The Iron Age 1926-08-12: Vol 118 Iss 7

THE IRON AGE New York, August 12, 1926 ISHED 1855 VOL. 118, No. 7 Welded Joints Searched by X-Rays Defects Which Can Be Detected and Some Which Cannot—Methods of Making and Testing Welds—tTypical Radiographs BY JOHN T. NORTON* POUL LUCILLE LG ELL DUPAREVELEENSUODSTALA TUS LAB RAT LS ETT 1 ete! "s HE radiographic method of studying welded joints is briefly described in this arti- cle and its possibilities discussed. The various types of defects common to welds are illustrated by radiographs and the limitations of the method considered as well as the advantages. It is concluded that, although it does not give complete information about the joint, it is a practical and worthwhile method of examination. UU DUUUUNUDUOUL/UUNOLS SEQUENT TT \HE part played by welding processes in the multi- tude of fabricated structures made of metal is a very important one. This importance is being emphasized as more and more uses are being developed. txamples of such applications, where gas and electric rechnology, Cambridge, Mass. Fig. *Assistant Professor of Physics, Massachusetts Institute HU I \ lse4d! ULL MAUDERERODDLLAA ENTE CSOSA DIRS methods have completely revolutionized well-known processes and made possible entirely new ones, are familiar to everyone. As these methods and their application are devel- oped the question arises as to the value of articles made in this way as compared with those made by other methods and as to just how far the welded joints 1—General Arrangement of the X-Ray Apparatus. Note the riveted walls and ceilings of lead i Ricca ibaniantition re NI Np 2 auteur 4 410 THE ee ‘ Fig. 2 Fig. 3 i depended upon. In order to answer such ques- tio1 it is necessary to subject the welds to tests which \ ndicate their fitness for the particular purpose. Mar l sts have been devised. It he purpose of this paper to describe briefly the newer methods of examining welds, a ethod which has been used with considerable success n other directions, and to show its possibilities and mitations in this particular field. Welding Methods in General Fusion welding is a very common method of joining netal parts. The process consists in bringing the two parts to be joined close together and filling the space between with molten metal in such a way that it fuses with the base material on both sides and forms a strong, continuous joint. The welding material used for joining the parts is usually applied in the form of a rod which is melted and, to prevent it from oxidizing it this very high temperature, some sort of a low melting point slag is sometimes applied to cover the surtace The high temperature necessary for melting the welding material and for heating the base metal sur- faces so that the welding material will unite is ob- tained in two general ways. The first is known as gas ¢ welding and employs some sort of a torch which burns an inflammable gas such as hydrogen, or more often acetylene, together with oxygen in the form of a very small intense flame. The other method makes use of ; an electric arc, struck either between two carbon rods, ; a carbon rod and the base metal, or between the base metal and a rod of the welding material. Each of these methods has its particular field of application and its enthusiastic exponents, but it is not necessary to discuss their relative merits here. i A welded joint of this sort may, and usually does, have any of a number of typical defects. In the first place, because of the nature of the welding process, : the joint will have the characteristics of cast material, which is usually not the best condition of a metal as ‘| far as physical properties are concerned. This condi- tion may be improved by proper heat treatment. In et addition there are a number of other gross defects ey which cannot be improved, once the welding material has solidified. These defects are gas pockets, slag inclusions, oxide inclusions, lack of fusion, layers, seams and cracks, IRON AGE August 12, 1926 all of which tend to weaken the joint. Gas pockets are due to the trapping of gases of various kinds, a the metal hardens, which come from the welding fia: or from the oxidizable impurities in the metal. T) slag used to prevent oxidation often becomes mix: with the molten metal and is retained on solidificat resulting in an inclusion which has very little strengt! Frequently, due to a thin layer of oxide on the surfac or to insufficient heating, the welding material does : adhere to the base metal or in some cases does even fill up the space between the two base metal su faces, with a resulting weakness of the joint. Laye: and seams in the welding material are due to thin oxid layers and improper fusion. Because of the very great differences in tempera ture between different parts of the weld, considerab stresses are introduced on cooling which may be suffi cient to pull the welding material apart, causing shrinkage crack. All of these defects result in a weak- ening of the joint and are particularly troublesom because they seldom are visible on the surface. Methods of Testing W elds Such defects are quite common in welds but, be- cause an indifferent or careless workman can make a weld which looks satisfactory on the surface, testing is necessary. There are several methods for such test- ing and perhaps the most useful is the tensile test. In this case the joint is loaded in a fashion similar to that which it will meet in practice and the actual point of failure determined. The method is useful in study- ing welding methods but of course cannot be applied to a particular sample which is to be used. Another method is to take a section of the joint, polish it roughly and etch it with a suitable solution for macroscopic examination. This shows very clearly such defects as have been mentioned above, if they happen to be on the particular section taken. Also a microscopic examination of these sections often yields much useful information. However, these are all open to the same objection; they destroy the usefulness of the joint in the examining process. Another method, known as radiography, which has been used with considerable success for studying cast- ings and forgings, has also.been applied to welds of