate the point. a a particular type of metal is 18-8 and it was especially processed at the mill to fit the particular requirements of this job. The structure of the metal is shown in the accompanying photo- micrograph. A number of unsuccessful attempts were made with various other stain- less steels. When this job was finally successfully completed, it was done on the regular set-up and dies used for 895 ordinary steel, with some slight ad- justments. The blank size was 0.078 in. thick, 4% in. wide and 55 in. long. The first operation was to trim the blank to proper size and contour, which was followed by drawing cups of approximately 1%-in. depth suitably spaced. The blank was then annealed at 1900 deg. F. for 3 min., followed by quenching in water. The very slight oxide formed in annealing was not removed, as it has been found that such an oxide is often beneficial, act- ing as a lubricant. The final operation, which is pro- gressive and is done in six steps, was completed without further annealing. After a trimming operation the sec- tion was rolled into a ring and the ends flash welded together. The con- cluding operation consisted of expand- ing to correct size, spinning in of the flange and flattening it. The expand- ing operation, by the way, is a good test of the quality of the weld. The spider was polished in three operations to a mirror finish compa- rable to that of chromium plate, and it is a finish that will remain bright and free of rust and _ corrosion throughout its life. Similar wheels of plated composition show rust with- in a few months, due to the hard usage a wheel encounters. This is not, how- ever, intended to be a discourse on the relative merits of chromium plate versus stainless, but primarily a dis- cussion of some of the difficult form- ing jobs wherein 18-8 has been suc- cessfully applied. Hot-Forming 18-8 Seamless Cylinders A second example applies to the hot forming of large seamless cylinders from 18-8S material. Such cylinders, after considerable experimental work and close cooperation between the steel producer and fabricator, have been made not only from 18-8 but an- other analysis commonly known as NC-3, in which the chromium and nickel contents are approximately 25 and 20 per cent respectively. The completed cylinder, as here shown, is the ordinary gas cylinder. It was made on the same equipment as used for making common steel cylinders. The fabricator in this case was the Taylor-Wharton Iron & Steel Co., Easton, Pa. The billets used in the manufacture of the cylinders were heated carefully to about 2250 deg. F. and hot pierced under a_ powerful press. Following reheating the par- tially completed cylinder was_ hot drawn through successively smaller dies until the desired size was ob tained. The opened end of the cylin- der was then necked down, making the completed seamless tank. Several cylinders of 18-8 and NC-3 have been in service for several years, operating under high pressures and subject to the action of severely cor- rosive gases. The availability of this type of cylinder for the shipment of corrosive gases and liquids or for re- torts in the processing of such prod ucts should be of considerable value to the manufacturing chemical plant. dye plants and allied industries. The two grades of stainless steel which lend themselves to this type of fabri- cation are completely corrosion resist- ant to a great number of chemicals, acids, gases, etc.; the notable excep- tions are hydrochloric, sulphuric and hydrofluoric acids. The 18-8 type is oxidation-resistant PIDER and the com pleted assembly of a wheel made by the Cleveland Welding Co. of Enduro 18-8 metal, with the hub cap chrom ium plated. to approximately 1600 deg. F., and NC-3 to 2000 deg. F., both types hav- ing very high creep strengths at ele- vated temperatures. Heavy walled seamless tubing can also be furnished by the above process, although there is a restriction to the length that can be furnished. Such tubing should be satisfactory in connection with oil re- fining equipment, particularly in sizes beyond the limits of the seamless tube mills, both for diameter and wall thickness. There have been a number of other pieces of equipment made from vari- ous grades of stainless steel, which at first glance seemed impossible to proc- ess. Continued cooperation between the steel producer and the fabricator, however, has resulted in the success- ful application of stainless alloys to many articles, which have allowed the ultimate user to make extensive sav- ings. The initial cost in many instances is greater for the stainless, but the added life of the equipment and re- duced maintenance costs result in sub- stantial savings. Where foods, dyes, chemicals, etc., are being processed in stainless steel equipment there is no chance of spoilage, decomposition and deterioration due to contamina- tion from the metal. New Silicon-Carbide Refractory Brick N improved silicon-carbide refrac- 4 tory brick for electric furnaces has been developed. It has been given the name tercod and was described by G. S. Diamond, vice-president, Electro tefractories & Alloys Corpn., Buffalo, N. Y., in a paper presented to the recent meeting in Montreal of the Electrochemical Society. The brick consists of a mixture of silicon carbide, with or without graph- ite, a earbon bond and a protective boro-silicate glaze to prevent oxida- tion. An outstanding physical prop- erty is a low coefficient of thermal ex- Gas cylinder of Enduro 18-8S metal, made by the Taylor-Wharton lron & Steel Co., Highbridge, N. J 896—The Iron Age, June 8, 1933 pansion—one-ninth that of _ silica brick and less than one-half that of any other low-expansion refractory brick. It is therefore regarded as having a particular field where rapid temperature changes