Curling iron

“ Ordinary cast iron, while strong and hard enough for many purposes, still is brittle by reason of the large proportion of carbon and other impurities which it contains. These impurities may be burned out in the puddling process, and the nearly pure iron thus obtained, called malleable or wrought iron, has a toughness enabling it to resist far greater strains than cast iron can stand. Intermediate between the two irons, and containing one per cent of carbon, more or less, is still another product, steel, which may be made even more tenacious than wrought iron, or even harder than cast iron. ”

“ Open-hearth iron is practically pure iron, having no constituents or slag inclusions which materially affect its properties.
2. Wrought iron, for all practical purposes, is pure iron 86except for its content of slag. It is the only one of the iron family which does normally contain slag.
3. Neither open-hearth iron nor wrought iron contains carbon in appreciable quantities.
4. The distinguishing and active element of the steel family is carbon. With increase of carbon the hardness of the alloy increases as does its tensile strength, but the ductility (elongation or stretch) decreases. ”

“ During the melting of the charge the heat is kept as high as possible and the molten iron is “puddled,” i. e., stirred, by the “puddler” or his helper with a “rabbler” or iron bar. In order to take out the phosphorus and sulphur, which for best results should be removed before the carbon is eliminated, the heat of the furnace is lowered somewhat as soon as all of the pig has melted, and some iron oxide is mixed into the “bath” of molten iron and cinder. Most of the phosphorus and sulphur are chemically acted upon and pass into the cinder which covers the iron. ”

“ We say that the iron made by the ancients was in reality a variety of what we now term wrought iron, for it fulfilled three of the principal requirements for wrought iron, viz., it was not necessarily melted during production, it was a malleable metal, and it contained cinder or slag, but practically no carbon. ”

“ It is so highly 75refined that it can hardly be called steel at all but is often called “open-hearth iron” or “ingot iron.” It is probably the purest iron on the market in commercial quantities to-day. While in the chemical laboratory iron of considerably greater purity can be made, for a commercial product this is remarkably pure, seldom containing more than 1⁄4 per cent of elements other than the metal, iron. ”

“ The greater the amount of carbon chemically combined with the iron, the whiter, harder, and more brittle does it become.
The white cast iron is stronger than the grey, but being more brittle it is not so suitable for resisting suddenly applied loads. White iron melts at a lower temperature than grey iron, but after melting it does not flow so well, or is not so liquid as the grey iron. White iron contracts while grey iron expands on solidifying. The grey iron, therefore, makes finer castings than the white. ”

“ The iron rapidly melts and saturates itself with carbon. After a few minutes’ heating to a temperature above 4000° C.—a temperature at which the iron melts like wax and volatilises in clouds—the current is stopped and the dazzling fiery crucible is plunged beneath the surface of cold water, where it is held till it sinks below a red heat. As is well known, iron increases in volume at the moment of passing from the liquid to the solid state. The sudden cooling solidifies the outer layer of iron and holds the inner molten mass in a tight grip. ”

“ Cast iron or crude iron is the metal when first extracted from the ore; it usually contains carbone, oxygen, phosphorus and silica, in small proportions, with perhaps other earths occasionally. It cannot be considered as having these elements united in definite proportions; for they vary much, and probably give to crude iron its several modifications. Cast iron contains about 80 per cent. of its weight of iron in a state capable of solution in dilute sulphuric acid, and yielding a corresponding quantity of hydrogen gas. ”

“ Billy looked at him questioningly.
“That was rather technical, wasn’t it, Billy? You see, I was talking to a technical man. Just between you and me, meteoric iron comes down from the sky, from what we call shooting stars. Sometimes large pieces are found. I suppose that much of it falls into the sea. It is the purest iron that has ever been found.”
“What about magnetic iron?” asked Dr. Crandon. “Where does that come from?”
“At the present time,” answered Mr. Prescott, “most of it comes from Sweden and Norway. It makes the best kind of steel. ”

