Popular Science Monthly/Volume 39/October 1891/The Development of American Industries Since Columbus: Iron and Steel Industry V
|THE DEVELOPMENT OF AMERICAN INDUSTRIES SINCE COLUMBUS.|
VIII. THE MANUFACTURE OF STEEL.
By WILLIAM F. DURFEE, Engineer.
IT is now two hundred and thirty-six years since the first American steel maker of which we have any record, Mr. John Tucker, of Southold, Long Island, informed the General Court of Connecticut of his "abilitie and intendment to make Steele there or in some other plantation in this jurisdiction, if he may have some things granted." The court (says Bishop) acquiesced in a grant of privileges, and, in the following May, Tucker obtained from the Assembly a declaration "that if he doe laye out his estate in such a manner about this publique worke, and that God shall cross him therein so that he be impoverished thereby, they are willing that that small remaining part shall be free from rates for ten years." Possibly Tucker thought that the "protection" guaranteed by the colony was not sufficient, as we have no evidence that he ever availed himself of it, or was ever "impoverished thereby."
In 1728 Samuel Higley, of Simsbury, and Joseph Dewey, of Hebron, in Hartford County, Connecticut, represented to the Legislature that the said Higley had, "with great pains and cost, found out and obtained a curious art by which to convert, change, or transmute common iron into good steel sufficient for any use, and was the first that ever performed such an operation in America." Swank gives on the authority of Mr. Charles J. Hoadly, Librarian of the Connecticut State Library, a certificate, signed by Timothy Phelps and John Drake, blacksmiths, which states that, in June, 1725, Mr. Higley obtained from the subscribers several pieces of iron, so shaped that they could be known again, and that a few days later "he brought the same pieces which we let him have, and we proved them and found them good steel, which was the first steel that ever was made in this country that we ever saw or heard of."
A patent was granted Higley and Dewey for ten years, provided "the petitioners improve the art to any good and reasonable perfection within two years from the date of this act." They do not appear to have done this, or to have continued the business of making steel.
In 1740 the Connecticut Legislature granted to Messrs. Fitch, Walker & Wyllys "the sole privilege of making steel for the term of fifteen years upon this condition, that they should in the space of two years make half a ton of steel"; this condition not having been complied with, the privilege was extended to 1744, before which time Aaron Eliot and Ichabod Miller certified that more than half a ton of steel had been made at the furnace in Symsbury.
Some time before 1750 a steel-furnace was in operation at Killingworth, in Middlesex County, Connecticut. This furnace (says Swank) was owned by Aaron Eliot, and in it he succeeded, in 1761, in converting into good steel a bar of iron, made in a blomary fire from magnetic sand, by his father, the Rev. Jared Eliot.
Mr. Swank quotes from Mr. Hoadly a petition presented to the Legislature of Connecticut in May, 1772, by Aaron Eliot, in which the petitioner recites that his capital "has not been large enough to supply himself with a sufficient stock to carry on his business, & has, therefore, hitherto been obliged to procure his stock of iron from New York on credt, and pay for the same in his steel, when made, at the moderate price of £56 per ton [$186.662, the £ being equal to $3.331], from whence it has been again purchased in this Colony at the price of £75 and £80 per ton; and, for several years past, almost the whole supply of steel in this Colony has been from New York, of the manufacture of your memorialist, at the aforesd enormous advance." He accordingly begs for a loan of £500 from the public treasury for three years without interest; this, he says, would "save large sums of money within this Colony, which is annually paid to New York for the steel manufactured in this Colony."
Eliot's prayer was granted, and in 1775 the loan was renewed for two years longer. It appears from returns made by the Colonial Governors in 1750, in conformity with the Act of Parliament, that Massachusetts, Connecticut, and New Jersey had each one steel furnace, and Pennsylvania two; both of these were in Philadelphia, owned by William Branson and Stephen Paschal, respectively. Branson stated in regard to his steel that "the sort he made, which was blistered steel, ten tons would be ten years in selling." Paschal's furnace was built in the year 1747, on a lot at the northwest corner of Eighth and Walnut Streets; this furnace in 1787 was owned by Nancarrow & Matlock, when it was visited in that year by General Washington, and said to have been "the largest and best in America." Whitehead Humphreys, who in 1770 was the owner of a steel-furnace on Seventh Street, Philadelphia, and made steel for the Continental army, was granted in 1786, by the Legislature of Pennsylvania, a loan of £300 for five years, to aid him in making steel from bar iron "as good as in England."
In 1777 Rhode Island "gave £60 per gross ton for good German steel made within the State."
The Legislature of Massachusetts granted in 1778, to the Rev. Daniel Little, "£450, to aid in erecting at Wells [in the District of Maine] a building 35 X 25 feet, to be used in manufacturing steel."
In 1787 the manufacture of steel was commenced in the town of Easton, Massachusetts, by Eliphalet Leonard, and we are told by Bishop that "the article was made in considerable amount, and cheaper than imported steel." About 1797 steel was made at Canton, in the same State, "from crude iron, by the German process." Peter Townsend, the proprietor of the Sterling Iron Works, in New York, made in 1776 the first steel produced in that province, and his son, Peter Townsend, Jr., is said to have made, at the same works, in 1810, steel "of as good quality for the manufacture of edged tools as that made from Dannemora iron."