occur. Thus it is considered as promising especially to eliminate spalling troubles and to reduce strains in furnace linings and roofs. It is stated, for example, that a wall of tereod 10 ft. long expands 0.22 in. when heated from room tem- perature to 1300 deg. F., while the same size wall of silica expands 2 in. under the same heating. The accompanying tabulation, con- tributed by the author, covers some of the properties of the glazed tercod brick, together with corresponding properties of silica brick. He says that tercod is inert to acid or neutral slags and also inert to non-ferrous met- als. It is also inert to contact with cast iron of a total carbon of 3 per cent or higher. It is not inert to iron having lower carbon percentages, as such iron will absorb carbon from the refractory. This absorption of carbon and also easy attack by basic slags and fluxes precludes the use of tercod as bottoms in electric steel melting furnaces. Accordingly the field for this refractory in steel melting fur- naces comprises upper walls, door jambs, door arches, door bricks, sills, (Concluded on page 914) between ibricator, success- alloys to owed the sive say- tances is but the and re- t in sub- ls, dyes, rocessed there is position itamina- silica that of fractory ‘ded as ‘e rapid Thus it pecially and to ngs and le, that ‘xpands m tem- ile the is 2 in. nm, con- some of tercod onding 2 says neutral us met- t with 3 per to iron res, as om the carbon slags tercod 1elting ld for y fur- door , sills, ¢ ¢ ¢ 5 i : OUEST a | HE chromium-bearing iron treated with 1 per cent ferro- titanium was especially note- worthy, since it was the strongest of any in the tests shown in Table III. (See previous instalment, THE IRON AGE, May 11). Yet this mixture had the lowest cutting resistance in the shaper and lathe tests. The nickel- chromium and molybdenum irons were distinctly inferior. The microstruc- tures of all these samples were ex- amined, and the titanium-treated irons showed the finest graphite as usual. The nickel-chromium iron was even coarser grained than the un- treated, and the plain chromium and molybdenum irons were nearly as coarse. The latter was peculiar in showing much more ferrite than any of the others. All the samples con- taining chromium showed no ferrite, more finely lamellar or sorbitic pear- lite than the samples without chro- mium, and distinct particles of a hard white carbide (probably chromium carbide) associated with the steadite (phosphide eutectic). These charac- teristics of the chromium-bearing iron were always found in subsequent tests with chromium. For illustrations of similar structures Figs. 9 to 17, rep- resenting a latest test, should be re- ferred to. The fractures of these alloy cast irons were also interesting, the titani- um-treated fractures being distinctly and consistently darker and finer than the untreated or those treated with chromium or chromium and _ nickel. Titanium in Gray Cast Iron By GEORGE F. COMSTOCK Metallurgist, Titanium Alloy Mfg. Co. . a a 4 & HIS is the second and con- cluding part of the author’s description of recent results ob- tained by the addition of titanium to foundry iron. The previous instalment appeared in the May 11 issue of The Iron Age, on pages 744 and 745. Increased strength combined with machin- ability, the author concludes from the tests, is best obtained by combining chromium and titanium as alloying materials. vrvrv The molybdenum iron fractures were as dark as those with titanium, but not so fine. Some chill-test castings of these irons with sections only % in. thick showed white iron % in. from the edge with chromium alone, while both titanium and nickel, with the chromium, decreased the white border to a thickness of % to % in. Titanium in Electric Furnace Iron It will be noted, in studying Table III, that although the carbon contents of the samples in Test E were quite uniform, the silicon contents were not. Thus the effects of the alloys that were added intentionally may have been masked by variations in the silicon content. To avoid this un- certainty, which seems to be inherent in cupola melting, it was decided to have a similar series of samples made from a heat of electric-melted iron, where all the metal used would be drawn from one bath of uniform com- position. The first heat tested in this way (Test F) contained 1.35 per cent silicon and 2.83 per cent carbon, and the test bars were all noticeably white in fracture except the one treated with 1 per cent fer- rotitanium, and the one treated with chromium and nickel. The former was entirely gray and was easier to machine, but less strong than the latter, which showed traces of white- ness. Fractures of sections % by 1% in. are illustrated in Fig. 18, where the graphitizing tendency of the ferrotitanium is evident. The microstructures again showed finer graphite in these titanium-treated test bars than in those treated with chromium and nickel, or with molyb- denum. Two later tests in electric-melted cast iron were more successful, and results from them are given in Table IV. These values were obtained by the use of the same test methods as have already been described. Cut- ting tests were made on only three samples, as indicated. The silicon and total carbon con- tents of the samples in each of the two tests, G and H, respectively, were sufficiently uniform to permit valid conclusions to be drawn as to the effects of the various alloys intention- ally added. In test G, molybdenum TABLE IV—ELECTRIC-MELTED GRAY IRON TREATED WITH VARIOUS ALLOYS — NE Qerectnietaernmen Ferrotitanium added, per cent............. None 1.00 None 1.00 0.5 None None Titanium comtemt, POF Comtb..ccsccccceccsce 0.051 0.147 0.072 0.138 0.105 0.087 0.084 Chromium content, per cent............