CONTENTS
| CHAPTER | PAGE | |
|---|---|---|
| I | The Early History of Iron | [1] |
| II | The Raw Materials | [17] |
| III | Raw Materials (Continued) | [37] |
| IV | The Blast Furnace | [52] |
| V | A General Glimpse Ahead | [69] |
| VI | Wrought Iron | [91] |
| VII | Cementation and Crucible Steels | [106] |
| VIII | Bessemer Steel | [123] |
| IX | The Open-Hearth Process | [142] |
| X | Cast Iron | [160] |
| XI | Cast Iron (Continued) | [178] |
| XII | Malleable Cast Iron | [195] |
| XIII | Cast Steel | [214] |
| XIV | The Alloy Steels | [233] |
| XV | The High-Speed Steels | [240] |
| XVI | The Mechanical Treatment of Steel | [245] |
| XVII | The Rolling Process | [259] |
| XVIII | The Rolling of Rods | [277] |
| XIX | Wire and Wire Drawing | [284] |
| XX | The Manufacture of Pipe and Tubes | [292] |
| XXI | The Manufacture of Seamless Steel Tubes | [302] |
| XXII | Transformations and Structures of the Steels | [310] |
| XXIII | The Equilibrium Diagram of the Iron-Carbon Alloys | [335] |
| References | [350] | |
| Index | [355] |
NON-TECHNICAL CHATS ON IRON AND STEEL
CHAPTER I
THE EARLY HISTORY OF IRON
Prehistoric Man
When in imagination we see the iron maker of early days sitting cross-legged on his platform between two crude bellows formed from goat skins with slits for air intakes and nozzles of bamboo, working them alternately to deliver their pitifully small streams of air into the hole in the side of a bank of clay which served as a furnace, we wonder at his patience; and after long hours of such effort his reward was only a few pounds of iron!
Contrast with this, if you please, the modern blast furnace with its towering height of 100 feet, its four huge heating stoves, the big blowing engines which each minute deliver to the furnace 50,000 cubic feet of blast, and the whole array of dust arresters, gas washers, and automatic ore and coke handling machinery which are essentials of this king of modern metallurgical devices. How insignificant seems the output of the ancient furnace when compared with the daily yield of 500 tons from this giant of to-day!
How has this come about?
The First Razor
Looking back over the centuries we see a period many thousands of years ago when primitive man lived in caves or other rude habitations and was entirely without the implements which we now consider indispensable. The weapons with which he defended his wife and babes from the wild beasts and from his warlike neighbors were clubs, wooden spears with perhaps a bone or shell tip, and hatchets of chipped stone tied with thongs of hide into a split stick. He managed by ingenious snares and his crude weapons to provide game and fish for the support of his family.
He did not shave often, for his wife was not as particular in regard to his appearance as are modern women, but when such a thing happened, a piece of shell was his razor. The good wife had no steel needles with which to sew together skins for their crude clothing. If she darned her husband’s socks it is not recorded, nor did she use steel crochet hooks in making the “doilies” for their parlor table.
When grain began to supplement the wild game, fruit, and berry diet, it was broken between flat stones or ground in stone mortars. Fires were kindled after long and laborious twirling or rubbing together of two dry pieces of wood. With his stone hatchets and by liberal burning away of parts by fire he formed his canoes from trunks of fallen trees.
This was the “Stone Age,” and iron and steel were unknown and not to be heard of for many thousands of years.
In various parts of the world copper always has occurred “native”; i.e., in the metallic form and not in combination with other elements as an earth or ore. As the centuries rolled on, man eventually learned that this soft red metal could be pounded into thin-edged implements and that it made more useful tools than those of stone, which his ancestors had taught him to form. Some of these metal implements were hard and had fairly good cutting edges, made so by accidental or intentional presence of tin, and little did he dream that the twentieth century upon finding his buried bronze implements would think his crude alloy so wonderful and talk reverently of a “lost art of tempering copper.”