Alexander Hamilton, in a report dated December 5, 1791, says, "Steel is a branch which has already made considerable progress, and it is ascertained that some new enterprises on a more extensive scale have been lately set on foot." In the same year Tench Coxe, in replying to Lord Sheffield's Observations on the Commerce of the United States stated that "about one half of the steel consumed in the United States is home-made, and new furnaces are building at this moment."
Swank states that "in 1805 there were two steel-furnaces in Pennsylvania which produced annually one hundred and fifty tons of steel. One of these was in Philadelphia County. In 1810 there was produced in the whole country nine hundred and seventeen tons of steel, of which Pennsylvania produced five hundred and thirty-one tons in five furnaces. . . . The remainder was produced in Massachusetts, Rhode Island, New Jersey, Virginia, and South Carolina; each State having one furnace. In 1813 there was a steel-furnace at Pittsburgh, owned by Tuper & McKowan, which was the first in that city."
All the steel manufactured in 1 America prior to the year 1810 was produced either by what was called the "German method," which was conducted in a "hearth" similar to that used for a "blomary fire," or by the "cementation process." The " German steel" was made directly from the ore or a suitable quality of "pig iron" was used. The operation, when ore was employed, consisted in removing the oxygen, and then by appropriate manipulation, together with a regulation of the blast and heat, the iron was combined with carbon derived from the fuel to such a degree as to convert the metal into a mass of crude steel; this was carefully drawn under a light, quick-working hammer into bars about an inch square; six or eight pieces of these bars were made into a "pile," welded together, and drawn into smaller bars. This process, called "refining" was repeated a number of times, and the quality of the resulting steel was designated by the terms "single" "double," or "triple refined," according to the number of weldings and hammerings. When "pig iron" was used, the operation consisted in so manipulating the metal and regulating blast and heat that a portion of the carbon in the "pig" remained in the resulting "bloom" of crude steel, which was subjected to the same "refining" as has just been described.
All the early attempts to make steel in America were in the "German manner"; but it was soon discovered that the ores and pig irons available were not of a proper quality, and attention was early directed toward the "cementation process," the details of which were fully described by Réaumur in 1722.
The operation of making "cemented" or "blister" steel consisted essentially in packing bars of wrought iron in charcoaldust in long boxes or "pots" made of sandstone or fire-brick. These "pots" were covered as nearly air-tight as possible and subjected to a high degree of heat (not, however, sufficient to melt the bars of iron), which was regulated as to temperature and duration according to the contemplated use to be made of the steel. As a rule, the higher the temperature and the longer time it was kept up, the greater the degree of carburization of the bars in the "pots" and the harder the resulting steel. When the iron is packed in the charcoal, one or more bars are allowed to project through openings in one end of the "pots"; these bars are removed at proper intervals of time, and from their appearance when cold the progress of the operation was judged. When the process of "cementation" was finished, the furnace was allowed to cool, and, as soon as men could work therein, the metal was removed from the "pots," and it was found that it had undergone a great change: instead of having a smooth surface, it was covered with a large number of "blisters" of varying size and thickness (hence the name "blister steel"), and, although when put into the "pot" the metal was very fibrous and tough, it was found on removal to be very crystalline and brittle. These changes of structure and fracture were due to the absorption of carbon from the charcoal dust in which the bars had been packed.
Fig. 50 is a cross-section of a "cementation" or "blister-steel" "converting furnace" in which the various parts are so plainly designated that additional description is unnecessary. The degree of carburization, and consequently the hardness of the steel produced in such a furnace, necessarily varied, and for the convenience of manufacture and trade the product was assorted into six grades or "heats."
When steel was wanted of closer grain, firmer texture, and more reliable character, a certain number of bars of this "blister steel" were made into a bundle or "fagot" and welded together, and the resulting bar was called "single shear" steel; and if a still higher quality was required, bars of "single shear" were welded and drawn into bars called "double shear steel."
Previous to the year 1812 we have no record of there having been any steel produced in America by other than the processes already described, but in that year John Parkins and his son, Englishmen, "are said to have made an unsuccessful attempt to make cast steel in New York City," and the same authority tells us that they were employed, in 1818, at Valley Forge, Pa., to make cast steel for a saw manufactory.
In 1831 John R. Coates, of Philadelphia, stated that there were then in the United States fourteen blister-steel furnaces, which had "a capacity sufficient to supply more than sixteen hundred tons of steel annually, an amount equal to the whole importation of steel of every kind. . . . The only steel now  imported from Great Britain is of a different and better quality than that just mentioned." Cast steel was not then made in the United States. This variety of steel was invented in England, by Benjamin Huntsman, in 1740. Mr. Huntsman was a watch-maker, and also made clocks, roasting-jacks, and other mechanical contrivances.