various kinds, and it appears to have some very worth- while possibilities. The method employs the great penetrating power of X-rays to render visible the in- Fig.5 August 12, 1926 tel tructure of the weld. The author is familiar with the previous work which has been done in this tion, but it is his purpose to consider the prac- y of the method rather than any particular teristics of welding. How X-Rays Function on Metals radiation, which is like light of very short wave- possesses the property of passing through rdinarily considered opaque without much loss ensity. This penetrating power depends upon the ty of the radiation and upon the density and thick- f the material which is being penetrated. The ition also will blacken a photographic plate so that ord of its intensity may be obtained. So, if a of X-rays is passed through a body and a photo- hic plate is placed immediately behind it, a sort hadow picture will result, the light or thin spots the object corresponding to black areas on the plate the dense or thick spots showing light. In this a very complete picture of the gross interior struc- f the body may be obtained. [he X-rays are produced by an X-ray tube and a voltage generator. The penetrating power of the increases with the voltage and, for 3 in. of steel, tential of about 250,000 volts is necessary. The tensity of the beam is determined by the current wing through the tube, and it is customary to meas- exposures as a product of the tube current and Fig. 1 shows the general arrangement of the iratus, and reference to the pictures of some of the is will indicate what surprisingly fine detail can /btained in this way even in quite large thicknesses material. The technique of making radiographs is usually uite simple, chiefly because thicknesses of less than in. of metal are the most common. The time of exposure for steel plate 1 in. thick is about 5 min., nd for plate % in. thick, about 30 sec. In radiograph- ng welds in thin plate, where the surface irregularities of the welding material are comparable with the thick- ness of the plate, it is sometimes necessary to smooth ) the surface by chipping or grinding. If, however, e condition is understood when viewing the finished cture, this procedure is not always necessary. Typical Radiographs of Welds Following are some typical radiographs of welds Fig. 6 Fig.7 THE IRON AGE 411 Fig. 8 Fig. 9 which show very plainly the appearance of defects as revealed by X-ray. Fig. 2 is the radiograph of a good oxy-acetylene weld in steel plate. The weld is of the single V-type and the plate is 1 in. thick. According to the radto- graph, this is a satisfactory, sound weld which should give good service. There are no evidences of gas pockets, slag inclusions, oxide of joining of the plates. The mottled appearance of the blackening is due to irregularities in the surface of the welding material. or lack this with Fig. 3, which is quite evidently a poor weld. This is a double V electric arc weld in l-in. steel plate. It contains many inclusions of gas, and there is a definite lack of fusion between the plates It is interesting to note how plainly even Contrast in the center. minute holes show up Fig. 4 is another typical example of the appearance of gas pockets in welds and is an are weld in 1-in. plate. This and Fig. 3 were made with an atmosphere of hydrogen to prevent oxidation and some of this hy- drogen, which is very soluble in the molten metal, has been retained in small globules as the metal solidified. The weld is much less brittle because of the removal of the oxide, but the area of sound metal is also much reduced by the presence of the gas bubbles. Fig. 5 is an example of the appearance of gas pockets in a gas weld. In this case, the plate is only % in. thick. Gas pockets have in general a more or less spherical! shape and, since the gas is more transparent than a corresponding thickness of metal, they appear as dark spots on the negative or light spots on the print. In the same way, inclusions of slag or oxide are more transparent than the metal and appear as light areas on the print, but they do not have the smooth, rounded outlines which are characteristic of the gas pockets. They are usually irregular in shape and sometimes appear as long lines or streaks. Fig. 6 shows such inclusions very plainly and indicates how readily they are distinguishable from yas pockets. Fig. 4mlso shows some slag inclusions. Layers of oxide separating the base metal and the welding material and also different portions of the welding material are sometimes quite plainly seen, as in Fig. 6, and more clearly in Fig. 7. However, unless the layer is approximately parallel to the direction of the X-ray beam, it will not show, as was plainly indi- cross-sectional ncn Me te Wigs eT eee ae (arate ni A No a alps mg Ae el oan ges + EE. SA OIE! OO A ADE DRAPE IES TY IR 8S Saige ie SR Piss ns les TO Yn ie wm mnie J meme p nee es § Ti Ne Regehr treme ae eB ome a = oa hme P, 412 THE IRON AGE August 12, 199¢ bite ated when the weld of Fig cut up into thin the lack of fusion. Only when there is an app) le ir section space between the two will it be evident. - f fusion, « , material between The method is limited, due to the equipn at the plates, is indicated o1 print by a white line, present available, to thicknesses of about 2 for thi quite evident Figs. 6 and 8. The latter brass or bronze, 3 to 3% in. for steel, and abou: 5 to ¢ how eff ng up the welding material in. for aluminum or duralumin. Within thes: k- ness limits are included practically all comn SI ‘ n welds are particularly trouble- welding jobs. i 1 welded joints, but they do not General Conclusions radiograph will show them distinctly : : : parallel to the X-ray beam. None These considerations may be generalized brie‘ nd in any of the welds examined in the follows: investigation. A gas pocket or similar 1. The radiographic method will definitely sh« certain size will show much more plainly the case of welded joints inclusions of gas, slag, ; : . or other impurities whose thickness in a dir: liograph of a thin specimen than in the case parallel to the X-ray beast ieeeee Shae 6 per o ck one. This is evident on a comparison of of the total thickness of the