Implements of the Stone Age
Gold, too, became known to him because it also occurs “native.” Its melting point was low enough that he could fashion it into ornaments, idols, and other articles for religious purposes. But during the hundreds of centuries of the “Stone Age” and during much of this—the “Bronze Age”—copper, bronze, and gold were the only metals used. Though the smiths became very dextrous in casting and modeling these metals, they yet knew not iron or steel.
Implements of the Bronze Age
Round about them during these many centuries, as multi-colored earths or rocks, were the ores of various metals. They little dreamed that when rightly treated certain of the heavy red, yellow, or black earths which lay right at their doors could give up that most useful metal, iron. No one even had knowledge of such a substance, for, unlike copper and gold, iron never occurs “free,” having too great a tendency to chemically combine with other elements, for example, oxygen of the air, with which, in moist climates, it so readily forms “iron rust.” Besides, its melting point is high and so much heat and carbon are needed for its “reduction” from the ore that, during the thousands of years that had gone before, it had never been produced.
Primitive Furnace for Smelting Iron
But one day by accident and under fortunate coincidence of rich ore, high heat, and plenty of carbon in the form of charcoal from the wood, a lump of metallic iron was formed underneath a pile of logs which had got afire and burned fiercely because of a high wind. When pounded between two stones this new heavy metal, too, was malleable and could be formed into a spearhead superior to anything yet known. Every one was interested and an observant one soon “doped out” that certain earths could be made to yield this new metal, iron.
The art of extracting it spread slowly, each artisan learning from his neighbor, and, as rich ores were plentiful in many districts, iron became more and more generally produced. Not only in one country was this so but evidence shows that in many others—in Egypt, Chaldea, Borneo, India, China, etc.,—roughly similar processes and crude furnaces came to be used.
Tubal-Cain, supposedly about 4000 years B.C., is mentioned in the Bible as an “artificer in iron and brass,” and a wedge of wrought iron was buried in the great pyramid of Cheops probably as early as 3500 B.C. This wedge was recently found and is now the property of the British Museum. The Chinese made use of iron many centuries before the Christian era, but the Assyrians are supposed to have been the first to use the metal on a really extensive scale.
The Pillar at Delhi, India
The much discussed pillar at Delhi, India, which is still standing in a remarkable state of preservation, is twenty-two feet high. It is made up of several wrought iron sections cleverly welded together. As the natives regard it with religious awe, metallurgists have been unable to make thorough investigation and chemical analysis. While the date of its erection is somewhat in doubt, it is supposed to have been about the 4th or 5th century A.D.
But from our modern viewpoint those early iron furnaces were queer things. The first were little more than piles of ore and wood or charcoal on the tops of hills where a brisk wind would make a hot fire. Later, with the invention of the crudest of bellows, the smelting was done in small holes in the side of banks of clay, charcoal made from the forest trees being used as fuel. Indeed, some of these types of furnaces still exist and are so operated to-day in neglected districts in Western India and elsewhere, producing their little five to 100 pound balls of iron after several hours of tedious work.
When the Romans invaded Britain (now England), they found the Britons making iron in crude furnaces called bloomaries; and not a great deal of improvement, except in size, was made up to Queen Elizabeth’s time, when strict laws had to be enacted to prevent destruction of the forests which were being denuded for production of charcoal, coke, which we know so well, not yet having been produced for fuel.
Milady’s Needle
The Catalan Forge
But the real forerunner of our modern blast furnace was the Catalan forge, developed in and named from Catalonia, north Spain, where it originated. The Catalan, however, and all of such crude early furnaces, including those thus far described, produced a variable kind of what we now know as “wrought iron,” and our modern “cast” iron did not appear until about 1350 when, with larger furnaces, an excess of charcoal, with greater heat and other favorable conditions, the Germans found that the pasty, difficultly melting metal could be made to absorb carbon enough to make it easily fusible. This was the secret.