“ On the application of heat in furnaces, constructed for the purpose, the charcoal unites with the oxygen of the oxide, reducing it to the metallic state, and escapes in the form of carbonic acid; and the lime, if the ore be argillaceous, unites with the clay, forming a kind of glass, which floats on the melted metal. When the iron is suffered to run into moulds, prepared for its reception, it usually takes the name of pig iron.
Manufacturers distinguish cast iron by its colour and other qualities. The white cast iron is hard and brittle, and can neither be filed, bored, nor bent. ”

“ A quantity of molten iron should be kept in the cupola or in a large ladle, so as to give the different brands of iron a chance to mix. In most all the foundries at Wheeling, West Virginia, the cupolas are never stopped from the time the blast is put on until the bottom is dropped. A large ladle is set on trestles in front of the cupola, in such a manner that the iron can run into it from the cupola and be poured out into the smaller ladles at the same time. The iron is all run out of the cupola as fast as it is melted, and is mixed in a large ladle. I think this is a good way of mixing iron. ”

“ Some kinds are broken up to be used as foundation for roads; others are granulated by being run into water, and so made into cement. Over in Germany, where the ores are rich in phosphorus, they grind up the linings of the furnace to make phosphatic fertilizers for the farmers.”
“Then,” said Dr. Crandon, “the making of iron involves the use of chemistry, doesn’t it?”
“It certainly does,” answered Mr. Prescott; “from the chemical composition of ores to the finished product. We are learning a great deal just now from the chemists about steel alloys. ”

“ Soft iron is characterised by its attaining a fibrous fracture after forging, whilst tough iron preserves its granular structure after this operation. Certain sorts of iron, although fairly soft at the ordinary temperature, become brittle when heated and are difficult to weld. These sorts are less suitable for being worked up into small objects. The variety of the properties of iron depends on the impurities which it contains. In general, the iron used in the arts still contains carbon and always a certain quantity of silicon, manganese, sulphur, phosphorus, &c. ”

“ Thus, when combined with carbon, in varying proportions, substances are produced, so different, but each so valuable, that they might almost be regarded in the light of distinct metals,—such, for example, as cast-iron, and cast and bar steel; the various qualities of iron enabling it to be used for purposes so opposite as a steel pen and a railroad, the needle of a mariner's compass and an Armstrong gun, a surgeon's lancet and a steam engine, the mainspring of a watch and an iron ship, a pair of scissors and a Nasmyth hammer, a lady's earrings and a tubular bridge. ”

“ Similar alloys of iron with the other elements mentioned are made in an electric furnace by reducing the mixed oxides with carbon.
Pure iron. Perfectly pure iron is rarely prepared and is not adapted to commercial uses. It can be made by reducing pure oxide of iron in a current of hydrogen at a [Pg 349] high temperature. Prepared in this way it forms a black powder; when melted it forms a tin-white metal which is less fusible and more malleable than wrought iron. It is easily acted upon by moist air.
Compounds of iron. ”

“ The strength of iron is at its maximum in the smallest mechanical structures.
2. The quality of the metal is improved as it is subjected to greater pressure and condensation.
The extent to which this improvement may be carried has never yet been ascertained; every fresh manipulation improves its quality. The tenacity of wrought iron is best displayed in a wire, drawn out until it is not thicker than a human hair. Large masses of wrought iron are weak and spongy in geometrical progression with the mass, and the crystalline or molecular form increases with the mass. ”

“ When iron contains more than 2.2 per cent. of carbon it is hard, brittle, and more easily melted, and is known as crude iron, or raw iron, because it is derived from the raw product,—black ore. The melted crude iron is called cast iron. Iron is ductile when it contains less than 2.2 per cent. ”

“ CHAPTER XI. IRON—NICKEL—COBALT—ZINC—CADMIUM. IRON.
Iron rusts or oxidises very readily, and, consequently, is rarely found in the metallic state in nature; such native iron as is found being generally of meteoric origin or imbedded in basalt and other igneous rocks. It chiefly occurs as oxide, as in magnetite, hæmatite, and in the brown iron ores and ochres. Chalybite, which is carbonate of iron, is an ore of great importance. Iron is found combined with sulphur in pyrrhotine and pyrites, and together with arsenic in mispickel. ”