++. eee ie 0.56 054 0.48 0.62 Other alloy content, per cent............. Silicon content, per cent......cccececsecces Graphite content, per cent... cccccccceces Combined carbon, per cent..........-.+++: Total carbon, per cent............ Qo cccece Transverse strength, Ib.............++s0++ Increase over untreated, per cent........ DOMRCHON Ti aren RN ds sc crac as kes Increase over untreated, per cent........ Brinell hardness at center.............+. Brinell midway between center and edge. . Comparative resistance to cutting: Lathe test, 0.00318 in. feed............ Lathe test, 0.00694 in. feed............ Srl) task; WG aoViec dp cbccoshcceunes rill Genk; Gee a, sce sd ecetaw —_— 0.153 0.149 ee nee 1,85 Ni 0.46 Mo 221 212 2.10 2.19 2.10 . 2.74 2.71 2.74 2.71 2.77 0.55 i 0.73 0.72 0.70 0.70 0.62 3.46 3.47 347 3.43 3.44 3.41 3.39 4,450 4,673 4,8 4 28 5,004 4,835 4,789 5,093 5.0 8.4 12.4 8.7 7.6 14.4 0.145 0.146 0.145 0.139 0.170 33,820 35,660 36,520 38,700 37,240 38,640 38,960 rr 5.4 8.0 144 10,1 14.2 15.2 7 196 202 207 187 207 202 187 196 207 217 207 217 207 22.5 28.0- 27.0 37.5 41.0 39.0 19.0 20.5 20.5 880 900 900 — ——_—_———-~—Test H _- — None 1.00 None 1.00 15 None None 0.042 0.114 ans 0.126 0.138 . one Trace aaa 0.72 0.74 0.73 0.75 ian an ae oa ae aah 1.27 Ni 0.42 Mo 2.24 2.26 2.23 2.25 2.24 2.24 2.24 2.49 2.54 2.85 2.34 2.34 2.36 2.47 0.68 0.64 O83 0.82 0.84 0.81 0.69 3.17 3.18 3.18 3.16 38.18 8.17 3.16 4,400 4,512 4,390 4,930 4,625 4,672 4,362 2.5 12.0 5.1 6.2 . 0.125 0.184 0.107 0.112 0.110 0.106 0.115 38,840 39,900 43,020 46,680 45,980 42,940 44,300 ees 2.7 108 20.2 184 105 14.0 192 196 217 223 217 217 217 196 207 223 235 235 223 228 The Iron Age, June 8, 1933—897 asmhe | outs ie _ ual ~ > -™ ” . uo , e. * ty © e: 4 ea + Mg ot EBS at, oe yoo pa Stes t VT * .'> ~ . . » s ? * . 3 } e A. - \ ‘\ : ; ~ * etary , =. oa fs \ +> > é: *. - ) : } ’ Rae vb . } * — s>. o> ' se a = X - €/. x ‘ ¢ 4 ! “° . a 1 ion, Staal 6 i ’ ae > eye , ~ ae! . e *- we wo Ne ~ ’ as ji * 2 - { f > e - ~ , om ~ - * on ’ - rk, ‘ > *.* ” es Pe a. , ag a A o a7: ees. . - —s te 7 ~ 34 y 1 te 4 » . > - + s * ’ s e z x > * . ‘ - - . — . ¢ . a ~ . ; ~, * “ . - ~~ - ~’%. : a , ‘ . . . ok x ; “ ‘ ‘ . .-¢ ~ . ‘ a . . : : os . ; w . oe Read Wa : hk cee: = ; 5 . 3 . 2% ~ “ a 7 e ot, ° ‘ vor ‘> ieee ° ‘ . ih ot a n% *.: é ° ps ; X. . ~— . xs . » . = 2° 7. . 7 t ft a. - VN, ee Aer Nis aes sett 3) Day ea eo: + et >, 3 Hegre See os Lp: 54 . ‘@ 3 gio - 3 : e 2 °F a >. ‘sami’ ee oe ‘im ¢. oF it 5 / ea . Ne ’ ° »s « mS ° re e., . ». ©. Wage eee : ee . - wets : oes Sak S ag ; « .. 7 ‘ a i s < “4 .« ®, 7 as ts . . =~\ -« > ; oy cng | aS stays 5 ¥ . Q. oo. € i" » \ : Pee 3 eosv -@ 9 pS Pe OP aS eK x » Se ys a, ee me eer = < ny o *ys 2 . . a” e Pe : ‘ é B a - : \ a < Fig. 9 Untreated Iron Fig. 10. Iron Treated with 1 Per Cent Fig. 11. Iron Treated with Chromium Ferrotitanium Alone and 1 Per Cent Ferrotitanium n to, ‘ Cente. obpotS . See Le Faden Sy tenaaen to uty DAS ited Cy 5 oa Bee: SQ etree wad Fe 7 ee fe AG ~, 2 > ms 2 yey cee ~ , ee At ~ m ° > ” ™. . " ¢ | ¢ YPICAL views of ny kg a é 4 * .* . ae “ " a ‘d, ‘ a, ‘ 7S. se J ine ome r the graphite mid- & CP on. coy Re ye ee 4 i Pe ‘ _ Si lew . ss mee GSN ow way between center Yee Cg FB ik Ce , ‘ ; - . . ‘ ; em % / . - P - sb io and edge of cross- Be Neel io G ‘S\. , .* ’ . ’ hy an tr. . . a3 Pe 3 2 “* 4 af 4 4} Ey — h sections of bars 1.23 ro cae She /- Sa . J A ; 7? Ld a a. Pee & in. in diameter, from, |) 2 = poe ee) oir eer ee eo: + atc > =x (<u ~~“ Test G (see table 4). 0G PA ee ae my.” ong BU GE 7 ‘; * 1 “7,7 * All umetched and fF *s/ er es” hve BS. ' : _ et J @ « ae oe is » ; ogs . me : . 4 # ; pS Boe es ote . og magnified 50 diam- ow a Pee ‘ Cap a oe i ” . + alt . ’ : anh, - - 7 ¥en . *, # - eters wo a = . = ~ os ae _ - . ‘ —— «7 s ; at > sx Ree 4 . ea. 7h os | +e ~ ‘ 4 , ‘°° % . j rs i Be a < On, foo Pit Fig. 12. Iron Treated with Chromium Fig. 13. Iron Treated with Molybdenum and Nickel Alone yave the strongest iron, but the ma- in any of the three tests. In the an increase in strength in all in- £ g£ ’ chinability was not so good as that of the chrome iron treated with 1 per cent ferrotitanium, which was very little inferior in strength. In test H, as in test E, the chrome iron treated with 1 per cent ferrotitanium was stronger than any of the others. The nickel-chromium iron was not so good Fig. 18. follows from left to right :—1—Untreated iron. 5—Chromium and 0.5 per cent ferrotitanium. Top row shows % in. and % in. sections from Test G and % in. sections of lower-silicon iron from 898—The Iron Age, June 8, 1933 Fractures of Chill-Test Castings from Tests F and G, Enlarged 1.0 Diameters. 2—Treated with ferrotitanium alone. 6—Chromium and nickel. chromium-bearing irons neither 0.5 per cent ferrotitanium as in test G, nor 1.5 per cent ferrotitanium as in test H, gave as good results as the 1 per cent addition. There was some increase in strength with titanium alone, and some with chromium alone, but the combination of the two gave 7— Molybdenum alone. 3—Chromium alone. Bottom row shows 1 b stances nearly equal to, or sometimes even greater than, the sum of the effects of the two additions separately. Microstructures and Fractures The microstructures of all these samples were examined in the usual way, using polished specimens about (The order of arrangement is the same as in table 4, or as 4—Chromium and 1 per cent ferrotitanium. 1.5 in. sections from Test est F) il in- times f the ately. es these usual about or as anium. 