To state the matter in a simple way, iron ore, which is essentially a natural “iron rust,” is the metal, iron, held in the strong chemical grip of the gas, oxygen, which normally forms one-fifth of the air we breathe. As you note, the combination forms a substance entirely unlike either the iron or the oxygen, but both of these can be regenerated from it (the ore) by chemical methods. Under influence of high heat (this is one of the chemical methods, by the way), this stranglehold can be broken by carbon, of which lampblack, graphite, charcoal, and coke, are our most familiar examples. The result, in the small, crude, and inefficient furnaces of long ago was a disappointingly small ball of crude iron, pasty and scarcely meltable, even at highest heats, but soft and malleable when cold. As mentioned, it was a variety of what is now commonly called “wrought iron.”
A Catalan Forge With Italian Trompe, or Water Blower
The ancients got this far.
But this was not “cast iron.” When, however, much more charcoal was present in the highly heated furnace than was necessary simply to combine with the oxygen of the ore, the liberated iron greedily absorbed enough of the extra carbon to change its own nature. The metal then became very fluid, whereas before it had been pasty and stiff even at much higher temperatures, or, indeed, at white heat. This liquid iron could be “cast,” that is, poured into molds and in that way made into various useful shapes. It therefore became known as “cast iron” because of this property.
So the brittle metal (cast iron) in our kitchen ranges, for instance, is only the early malleable form of the metal surcharged with or having a large amount of carbon (3½ per cent to 5 per cent) in its make-up, and it is this supercarbon content which confers the fluid quality while hot and the extreme brittleness when cold. True, there are other important constituents in our modern cast iron, but for our present purpose they need not be dealt with.
It has been stated that the ancients got only as far as balls of wrought iron. They really got further as their very fine sword steels show—the “Wootz” of India, the “Damascus” of Syria, and later the “Toledo” of Spain. These they produced by heating rich ore in very small, closed crucibles with just enough carbon (pieces of wood or green leaves) to make what we now call “carbon tool steel.” As carbon steel is simply iron which has absorbed not over 2 per cent of carbon (cast iron described above has a supersaturation with its 3½ per cent to 5 per cent of carbon and therefore is entirely different) they were able to make it in small quantities. When hardened by cooling quickly in water, a forged-out blade of this product would cleave without dulling its edge a piece of iron, it is said, or cut cleanly a tuft of silk floss tossed into the air. These steels attained well deserved renown.
While no one can desire to cast the slightest disparagement on the product of that period, much of which was excellent, astonishingly so considering the period, a moment’s consideration will convince one that modern products not only do not suffer in comparison but in reality are immensely superior. The ancients had little or no knowledge of the reason for the proper qualities of their tools and they made the metal from variable materials in a crude way in such small quantities that little uniformity was possible. While some of the product was undoubtedly excellent, much must have been less desirable.
Modern discoveries and inventions, with the great mechanical progress of the last three centuries and the scarcely half-century-old application of chemical control, have given during recent years products of great uniformity and marvelous quality. What can compare with thirty thousand pound lots of steel turned out from one Bessemer converter each seventeen minutes during the 24 hours in the day, that is, a total of 1300 tons or 2,600,000 pounds, in which not only the main controlling element, carbon, but also four lesser ones, silicon, manganese, sulphur, and phosphorus, are held within extremely narrow limits; or the modern blast furnace which produces a million pounds each 24 hours, run with the same certainty of control? Modern high-speed steels which are every day being made have such high quality that tools formed from them will stand up for hours working red-hot under a lathe speed of two or three hundred linear feet per minute taking a deep cut and “plowing out” chips faster than a laborer can carry them away.
The German Stuckofen
Modern war armament which has recently been so well advertised is sufficient answer as to whether modern metallurgy is in advance of that of centuries ago.
The only necessity for such comparisons is that it seems to be a failing of many to think that our forefathers were more wise and better in other ways than we. It was but a few years ago that the fallacious announcement was made that during archeological excavations in Egypt there had been found a fully equipped telephone system. The inference intended to be conveyed, of course, was that Bell’s invention of the telephone had been antedated many hundreds of years.
