with analysis, and unless the condition of furnace, whether the iron ran fast or slow, and from what part of pig bed the sample is taken, are known, the fracture is often very misleading. Take the following analyses: A. Very close-grain iron, dark color, by fracture, gray forge. C. Very close-grain, by fracture, gray forge. D. Medium-grain, by fracture, No. 2, but much brighter and more open than A, C, or F. E. Very large, open-grain, dark color, by fracture, No. 1. F. Very close-grain, by fracture, gray forge. By comparing analyses A and B, or E and F, it appears that the closegrain iron is in each case the highest in graphitic carbon. Comparing A and E, the graphite is about the same, but the close-grain is highest in silicon. Analyses of Foundry Irons. (C. A. Meissner.) DESCRIPTION OF SAMPLES.-No. 1. Well known Ohio Scotch iron, almost silvery, but carries two-thirds scrap; made from part black-band ore. Very successful brand. The high silicon gives it its scrap-carrying capacity. No. 2. Brier Hill Scotch castings, made at scale works; castings demanding more fluidity than strength. No. 3. Formerly a famous Ohio Scotch brand, not now in the market Made mainly from black-band ore. No. 4. A good Ohio Scotch, very soft and fluid; made from black-band ore-mixture. Nos. 5a and 5b. Brier Hill Scotch iron and casting; made for stove purposes; 350 lbs. of iron used to 150 lbs. scrap gave very soft fluid iron; worked well. No. 6a. Shows comparison between Summerlee (Scotch) (6a) and Brier Hill Scotch (6b). Drillings came from a Cleveland foundry, which found both irons closely alike in physical and working quality. No. 7. One of the best southern brands, very hard to compete with, owing to its general qualities and great regularity of grade and general working. DESCRIPTION OF SAMPLES.-No. 8. A famous Southern brand noted for fine machine castings. No. 9. Also a Southern brand, a very good machine iron. Nos. 10a and 10b. Formerly one of the best known Ohio brands. Does not shrink; is very fluid and strong. Foundries having used this have reported very favorably on it. No. 11. Iron from Brier Hill Co., made to imitate No. 3; was stronger than No. 3; did not pull castings; was fluid and soft. No. 12. Copy of a very strong English machine iron. No. 13. A Pennsylvania iron, very tough and soft. This is partially Bessemer iron, which accounts for strength, while high silicon makes it soft. No. 14. Castings made from Brier Hill Co.'s machine brand for scale works, very satisfactory, strong, soft and fluid. No. 15. Castings made from Brier Hill Co.'s one half machine brand, one half Scotch brand, for scale works, castings desired to be of fair strength, but very fluid and soft. No. 16a. Brier Hill machine brand made to compete with No. 3. No. 166. Castings (clothes-hooks) from same, said to have worked badly, castings being white and irregular. Analysis proved that some other iron too high in manganese had been used, and probably not weii mixed. No. 17. A Pennsylvania iron, no shrinkage, excellent machine iron, soft and strong. No. 18. A very good quality Northern charcoal iron. "Standard Grades" of the Brier Hill Iron and Coal Company. Brier Hill Scotch Iron.-Standard Analysis, Grade Nos. 1 and 2. Used successfully for scales, mowing-machines, agricultural implements, novelty hardware, sounding-boards, stoves, and heavy work requiring no special strength. Brier Hill Silvery Iron.-Standard Analysis, Grade No. 1. ............................... 3.50 to 5.50 1.00 to 1.50 2.00 to 2.25 Used successfully for hollow-ware, car-wheels, etc., stoves, bumpers, and similar work, with heavy amounts of scrap in all cases. Should be mainly used where fluidity and no great strength is required, especially for heavy work. When used with scrap or close pig low in phosphorus, castings of considerable strength and great fluidity can be made Fairly Heavy Machine Iron.-Standard Analysis, Grade No. 1. Silicon 1.75 to 2.50 0.50 to 0.60 The best iron for machinery, wagon-boxes, agricultural implements, pump-works, hardware specialties, lathes, stoves, etc., where no large amounts of scrap are to be carried, and where strength, combined with great fluidity and softness, are desired. Should not have much scrap with Regular Machine Iron.-Standard Analysis, Grade Nos. 1 and 2. it. Silicon.... Manganese.. 