sample. g which is % in. thick, and Fig. 9, which is 2% 2. This method of examination will show the | thicl However, the minimum size of hole which ence of cracks or seams which are nearly paralle! n be detected does not increase so fast as the thick- the direction of the X-ray beam. and it has been shown experimentally that it is 3. The method will indicate the failure of the w: ich easier to detect hole, whose diameter is 5 per ing material to join completely the base metal plat ent of the thickness of the sample, in a thick sample 4. The method = Oe eer aerers wi! n in a thin one. are normal to the X-ray beam. The method will not tell anything about Defects Not Shown by X-Revs crystalline condition of the metal, ; ; As a result of these considerations, it seems that As contrasted with the sort of defect that the X-ray this method should be useful for. the examination of method will show, there are a number whose presence welds in many cases. Because of its expense, it cannot will not indicate. Of course a radiograph will tell be at present applied to the routine imspection of an nothing of crystalline condition of the weld and the article in quantity production. But there are many irrounding metal. There are X-ray methods which examples of the development of new processes and of will do this, but they cannot be discussed here, and articles on which no expense should be spared which y are probably not so satisfactory in most cases would tend to prevent failure, where the method should a microscopic examination. The radiograph also will prove valuable. No amount of inspection can take ot show cracks, seams and layers of oxide which are the place of careful and thorough workmen and nowhere nearly normal to the direction of the X-ray beam, and is this more true than in the welding industry, but ‘ the latter defects are commonly present, as was indi- even when the workman has done his best under the : ated when several of the welds were sectioned. most favorable conditions, there is the ever-present bod In practically every case, however, where a weld doubt which the penetrating eye of the X-ray beam " a seriously defective in this manner in a plane nor- will do much to set at rest. mai to the X-ray beam, there were also similar defects In conclusion, the writer wishes to acknowledge the arranged in a direction parallel to the beam which assistance of R. D. Carlson and W. C. McClure, who did show plainly. Furthermore, if the welding ma- were associated with him in this work, and to express terial and the base are in intimate contact but not his appreciation to the various companies who so kindly actually fused together, the radiograph will not show prepared the welding joints. J. & L. Statue Unveiled at Sesqui- Centennial Exposition “Steel,” the heroic sized group of sculpture donated by the Jones & Laughlin Steel Corporation to the city of Philadelphia and the Sesqui-Centennial Exposition, was unveiled on Aug. 4. The statue was presented by B. F. Jones, 3rd, secretary Jones & Laughlin Steel Corporation, whose address was in part as follows: “It is fitting that the steel industry should be memorialized upon the occasion of celebrating 15° years of American independence, because so much of the amazing progress made in that period by this young nation can be attributed to steel. Without steel, P America would never have been the parent of modern railroad transportation that has linked our far-flung States into a closely related Union. But for stee! those swift couriers, the telegraph and telephone, would have been impossible. Steel has developed the automobile, the ocean grayhound, the airplane. 10° steel we are indebted for the high-speed printing press. which enables our people daily, almost hourly, to know what the nation and the world are doing and thinking. Steel goes with us in every gesture of work and play. Steel frames our offices, our schools, hotels, hospitals . and farm buildings. Without steel American agricul- ture would still be plowing with a crooked stick be- hind oxen instead of using gang plows drawn by trac- on Unveiling of Statue to the Steel Industry of America at Sesqui-Centennial Exposition Last Wee k — it ge Bes eery oo tors that turn many rows of furrows in rapid prog- a around vast fields. Steel harvests our grain, ears it to mill and market . ate : i : , grinds it into flour, an —— us our daily bread in rapid transit, fresh from © huge steel ovens of the modern baking plant.” Jolting Iron to Desulphurize It Special German Apparatus Agitates the Metal in the Forehearth—Sulphur in Iron Lowered as Much as 55 Per Cent—Benefits Semi-Steel and Steel Castings Society, held at Loeben, May 15 to 17, and re- ported upon by Carl Irresberger for Stahl und (June 30, 1926), Dr. Joseph Dechesne presented practical development of an old observation—that transportation of blast furnace metal some dis- , the jolting, incident thereto, has a desulphurizing This jolting action, as he understands it, is two- ind consists of the vertical, upward, central jolt is valuable in liberating dissolved gases; and the tric, or shaking, jolt which forms wavelets and thus n thorough mixing of the metal. That sulphur is A’ the annual meeting of the Austrian Metallurgical 4 seONUAPUOG SOU EDEEEORERE DEER ONEETPOEREESENON EEF OHBOMANUENEEDEEEAHIONDERUENONOETUNELOEECOETNENS/ Fess bene CeS Gee The Jolting Is Done in the Forehearth of a German Cupola by the Mechanical De- vices Here Reproduced thus removed in the transit of molten metal from the blast furnace is proved by the sharp smell of sulphur dioxide accompanying this, as also by analytical deter- minations made of the metal itself. Two Theories Offered There are two theories to explain this occurrence One, that of the jolting action referred to, and the — that manganese sulphide is separated out. Probably both of them are right, it being easy to see that a com- paratively slow action on the part of any 5 gga sulphide formed in- going upward would be mu hastened, were the metal thoroughly jolted. Sulphur is combined with iron and manganese In the form of sim ple sulphides. Since manganese has the greater affinity for sulphur, it would tend to be satisfied first, only sur- plus sulphur going to the