otherwise broken at the joint which have not shown a smooth cleavageplane, as it were, such as in iron would be condemned as an imperfect weld. My experience in this matter leads me to agree with the position taken by Mr. William Metcalf in his paper upon Steel in the Trans. A. S. C. E., vol. xvi., p. 301. Mr. Metcalf says, I do not believe steel can be welded." Oil-tempering and Annealing of Steel Forgings.—H. F. J. Porter says (1897) that all steel forgings above 0.1% carbon should be annealed, to relieve them of forging and annealing strains, and that the process of annealing reduces the elastic limit to 47% of the ultimate strength. Oil-tempering should only be practised on thin sections, and large forgings should be hollow for the purpose. This process raises the elastic limit above 50% of the ultimate tensile strength, and in some alloys of steel, notably nickel steel, will bring it up to 60% of the ultimate. Hydraulic Forging of Steel. (See pages 618 and 619.) INFLUENCE OF ANNEALING UPON MAGNETIC CAPACITY. Prof. D. E. Hughes (Eng'g, Feb. 8, 1884, p. 130) has invented a "Magnetic Balance," for testing the condition of iron and steel, which consists chiefly of a delicate magnetic needle suspended over a graduated circular index, and a magnet coil for magnetizing the bar to be tested. He finds that the following laws hold with every variety of iron and steel: 1. The magnetic capacity is directly proportional to the softness, or molecular freedom. 2. The resistance to a feeble external magnetizing force is directly as the hardness, or molecular rigidity. The magnetic balance shows that annealing not only produces softness in iron, and consequent molecular freedom, but it entirely frees it from all strains previously introduced by drawing or hammering. Thus a bar of iron drawn or hammered has a peculiar structure, say a fibrous one, which gives a greater mechanical strength in one direction than another. This bar, if thoroughly annealed at high temperatures, becomes homogeneous in all directions, and has no longer even traces of its previous strains, provided that there has been no actual separation into a distinct series of fibres. Effect of Annealing upon the Magnetic Capacity of Different Wires; Tests by the Magnetic Balance. Magnetic Capacity. Bright-yellow heat, cooled completely in cold water. 66 blue... cooled completely in oil Reheat, cooled completely in water.. 66 Magnetic 28 33 43 51 58 66 72 84 STANDARD SPECIFICATIONS FOR STEEL. The following specifications are abridged from those adopted Aug. 10, 1901, by the American Section of the International Association for Testing Materials.* Kinds of Steel Used for Different Purposes.-O, openhearth; B, Bessemer; C, crucible. (1) Castings, O, B, C. (2) Axles, O. (3) Forgings, O, B, C. (4) Tires, O, C. (5) Rails, O. B. (6) Splice-bars, O. B. (7) Structural Steel for buildings, O, B. (8) Structural steel for ships, O. (9) Boiler-plate and rivets, O. CHEMICAL REQUIREMENTS FOR THE ABOVE NINE CLASSES. (The minus sign after the figures means "or less.") (1) ordinary, P, 0.08-; C, 0.40; tested castings, P, 0.05; S, 0.05-. (2) P, 0.06; S, 0.06-. Nickel steel, Ni, 3.00 to 4.00; P, 0.04; S, 0.04-. (3) soft or low carbon, P, 0.10-; S, 0.10; Class B (see below), P, 0.06; S, 0.06-. Classes C and D, P, 0.04; S, 0.04-. (4) P, 0.05 - ; S, 0.05; Mn, 0.80-; Si, 0.20+. (5) P, 0.10-; Si, 0.20-; C, a, 0.35 to 0.45; b, 0.38 to 0.48; c, 0.40 to 0.50; d, 0.43 to 0.53; e, 0.45 to 0.55; Mn, a, b, 0.70 to 1.00; c, 0.75 to 1.05; d, e, 0.80 to 1.10. [a, 50 to 59+ lbs. per yard; b, 60 to 69+ lbs.; c, 70 to 79+ lbs.; d, 80 to 89+ lbs.; e, 90 to 100 Ibs.] (6) P, 0.10-; C, 0.15-; Mn, 0.30 to 0.60. (7) P, 0.10-. (8) acid, P, 0.08; S, 0.06; basic, P, 0.06; S, 0.06-. (9) a, P, 0.06-; b, c, e, P, 0.04-; d, P, 0.03; a, b, S, 0.05; Mn, 0.30 to 0.60; c, d, e, S, 0.04 - ; Mn, 0.30 to 0.50. [a, flange or boiler steel, acid; b, do. basic; c, fire-box, acid; d, do. basic; e, extra soft.] "Where the physical properties desired are clearly and properly