The invention of Huntsman consisted substantially in breaking "blister steel" into small fragments, placing these in a crucible, and subjecting that to sufficient heat to render its contents perfectly fluid; the fluid steel was then poured (or "teemed") into a cast-iron mold. Melting the "blister steel" removed all its solid infusible impurities, and when the ingot which resulted from the "teeming" (or "casting," hence the term cast steel) was hammered or rolled, the product was found to be much more homogeneous, and the temper more uniform, than was ever the case in steel made by the old welding process. The first attempt to produce "cast steel" in America that is fairly entitled to be called successful was made by the brothers William and John Hill Garrard, natives of England, who in August, 1832, commenced the manufacture of "cast steel" in works located on the Miami Canal, at Cincinnati.
Metallurgical history is indebted to James M. Swank for a full account of these works, including a statement of Dr. William Garrard, who was living in 1884. As to the commercial success of his manufacture, Dr. Garrard says: "I sold my steel and manufactured articles principally to manufacturers. There were some wholesale houses that bought of me, but they were importing houses, and when the Sheffield manufacturers found that I was making as good steel and manufactured saws and files as good as they did, they gave our merchants such an extended time of credit that they bought as little as possible from us." The Cincinnati Steel Works, as this establishment was called, continued in operation until 1844, although in the last seven years of their existence the principal product was blister steel. That the cast steel made in these works was of excellent quality there is abundant proof.
It is impossible within the space available to give in detail an account of the many attempts that were made in various parts of the country, but chiefly in Pennsylvania, between the years 1830 and 1860, to manufacture steel of the best quality. The reasons for the almost uniform failure can now be very easily assigned; there was a universal ignorance of chemistry and a consequent contempt for its teachings, and the experimenters had not sufficient knowledge of practical metallurgy to utilize their occasional successes, or to draw intelligent inferences from their much more common failures. One somewhat prominent firm was so persistent in their ignorant faith that a certain iron was the best in America that, when they discovered that good steel could not be made therefrom, they abandoned an enterprise in which many thousands of dollars had been expended, because they firmly believed that they had demonstrated that it was impossible to make cast steel from American iron.
Swank tells us that in 1850 there were thirteen steel works in Pennsylvania which produced in that year 6,078 tons, of which but 44 tons were "cast steel." According to the same authority, the "Adirondack Iron and Steel Company, whose works were at Jersey City, N. J.," succeeded in February, 1849, in making "cast steel" in black-lead crucibles by melting "blister steel," made from iron that had been puddled with wood as the fuel. "Of the excellent quality of the "cast steel" manufactured at this time at these works there is abundant evidence in the testimony of Government experts and of many consumers. . . . It was used for chisels, turning and engravers' tools, drills, hammers, shears, razors, carpenters' tools, etc. Its manufacture was continued with encouraging results until 1853, when the business was abandoned by the company. It had not proved to be profitable, partly because of the prejudice existing against American 'cast steel,' and in some degree to the irregularity of the temper of the steel produced." The firm of Hussey, Wells & Co., of Pittsburg, began the erection of works in 1859, and in the following year they entered upon a successful business in the making of crucible cast steel of the best quality from American iron. In 1862 the firm of Park Brothers & Co., also of Pittsburg, achieved success with the same material. These were the first firms in America who were commercially as well as mechanically successful in the manufacture of "cast steel." Their works are still in operation and their products are well and favorably known.
There are various methods of making "crucible cast steel" besides that already mentioned as the discovery of Huntsman; one of these, which is in very common use, consists of melting in a plumbago crucible a certain weight of wrought iron cut into small pieces together with a sufficient amount of charcoal powder to properly carburize it during the process of fusion. Another method is to melt together proper proportions of "pig" and "wrought" iron. In all of the modern processes of making "cast steel" manganese enters in some form, its chief use being to effect the removal of any oxygen that may be present in the metal used.
We shall not attempt a description of the multitudes of "mixtures," "fluxes," and "physics," each intended to work wondrous beneficent changes in material positively bad, and to so purify and purge it that it would inevitably produce steel phenomenally good, that wearied the minds, vexed the souls, and too often imparted a lurid hue and sulphurous flavor to the language of the early makers of cast steel. These nostrums represented every school of "medicine"; one prescribed heavy doses of certain "salts," another was loud in the praises of minute pellets of his most potential preparation; one of the advocates of the botanical treatment extolled the efficacy of a raw potato to "agitate the metal and cause it to throw off all its superfluities, while the "eclectics" roamed through all the fields of "physic" and claimed to appropriate all the virtues and ignore the vices of the other practitioners.
The original method of melting cast steel consisted in placing a single "pot" with its contents in a square vertical furnace, or "hole," whose top was level with the floor of the "casting house"; the furnace was then filled with either coke or anthracite coal, care being taken that the fuel was distributed equally on all sides of the "pot," which was provided with a "lid" to protect its contents from contamination by the entrance of coal or other matter.
The fire was then urged by the powerful draught of a chimney, or frequently by a "blower." Many of the later "melting holes," in which solid fuel was used, were made large enough to contain two, and some of them four "pots."