iron. Since pr sul- phide has a specific gravity of 3.6 to 4.0, and melts at - *Abstract and comments by Dr Richard Moidenke, Watchung. N. J about 2900 deg. Fahr., and the temperature of the molten iron would not be much over 2550 deg. Fahr. the former will have solidified and, from its lightness risen to the surface little by little or until progressive cooling has made the metal sluggish. Any jolting ap- plied under these conditions cannot but accelerate the removal of manganese sulphide to the surface of the ladle, where contact with the air burns it in accordance with the following reaction: MnS + 30 MnO + SO Manganese oxide goes into the slag, while sulphur dioxide is dissipated into the atmosphere. A series of tests indicated that desulphurization up to 55 per cent was accomplished, the sulphur content just under the surface of the metal rising to 0.50 per cent. Without doubt even better results would have been obtained had the cooling of the metal been prolonged artificially. There are, however, other advantages to be gained by this jolting process. Effect of Super-Heat Recent developments in improving molten iron for foundry purposes indicate that this depends upon ob- taining a high degree of super-heat as the metal leaves cupola or furnace, and in prolonging the retention of this heat as much as possible either before or after pouring the molds. Piwowarsky, who belongs to the more recent school of investigators of cast iron, holds that every blast furnace or cupola iron has a given critical temperature, depending upon its composition above which critical temperature it has an accelerating tendency to set as a high-grade gray iron. Setting as gray iron results from two parallel proc- 413 As Pept eno emg pee oS wey SE LN SRE ORI T+ vient, . ae . v" ne . _ ne Nee OTE Gey enka Le oe! eet 414 THE IRON AGE August 12, 1926 ecces: The solution at these high super-heat tempera- 1% in. and at the rate of 100 jolts per min. as the best ast ne a ns oaths ethieaien a speed. A 5-hp. motor operates the device. tures of parti les « —— nd forming nests of No attempt is made to make a tight joint between eee aoe ee ig als in the solidified metal, cupola spout and forehearth, and the latter, previously very . ra} hit paggscth iin 8 of iron carbide. heated up, is brought to about 2200 deg. Fahr. by cs ‘inn the molten metal under conditions of a high means of the cupola gases directed through the breast ee ee ee Scla hould facilitate this solution of when the blast is put on, and allowed to follow their le cael the metal and make the subsequent regular course up the cupola only when the molten e iron carbide a uniform process. rt ) the microstructure of the resulting pearlitic with eutectic graphite in {dvantages When Scrap Steel Is Used Dechesne also claims great advantages for much scrap steel is added to the xture, holding that the jolting action pre- setting, with its accompanying disadvan- heavy shrinkages and chilling to white iron. s that this part of the program is still rather us, but cites the following physical strength fig- as obtained with jolted metal with 1.6 to 2.6 per roce when icon, and 3.2 to 3.6 per cent total carbon, with mal pouring temperatures of 2450 to 2550 deg. } gave a ensile strengtl I q. iz When such test upon supports 24 in. apart and broken lect ran up to 0.6 in. (which high when compared with the results obtained bar Ar can cast iron) Brinell fron t ill the above figures both greer nd dry-sarnd work Jolted metal poured into even the thinnest castings, ich as the ribs of motorcycle cylinders, came out per- + +1x, Le \ ly gray in fracture and easily attacked by the file. (gain, the process also did much good to molten steel, removing the contained gases in great measure and ing fewer blow holes in the resulting castings. How the Jolting Is Applied The illustrations indicate the manner of applying a ting ig system to the forehearth of a cupola—for Amer- conditions the application would be to a tilting mixing ladle—jolting being done during the tapping period and continued until ready to transfer into the crane ladles. The section of cupola and forehearth hows the arrangement of the power device. The hearth consists of a cast steel bottom plate, the rest of the box being of cast iron. The front edge of the appa- ratu lifted by a cam device, to a height of about 17 Automotive Engineers to Join Steel Treaters at Chicago During the annual convention and national steel n to be held in Chicago the week of Sept. 20 y the American Society for Steel Treating, the produc- tion meeting of the Society of Automotive Engineers, with headquarters at Hotel Sherman, will be in session on Tuesday, Wednesday and Thursday, Sept. 21, 22 : 22 and 23. There will be Among the expositi ryt four technical sessions. ts to be discussed are the following: Two papers will be presented at the conveyor ses- , each dealing with the design, installation and ap- plication of conveyors. Paul Phelps and N. H. Preble, of Mechanical Handling Systems, Inc., are the authors of one of the papers; the other is being prepared by Clarence A. Brock, of the Miller-Hurst Co. “Inspection Along the Line” is the subject upon which A. H. Frauenthal, of the Chandler Motor Car Co., will speak at the inspection session. The latter portion of this session will comprise a symposium at which several inspection men will talk about unknown or little-known inspection gages that have proved help- ful. The men participating will include A. R. Fors, of the Continental Motors Corporation; P. W. Rhame, of the A. C. Spark Plug Co.; J. B. Scott, of the Yellow Sleeve Valve Engine Works, Inc.; C. S. Stark, of the subjec oT iron begins to appear. There are special devices for accomplishing this process. The operation of the jolt- ing device is left to the cupola tender, who simply has to start and stop it by the usual motor switch. Current expense is given at % to 1%c. per ton of jolted molten metal. There is no loss of time or other expense at- tached to the proceeding, and it is recommended for gray iron, malleable, and steel casting foundry pur- poses. General Comment This application of the unavoidable jolting incident to the transportation of blast furnace metal between furnace and