1.50 to 2.00 0.30 to 0.50 0.80 to 1.00 Used for hardware, lawn-mowers, mower and reaper works, oil-well machinery, drills, fine machinery, stoves, etc. Excellent for all small fine castings requiring fair fluidity, softness, and mainly strength. Cannot be well used alone for large castings, but gives good results on same when used with above-mentioned heavy machine grade; also when used with the Scotch in right proportion. Will carry but little scrap, and should be used alone for good strong castings. For Axles and Materials Requiring Great Strength, Grade No. 2. A good neutral iron for guns, etc., will run about as follows: Silicon.... Phosphorus.. Sulphur.. Manganese.. It should be open No. 1 iron. 1.00 0.25 0.20 none. This gives a very tough, elastic metal. More sulphur would make tough but decrease elasticity. For fine castings demanding elegance of design but no strength, phosphorus to 3.00% is good. Can also stand 1.50% to 2.00% manganese. For work of a hard, abrasive character manganese can run 2.00% in casting. No. 31. Sewing-machine casting, said to be very fluid and good casting. This is an odd analysis. I should say it would have been too hard and brittle, yet no complaint was made. No. 32. Very good machine casting, strong, soft, no shrinkage. No. 33. Drillings from an annealer-box that stood the heat very well. No. 34a. Drillings from door-hinge, very strong and soft. No. 346. Drillings from clothes-hooks, tough and soft, stood severe hammering. No. 34c. Drillings from window-blind hinge, broke off suddenly at light strain. Too high phosphorus. No. 35a. Casting for heavy ladle support, very strong. Nos. 35b and 35c. Broke after short usage. Phosphorus too high. Carbumpers. No. 35d. Elbow for steam heater, very tough and strong. No. 36. Cog-wheels, very good, shows absolutely no shrinkage. No. 37. Heater top network, requiring fluidity but no strength. No. 37a. Gray part of above. No. 376. White, honeycombed part of above. Probably bad mixing and got chilled suddenly. STRENGTH OF CAST IRON. Specific Gravity and Strength. (Major Wade, 1856.) Third-class guns: Sp. Gr. 7.087, T. S. 20,148. Another lot: least Sp. Gr. 7.163, T. S. 22,402. Second-class guns: Sp. Gr. 7.154, T. S. 24,767. Another lot: mean Sp. Gr. 7.302, T. S. 27,232. First class guns: Sp. Gr. 7.204, T. S. 28,805. Another lot greatest Sp. Gr. 7.402, T. S. 31,027. Strength of Charcoal Pig Iron.-Pig iron made from Salisbury ores, in furnaces at Wassaic and Millerton, N. Y., has shown over 40,000 lbs. T. S. per square inch, one sample giving 42,281 lbs. Muirkirk, Md., iron tested at the Washington Navy Yard showed: average for No. 2 iron, 21,601 lbs.; No. 3, 23,959 lbs.; No. 4, 41,329 lbs.; average density of No. 4, 7.336 (J. C. I. W., v. p. 44.) Nos. 3 and 4 charcoal pig iron from Chapinville, Conn., showed a tensile strength per square inch of from 34,761 lbs. to 41,882 lbs. Charcoal pig iron from Shelby, Ala. (tests made in August, 1891), showed a strength of 34,800 lbs. for No. 3; No. 4, 39,675 lbs.; No. 5, 46,450 lbs.; and a mixture of equal parts of Nos. 2, 3, 4, and 5, 41.470 lbs. (Bull. I. & S. A.) Variation of Density and Tenacity of Gun-irons.—An increase of density invariably follows the rapid cooling of cast iron, and as a general rule the tenacity is increased by the same means. The tenacity generally increases quite uniformly with the density, until the latter ascends to some given point; after which an increased density is accompanied by a diminished tenacity. The turning-point of density at which the best qualities of gun-iron attain their maximum tenacity appears to be about 7.30. At this point of density, or near it, whether in proof-bars or gun-heads, the tenacity is greatest. As the density of iron is increased its liquidity when melted is diminished. This causes it to congeal quickly, and to form cavities in the interior of the casting. (Pamphlet of Builders' Iron Foundry, 1893.) Specifications for Cast Iron for the World's Fair Buildings, 1892.-Except where chilled iron is specified, all castings shall be of tough gray iron, free from injurious cold-shuts or blow-holes, true to pattern, and of a workmanlike finish. Sample pieces 1 in. square, cast from the same heat of metal in sand moulds, shall be capable of sustaining on a clear span of 4 feet 6 inches a central load of 500 lbs. when tested in the rougn bar. Specifications for Tests of Cast Iron in 12" B. L. Mortars. (Pamphlet of Builders Iron Foundry, 1893.)