1 Test Fig. 14. Untreated Iron, Showing Coarse Graphite, Lamellar Pearlite, and very little Ferrite l in. wide, cut from cross-sections of the 1% in. round bars so as to ex- tend from the edge of the section to beyond the center. The results of this study agreed almost exactly with what has been reported for Test E. ‘The titanium-treated irons showed the finest graphite; the chromium-bearing irons showed more sorbitic pearlite, and carbide in the steadite; and the molybdenum iron was not particular- ly fine-grained, showed considerable ferrite, and usually less steadite than the others. The only structural ex- planation for the high strength of the molybdenum iron in Test G that could be arrived at was that the slightly more sorbitic pearlite con- ferred a superior notch toughness on the iron, so that the coarse graphite flakes did not have such an injurious effect. The graphite did not appear to be enough finer in that iron than in the untreated to account for its high strength, as was true of the Fig. 19. Fractures of Chill-Test Castings from Test H, Enlarged 1.2 Diameters. Fig. 15. Iron Treated with 1 Per Cent Ferrotitanium Alone, Showing Finer Grain and More Ferrite than Fig. 14 TARE YPICAL microstructures of cross-sections of bars 1.23 in. in diameter from Test G (see table 4). All etched with picric acid and magnified 400 diameters titanium-treated irons. Photomicro- graphs of representative structures of the irons of Test G are shown as Figs. 9 to 17, and these may be con- sidered as quite typical also of Tests E and H, except that in the latter there was less graphite. cee he, of the fracture of the 1 in. section of the same casting. The bottom row includes from left t €rrotitanium alone; 3—with Chromium alone; 4—chromium and 1 per cent ferrotitanium; and continuing in the upper row, 5—Chromium and 1.5 per cent ferrotitanium; 6—chromium and nickel; 7—molybdenum alone) (The fracture of the ' right, the untreated iron first; 2—treated with Fig. 16. Iron Treated with Chromium and 1 Per Cent Ferrotitanium, Show- ing Sorbitic Pearlite, Bright Carbide Areas with the Spotted Steadite, and fine Crystals of Titanium Cyanonitride. Fig. 17. Iron Treated with Molybdenum Alone, Showing Considerable Ferrite, and Less Coarsely Lamellar Pearlite than Figs. 14 or 15 The fractures of the samples in Tests G and H showed about the same comparative appearances as have been described for Test E, the titanium- treated irons being characterized by dark and fine fractures. Chill-test castings were made of all these elec- oe ae | 1% in. section of each kind of iron is shown on The Iron Age, June 8, 1933—899 tric-melted irons in the form of a stepped bar about 8 in. long, 1% in. wide, and varying in thickness in five steps from 1 in. at one end to %& in. at the other. These bars were broken in a vise through the centers of the steps of 1 in., % in., and % in. thick- ness. The %-in. fractures in test H were all white; the other fractures for tests G and H are shown slightly enlarged in Figs. 18 and 19. In Fig. 18 are also shown the %-in. fractures from Test F, as has been mentioned below. These illustrations probably do not require further comment; the fineness of the thick titanium-treated fractures may not be very striking in the printed reproductions but the graphitizing tendency of the ferro- titanium on the white iron and on the thin sections which tended toward whiteness at the edges, should be quite evident. In every test, titanium showed as much effect as nickel in counteracting the tendency of chro- mium to make the iron white. Cost Relations The cost relations of these alloy irons should be of considerable prac- tical interest, in view of the properties that have been described. The regu- lar price of chromium in the form of the high-carbon alloy which is used in cast iron is believed to be 10c. per pound; the price of the ferrotitanium used is 25c. per pound; nickel is 35c. per pound; and molybdenum in the form added to cast iron is believed to be 95c. per pound. The cost of alloys per ton of iron in test G and H was computed at those prices, assum- ing no losses of chromium, nickel, or molybdenum, with 1 per cent ferro- titanium, 0.45 per cent molybdenum, and 1.25 per cent nickel used in both tests, 0.55 per cent chromium in test G and 0.75 per cent chromium in test H, with results as follows: Test G Test H Chrome-titanium .... $6.10 $6.50 Chrome-nickel wens 9.85 10.25 Molybdenum . 8.55 8.55 It is realized of course that in these tests we have not secured the high strength values that have been reported by others for chrome-nickel or molybdenum cast iron. Some of those results, at least, were obtained by the use of such large alloy addi- tions as would make the iron rather expensive for commercial applica- tions. We have tried to confine our tests to strictly practical conditions, bearing in mind the value of economy, as well as the adaptability of the al- loy to ordinary foundry practice. The results so far obtained with titanium in cast iron may be sum- marized by stating that it has been found to decrease the size of the graphite flakes, and to promote graph- itization and the formation of ferrite. The first effect strengthens the iron, but the latter effect may weaken it. Therefore in most irons of ordinary composition it is better to use a hardener, such as chromium, with titanium, if the maximum strength is 900—The Iron Age, June 8, 1933 desired. Chromium has been found to counteract the graphitizing effect of titanium, and strengthens cast iron by making the pearlite more sorbitic; titanium counteracts the hardening or chilling effect of chromium, and strengthens the iron by reducing the size of the graphite flakes. With the combination of titanium and chro- mium in cast iron, a more easily ma- chinable as well as a less costly high- strength iron has been made than by the use of other alloys such as chro- mium and nickel, or molybdenum. Carbon Steel Beer Keg Is Cold-Formed and Welded the steel beer keg. Although numerous designs of steel kegs are now available, there is one