All the cast steel made in America prior to the year 1868 was melted by solid fuel in "holes" such as have been described; but in November, 1867, Messrs. Anderson and Woods, of Pittsburg, procured a license from the American owners of the Siemens patents for "regenerative gas furnaces," and under this license a "twenty-four pot" melting furnace was erected under the supervision of William Durfee, in their works at Pittsburg, Pa., in the spring of 1868, according to plans prepared by J. Thorpe Potts, C. E., who represented Dr. Siemens in America. This was the pioneer furnace in the United States using gaseous fuel for melting cast steel, and its success led to their rapid introduction in other works, so that to-day there are not many of the old-fashioned "holes" using solid fuel to be found.
In Fig. 51 we have a vertical cross section of a "Siemens regenerative gas furnace" for melting cast steel. Fig. 52 is a top view of the furnace, showing two of the "melting holes" covered and six "pots" in place in the open hole; the top of the furnace
Fig. 51.—Vertical Cross-section of a Siemens Furnace for melting Steel in Pots.
on the left having been removed to show the flues. The distinguishing peculiarity of the "Siemens furnace" is the method of utilizing the escaping heated products of combustion for heating the incoming gas and air. This is accomplished by what are called the "regenerative chambers," which are situated to the right and left of, and at a lower level than, the "melting holes." As will be seen in Fig. 51, there are four of these chambers, the two smaller being for gas, and the two larger for air.
Air enters the flue at the lower part of the left-hand chamber, and, passing upward, it absorbs whatever heat may be in the reticulated mass of fire-brick with which the chamber is filled, and, on reaching its top, it turns to the right in the direction of the arrow, and, just previous to entering the "melting hole," it encounters and combines with the incoming gas, which also has been highly heated by contact with the bricks in the "gas chamber." The result is the ignition of the gas immediately at the entrance to the "melting hole"; intense combustion ensues, the ignited gas expanding and completely enveloping the "pots," and the highly heated products of this combustion leave the "melting hole" on the side opposite to that at which they entered, and on their way to the chimney they pass through each of the right-hand chambers of the furnace, and in their passage raise the bricks therein to a high temperature.
After the furnace has worked for a proper time in the way described, the brick-work in the left-hand chambers will have become considerably cooled, and then the "melter" reverses certain valves (not shown in the figures), causing the currents of gas and air to be reversed—that is to say, the gas and air will now come in through the right-hand chambers and pass out through the left. In this way a very intense heat is maintained in the "melting hole," which can be regulated at pleasure by varying the amount and proportion of the gas and air used. The advan-
Fig. 52. Plan of Siemens Pot Furnace.
tages of this furnace are sufficiently numerous and important to make its employment compulsory in all well-administered establishments.
In whatever kind of a furnace the steel is fused, as soon as the metal in the "pots" is thoroughly melted they are removed therefrom by a pair of tongs similar to those shown on the "pot" at the right hand of Fig. 53. and the "teemer" then grasps the "pot" with another pair of tongs and "teems" (pours) the fluid steel into an ingot mold of cast iron, care being taken that the stream of metal passes down the center of the mold without coming in contact with its sides.
The heat of the whole operation of "pulling out" the "pots" and "teeming" the steel (which last is well represented in Fig. 53) is so great that the workmen envelop their limbs in thoroughly soaked woolen cloths (technically called "rags"), which require wetting repeatedly during the casting of a "heat" of steel.
When the manufacture of cast steel was first undertaken in England, the "ingots" of steel were drawn into bars of various sizes and shapes, under quick-working "tilt-hammers," and this operation was called "tilting the steel"; the "filter" sat in a suspended seat, and moved his body to and from the anvil by his feet, while his eyes were fully occupied in watching the size and form of the bar, and his hands in turning it upon the anvil. The English machinery and practice were copied in this country, in the
Fig. 53.—"Teeming" an Ingot of Steel.
early steel works, and a plant of steel "tilting-hammers" is shown in Fig. 54. No small part of the expense of maintaining such a plant was the cost of timber for the wooden "helves" of the hammers, which, notwithstanding the heavy bands of iron encompassing them, required frequent renewal, owing to the shattering effect of the heavy and constantly repeated blows to which they were subjected. At the present time all "cast steel r is drawn under steam hammers, whose construction is a modified form of that invented by Nasmyth, already described.
The first step toward the production of steel in such large masses as were required for cannon, armor-plate, the shafts of ocean steamers, and parts of steam-engines of the largest class, was the making of steel by a modification of the puddling process, whence the new product was called "puddled steel." The operation consisted in using a superior quality of charcoal pig iron, and in so manipulating it that the carbon was only partly removed; and the resulting product was a weldable and forgeable metal, possessing many of the qualities of the softer varieties of steel. The art of puddling steel is of German origin. The first efforts to practice it are said to have been made at Frantschach, by Schlegel and Müller, in 1835. This and several other attempts failed, and "it was not until 1850 that good puddled steel was produced in the iron-works of Messrs. Lehrkind, Fakenroth & Co., at Haspe, by following the suggestions of the chemist Lahaye."
The process was introduced into England in 1850 by Ewald
Fig. 54.—Old Style of Steel "Tilting-Hammers."