open-hearth or Bessemer plants to the beneficiation of molten foundry metal is of special in- terest to the metallurgist and foundryman alike. It is well known that molten iron will lose much of its sul- phur, if allowed to stand quietly for a time—provided the high-sulphur surface metal and slag can be re- moved from the ladle satisfactorily. It is also known that blowing a small stream of air into the bottom of a ladle full of molten iron, by pushing the compressed air pipe down into it, will remove half the sulphur con- tent in a few minutes, provided you can get it away by skimming. Prince did this many years ago. But these occurrences are not dependable for regular use. Hence a systematic movement of the metal by jolting under predetermined optimum conditions should be of special interest by way of desulphurization as compared with the chemical method now being introduced in the foundry world. For the metallurgist, the theory of Piwowarsky of graphite nuclei undissolved in ordinary molten iron, but disappearing when highly superheated, will give rise to considerable thought; as also another theory. advanced by Profesor Goerens, of Krupp at Essen, who holds that, depending upon the degree of super- heat of the molten metal, there are nuclei of iron car- bide crystals which have a great influence upon the final structure of the casting, so that it is decidedly advisable to start with intensely hot metal with all these chances for starting points of bad spots wiped out, rather than melting cold. The foundryman is fully aware of the fact that melting very hot always give* the best results, but did not know just why. Packard Motor Car Co., and R. R. Todd, of the Oak- land Motor Car Co. “What Goes Wrong with Machine Tools” will be the important question discussed at the machine tool ses- sion by E. R. Stoddard of the Studebaker Corporation of America. O. C. Kayle, consulting engineer, Syra- cuse, N. Y., will give information on “Fitting the Tool to the Job.” The gear production session will include two papers, one by John Bethune and Walter Hildorf, both of the Reo Motor Car Co., and one by Charles L. Cameron, of the Gould & Eberhardt Co. Arrangements have been made for inspection trips to the Kenosha plant of the Nash Motor Car Co. and to the International Harvester Co. A cordial invita- tion has also been received from the Yellow Truck & Coach Mfg. Co., affording the members an opportunity to visit its plant. Weekly earnings in factories in New York (State) are reported by the Industrial Commissioner to have averaged $28.99 in June, being 128 per cent higher than in June, 1914. Except for December, 1925, and January and March, 1926, all of which showed $29.03 to $29.05, the June figures are the highest ever re- — They exceed the maximum of 1920 (October ) by 6c. Determining Carbon in Cast Iron Simplified Combustion Train Found Satisfactory for Routine Analyses in Laboratory Aad} of Large Cast Iron Pipe Foundry BY J. T. MACKENZIE” r E modified form of carbon combustion train, wn in the illustration, has been used in the la- ry of the American Cast Iron Pipe Co., Birming- r some time and has been the most satisfactory many trains tried for routine work on cast iron. assembled with standard equipment, except for ry excellent chromic-sulphuric acid bulb. This available in Pyrex glass and it is carried in by Doster-Northington, Inc., Birmingham. It made from sketch, by the writer, after seeing the in operation in the ferrous metals laboratory of nited States Bureau of Standards. (he oxygen is controlled with an ordinary welding (60 lb.). The cutting gage (200 lb.) is not so tive. The Johnson tower “A” is filled halfway th coarse (4 mesh) moist (15 per cent) soda lime. er of asbestos is put in and the top of the tower ‘ed with medium (12 mesh) dry (2 per cent) soda Ascarite may be used throughout but it is more sive. A “Y” tube may be inserted here for a sure indicator or a sulphuric acid bottle may be n as a further drier, or as a “bubbler,” but neither necessary. Any combustion furnace may be used, but the larger re—1%% in.—is more useful. The tube is plain end at e entrance with a constricted exit for slip over rub- ber tube connection. The alundum thimble at “B” eeps the rubber stopper perfectly cool even in silica tubes, and the thimble at “E,” packed with asbestos, rves as a “stop” for the boat and as a heat storage thout clogging, which an asbestos packing is prone do. The copper gauze “E,” just beyond the red heat inge, serves as catalyst in case any monoxide is escap- oxidation. Glazed silica tubes have been found nuch superior to unglazed, but neither lasts as well as e porcelain, such as McDanel, though they lend them- ves more readily to quick changes in case of a burnt- it furnace. Tubes not less than % in. bore give much etter service than smaller tubes but there is no ad- antage in larger diameter than 1 in. The tube with nstricted end can be used with exit end much closer the furnace than the plain end tube, for the rubber not so much exposed to the heat. The chromic-sulphuric acid bulb “G” is held up- right by a clamp. The left hand bulb is packed loosely with glass wool or asbestos, and the right is about two- thirds full of glass beads. The top bulb, with glass stopper, allows a fresh undiluted reservoir of the mix- ture to be kept always available and the two stop cocks *Chief chemist, American Cast Iron Pipe Co., Birminghan ere nav se penser ne eote Tere N CLEVAUNERRENOONDEDNEDENERENDE DA EEREEELEOYEOSEETEEDEPHSELPUAISEEDSTOUEOUEERETEEDESEEREISTEDEETEN ENTE NE’ z= i a= Zé allow easy and rapid changing of the solution as soon as its green tint begins to indicate exhaustion or, if experience indicates, at the end of every fixed number of runs. The absorption of sulphur is practically complete in this solution (concentrated sulphuric acid saturated with chromic acid), the sulphur dioxide being oxidized to trioxide and absorbed while the chromic acid is re- duced to the green chromous compound. The capacity of the left hand bulb is such that, in case of a “kick back,” none of the acid will get into the tubes behind. Another great advantage is that the resistance is very small as compared to zinc and phosphoric anhydride, so