made by the A. O. Smith Corpn., Milwaukee, known as the “New-Way” barrel, in which special efforts have been made to approximate closely the advantages in handling that were offered by the old-time wooden keg. Othe tes are rapidly adopting The steel keg has come about not only because of the alertness of steel fabricators, but also because there is the factor of wood supply for manu- facture of wooden kegs. During the period of national prohibition white oak forests were neglected, with the result that practically only two States, Mississippi and Arkansas, have stands that are available for use. Further, the fibre structure of white oak, the most satisfactory wood for beer keg use, is such that the cut lumber requires a long period for air drying. Beer is here, and there is an urgent demand for kegs. Steel is, therefore, taking its logical place in the industy. Steel Keg Weighs 60 Lb. Various estimates place beer keg requirements at 12,000,000 units. The Parts for this steel beer keg are formed cold and welded in place. Medium high carbon steel is used throughout. Smith package, in the popular half barrel size, weighs approximately 60 lb. If this barrel is typical of what will be used and steel barrels to the above extent were required, it is simple to figure that there is a po- tential market for upwards of 350,- 000 tons of steel. Cut this figure in two and it is still impressive. Wooden packages in the half barrel size sell for $6.50 each and an empty half bar- rel weighs 70 lb. The steel keg manufacturer, therefore, has had to consider price, service, weight and convenience of handling. The half barrel container manufac- tured by the Smith corporation con-* sists of a steel cylinder of 15%-gal. capacity. It is made of medium high carbon steel and is expanded % in. on the diameter at the center so that the barrel will drain. The longi- tudinal seam is electrically welded. The bilge on wooden kegs was needed so that the hoops could be driven tight. However, workmen handling these barrels soon learned a few tricks one was that the keg could be up-ended easily by rocking it on its side, which lessened the physical effort of setting the filled barrel on end. Also, the bilge aided the han- dler to roll the keg and make it take a direction other than at right angles to the axis of the keg. With these advantages of the wooden barrel in mind, the Smith keg was designed with a steel bilge which is welded to the outside of the cylinder. This bilge is pressed to the desired con- tour as it is rolled to a circle. Its seams are welded. Dents in the bar- rels and in the flanges are to be avoided and all precautionary meas- ures are taken in the design and selection of the material to avoid dents occurring in these parts. The heads, made of medium high carbon steel, are electrically welded into the barrel. Flanges, or chimes, are espe- cially rolled and welded to the barrel ends; corners of the flanges are rounded and are easily gripped, but the area that bears on the floor is broad and flat, facilitating stacking one barrel on top of another. The free edge of the flange is turned un- der so that no raw steel edge is ex- posed. The bung fitting is made of cold worked carbon steel welded to the (Concluded on Advertising Page 12) a. “am: an ee With the nd chro- asily ma- stly high- » than by as chro- enum, ilar half 1ately 60 of what Is to the a & & is a po- of 350,- figure in Wooden size sell half bar- teel keg ; had to ght and nanufac- sion con-* 1544-gal. um high d % in. * so that e longi- welded. s needed > driven ng these vy tricks ould be r it on physical arrel on the han- » it take t angles th these arrel in designed elded to , fa red con- cle. Its the bar- 2 to be y meas- gn and 0 avoid ‘ss. The carbon into the re espe- e barrel res are ed, but floor is stacking r. The ned un- e is ex- of cold to the ge 12) 8 f PPLYING enamel and burn- ing or vitrifying it at high temperatures, lends itself admir- ably to progressive, straight-line machine production with the fur- ‘nace converted into a heating machine that is continuous and automatic in operation. All of this is accomplished by grouping the different operations such as dipping, spraying, drying, brush- ing, burning, etc., about a single overhead loop conveyor which takes the product from one to the other. vrvrv ECHANIZING the processes M of decorating steel products grows apace in manufacturing plants where the volume of sales is sufficient to support mass produc- tion. Practically all of the plants of the American Stove Co., the world’s larg- est manufacturer of stoves, gas ranges, etc., are thus equipped. One of these automatic units in its New Process-Reliable Division, Cleveland, is here described. The furnace proper is built of brick, properly stayed and is fired with gas fuel. It is 62 ft. long and 4% ft. wide, with the excep- tion of the hot zone, where the gas burners are located. This zone is 17 ft. long and 10% ft. wide, and one end of it is about 22% ft. from the charging end of the furnace. This 22% ft. is known as the preheating zone, for the waste heat from the hot zone flows in this direction and pre- heats the cold ware coming through. Conveyor Is a Single Chain Loop That portion of the furnace beyond the hot zone, which is about 26 ft. in length, is known as the cooling zone, and here the ware cools off to a point where it can be handled by operators as it leaves the furnace. The con- veyor consists of a closed chain loop, suspended from _ supporting steel work, one portion located just above the roof of the furnace and the other side 8 ft. away and parallel to the first. It extends 8 ft. beyond the Clede 72222 p AC aN . AV} > . - or. SS Enameling In Automatic Gas Furnaces By J. B. NEALEY American Gas Association charging end and 20 