Reipe, and hence became known there as the "Reipe process"; it was patented in 1859 in the United States by Anton Lohage, and was operated for a time by Messrs. Corning & Winslow, of Troy, K Y., and by Messrs. James, Horner & Co., at Pompton, N. J. In 1870 there were eleven hundred and eighty-five tons of "puddled steel" made in this country, valued at $218,500; but before the year 1880 the process appears to have become obsolete in America. By their neglect of tins process the owners of American iron and steel works threw away what would have been to many of them a source of great profit during the twenty years preceding the introduction of the "Bessemer" and "open-hearth" processes of manufacturing steel. In Europe, however, during the past forty years, a very large amount of stool has been made in this way, much of it for remelting in pots, and a great deal being used for forgings. In the "Centennial Exhibition of 1876" there was shown in the Swedish department by the "Motala Iron and Steel Works" a number of welded coils of "puddled steel" intended for "gun-hoops" and several finished "hoops."
The introduction of the "Bessemer process" into the United States preceded by a few years that of the "open-hearth," but their advent was practically coincident. For convenience, the latter will be described first. By this process pig iron of a suitable quality is melted on the hearth of a reverberatory furnace, and then either wrought-iron "scrap" or iron ore is mixed therewith.
The principle of the "open-hearth" process was well understood by metallurgists for many years before it could be carried into practice, owing to the impossibility of securing a sufficiently intense and continuous heat in any ordinary form of reverberatory furnace. As early as 1824, M. Bréant stated that "it would be possible to produce cast steel on a very large scale in reverberatory furnaces by following a process analogous to that of the depuration of bell-metal—that is to say, by adding to the metal in fusion [pig iron] a portion of the same metal oxidized, or, still better, natural oxide of iron." In 1845 Josiah Marshal Heath (who invented the use of manganese in melting steel in pots) patented a method of making steel in large quantities by melting cast and wrought iron together upon the open hearth of a reverberatory furnace; and, for the purpose of preventing the contamination of the metal by the ashes of solid fuel, he designed to heat his furnace by jets of gas. But the experiments of Heath, although pointing out clearly the road to success, were not themselves successful. M. Alfred Sudre patented in England, December 31, 1858, a method of melting steel in a reverberatory furnace. He made experiments in 1860 and 1861 near Paris, the expense of which was defrayed by the Emperor of the French, but they fell short of a commercial success. It was not until 1864—forty years after the original suggestion of M. Bréant—that the making of steel by the fusion of pig iron and wrought-iron "scrap" on the open hearth of a gas-fired reverberatory furnace could be regarded as commercially and technically successful. This result was attained by a combination of the "regenerative gas furnace," then recently invented, with the perseverance and technical skill of Messrs. Émile and Pierre Martin, who, notwithstanding its failure in other places, erected one of the Siemens furnaces in their works at Sireuil, France. Evidently there was a lurking doubt in the minds of the Messrs. Martin, for this furnace seems to have been so constructed that, if it failed as a melting, it would succeed as a heating furnace. Nevertheless, they succeeded in producing in it cast steel of excellent quality, of a variety of tempers, for which they were awarded a gold medal at the French Exhibition of 1867. The success of the Messrs. Martin, together with the fact that patents had been granted them for certain details of manipulation, brought about a combination of the interests of the Messrs. Siemens and Martin in the process, which has come to be known as the "Siemens-Martin open-hearth process." The construction of a small furnace for conducting this process is illustrated by Figs. 55 and 56—the first being an elevation showing the "ingot molds." arranged in order upon a traveling carriage, k, by which they are successively brought under the "tapping spout," b, to
Fig. 55.—Elevation of an Open-hearth Furnace.
be filled. Fig. 56 is a vertical cross-section, taken through the "charging door," a, and the "tapping spout" b, of the same furnace. Beneath the melting chamber will be seen the "regenerative checker-work," C, C, whose function and operation are the same as in the "pot melting furnace" already described.
The earlier "open-hearth" furnaces were like that illustrated, quite small, making but two or three tons of metal; but at the present time there are a number in operation of upward of twenty tons capacity, equipped with much more perfect apparatus for casting ingots than that shown in the engraving.
To the Hon. Abram S. Hewitt is due the credit of introducing the "Siemens-Martin" "pig and scrap" process into this country. While serving as one of the United States commissioners to the Paris Exposition of 1867, he became favorably impressed with the merits of the process, and sent Frederick J. Slade to Sireuil to study it in detail. In 1808 Mr. Slade built for Cooper, Hewitt & Co., at Trenton, the first "open-hearth" furnace constructed in America, which was put in operation in December of that year. The process made slow progress for several years, and we find that in 1874 there were but 7,000 net tons of steel made in that way in the whole country; but from year to year the manufacture has increased, until in the census year ending June 30, 1880, there was reported 84,302 net tons, which we find augmented to 504,351 net tons for the census year ending June 30, 1890.