specified, the chemistry of the steel, other than prescribing the limits of the injurious impurities, P and S, may in the present state of the art of making steel be safely left to the manufacturer.' "" PHYSICAL REQUIREMENTS. (1) Castings subjected to physical tests. Test-piece in. diam. Bend The above are the minimum requirements. ing test: Specimen 1 X 14 ins. to bend cold around a diam. of 1 in. through 120° for soft and 90° for medium castings. (2) Axles. For car, engine-truck, and tender-truck axles no tensile test is required. For driving-axles, minimum requirements: T. S. 80,000; Y. P. 40,000 for carbon steel (a), 50,000 for nickel steel, 3 to 4 per cent Ni, oil-tempered or annealed (b). Elongation in 2 ins, 18 per cent for a, 25 per cent for b. Contraction of area, 45 per cent for b. Test-piece in. diam. For other axles one axle Drop-test.--Not required for driving-axles. from each melt to be tested on a standard R.R. drop-testing apparatus, with supports 3 ft. apart, tup 1640 lbs., anvil 17,500 lbs., supported on springs. The axle shall stand the number of blows named below without rupture and without exceeding at the first blow the deflection stated. It is to be turned over after the first, third, and fifth blows. Diam. of axle at centre, ins... 41 48 No. of blows Height of drop, ft. 4/ 44 51 51 5 5 5 5 5 5 Deflection, ins.. (3) Steel Forgings.-Classification: A, soft or low carbon; B, carbon steel, not annealed; C, do., annealed; D, do., oil-tempered; E, nickel-steel, annealed; F, do., oil-tempered. Sub-classes: a, solid or hollow forgings, diam. or thickness not over 10 ins.; b, solid forgings, diam. not over 20. ins., or thickness of section not over 15 ins.; c, solid, over 20 ins. diam.; d, solid *The complete specifications may be found in book form in "American Standard Specifications for Steel," by Albert Ladd Colby (Chemical Fublishing Co., Easton, Pa., 1902). Mini or hollow, diam. or thickness not over 3 ins.; e, do., not over 6 ins. mum requirements of test-piece in. diameter, 2 ins. between gauge-marks: The number and location of test specimens to be taken from a melt, blow, or forging depend upon its character and importance, and must therefore be regulated by individual cases. The yield-point (in steels A and B) shall be determined by observation of the drop of the beam or halt in the gauge of the testing-machine. The elastic limit shall be determined by means of an extensometer, and will be taken at that point where the proportionality changes. Bending Test.-A specimen 1X1 ins. shall bend cold 180° without fracture on outside of bent portion, as follows. The test may be made by bending or by blows. 11 1 Cc Cab 1 F in. diam.. Tires for Tires for freight (4) Tires.-Physical requirements of test-piece passenger engines: T. S., 100,000; El. in 2 ins., 12 per cent. engines and car wheels. T. S., 110,000; El., 10 per cent. Tires for switching engines: T. S., 120,000; El., 8 per cent. Drop-test.--If a drop-test is called for, a selected tire shall be placed vertically under the drop on a foundation at least 10 tons in weight and subjected to successive blows from a tup weighing 2240 lbs. falling from increasing heights until the required deflection is obtained, without breaking or cracking. The minimum deflection must equal D2 ÷ (40T2+2D), D being internal diameter and T thickness of tire at centre of tread. (5) Rails. One drop-test shall be made on a piece of rail not more than 6 ft. long, selected from every fifth blow of steel. The rail shall be placed head upwards on solid supports 3 ft. apart, which are part of, or firmly secured to, an anvil-block weighing at least 20,000 lbs., and subjected to the following impact tests. 18 Weight of rails, lbs. per yd. 45 to 55 55 to 65 65 to 75 75 to 85 85 to 100 Height of drop, ft.. 15 16 17 19 If any rail break when subjected to the drop-test, two additional tests will be made of other rails from the same blow of steel, and if either of these latter tests fail, all the rails of the blow which they represent will be rejected, but if both tests meet the requirements, all the rails of the blow will be ac/cepted. (6) Splice-bars.