ft. beyond the discharge end so as to provide plenty of space for the operators to place and remove the ware from the tools suspended from the chain. There are 64 tools. Below the hearth level is a tunnel 2% ft. square which extends the en- tire length of the hot and preheating zones, beginning at the cooling zone. This furnace is of the full muffle type, two muffles of Carborundum slabs, one ft. wide and two ft. high, being located on each side of the furnace chamber, and extending the length of the heating zone. The gas burners fire directly into these muffles and the heat flows down into the tunnel where it heats the hearth of both the hot and preheating zones. The waste products of combustion are finally ex- hausted at the far end of the preheat- ing zone through a stack located close to the charging end of the furnace. Burners Located in End Walls As stated, there is one muffle on each side, or two in all. These are heated with a burner each, the burn- ers being located in the end walls of the preheat zone and firing directly into the ends of the muffles. The muf- fles are above the hearth level and the hot products of combustion flow from these, through ducts, down into the tunnel below the hearth and heat the hearths of both the hot and pre- heating zones, during their passage to the stack. The furnace chamber in the preheat zone is composed of Carborundum slabs 2% in. thick. The tunnel is arched to support the Carborundum slab hearth throughout the two heat- ing zones while a suspended flat arch Cross-Sections Through Hot and of Enameling Furnace. Cold Zones composes the roof of the furnace chamber proper. The side walls of the muffles in the hot zone are also of Carborundum but are 4 in. thick while the top slabs are 2% in. thick. The furnace chamber proper is 4 ft. from hearth to roof and as the muffles are only about 2 ft. high this leaves a 2-ft. space between them and the roof. Thus the tops of the muffles are util- ized as heat-radiating surfaces as well as the sides, and the air heated in the spaces above them is circulated through the furnace chamber. The furnace chamber, through which the ware passes, is thus seen to be T-shaped, 4 ft. high, 8 ft. wide above the muffles and 4% ft. wide between the muffles. In the cooling zone it is only 3 ft. wide from top to bottom. The furnace walls in the hot zone are 1% ft. thick, composed of 9% in. of pressed firebrick, 4% in. of pressed refractory slab and 5% in. of Sil-o- cel, the latter layer being on the out- side of the furnace. Roof Composed of Suspended Tiles The roof of the furnace is com- posed of special arch tile blocks about a foot square, each suspended from steel work, dovetailed and cemented together. A 2%-in. space is left be- tween the two center blocks, thus leaving a narrow opening, for the en- tire length of the furnace, for the passage of the tools, which hang down from the conveyor chain into the furnace chamber and carry the ware. The chain itself is suspended by a series of brackets with rollers which ride in an I-beam located above the furnace slot. On the shank of each tool is a short steel plate, the plates from adjacent tools overlapping and The Iron Age, June 8, 1933—901 A Single-Loop Chain Conveyor Carries the Work Through the Enameling Furnace. all riding on top of the furnace so as to cover the roof slot and keep the heat from escaping. The burners are of the premix type and each is provided with an automa- tic temperature controller and re- corder. Gas is piped into the mixer, where it is mixed with the proper amount of air for complete combus- tion, the volume of air drawn in be- ing controlled by a shutter which regulates the size of the air intake opening. The also be ratio can 902-—The Iron Age, June 8, 1933 changed so as to provide any furnace atmosphere required, such as oxidiz- ing, reducing or neutral. Safety Valve Provided for Gas Cutoff The temperature control consists of a motor-operated valve in the gas sup- ply line so close to the rotary mixer that the same motor that opens and closes the valve will also open and close the air intake shutter of the mixer by means of a lever. The cur- rent to the motor is alternately made and broken with a potentiometer and a thermocouple in the furnace. When the temperature of the furnace rises above that set on the indicator of the controller, the valve motor is ener- gized so that it shuts off the gas flow and closes the air shutter. Conversely, as soon as the temperature has drop- ped again, the motor is again ener- gized, through the thermocouple and potentiometer, and restores the fuel and air flow. is a type, into the gas line of the magnetic Also cut safety valve Inspecting and Hang- ing the Work on the Conveyor (at Left). vrvyv ~— ma & A Motor - Operated Mixer (at Right) Supplies Gas and Air to. the Furnace Burn- ers. Note Automatic Temperature Control and Safety Valve. the magnet also being cut into the electric circuit operating the mixer motor. As long as the current flows through the circuit the magnet holds the valve in the open position, but if, for any reason, the current to the motor fails, the magnet lets go and the valve instantly shuts off the gas flow. This furnace is employed for three- coat work, the dip tubs, brushing wheels, spray booths, etc., being grouped about the exposed portion of the overhead chain conveyor, which is motor driven through a speed re- duction gear train. The ground coat is dipped on and the dipped ware stacked on racks handled with high lift trucks. This ware is then hung on the conveyor, passed through the furnace for burning, and, as it comes out, is transferred to inspection tables where it is inspected and replaced on the racks for delivery to the spray booths. Here the first white coat is sprayed on, air dried, brushed, and (Concluded on Advertising Page 12) wwe ee t into the the mixer ‘rent flows gnet holds on, but if, nt to the ts go and ff the gas for three- brushing tc., being d portion yor, which speed re- ‘ound coat ped ware with high then hung rough the s it comes tion tables placed on the spray te coat is shed, and Page 12) ST et What the User Should Know About Free-Cutting Steels ganization was manufacturing Bessemer free-cutting steel to ap- proximately the following limits: |: 1903 the Jones & Laughlin or- Re ae ree 0.08 to0.16 percent Manganese ........ 