A German Blast Furnace of Fifty Years Ago
The forerunner of the modern steels was crucible steel, first made by Huntsman about the middle of the eighteenth century. Previous to his time steel had been made by the “cementation” process by which method hammered-out bars of wrought iron were given a hard steel crust by heating to a red heat in charcoal or bone dust. Huntsman’s product began to come so uniform and of such quality that his competitors were quite outdistanced. It is related that one of them took advantage of a very severe storm to gain admittance to the forest forge of Huntsman, who, he knew, could not refuse shelter at such a time. What he beheld was a very simple thing—the melting in a clay pot of pieces of cementation steel.
Even to-day the crucible process is holding its own where quality is the main consideration. It is the method by which practically all of the tool, automobile, and other special steels of to-day are manufactured and can hardly be given too high a rating. The newly devised electric furnace process is the only possible competitor in sight. Of course for quantity and for lower cost the Bessemer and the open-hearth processes are the only available ones, but crucible steel has been the mighty factor in the commercial development of the world—at least until the latter half of the last century when the two other processes last mentioned began to acquire honor of their own without, however, detracting much from the importance of crucible steel as the steel of “quality.”
The First Iron Casting Made in America
Though more interesting than any of the “six best sellers” much of the subsequent history of iron will have to be passed over at this time. We can now only mention those very great and revolutionary discoveries and inventions which led to and absolutely are the basis of the quantity and excellence of modern irons and steels; namely, the trial for a time of coke made from pit coal by Dud Dudley of England and its failure which was turned into a great success a century later (about 1713) by Abraham Darby; Watt’s invention of the steam engine in 1770 which made possible application of a strong continuous blast; invention of the process of “puddling” of iron and of the rolling mill by Cort about 1784; the introduction by Neilson about 1830 of the hot instead of the cold blast which increased blast furnace production fourfold; the regenerative system of furnace heating invented by Frederick and William Siemens; and the invention of the Bessemer and Siemens-Martin or open-hearth processes which provided methods for steel making on such an immense scale that this invaluable material was made available for general purposes.
It should be repeated that the inventions just mentioned have been of the utmost importance to the iron industry, and through them only has it acquired its consequence of to-day. Without them we would not have the wonderful steel bridges, the skyscrapers, the gigantic steel ships, the all-steel railway trains, etc., and the hundreds of iron products that are to-day so plentiful and so constantly about us that we disregard their presence. It is difficult thus to pass them by, but as most of them will be referred to in later chapters we must do so.
Early iron making in America is of interest to us and must be briefly stated.
The colonists were aware of some of the iron ore deposits about them and sent samples to England where these yielded very fine iron. In 1619 a company known as the “London Colony” was sent out from England to engage in the manufacture of iron at Falling Creek, near Jamestown, Virginia, but three years later all were massacred by Indians. It was many years before attempt was again made to manufacture iron in Virginia.
About 1637 the General Court of Massachusetts granted to Abraham Shaw one-half of the benefit of “any coles or yron stone wch shall bee found in any comon ground wch is in the countryes disposing.” Apparently little resulted from this high-sounding grant.
Real iron making in America began six years later with John Winthrop, Jr., and his “Company of Undertakers for the Iron Works” which for many years operated in several localities in the New England States. Heaps of cinders left from their furnaces may still be seen and testify to their very extensive operation. One of Winthrop’s men was Joseph Jenks, who became known as the “Tubal-Cain” of New England. What is claimed to have been the first casting made on the Western Continent was made by him. It is a small pot, which was acquired and is said to be still owned by the family of Thomas Hudson, a descendant of Hendryk Hudson.
Sand molding as used at present was introduced by an ingenious Englishman, Jeremy Floris, and is vastly superior to the previously used system of molding in clay. Hollowware began to be extensively produced about this time.