-Tensile strength of a specimen cut from the head of the bar, 54,000 to 64,000 lbs.; yield-point, 32,000 lbs. Elongation in 8 ins., not less than 25 per cent. A test specimen cut from the head of the bar shall bend 180° flat on itself without fracture on the outside of the bent portion. If preferred, the bending test, may be made on an unpunched splicebar, which shall be first flattened and then bent. One tensile test and one bending test to be made from each blow or melt of steel. (7) Structural Steel for Buildings. Modifications in elongation requirements: For each increase of in. in thickness above in., a deduction of 1 per cent in the specified elongation. For each decrease of in. in thickness below in., a deduction of 24 per cent. For pins the required elongation shall be 5 per cent less than that specified, as determined on a test specimen the centre of which shall be 1 in. from the surface. Bending Tests.-Rivet-steel shall bend cold 180° flat on itself, and medium steel 180° around a diameter equal to the thickness of the specimen, without fracture on the outside of the bent portion. One tensile and one bending-test specimen shall be taken from the finished material of each melt or blow. (8) Structural Material for Bridges and Ships. Modifications in elongation: Same as in structural steel for buildings. Eyebars.-Full-sized tests: T. S. not less than 55,000 lbs.; El., 12 per cent. in 15 ft. of the body. Bending Tests.-Rivet and soft steel, 180° flat on itself, and medium steel 180° around a diameter equal to the thickness of the specimen, without fracture on the outside of the bent portion. (9) Boiler-plate and Rivet-steel. Modifications in elongation requirements for thin and thick material same as in structural steel for buildings. Bending Tests.-A specimen cut from the rolled material, both before and after quenching, shall bend cold 180° flat on itself without fracture on the outside of the bent portion. For the quenched test the specimen shall be heated to a light cherry-red as seen in the dark and quenched in water of a temperature between 80° and 90° F. Number of test-pieces: One tensile, one cold-bending, and one quenched-bending specimen will be furnished from each plate as it is rolled, and two specimens for each kind of test from each melt of rivet-rounds. Homogeneity Test for Fire-box Steel. This test is made on one of the broken tensile-test specimens, as follows: A portion of the test-piece is nicked with a chisel, or grooved on a machine, transversely about a sixteenth of an inch deep, in three places about 2 in. apart. The first groove should be made on one side, 2 in. from the square end of the piece; the second, 2 in. from it on the opposite side; and the third, 2 in. from the last, and on the opposite side from it. The testpiece is then put in a vise, with the first groove about in. above the jaws, care being taken to hold it firmly. The projecting end of the test-piece is then broken off by means of a hammer, a number of light blows being used, and the bending being away from the groove. The piece is broken at the other two grooves in the same way. The object of this treatment is to open and render visible to the eye any seams due to failure to weld up, or to foreign interposed matter, or cavities due to gas bubbles in the ingot. After rupture, one side of each fracture is examined, a pocket lens being used if necessary, and the length of the seams and cavities is determined. The sample shall not show any single seam or cavity more than in. long in either of the three fractures. VARIOUS SPECIFICATIONS FOR STEEL. Structural Steel.-There has been a change during the ten years from 1880 to 1890, in the opinions of engineers, as to the requirements in specifications for structural steel, in the direction of a preference for metal of low tensile strength and great ductility. The following specifications of different dates are given by A. E. Hunt and G. H. Clapp, Trans. A. I. M. E. 1890, xix, 926: TENSION MEMBERS. Elastic limit.... Tensile strength.. 