0.60 t00.90 percent CS gree 0.080 to 0.130 per cent With only a moderate increase in sulphur content, these limits substan- tially represent the specification that is in effect today. About 1925 there began efforts in a number of quarters to achieve im- proved machining performance by juggling of analysis limits. This move- ment largely spent itself by 1930, but there are still those who feel that the metallurgical design of a screw steel rests in the writing of a prescription. At the time this movement began the general specification for Bessemer screw steel set the limits of sulphur content at about 0.100 to 0.160 per cent although the maximum limit was little observed; the records in our or- ganization show sulphur contents over 0.250 per cent as far back an 1910. When this furor of analysis juggling had at least partially subsided there was observed this permanent out- come; the original grade had been re- placed by two grades: A “standard” grade at about 0.130 to 0.180 per cent and a “high sulphur” grade at about 0.200 to 0.300 per cent sulphur. Cer- tain manufacturers went to further sub-divisions of grade, based upon various limits for carbon, manganese and sulphur. Here the matter stands today. In view of the success that attended the added or high-sulphur grade of Bessemer steel, it was only natural that similar methods would be tried with open-hearth steel. In this man- ner there came into existence open- hearth screw stock, best known as SAE 1120, the limits of which are shown in the table. This grade is still used in substantial quantities: By H. W. GRAHAM General Metallurgist, Jones & Laughlin Steel Corpn., Pittsburgh HE case of free-cutting steels, or so-called screw stock, was discussed by Mr. Graham at a recent meeting of the Baltimore chapter of the American Socie- ty for Steel Treating. The sub- ject was covered largely from the standpoint of the user. What the speaker had to say about the sulphur content, the open-hearth competition with the Bessemer converter for making these steels, factors which make for free cut- ting, behavior in heat treating and the economic importance of using the cold-finished product is given substantially in full in the accompanying review of the address. wrvrywvw About 1922 our organization was impressed with the difficulty being ex- perienced in the trade in machining operations on SAE 1020, a low-sul- phur steel widely used for carburizing. At that time we were interested in higher manganese contents in various applications, and finally a high-man- ganese, high-sulphur, carburizing steel was developed which machined very readily. The chemical limits were gradually standardized, and the grade was adopted as SAEX 1315. Later another grade came into some use, intermediate between 1120 and X 1315, with a manganese content of 0.90 to 0.130 per cent, but this grade has not yet been sponsored by the So- ciety of Automotive Engineers. Bessemer vs. Open-Hearth Screw Stock The excellent machining quality of Bessemer screw steel has never been seriously challenged by open-hearth screw stock, except by X 1315 and then usually only under special condi- tions. However, the success of Besse- mer screw stock has stirred the inter- SCREW STEEL SPECIFICATIONS ————_ Bes semer——— . oo —Open-Hearth — Element Standard High Sulphur SAE 1120 SAE X 1315 Carbon, per cent............ 0.08 to 0.16 0.08 to 0.16 0.15 to 0.25 0.10 to 0.20 Manganese, per cent..... . 0.60 to 0.90 0.60 to 0.90 0.60 to 0.90 1.25 to1.55 Phosphorus, per cent........ 0.090 to 0.130 0.090to 0.130 0.06 max. 0.050 max. Sulphur, per cent 0.100 to 0.180 0.180 to 0.250 0.075 to 0.150 0.089 to 0.130 est of those steel manufacturers who possessed no Bessemer converters. In such a situation it was natural that an effort be made to duplicate Besse- mer quality by the addition of ferro- phosphorus to open-hearth steel. It was inevitable that such efforts should be attended by little or no success. The nature of Bessemer screw stock which causes it to be free-machining is a complex interaction of phos- phorus, manganese and sulphur under the conditions that exist in Bessemer operation; and identical results can- not be achieved in any other way. There have been those who have criticized the quality of duplex steel, which is made by combining the Besse- mer and open-hearth processes. With- out discussing duplex steel in general, in referring to free-machining steel, it may be pointed out that the manu- facturer who possesses duplex facil- ities is in a position to introduce into open-hearth screw stock scme portion of the Bessemer effect with a con- sequent gain in machinability. Rolling and Cold Finishing There is little to be said about roll- ing of high-sulphur steels except that they are generally of poor rolling quality and inherently disposed to seaminess. Somewhat better results are obtained with rolling tempera- tures above the usual level. If the rolling process is interrupted and the still hot, partly-rolled steel is reheat- ed, better surface is obtained, but at a considerable sacrifice in cost. In fact, the cost of producing satisfac- tory bar steel in the high-sulphur grades is such that the small extras charged for these grades over com- mon bars are