the pressure is kept low and leakage avoided. The Fleming bulb is used, packed with ascarite (bot- tom) and phosphoric anhydride (top). The author prefers the two-piece bulb, for one packing of the top will usually take care of three bottom fillings. The ascarite becomes very hard and it is difficult to remove from the one-piece bulb but the two-piece causes very little trouble. The Nesbitt bulb was used for some time without the phosphoric anhydride but several lots of ascarite seemed to lose a great deal of moisture, so the Fleming was adopted with the double pack, as very little more trouble and much safer. The phosphoric anhydride can, of course, be packed over the ascarite in a Nesbitt bulb but the double-bulb Fleming is much more suitable. A guard tube is useful in observing the rate of flow of the oxygen and, if filled with barium hydrate solution, the ascarite may be used to its limit without hesitation. For very exact work, where the difference in drying power of sulphuric acid and phosphoric anhydride might be a factor, a Fleming phosphorus tower, packed very lightly, may be introduced after the chro- mic-sulphuric bulb and will last a long time, as it has very little work to do. The writer uses ferric oxide (B and A red powder) ignited in his own laboratory for 6 hr. at 950 deg. and sifted through a 20-mesh sieve. The Johnson clay boat is lined with oxide and the sample put into the boat as found best for the particular material. Sometimes, with high-silicon cast iron, ingot iron is added to assist, but usually the iron oxide is sufficient—most of it fusing with the sample. Cast iron can be burned at from 50 to 100 deg. lower temperature on a good oxide bed than on one of alundum. Some oxides, especially the brown, granular ones, seem to be of no assistance whatever. For graphite, the crucible (G5) is most excellent. A very thin layer of asbestos is sufficient to retain the Arrangement of the Simplified Combustion Train as Developed in the Laboratory of an Alabama Pipe Foundry ee A I eR RR a RRR A RS ey Sma Ny SR ate es Sem Skee an op sarees Oa: ty: 82 Oe mp tert SO ag atin se ‘ i t ' ; : Z a : fe Pe | 1 oj a : iG ; : se dep saicommiants mannan a y | 416 THE IRON AGE August 12, 1925 * i : = east irot y drops of hydro- per cent, without changing anything but the Fleming toric acid may be added to insure non-interference of bulb. it ine eamecks mples resistant to ni- 4. Accuracy.— This train is fully as accurate cag) oO ot lla e very little. if used the more complicated set-ups. In the hands of th ric at It attack : re c routine man, it 1s more accurate, for there is so muc! ere The aret bles (% in.) are much less chance for trouble. In routine work, much wor enient t th il] ones but demand a full is lost before a small leak is discovered, and the mor: nh i e of the tube, though 1% in. is safer. joints there are, the longer it takes to find it after ith eC it with a stiff bronze or ward. Consequently, every move toward simplicity . < bent at the end. a step toward accuracy so long as a few fundament n } immed up as follows: conditions are complied with. (A.S.T.M. Standard equent freedom fron 1924—page 260.) ‘ei te I wish to thank H. A. Bright and J. I. Hoffman ; the United States Bureau of Standards for the chrom 1 - Iphuric sulphuric bulb and other helpful ideas. Also Ma» asi tan: Uinamet tame Daehn me eel Kuniansky, chief chemist Lynchburg Foundry Co., f urbons, averaging | the suggestion of the iron oxide. Chromium Alloys Resist Chemicals Use in Chemical Apparatus—How Chromium Acts in Creating Resistivity—Proper Precautions in Welding BY C. E. MAC QUIGG Ty {E field of alloying presents almost unlimited pos- metallographic constituents; these may be either pure ibilities [in resistance to corrosion] and is being metals, solid solutions, definite chemical compounds, or pidly developed. Metals, which are not by them- their mixtures. The interrelation of chemical resis- ; mmune to attack when alloyed in a proper man-_ tivity and structural constitution has not yet been the . el ( \ite satisfactorily resistant. The general subject of more than a cursory investigation, but it rincipl f chemical stability are hardly more than seems safe to say that this study affords greater means limpsed in our present knowledge of alloys, but some of advance than any other, since more information of general « iderations may be noticed. an indicative nature will be discovered by a correlation of metal structures with chemical properties, than any Grouping Vetals as to Resistance other means.” Metals (and alloys) may be divided into two main Alloys are loosely classified into ferrous and non- groups according to whether thev owe their resistance ferrous, depending on whether or not the base is me- ‘rroding influences to: tallic iron. While this classification was formerly more tn settle int nthestiadihiclatiaiels ta satisfactory, because formerly nothing but iron or steel , a : oe Mati had properties such as amenability to heat treatment and certain features of microstructure, such is not now ; the case because some non-ferrous alloys have proper- Ane first nam d effect will readl y be recognized as ties very similar to steel. Ferrous alloys are particu- the relative position of the material in the elec- Jarly subject to attack by acid or oxidizing agents. On t emical series, as platinum, gold, silver, copper, the other hand they have those desirable attributes of ea ckel, cobalt, iron, zinc, manganese, aluminum = workabilitv and strength and, in addition, they are the rl lum, mentioned in the descending scale of cheapest. p enera! resistivity, or expressed differently, in their Effort has been directed in the rather recent past ending te ndency to go into solution in electrolytes. toward alloying with iron some element or elements lhe second effect will be a function of the nature of which would enhance its chemical stability without the filr r product of the reaction. For example, al- sacrifice of physical properties and undue increase in hough aluminum has a very high solution pressure, cost. Numerous elements were and are being tried, pea —_ al . ent pmane tenden: y to go into solution, itis such as nickel, molybdenum, copper, cobalt, tungsten, ; . apne