Scrap 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. ”

“ Pig-iron contains silicon, sulphur and phosphorus, and these impurities make it brittle so that a cast iron teakettle will break at a blow, like a china cup. Armor of this kind would have been no good for our iron-clad ancestors. When a knight in iron clothes tried to whip a leather-clad peasant, the peasant could have cracked him with a stone and his clothes would have fallen off like plaster from the ceiling. So those early iron workers learned to puddle forge iron and make it into wrought iron which is tough and leathery and can not be broken by a blow. ”

“ Pig-iron, or, as it is sometimes called, crude iron, being saturated with carbon and oxygen, and containing also a portion of scoria, is too brittle for any other purpose than castings. Many of these, such as stoves, grates, mill-irons, plough-irons, and kitchen utensils, are commonly manufactured at blast furnaces, and in many cases nearly all the iron is used for these purposes. In such cases, the metal is taken in a liquid state, from the hearth, in ladles. ”

“ One has no difficulty in realizing that these flakes, which cut in every direction through the metal, make it structurally weak, especially toward a sudden blow.
No. 1d shows a typical section of wrought iron cut lengthwise of the rolled bar. It will be noted that, as in photomicrograph No. 99b, there are no graphite flakes.
In the process of wrought iron manufacture practically all of the carbon of the original pig iron is burned out, leaving little besides the iron itself and some viscous cinder or slag. ”

“ The reduction of rich ores of iron, such as are almost wholly made up of its oxides, and contain but little earthy matter, may be performed in a common smith's forge. The reduction in this case takes place immediately in the blast of the bellows, where the intensely heated ore is in contact with the burning charcoal; and if a carburet be formed, it is immediately decomposed, and pure iron is the result. Such is probably the more ancient of all the processes for obtaining malleable iron, and it is still used to a certain extent even at the present day. ”

“ It is only slightly malleable, except when specially treated, is rigid and has great resistance to crushing, but is more or less brittle and not adapted to tensile strains. Wrought iron is nearly pure iron, and in modern metallurgical processes is usually obtained by removing the carbon and other impurities from cast iron. ”

“ Plunging it suddenly in cold water is apt to render the metal brittle. In the purchase of all iron fittings for either waggon work or horse equipment, about which we shall have more to say as our work proceeds, insist on seeing it, without paint or varnish, bare from the forge, as you can then see that there are no hollows, cracks, or defects in it. It is wonderful what a number of shortcomings a good thick coat of coal-tar will cover when laid on over the hot metal. Avoid malleable cast iron as you would a broken limb. It cannot be bent without the danger of nipping off short. ”

“ That is, as soon as a vessel costing millions of dollars leaves the docks, she enters into active competition for a place on the junk pile."
The greatest improvement that can be imagined in the iron situation will be in the discovery and use of alloys or mixtures of iron with other materials. Steel, the strongest of all forms of iron, is an alloy of iron and carbon, and for various purposes these are further mixed with nickel and silicas. Many other alloys have been discovered within the last few years, and each makes possible new uses for iron requiring greater strength. ”

“ It is so, and that is one of its worst properties. Every liquor, and even a moist air corrode it. But the rust of iron is not pernicious: on the contrary, it is a very useful medicine.
Geo. I have heard of steel drops and steel filings given for medicine.
Tut. Yes; iron is given in a variety of forms, and the property of them all is to strengthen the constitution. Many springs are made medicinal by the iron that they dissolve in the bowels of the earth. These are called chalybeate waters, and they may be known by their inky taste, and the rust-coloured sediment they leave in their course. ”

“ With such a volume of weakening constituents and particularly with the graphite flakes cutting through and separating the iron grains as the photomicrographs show, can one wonder that cast iron is fragile—more so than steel or wrought iron? ”

“ Today wrought iron is nearly always obtained by treating pig or cast iron made in the blast-furnace, and the process is said to be ‘indirect,’ as compared with the ‘direct’ process of the ancients. The direct process is still employed by all savage races who make iron, and is also in use where the character of the ore, the fuel, or other conditions make the adoption of the blast-furnace impracticable. ”

“ First it must be mentioned that iron frequently contains injurious contaminations, sulphur, phosphorus, etc., and that it must have been very difficult for these primitive metallurgists to remove these contaminations, and to introduce the proper quantity of carbon into the iron. We must also consider that even a good, pure steel would be a useless product unless it was worked by a skillful and experienced smith. Finally, iron is much more rapidly destroyed by oxidation than bronze. ”