Within recent years there have been several efforts to produce "direct from the ore" "blooms" or "muckbar" for use instead of "wrought scrap" in the open-hearth furnace, some of which give promise of success under favorable conditions of location, ore, and fuel. There have also been several attempts to make what has been very properly called "iron sponge" for use in the "open hearth." Of the details of some of these it can be said that whatever was new was not good and all that was good was not new. However, it is not improbable that a good way of making "iron sponge" will yet be devised, and there are some encouraging experiments even now in progress. In the past twenty years variously contrived rotating furnaces have been invented to produce "blooms," in which for the severe manual labor of puddling was substituted a mechanical movement of the furnace itself. Some of these contrivances have had an ephemeral success, but none have won a place among generally approved apparatus.
The Bessemer Process.
No improvement in practical metallurgy since the time of Tubal-Cain has realized such magnificent results in increasing the quantity produced and diminishing the selling price of a metal as that which is known world-wide as the "Bessemer process" of manufacturing steel. In general terms the "Bessemer process" may be described as the art of decarburizing molten cast iron by blowing streams of atmospheric air into and through it.
For over three quarters of a century the germ of this wonderful process lay dormant in the "refinery fire," awaiting the time when the needs of man should call it forth. It will be remembered that the decarburization of the molten iron in the hearth of the "refinery fire" was accomplished slowly and imperfectly by blowing air upon its surface beneath a large mass of fuel whose presence was believed to be absolutely necessary in order to maintain the heat of the metal under treatment. Had those early refiners blown the air into the metal, they would have been astonished to find that its temperature increased rather than diminished; that the refining operation was very much shortened; and that, if the blowing was continued for a short time longer than was necessary to make refined cast iron, the metal would become malleable—in short, they would have discovered what is now called the "Bessemer process."
Success is always perilously near to failure. All great inventions and discoveries have usually more than one claimant, and this revolutionary process is no exception to the rule—a rule which is so universal that it almost justifies the belief that when in the fullness of time the world is prepared for a decisive advance in the sciences or the arts, an overruling power indicates simultaneously to minds separated oftentimes by continents and oceans some way to satisfy the growing needs of the world, and all to whom such revelations are given, who contribute to their promulgation and success, are entitled to an honorable recognition and reward commensurate with the value of their services to mankind. The first mention of an attempt to improve the refining of molten cast iron by the action of air introduced below its surface is in an English patent granted September 15, 1855, to Joseph G. Martien, of Newark. N. J., then residing in London. The general nature of Martien's process is thus stated in the specifications of his patent. "In carrying out my invention, in place of allowing the melted iron from a blast-furnace simply to flow in the ordinary gutter or channel to the bed or molds, or to refinery or puddling furnaces in the ordinary manner, I employ channels or gutters so arranged that numerous streams of air, or of steam, or vapor of water may be passed through and among the melted metal as it flows from a blast-furnace."
In commenting upon this patent the late Dr. Percy very truthfully says: "It is perfectly clear from the specification that the patentee did not propose to effect by his process the conversion of pig iron, whether unrefined or refined, either into steel or malleable iron; and it is equally clear that he simply intended it to be employed as accessory to the ordinary process or processes in common use for effecting the conversion of pig iron into malleable iron. . . . The patentee emits not the slightest hint to show that he was aware of the fact that by blowing atmospheric air through molten pig iron sufficient heat would be developed to keep it in a state of liquidity, even for a very short time. Air and steam are spoken of precisely as though they were similar agents, and would produce similar effects, whereas their effects would be radically dissimilar. . . . However, in October or November, 1855, that is, two or three months prior to the jmblication of Bessemer's first patent, in which he first announced that he could perfectly decarburize molten pig iron by blowing air through it without the further application of external heat, the following remarkable experiment was proposed and conducted by Mr. George Parry, of the Ebbw Vale Iron "Works: . . . 'In the bed of a reverberatory furnace several wrought-iron pipes, about one inch in diameter, were laid parallel to each other and about three inches apart, in the direction of the long axis of the furnace. The pipes were all put in connection with the blast apparatus. Their upper surfaces were perforated with holes about three inches apart, of which there were about eighty or one hundred altogether; and wires having been first stuck in these holes, the pipes were covered solidly over with fire-clay. When the clay bottom, thus formed, had become dry, the wires were pulled out. The furnace was very gradually heated, and then about 11 tons of pig iron from No. 1 blast-furnace at the Victoria Works was run in, the blast having been previously let into the pipe. Vigorous action occurred, when, by some mishap, the molten metal escaped from the furnace into the road. The then managing director of the works was unwilling that the experiment should be repeated, and the furnace was dismantled, happily for Bessemer.'"
On October 17, 1855, Henry Bessemer (now Sir Henry Bessemer) was granted his first English patent for "improvements in the manufacture of cast steel"; other patents for improved methods and apparatus followed in rapid succession; and at the meeting of the British Association at Cheltenham in the early part of August, 1856, Mr. Bessemer read a paper before its Mechanical Section On the Manufacture of Iron and Steel without Fuel. "This paper," says Percy, "excited much attention, and was the first really public announcement of the invention." It was read in America with great interest; and it has recently become publicly known that under its stimulus the Hon. Abram S. Hewitt caused an experimental converter to be erected at the furnaces of Messrs. Cooper & Hewitt, at Phillipsburg, N. J. To an inquiry from me regarding this converter Mr. Hewitt has very courteously replied as follows:
New York,February 13, 1891.