neo — = oe — because the very titanium, manganese, vanadium, silicon, both singly ee ive coating of more or less hydrated alumi- and in combination. None has shown the results that nun - ee whicl instantly formed, successfully re- have been obtained singly by chromium. Very desir- aoe a ger egal oc ager metal. able effects are also achieved with the chromium-nickel tele tani cae ae eee s present penne combination with iron, sometimes modified by silicon. make them ame wre ae fa a aioe. _ tt al : m sas - the non-ferrous rep almost unlimited possibil- i: ga cree fee and V dons ‘ ane . ities exist for the discovery of corrosion resistant ma- or tin : —_— en COPper, 2OAc, Sim terials. The control by heat treatment of the various solid solutions and chemical compounds with their re- Resistivity a Function of Vetallographic Parts spective effects on physical and chemical properties all go to make probable the belief that here will occur in With the somewhat restricted possibilities seen the next generation some outstanding achievements of above, the oy is much more promising in the direc- metallurgy. tion of the alloy field. The resistivity of an alloy : corroding action is a function of the Bronte ite How Chromium Acts *From a paper, “Chromium Alloys in Chemical Plant Ap- Chromium imparts oxidation resistance to the ferrous paratus,” delivered at convention of Americar “Institute of alloys and this condition holds true for oxidizing condi- pen manage ee arn at pow a. H. June 21, 1926 The tions in general, either wet or dry, at low or high tem- Lahoratortes La ng_Isiand City, N. ¥ x f arson Mesearen peresnres. The resistance of the element chromium and dustr: Me Becket, “Rust Resisting Metals,” Chemistry in In- 18 alloys to chemical attack by solutions resides in the cen ARAzewr: Lighter and Robertson, “Some Physical Proper- geen or im other woede ta en en ne ee aoe _ nae 2 a 181080 ermination,” Proc, Roy. Soc. Lon re or in other words is dependent on the protective Vii August 12, 1926 THE IRON AGE 417 m alloys, which are at present of interest vegetable juices and mine waters. Against sulphuric ifacturer of chemical equipment, may be acid the plain chromium iron alloys are not reliable divided by their chromium contents. Such under all conditions, although some installations have ased on inherent qualities which have led been quite successful. Unfortunately they are easily to th tation of the alloys to their respective fields f sel The results of an attempt at such a classi- e seen in the table. It must be understood 4045 mits of composition and other factors are in the broadest sense only, nor has it been | necessary to go into minute justifications or al reasons for the various relationships. nection with the table, it is of interest to note some e properties imparted by chromium and the . f ying elements at present incorporated in the 30 illoys. Chromium is a sine qua non for oxi- ee eee istance at high temperatures. When used we ess it is present in amounts upward of at Ty 15 per cent, the alloy will not have the best esistance. The oxidation resistant property im is also imparted to its alloys against at- wet way, nitric acid being without effect tal contains about 12 per cent or more of even in the absence of other alloying ele- appreciable amounts. If the element is used ngle alloying component, it will be found that ee of immunity imparted is much higher if the 10 t im content is over about 20 per cent. This is irly true when the material must withstand at high temperatures, as will be seen by the c =, rEg istration, which shows the loss in oxidation plotted Pome =1FOF : igainst chromium content, no other alloying element Ny ei! resent. It must also be pointed out that the 0 a it 26 8 30 3) 34 n loss shown by the high chromium alloys is re SK about the maximum which would be obtained with in- ) exposure; this is not true for lower chromium : , alheaaia: aan oy : . 9 Loss in Weight by Oxidation of Specimens of 11 ntents since a critical point seems to exist around 20 Taerensina Chromium Coutent ent chromium. or resistance to wet attack in other than oxidizing no general rules can be formulated. Chromium nrome-nickel combinations have a remarkable ver- Among the chemicals which are successfully od are acetic acid, many hydroxides, fruit and Steel fs c o “ata -0ss in Weight, per cent ! i A 46086 K« ) 22 24 26 28 30 52 34 + rm Sry rr) ‘ U oith attacked by hydrochloric acid. Sulphur and sulphur gases are practically without effect on straight high chromium alloys. The presence of nickel, however, is disastrous, because of its vulnerability to sulphur. | oensame enennnscaeneueecencuennatenetstnenennensnecensanpnennenenscarnuservercerenner irate Table of Commercial Classication of Chromium Alloys , Some Typical Applicatior teristic Chromium Principal Properties - , Range I juctility nd Ball " K s, armor, armor piercing shells, high nes da . rt : i ictili ‘ sal per cent Cr. With High strength, - aaa speed cutting tools, automobile and airplane parts, Stamp vithout one or more toughness an¢ a rusher parts and rolls for ore preparation, grinding ; : ne y »t< 2 . = liek > Ps ; & metals, as nickel, ness. equipment, saws, files, multi-ply plates for safes and vault ‘ im, molybdenum, manufacture, 6 ; . ‘ on resists . “me yhere the ; : tha here Certain types of oxidation resistance requirements where ; lé > .e ‘ 2esistance to oxidation W per cent Cr. added " saben -operties of application will not bear the expense of the higher quality t iron. the physical prot vet : t iron ar atisfactory sllovs. as in annealing boxes for malleable cast iron as ‘ are satisf: l : foundries, roasting or muffle furnaces for temperatures up ; » 800 dew. C. (1475 deg. Fahr.) ; = : Resistance to corrosion to Cutlery kitchen utensils restaurant and hotel fittings, ; 6 er cea . sists > ) : ; ber cent Cr. Carbon Pree 6 axcellent phys- chemical plant apparatus to withstand nitric acid and very ; ; tent carefully con- gether with excellent } : i ] ical erties many other chemicals Good against oxidation up to about f . “g yrope ‘ - . a seal pees 800 deg. C. (1472 deg. Fahr.) Also being used extensively ; in engineering applications—as in turbine blades, internal ombustion engine valves, etc. Builders’ hardware and ; : decorative parts, sporting goods, marine equipment, etc. i ; : i High electrical resistivity and Electrical Heating Elements. All kinds of heat-treating ; ; 1] o 2 > ~ i ale z Siz 3 : acasahi ena ie : n-oxidizing High tensile equipment such as case carbonizing boxes, annealing boxes, ; + > >t . 