“ 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. ”

“ Between 1860 and 1870 the invention of the Bessemer and open-hearth processes introduced a new class of iron to-day called “mild” or “low-carbon steel,” which lacked the essential property of steel, the hardening power, yet differed from the existing forms of wrought iron in freedom from slag, and from cast iron in being very malleable. Logically it was wrought iron, the essence of which was that it was (1) “iron” as distinguished from steel, and 802 (2) malleable, i.e. capable of being “wrought.” ”

“ 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. ”

“ But the working door of a puddling furnace is the door through which the puddler does his work. It is a porthole opening upon a sea of flame. The heat of these flames would wither a man's body, and so they are enclosed in a shell of steel. Through this working door I put in the charge of “pigs” that were to be boiled. These short pieces of “mill iron” had been smelted from iron ore; they had taken the first step on their journey from wild iron to civilized iron. There isn't much use for pig-iron in this world. You've got to be better iron than that. Pig-iron has no fiber ”

“ In 1854 I took out a patent for puddling iron by means of steam. Many of my readers may not know that cast-iron is converted into malleable iron by the process called puddling. The iron, while in a molten state, is violently stirred and agitated by a stiff iron rod, having its end bent like a hoe or flattened hook, by which every portion of the molten metal is exposed to the oxygen of the air, and the supercharge of carbon which the cast iron contains is thus "burnt out." ”

“ It was only after the next great advance that we found man utilizing iron for his purposes of civilization. This metal, which with us is so common, was in those days very expensive, so much so that it could be used only for purposes of war and as the gifts of kings.
But the world was traveling fast and it was not long before the iron-carbon alloy, steel, was produced. Even so, many hundreds of years elapsed before the present wonderful age was ushered in through the great inventions of Henry Bessemer and the Siemens brothers. ”

“ If the iron has too much or too little carbon it cannot be hardened at all; if there is too little it is very soft and malleable and is called “wrought iron”. If there is too much carbon it is harder than mild steel, but is very brittle indeed ”

“ 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. ”

“ Iron, obtained in this way, is not however pure; for it contains either some of the other metals, or oxygen, carbon, silicon, or phosphorus.
When small pieces of iron are stratified in a crucible with charcoal powder, and exposed to a strong heat for eight or ten hours, they are converted into steel. Steel is brittle, resists the file, cuts glass, and affords sparks with flint. It loses its hardness by ignition and cooling. It is malleable at a red heat. It melts at 130 degrees of Wedgwood. By being repeatedly ignited in an open vessel, it becomes, by hammering, wrought iron. ”

“ Prescott, “just remember three things: fuel, blast, and hammer—power, of course, behind the hammer. It’s the different variations that men have been making on those three things that have brought iron where it is to-day.
“Iron ore has so many things besides iron in it that the problem has always been how to get the impurities out.
“The old blacksmiths used to put it in the fire and hammer it; put it back in the fire and hammer again, until they worked most of the other things out. They made what is called forge iron. ”

“ 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 ”

“ The toughness of malleable iron renders it applicable to purposes, where great strength is required, while its difficult fusibility, and property of softening by heat, so as to admit of forging and welding, cause it to be easily wrought.
2. Cast iron, from its cheapness, and from the facility with which its form may be changed, is made the material of numerous structures. Steel, which is the most important compound of iron, exceeds all other metals in hardness and tenacity; and hence it is particularly adapted to the fabrication of cutting instruments. ”

“ These two things are done simultaneously by heating and melting the ore in contact with coke, charcoal or anthracite, in the iron blast furnace, from which issue intermittently two molten streams, the iron now deoxidized and incidentally carburized by the fuel with which it has been in contact, and the mineral matter, now called “slag.” This crude cast iron, called “pig iron,” may be run from the blast furnace directly into moulds, which give the metal the final shape in which it is to be used in the arts; but it is almost always either remelted, following path 1 of fig. ”

“ That, heated by the bricks, is forced into the furnace.
“One of those great pipes up there is where they draw off the slag. It is so much lighter than the iron that it rises to the top, like cream on milk.
“Down here they draw off the iron. Sometimes they keep it hot for the next process; sometimes it is made into pig iron.”
“What,” asked Dr. Crandon, “becomes of the slag?” ”

“ 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. ”