very inadequate recom- pense to the steelmaker. After chipping to do what can be accomplished in the way of removing seams, the billets are further hot- rolled to bar or rod form by conven- tional methods that require no descrip- tion here. For accuracy of dimensions, for freedom from rolling mill scale, and for improvement of machinability, cold- drawing has been and is widely prac- The Iron Age, June 8, 1933—903 ticed. This processing commonly con- sists of acid pickling, coating with lime, and cold-drawing through a die with a reduction in diameter of 1/32 to 1/16 in. After cold-drawing the bars are straightened and polished or for special purposes surface-ground to a very high finish and very ac- curate dimensions. In the past decade there has been some tendency to increase speed and reduce the draft in cold-drawing. There are, however, very definite limi- tations to the amount of variation possible. Some purchasers apparently think that the amount of draft that can be taken is unlimited. An at- titude that is not infrequently met is shown by the demand that a de- sired increase in hardness be obtained by a heavier draft with no change in chemistry when the producer may al- ready be using the heaviest practical draft. The cost of production increases very rapidly with heavier cold reduc- tions, whether obtained in one or more than one draft. The gain in ma- chinability with heavy drafts as com- pared to lighter drafts is insignificant and greater hardness or other desired physical properties may be obtained in other ways. For these reasons cold-drawing of screw steel does not ordinarily involve drafts in excess of 1/16 in. Hot-Rolled vs. Cold-Drawn Stock In the working out of fundamental economics it is only natural that ef- forts would be made to use hot-rolled bars in automatic screw machines, thus obtaining a cheaper raw material by escaping charges for cold-drawing. To assist in this effort machine- builders have worked hard to design collets that would handle the hot- rolled bar with its inevitable variation in diameter and under normal condi- tions its surface of rolling-mill scale. The substitution of hot-rolled bars for cold-drawn in automatic screw machine operation has not been at- tended with any widespread success. In the first place the hot-rolled bars must be straightened and sheared more carefully than is usual practice on the hot-rolled product, and fre- quently it is necessary to pickle to re- move the scale. These operations eat up a substantial portion of the cost dif- ferential between hot-rolled and cold- drawn bars. Further, the hot-rolled bars cannot be equal in machinability to the cold- drawn product; and, finally, if any portion of the original bar surface re- mains on the finished part, the sur- face appearance is in no way equal to that obtainable with cold-drawn stock. For al] these reasons, it appears in most cases good judgment to pay the cold-drawing cost and take full ad- vantage of the qualities resulting from this processing. There is a fairly widespread but 904—The Iron Age, June 8, 1933 not well justified belief that high- sulphur steel is of poor physical quality, but the fact of the matter is that it is difficult to demonstrate any appreciable deterioration due to the introduction of added sulphur. In the field of dynamic stresses, so far as impact is concerned, there seems to be very little case against sulphur. From the standpoint of fatigue resistance, which is in the field of dynamic stresses, Bessemer steel, and even Bessemer screw steel, will give an excellent account of itself when com- pared with standard grades used for engineering construction. Carburizing Free-Cutting Steel A goodly proportion of parts manu- factured from open-hearth screw steel are subjected to heat-treating opera- tions. However, there is involved practically no difference in technique from that employed for ordinary carbon steels. The higher sulphur content of screw steels appears to slightly retard carbon penetration in carburizing, but this tendency is more than offset by the considerable content of man- ganese which is now ordinarily car- ried in high-sulphur steels. We do not know that there has ever been carried out a really exhaustive study of the rate of penetration of carbon in relation to the separate elements, but it is a fact that X 1315, for ex- ample, permits such rapid carbon penetration that care must be exer- cised in carburizing thin wall sections to see that a proper relation of case and core is maintained. While Bessemer steel cannot be claimed to produce a_ high-quality carburized part, yet it can be case- hardened and, if a certain amount of core-brittleness can be tolerated, the process can be justified in certain types of application where shock or dynamic stresses are either low or non-existent. Physical Basis of Machining Quality It is generally although vaguely understood that a certain brittleness is required for best machinability, and this understanding is entirely correct. However, it is not very important whether the bar is brittle or tough when put into the automatic machine, but it is essential for best perform- ance that the steel should develop a certain amount of brittleness during machining. Bessemer screw steel has the property of dropping very sharply in impact strength as it is cold- worked, and this characteristic con- tributes to good machining. Good free-cutting steel, however, not only is brittle but it must also possess a low order of work-hardness, that is, it must not harden too sharply under the cold work of ma- chining. In other words good free-cutting steel] must be soft and brittle, which is a rather unusual combination of physical properties. It must be ob- served, however, that these statements are made specifically with reg