As the country developed, iron works sprung up here and there and various kinds of articles came to be regularly manufactured. Of the early plants we can only mention the Stirling Iron Works, at Warwick, New York, which made the great 186–ton chain with links weighing 140 pounds each, which spanned the Hudson River near West Point, and where in 1816 was cast the first cannon made in America; the foundry of Sharp & Curtenius, in New York, where was cast the first steam cylinder; and the Trenton Rolling Mills, which first rolled iron as fireproof structural material.
Before the Revolutionary War the colonies exported considerable bar and pig iron to Europe, and as early as 1791 England began to foresee that this country would eventually be a serious rival.
Pittsburg’s great advantage as an iron and steel center has been due to its proximity to an extensive seam of bituminous coal and ore in adjacent counties, and to its location so near the Great Lakes, which provided cheap water transportation for the Lake Superior ores. The first iron works there was that of Turnbull & Company, which was established in 1790.
Though Reameur, a Frenchman, is the accredited discoverer of the process of malleableizing cast iron, Seth Boyden, in a little shop in Newark, New Jersey, made malleable iron castings a commercial success.
Two Modern Blast Furnaces, Showing Skip-Hoists, Cast Houses, Stoves, and Ore Pile
The utilization of the great beds of high grade coking coal of eastern Pennsylvania, well known as the Connellsville district, and the discovery and development of the Lake Superior ore deposits have made the United States the leading producer of iron and steel of the world. The development of the Birmingham, Alabama, district, also has been a chapter of great importance but lack of space forbids description at this time.
We can have only a very slight appreciation of the debt which civilization owes to iron, for practically everything we see or with which we daily come in contact contains or has resulted from application of iron in some way or other. Our cooking utensils and implements (even the enameled and tinned ones), the kitchen range, the water and drain pipes, and the furnace and heating plants of our houses, are they not largely of iron? Our main building materials—the steel frames of skyscrapers and bridges, and are not even wood, brick, stone, and cement either shaped, molded, or of necessity made by aid of iron machinery? The conveyances by which we travel—wagons, automobiles, street cars, steam railways and steamships—how would they be possible without iron or steel? Consider the power plants of our factories, of gas and electric lighting plants, the pumping machinery and distribution systems of water works, mines, etc. Would the electric current which supplies so much of our power and light be known to-day or even be possible but for the magnetic properties of iron? And how many of the materials and articles which we wear, use, and have about us constantly would be in any way possible without the wealth of steel machinery and tools which are available and absolutely necessary for their production?
The iron industry is often spoken of as the barometer of a people’s civilization. If all iron and iron products and their influence upon the world should be obliterated, it seems impossible that we could be even started on the road to civilization.
No matter how we try, probably none of us ever realizes the immensity and importance of the iron and steel industry with approximately 460 huge blast furnaces here, 5000 cast and malleable iron foundries, about 1000 Bessemer and open-hearth steel and some 3000 puddling furnaces, and the many thousands of factories which each day are turning the products of these into rails, plate, wire, pipe, and the infinitude of finished articles which enter into and are mighty factors of our civilization. Yet with these furnaces, forges and factories at our very doors, 99.9 per cent of us are entirely oblivious to their wonders and to their presence except to be annoyed by their noise and smoke. Even the blacksmiths and their service we scarcely note, though they are daily fashioning for us a material which is vastly more important and more wonderful than any of the “Seven Wonders of the World.”
CHAPTER II
THE RAW MATERIALS
A story has it that a minister once visited a friend who was a zoölogist. Upon realizing for the first time how highly organized a creature was the humble earth-worm with its three-layer skin covering, alimentary canal, nephridia or excretory system, reproductory organs, rude nervous system, and setæ for purposes of locomotion, he exclaimed: “Wonderful! I had always supposed that worms were only skin and squash.”
With millions of tons of heavy reddish-brown earth from northern Michigan and Minnesota going by our doors continuously during the shipping season, the position of most of us is very similar to that of the minister relative to the earth-worm. We know that something is going on but we are not aware of its importance or the immensity of it.