1879. 1888. 38,000 80,000 70@80,000 70,000 70,000 67@75,000 63@70,000 18% 18% 18% 20% 22% Elongation in 8 in....... 12% F. H. Lewis (Iron Age, Nov. 3, 1892) says: Regarding steel to be used under the same conditions as wrought iron, that is, to be punched without reaming, there seems to be a decided opinion (and a growing one) among engineers, that it is not safe to use steel in this way, when the ultimate tensile strength is above 65,000 lbs. The reason for this is, not so much because there is any marked change in the material of this grade, but because all steel, especially Bessemer steel, has a tendency to segregations of carbon and phosphorus, producing places in the metal which are harder than they normally should be. As long as the percentages of carbon and phosphorus are kept low, the effect of these segregations is inconsiderable; but when these percentages are increased, the existence of these hard spots in the metal becomes more marked, and it is therefore less adapted to the treatment to which wrought iron is subjected. There is a wide consensus of opinion that at an ultimate of 64,000 to 65,000 lbs. the percentages of carbon and phosphorus (which are the two hardening elements) reach a point where the steel has a tendency to become tender, and to crack when subjected to rough treatment. A grade of steel, therefore, running in ultimate strength from 54,000 to 62,000 lbs., or in some cases to 64,000 lbs., is now generally considered a proper material for this class of work. A. E. Hunt, Trans. A. I. M. E. 1892, says: Why should the tests for steel be so much more rigid than for iron destined for the same purpose? Some of the reasons are as follows: Experience shows that the acceptable quali ties of one melt of steel offer no absolute guarantee that the next melt to it, even though made of the same stock, will be equally satisfactory. Again, good wrought iron, in plates and angles, has a narrow range (from 25,000 to 27,000 lbs.) in elastic limit per square inch, and a tensile strength of from 46,000 to 52,000 lbs. per square inch; whereas for steel the range in elastic limit is from 27,000 to 80,000 lbs., and in tensile strength from 48,000 to 120,000 lbs. per square inch, with corresponding variations in ductility. Moreover, steel is much more susceptible than wrought iron to widely vary. ing effects of treatment, by hardening, cold rolling, or overheating. It is now almost universally recognized that soft steel, if properly made and of good quality, is for many purposes a safe and satisfactory substitute for wrought iron, being capable of standing the same shop-treatment as wrought iron. But the conviction is equally general, that poor steel, or an unsuitable grade of steel, is a very dangerous substitute for wrought iron even under the same unit strains. For this reason it is advisable to make more rigid requirements in selecting material which may range between the brittleness of glass and a ductility greater than that of wrought iron. Boiler, Ship, and Tank Plates.-Different specifications are the following (1889): United States Navy.-Shell: Tensile strength, 58,000 to 67,000 lbs. per sq. in.; elongation, 22% in 8-in. transverse section, 25% in 8-in. longitudinal section. Flange: Tensile strength, 50,000 to 58,000 lbs.; elongation. 26% in 8 inches. Chemical requirements: P. not over .035%; S. not over .040%. Cold-bending test: Specimen to stand being bent flat on itself. Quenching test: Steel heated to cherry-red, plunged in water 82° F., and to be bent around curve 11⁄2 times thickness of the plate. British Admiralty.-Tensile strength, 58,240 to 67,200 lbs.; elongation in 8 in., 20%; same cold-bending and quenching tests as U. S. Navy. American Boiler-makers' Association.-Tensile strength, 55,000 to 65,000 lbs.; elongation in 8 in., 20% for plates 36 in. thick and under; 22% for plates in. to 4 in.; 25% for plates 34 in. and over. |