35 aT. 10n-o) . togethe msg SS cate strength at elevated tem- pyrometer tubes, furnace parts, etc : L : le percentage of othe § : fe: : . f sature loying metals, nickel be- peratures 3 ® d cold [ My ng the most frequently Some have hot an ; ; . ote erties i f ised. Silicon and manga- working prope ‘ ese are present in same : ; analyses up to several per : i ent. : if Resistance to oxidation and All types of apparatus which are subjected to oxidation up at ~. . -sistane * : x per cent Cr. and upward. a many forms of chemical to about 1100 deg. C., such as stills, muffles, retorts. Crush- : * ’ : vi are a 7 No appreciable alloying attack, especially nitrates ing and grinding equipment. Nitric acid plant equipment. Ha Ry elements other than carbon ae sulsher. Softness and Mine pumps. ; f it workability in low carbon ranges; hardness. : 7 7 4 i ; 44 ——_——— : i ’ 4 kesitde PL in near Sonali Nia intet weeny 45° ' ' fe } le strength to its alloys romium content, some- itv. Alloys containing 20 ward are readily worked ment to form plates, sheet, wire. seamless tubing, ete. A peculiarly advan- chromium is that of imparting at high temperatures; this opens ions which is becoming quite ex- greatly enhances the diminishes the elongation ; increasing the resistance to ed loads at high temperatures. resence of nickel Welding Chromium Alloys ortant to the chemical equipment the question of weldability of the t hammer-weld but may welding, either gas or elec- interest will be in mmercial acing rie me general observations hromium-iron alloys is attended with ordinary chromium con- difficult to float defects chromium- lity tnar is the case e Ttormatiol f infusible The oxide formed is i vy give rise to such The welded, using for and sin ir defects 4 atistactorily are » material coated with a e with or dissolving rmed. Such electrodes, when _ suitably 1] polarity, will give Ae ee THE IRON August 12, 1926 AGE good dense welds. Some flux coatings will yield good results with either polarity, while others will work with reversed polarity only (electrode positive). Welds made by this process will possess good strength, are easily machinable, but will lack in ductility. For ordi- nary batch mixing or storage tanks, this lack of duc- tility in the weld would be of no consequence. How- ever, in vessels destined for high pressure and tempera- ture, lack of brittleness is important, and no such work should be undertaken without first consulting wit! someone experienced in the making and properties of welds in high chromium-iron alloys. In order to oxy-acetylene weld the high chromium. iron alloys, it was formerly found that satisfactory welds could be obtained by using an excess of acetylen in the welding flame. While this procedure does pr: vent oxidation and makes the welding easy, at the sam: time it charges the weld metal with considerable car- bon, making it quite brittle. This practice or method of welding, while satisfactory in some instances, is not generally recommended. Neutral flame welding may be used by coating the line of the weld and the welding rod with special fluxes capable of protecting the hot metal and dissolving any oxides formed. Another solution to neutral flame weld- ing is to use welding rods containing appreciable quan- tities of manganese and silicon whose oxidation prod- ucts yield a fusible protecting slag. It is recommended that a small amount of flux be used on the line of th weld to take care of oxidation of the base metal. Re- search work is proceeding in this field and it is be- lieved that the peculiar problems met in this type of welding will soon be overcome to permit safe welds for high pressure and resistance to shock. Electrolytic Zinc in Galvanizing It s Durability in Comparison with That of Prime Western—Experiments Under Way to Reduce Dross and Increase Tenacity of Coating P -OBLEMS which are perplexing to producers and nsume of galvanized sheets were brought into by the editorial in THE IRON Ace of “Some Trends in Galvanizing.” Leading mill executives who have on the article, in accord with all the opinions expressed, reely acknowledge that galvanizing practice can be nproved. In their belief, however, the extent to which heets are improperly or too lightly galvanized has n exaggerated in the minds of many because of the blicity the subject has received, much of it at the t e of the sheet manufacturers themselves in their effort to correct the evil. minence j ‘ i or commented It is perhaps not generally appreciated, one manu- act) +< acturer states , in discussing the subject with a repre- f THE IRON AGk, that complaints regarding inness of zine coatings on galvanized products have been confined mainly to galvanized sheets for roof- ng purposes. The cause for complaints of this char- o be found in mill methods but is traceable common among the final distributers, buying roofing sheets by the pound and selling them juare—a practice which has led to the sale of and thinner sheets with the correspondingly ig atings which the lighter gages tend to carry. Whereas formerly No. 24 and No. 26 galvanized sheets were standard for roofing purposes, the time came when the th acter is not t the practice, 1 hw + Vy the s nne? ter ¢c N 29 and even lighter sheets were employed. The thinner gages generally do not carry a heavy enough coating of zine to resist the severe weather con- ditions to which they are subjected. The elimination of excessively light-gage sheets for roofing was a part of the simplification program of the Department of Commerce and was one of the first things the Sheet Steel Trade Fxtension Committee set out to accomplish. Much has been done in that direc- tion, and in time, it is asserted, there will be an end to the use as roofing of galvanized sheets that are too light in weight of base metal and of zinc coating. Thin Coatings Required on Sheets for Rapid Working The charge th