W. F. Durfee, Esq.,Birdsboro, Berks County, Pa.
Dear Sir: In reply to your letter of the 11th instant, I cheerfully furnish the very meager description which is necessary to enable you to describe the introduction of the Bessemer process, so far as Cooper & Hewitt are concerned, in this country. On reading the paper of Mr. Bessemer, delivered at Cheltenham, I directed that an apparatus should be prepared at our works at Phillipsburg, N. J. The idea had been to use the ordinary blast from the furnace engines, which at the time were blowing about five pounds to the inch. I can not give you any drawing of the converter, but it was built according to the description contained in the Cheltenham paper. The capacity was about one ton. Before the apparatus was tried, Mr. Cooper went to Europe, where he ascertained that the Bessemer invention was a total failure, because the material produced was unfit for use. On receipt of this information, we suspended all further efforts to produce steel by the direct process, and, as a matter of fact, it now turns out that no steel was ever made in this experimental apparatus. So far as I know, therefore, the first actual steel made in this country by the Bessemer process was produced at Wyandotte; and, in ignorance of the fact that our apparatus was really never put in operation, I think I made a larger claim than would be justified by the facts; but you will remember that what I said was not intended to set up any claim for priority, but only to establish the fact that we were very hospitable to new ideas in the development of the steel business.
Sincerely yours,(Signed) Abram S. Hewitt.
This very frank letter is confirmatory of the fact (until recently undisputed) that "the first actual steel made in this country by the Bessemer process was produced at Wyandotte" more than eight years after Mr. Bessemer read his paper at Cheltenham. In 1856 Mr. Bessemer obtained two patents in the United States for his improved method of making steel; "but," says Swank, "was immediately confronted by a claim of priority preferred by William Kelly, an iron-master of Eddyville, Ky., but a native of Pittsburg, Pa."
Before speaking further of the relative claims of Bessemer and Kelly, we will explain as fully as space will permit the apparatus invented by the former, which, with slight modifications, is used wherever Bessemer steel is manufactured. The vessel in which the melted pig iron, or iron taken in a molten state directly from the blast-furnace, is transmuted into steel, is called a "converter." Fig. 57 is a vertical section of an early form of one of these vessels, which are made of heavy plate iron, and provided with a very thick lining of the best fire-resisting material. At the bottom of the converter is a chamber called a "tuyère-box," from which a number of "tuyères" made of baked fire-clay pass upward through the lining of the vessel.
The "converter" is hung upon "trunnions" (much as cannon are), through one of which the blast is conveyed to the "tuyère-box"; these trunnions rest in "bearings" which, in some of the earlier converters, were on the top of tall iron stands (the base of one of such stands is seen in Fig. 57) firmly bolted to foundations of masonry; but in more modern constructions these bearings are supported by iron girders sustained by columns, or masonry piers are carried up of sufficient height to receive them. The air blast being carried through the hollow trunnion permits the turning of the vessel upon its bearings without interrupting the blast by so doing; this turning is in modern practice generally effected by some adaptation of hydraulic machinery, and occasionally by "worm" or "spur" gearing as shown in Fig. 58. The pressure of blast used was at first four to five pounds, but this was soon increased to eight, and, although there are still a few converters blown at this pressure, in the larger establishments a blast of twenty to twenty-five pounds is usually employed. Why such pressures are used, involving very heavy and expensive machinery and an excessive amount of power, is not evident, as no better or cheaper steel can be made thereby.
The operations for making steel are as follows: The converter, after having been newly lined, is thoroughly heated by means of a coke fire built therein, and urged by a blast through the tuyères; when the lining is sufficiently hot, the converter is emptied, sufficient blast being used to blow out all the dust, etc. The vessel is then turned with its body nearly horizontal, and the charge of melted iron is run in at its mouth. The vessel is next turned so that its body becomes erect (as in Fig. 57), and, as soon as this turning commences, the blast is put on. An enormous discharge of particles of burning iron escapes from the vessel's mouth as it moves toward an erect position, and when the turning ceases it is evident that a most intense reaction is taking place between the oxygen of the air blown into the "converter" and the silicon and carbon contained in the
Fig. 58.—Pouring Steel from a Converter.
iron. The mechanical action of the blast in throwing about the liquid metal augments the internal tumult—intense flame issues with an angry roar from the converter's mouth, and the whole apparatus trembles as though it was possessed of a devil that was reluctant to be cast out.
Fig. 59.—Casting Ladle and Mold.