-Charcoal Gun Iron.--The tensile strength of the metal must average at each end at least 30,000 lbs. per square inch; no specimen to be over 37,000 lbs. per square inch; but one specimen from each end may be as low as 28,000 lbs. per square inch. The long extension specimens will not be considered in making up these averages, but must show a good elongation and an ultimate strength, for each specimen, of not less than 24,000 lbs. The density of the metal must be such as to indicate that the metal has been sufficiently refined, but not carried sø high as to impair the other qualities. Specifications for Grading Pig Iron for Car Wheels by Chill Tests made at the Furnace. (Penna. R. R. Specifications, 1883.) The chill cup is to be filled, even full, at about the middle of every cast from the furnace. The test-piece so made will be 71⁄2 inches long, 3% inches wide, and 134 inches thick, and is to be broken across the centre when entirely cold. The depth of chill will be shown on the bottom of the testpiece, and is to be measured by the clean white portion to the point where gray specks begin to show in the white. The grades are to be by eighths of an inch, viz., 8, 4, %, 1⁄2, 5%, 34, %, etc., until the iron is mottled; the lowest grade being of an inch in depth of chill. The pigs of each cast are to be marked with the depth of chill shown by its test-piece, and each grade is to be kept by itself at the furnace and in forwarding. Mixture of Cast Iron with Steel.-Car wheels are sometimes made from a mixture of charcoal iron, anthracite iron, and Bessemer steel. The following shows the tensile strength of a number of tests of wheel mixtures, the average tensile strength of the charcoal iron used being 22,000 lbs.: 66 66 66 "2% steel, 2% wro't iron, and 64% anth... 25,550 Cast Iron Partially Bessemerized.-Car wheels made of partially Bessemerized iron (blown in a Bessemer converter for 3 minutes), chilled in a chill test mould over an inch deep, just as a test of cold blast charcoal iron for car wheels would chill. Car wheels made of this blown iron have run 250,000 miles. (Jour. C. I. W., vl. p. 77.) Bad Cast Iron.-On October 15, 1891, the cast-iron fly-wheel of a large pair of Corliss engines belonging to the Amoskeag Mfg. Co., of Manchester, N. H., exploded from centrifugal force. The fly-wheel was 30 feet diameter and 110 inches face, with one set of 12 arms, and weighed 116,000 lbs. After the accident, the rim castings, as well as the ends of the arms, were found to be full of flaws, caused chiefly by the drawing and shrinking of the metal. Specimens of the metal were tested for tensile strength, and varied from 15,000 lbs. per square inch in sound pieces to 1000 lbs. in spongy ones. None of these flaws showed on the surface, and a rigid examination of the parts before they were erected failed to give any cause to suspect their true nature. Experiments were carried on for some time after the accident in the Amoskeag Company's foundry in attempting to duplicate the flaws, but with no success in approaching the badness of these castings. MALLEABLE CAST IRON. Malleableized cast iron, or malleable iron castings, are castings made of ordinary cast iron which have been subjected to a process of decarbonization, which results in the production of a crude wrought iron. Handles, latches, and other similar articles, cheap harness mountings, plowshares, iron handles for tools, wheels, and pinions, and many small parts of machinery, are made of malleable cast iron. For such pieces charcoal cast iron of the best quality (or other iron of similar chemical composition), should be selected. Coke irons low in silicon and sulphur have been used in place of charcoal irons. The castings are made in the usual way, and are then imbedded in oxide of iron, in the form, usually, of hematite ore, or in peroxide of manganese, and exposed to a full red-heat for a sufficient length of time, to insure the nearly complete removal of the carbon. This decarbonization is conducted in cast-iron boxes, in which the articles, if small, are packed in alternate layers with the decarbonizing material. The largest pieces require the longest time. The fire is quickly raised to the maximum temperature, but at the close of the process the furnace is cooled very slowly. The operation requires from three to five days with ordinary small castings, and may take two weeks for large pieces. |