99 



STEEL. 



Phosphorus tends to make the steel non-homogen- 

 eous bj being unequally distributed, to make it 

 " cold-short " or brittle when worked cold, and tends 

 to weaken steel that is reheated or subjected to vi- 

 bration, so that it must be kept below .06 per cent, 

 iu ship plates, shapes, and rivets, and below .03 per 

 cent in boilorstays, plates, and rivets. Pig contain- 

 ing phosphorus is very cheap, and the phosphorus 

 helps in the melting and pouring of the metal, and 

 gives a good elastic twist and strength with less work 

 on the material. So there is naturally a strong temp- 

 tation to use it on account of cheapness, and the ba- 

 sic processes are apt to rapidly grow in favor. In 

 bridge steel phosphorus is not permitted to be above 

 .05 per cent., and in rails it is limited to .10 per 

 cent. 



Silicon tends, in solid castings, to prevent blow- 

 holes and sponginess. The silicon is usually con- 

 sumed in the furnace when making mild steel, and 

 iu ship-plates does not amount to more than .04 per 

 cent. 



Sulphur is very injurious, leading to hot short- 



factnre of steel is in the making of malleable steel 

 castings; the heavy ram stern*, stern-post*, rudder- 

 posts, and struts, that hud until recently to lie l 

 out are now cast, and such coatings are, to r-ho\\ a 

 tensile strength of 60,000 Ibs., and an elongation i;i 

 8 inches of 10 per cent. 



Boiler shell plates are tested the same as tho 

 ship plates, but the gauge plates are to have an 

 elongation of 29 per cent in 8 inches. 



In the case of gun steel and steel for armor, the 

 specimen is 2 inches between witness marks, cylin- 

 drical in shape, J inch in diameter. For protective 

 decks the steel to be between 60.000 and 70,000 Ibs. 

 and 25 to 23 per cent, elongation, or between 70,000 

 and 80,000 Ibs. with 23 to 19 jter cent elongation, 

 or between 80,000 and 90,000 Ibs. with 19 to 1'J per 

 cent, elongation. For heavy steel minor, tin- ten-ilo 

 strength to be 82,000 His." and tho elongation not 

 less than 20 per cent, (inn steel must he of the 

 very best, and there are tests for the various parts of 

 the gun, the tests for the 8-inch gun being given 

 as an example. 



ness or brittleness when worked hot. It is not | 

 above .03 per cent, in ship steel. Arsenic makes 

 steel cold-short, copper red-short, and antimony 

 both red- and hot-short 



Test*. Steel is now subjected to rigid tests be- 

 fore being used for structural purposes. For the 

 mild steel which is used for the vessels now build- 

 ing for the Government, test pieces are taken about 

 16 inches long, with witness marks about 8 inches 

 apart, the sectional area being from .5 to .8 of an 

 inch. These pieces are placed in the testing-ma- 

 chine and subjected to a pull, the amount of whicli 

 can be accurately measured in pounds. The speci- 

 mens are first carefully measured to get the exact 

 sectional area, the mieronietric gauges used measur- 

 ing to .001 inch. An initial stress of about 30,000 

 Ibs. to the square inch and kept in continuous action 

 for about a minute, and observations taken to note 

 the corresponding elongation. The weight is then 

 increased gradually, till tho cracking of the mill- 

 scile and the unsteadiness of the beam show that 

 the elastic limit is being neared ; and when tho beam 

 drops suddenly, the weight is recorded as tho clas- 

 tic limit. From this time loads are gradually added 

 till the specimen is broken. The load necessary to 

 produce ultimate fracture is carefully* noted and the 

 pieces fitted carefully together, and the increased 

 distance between the witness-mark measured to ob- 

 tain the elongation. Plates and the shapes, as they 

 are called, such as angle steels, Z bars, bulbs, etc., 

 must show an ultimate tensile strength of 60,000 Ibs. 

 to the square inch, and an elongation in 8 inches of 

 25 per cent. Pieces cut from the finished heat must 

 bend over flat on themselves when cold without 

 breaking, and specimens, after being heated to a dark 

 cherry-red and then plunged into water at 82" F., 

 must bend round a curve whose diameter is 1 J time 

 the thickness of the plate, without cracking. Rivets 

 are to have a tensile strength of from 50.000 to 

 55,000 Ibs. per square inch, and an elongation in 8 

 inches of not less than 30 per cent, and they must 

 flatten out cold under the hammer to a thickness of 

 one-half the diameter, and hot to a thickness of one- 

 third the diameter, and bend in the form of a hook 

 when cold without showing cracks or flaws. / 1 



One of the most important advances in the manu- 



Material is, of course, subject to a rigid surface in- 

 s]x>ction for laminations, hair-cracks, scale-marks, 

 blisters, pits, snakes, and cobbles. Pits should 

 cause rejection, being due to burning. They occur 

 in the form of small cup-like holes, and must not be 

 confounded with cinder-spots, which are due to cin- 

 ders or pieces of firebrick being rolled into tho 

 plates. Ciacks are due to rolled-out blow-holes, while 

 snakes are small lines twisting in every direction, 

 due to foreign substances in the heat separating two 

 masses of pure steel. This should always cause re- 

 jection. Cobbles are irregularities due "to one side 

 being more heated than another. 



Ship plates and shapes con be bought, which will 

 pass tho above tests, for about 3.34 cents j>er Ib. 

 Steel castings cost about 16 cents a Ib. Steel forg- 

 ings for guns cost about 30 cents a Ib., though tho 

 price depends very much on the size, and twelve- 

 inch armor-plates cost about 8675 per ton. Steel 

 rails arc now worth about 827 per ton. 



The recent additions to the U. S. navy comprise 

 ten steel-protected vessels, begun in 1887 : tho 

 Baltimore, Newark, Philadelphia, Vesuvius, and 

 Yorktown, built at Cramps' ship-yard, Philadelphia ; 

 the Bennington and Concord, built at Roach's yard, 

 Chester, Pa. ; the Petrel, built at the Columbian 

 Iron Works, Baltimore ; and the Charleston and 

 San Francisco, built at the Union Iron Works, San 

 Francisco. In 1888 two armored cruisers were com- 

 menced the Maine, at the New York navy yard, 

 and the Texas at the Norfolk navy yard. The New- 

 ark, one of the largest, is a twin-screw, steel-pro- 

 tected cruiser of 4083 tons displacement. She is 

 328 ft. long, 49 ft beam, and 18} ft mean draught 

 The engines, boilers, magazines, shell-rooms, tor- 

 pedo spaces, and steering pear are protected hy a 

 thick steel ileek, resembling a turtle-back, extend- 

 ing fore and aft, and dipping below the water at the 

 sides and ends. The speed is to he 18 knots, and sho 

 will carry twelve 6-in. breech-loading rifle guns. The 

 contract price for hull and machinery is $1,248,000. 



In the preparation of thii article the following have been 

 drawn from: The E-emtnl* / Metallurgy, \>\ J. Arthur 

 Phillips; Tilt fntptftirii nf Structural aM fl->ilrr .Watrrial. 



. 



by Lieut. -Commander J. O. Eaton, U. R N. ; and the Rrport 

 of the American Iron and Steel Annotation. (i,. N.) 