After the lapse of a certain time (varying with the character and quantity of the metal being operated upon), the flame at the mouth of the converter undergoes a great reduction in volume and change in character, and it is by the appearance of this flame at this critical period of the process that the person in charge of the operation judges of the proper time to "turn down" the "vessel" and cut off the blast. When that time arrives, the vessel is turned with its body in a horizontal position, and a certain weight of a metal called spiegeleisen is added in a molten state, and the converter is then turned still farther down into the position shown in Fig. 58, and its contents poured into a casting ladle H, attached to the end of the arm of a crane, G. This ladle is provided with a, "tap-hole" in its bottom, which can be closed by a valve attached to the lower end of the spindle L (Fig. 59). Of course, the interior of the ladle as well as the valve and its spindle are made of the best fire-resisting material obtainable. The spindle L is raised or lowered to open or close the "tap-hole" by means of a lever, N (Fig. 58), which operates a vertical slide-bar to the upper end of which the spindle L is attached. The crane-arm G is attached to the upper end of a cylindrical ram or post capable of moving upward as well as rotating in a hydraulic cylinder, E. The ingot molds (of which one is shown at K) are placed in a circle, whose center is that of the cylinder E, and are filled in succession by swinging the crane about the same center. The molds K are made of cast iron, and are smaller at the top than at the bottom, in order that they may be readily "stripped" off the ingots of steel.
The apparatus shown in the above-described figures was the invention of Henry (now Sir Henry) Bessemer. It is remarkable for its ingenuity and perfect adaptation to the needs of the new process, and, notwithstanding the lapse of over thirty years and the accumulated experience of multitudes of metallurgists and engineers, substantially the same apparatus is to-day in use in every Bessemer steel-works in the world. Of course, there have been many changes and some improvements in details, but its essential features remain as they were planned by their inventor thirty-six years ago—the converters still turn on their trunnions and receive their air-blast as has been described; the casting-ladle continues to be attached to a hydraulic crane and to discharge its contents through a valve-closed "tap-hole" in its bottom; hydraulic cranes are still used to rapidly handle ingots and molds; and these foundation facts of ingenious design promise to continue in use for all time as enduring evidences of great originality in the selection and adaptation of means to ends, and fairly entitle their inventor to a foremost place among the mechanicians of the century.
[To be continued.]
- New Haven Colonial Records, vol. ii, p. 173.
- Bishop tells us that "the first patent granted in England for the manufacture of steel was to Richard Lord Dacre, Thomas Letsome, and Nicholas Page, on 8th April, 1626, for apparatus for making steel, according to the inventure of Letsome." In 1655 "there was but little steel made in England, and that very imperfectly and all of foreign Iron." Forty years after (in 1695) English writers speak of steeling articles by "boiling them in raw metal," and steel was made by a similar process, and was "made by cementation by John Heydon, at Bromley, in 1697."
- Economic and Social History of New England, 1620-1789, by W. B. Weeden.
- L'art de convertir le fer forgé en Acier, et l'art d'adoueir le fer fondu, ou de faire dea Ouvrages de fer fondu aussi finir que de fer forgé. Par Monsieur de Réaumur, de l'Académie Royale des Sciences. A Paris, 1722.
- No. 1, spring heat, about ½ per cent carbon; No. 2, country heat, about ⅝ per cent; No. 3, single shear heat, about ¾ per cent; No. 4, double shear heat, about 1 per cent; No. 5, steel through heat, about 1¼ per cent; No. 6, melting heat, about 1½ P er cent.
- Percy and other writers on the manufacture of steel have stated that the term "shear steel" originated from the fact that such steel was used in making the blades of shears; but, as steel of the same quality was employed for multitudes of other implements, and as "blister steel" was made in Germany before it was in England, it appears to the writer more probable that the result of refining and improving its quality by successive weldings received the German appellation of Sicher-stahl (sure, or trusty steel), which was mistranslated into the English term "shear steel." W. F. D.
- Swank Iron in All Ages.
- In Iron in all Ages.
- "Another "crank" claimed to have discovered a liquid in which if "pigs" of iron were "soaked" a certain time they would be cleansed of all their impurities, and could then be converted into steel by simple fusion. This might have been with propriety called the "hydropathic process."
- Father of the writer.
- Practical Treatise on Metallurgy, by Crookes and Röhrig.
- Annales de Mines, 1824.
- In this connection we are reminded of a hunter, who, on his weary way home without game after a hard day's tramp, thought he saw through the gathering mists of evening a deer entangled in a thicket; but, as he raised his gun, his companion suggested that it might be a calf. "All right," said the hunter, "I'm going to aim so as to kill it if it's a deer and miss it if it's a calf." A great many guns have been so aimed by hunters for metallurgical "game," but it is quite safe to say that they oftener killed the "calf" than the "deer."
- Swank's Annual Statistical Report of the American Iron and Steel Association for 1889.
- Census Bulletin, No. 13, Production of Steel. Report of Special Agent Dr. William M. Sweet to Robert P. Porter, Superintendent of Census.
- This is made from a rich iron ore by depriving it of its oxygen, leaving the metallic iron as a porous, spongy mass which can be put directly into the bath of an open-hearth furnace, or be balled up in a reverberatory furnace and rolled into "muck-bar."
- Illustrated on page 328 of vol. xxxviii.
- This patent was purchased by the Ebbw Vale Iron Company soon after it was issued.
- Percy's Metallurgy, Iron and Steel, London, 1864.
- The early "converters" had a capacity of from one to three tons, but we now hear of "vessels" holding from fifteen to twenty tons.