“ While I write, iron is doubtless flowing from blast furnaces in England, Wales, and Scotland; while I write, ingots of white-hot Bessemer steel are being dealt with under the steam-hammer or in the rolling-mills; while I write, horse-shoes are being forged, and, at each moment, in one way or another, pieces of iron of every temperature could be found, from those which are as cold as the iron apparatus used by Sir James Dewar in his experiments in the liquefaction of air, up to the glittering melted steel which is poured from the tilted converter. ”

“ Iron is only prepared on the large scale, and an account of the manufacture would be out of place here. Those requiring detailed information must consult the elaborate works of Percy, Hunt, Fairbairn, Phillips, and other metallurgists.
Pure iron may be prepared by introducing fine iron wire, cut small, 4 parts, and black oxide of iron, 1 part, into a Hessian crucible; covering with a mixture of white sand, lime, and carbonate of potassium (in the proportions used for glass-making) ; and, after applying a closely fitting cover, exposing the crucible to a very high degree of heat. ”

“ Wrought iron will occasion scintillations, somewhat of the same appearance, and steel, also, in greater abundance; and hence both are employed in sundry compositions. But the particular character, beauty, and brilliancy of Chinese fire must be attributed, first to the iron, and secondly to its peculiar state of combination with carbon and oxygen; for, we have said, that malleable iron, (which is deprived in a great measure of these substances in the operation required for its preparation) , produces an effect far inferior to cast iron. ”

“ It oxidizes, and the iron flies off in sparks that are scales red hot. When the smith sees the iron begin to sparkle, he takes it out of the fire, and rolls it in sand, and then puts it in again, or opens the fire, and sprinkles sand upon it. The sand melts, combines with the oxide of iron, and forms silicate of iron, spreads over the surface of the iron, protects it, prevents the formation of scales, and when it is struck with the hammer, leaves the surface clean, and the iron unites perfectly, and forms a solid junction. ”

“ An important feature in the process is, that by stopping it at a particular stage, immediately following the boil, before the whole of the carbon has been abstracted by the oxygen, the crude iron will be found to have passed into the condition of cast-steel of ordinary quality. By continuing the process, the metal losing its carbon, it passes from hard to soft steel, thence to steely iron, and last of all to very soft iron ”

“ Wrought iron is softer than cast iron, and, being pure iron, is more liable to be corroded by the action of the atmosphere and products of combustion of the powder; it possesses also considerable ductility. The tensile strength of wrought iron, which under the most favorable circumstances is double that of the best cast iron, depends on the character of the crystalline structure, and the manner of applying the tensile force, or in other words, wrought iron offers the greatest resistance to a force of extension when the structure is fibrous, and the force acts in the direction of the fibres. ”

“ The grey iron requires the greatest degree of heat for its fusion, is more fluid when melted, is softest, best fitted for castings which require to be turned or filed, and for those that must be thin; the white iron is very hard and brittle; the greatest degree of strength and tenacity is due to the mixture, or mottled iron, and to that variety of mottled in which the grey rather predominates. ”

“ As the carburets of iron, whether in the form of pig or of steel, may be considered as alloys, if they be presented to other metals, the results must necessarily be different from what occurs when pure iron is exposed to the same substance. The union that may take place in the one instance may not occur in the other. It may often happen, that when the iron is pure, a true chemical combination will occur, while in the other case, no more than a mechanical mixture can be effected. ”

“ For general purposes it is as well that he should know that perfectly pure iron is so soft and tough, and at the same time so malleable, that it can be rolled into sheets 1⁄300 part of an inch in thickness; and that when wrought iron can be twisted, cold, into almost any shape without breaking, he may rest assured that it is as near pure iron as any one could wish to have for the proper execution of smith’s work. ”