Alfred Kirby Huntington

“ The dominant idea in treating cast-iron for steel had always been to refine the metal by the action of atmospheric air, and this was effected by causing a current of air to impinge upon the surface of the metal, by means either of a blowing apparatus or the drawing action of a chimney-stack. What more natural than that it should occur to some one to refine iron by blowing air into it, instead of merely on to its surface? ”

“ IMPROVEMENTS in the arts and sciences have gradually modified the methods of producing iron and steel, and, in their turn, the arts and sciences have felt the reaction; for all improvements in the manufacture of iron and steel have consisted, not so much in the production of a better quality of the article, as in the cheapening of production by the application of the principles indicated by the progress of science, and by the use of superior machinery. ”

“ There are two methods now in use for the production of steel in the reverberatory furnace, or open-hearth, as it is called. In France, pig-iron and scrap-steel are fused together; in England, pig-iron is decarburized by means of iron-ore, some scrap, however, being generally added for the sake of utilizing it. As in the Bessemer process, the necessary amount of carbon is imparted to the metal by the means of spiegeleisen or ferro-manganese. ”

“ It is always very rich in oxide of iron. It appears that in this process, carburized iron is produced by the gradual reduction and fusion of the lumps of ore, and this, coming in contact at the bottom of the furnace with slag, very rich in oxide of iron, the carbon of the one combines with the oxygen of the other, and the result is that iron containing more or less carbon is produced, according as much or little oxide was present. ”

“ The discovery of steel appears to have naturally followed that of the means of reducing iron from its ore. In all primitive methods of iron-smelting, steel, in more or less quantity, is inevitably produced. Such methods have been carried on in India and Africa from time immemorial to the present day. A furnace of a similar primitive character has, for several centuries, been employed in Catalonia, in Spain. ”

“ There is some reason to believe that an excess of carbon, over that required to produce the hardest steel, has to be added, in order to fuse the metal at the temperature which can be commanded in these furnaces. Before being drawn out into bars, the cakes of metal obtained in this way are exposed in a charcoal-fire during several hours to a temperature a little below their melting-point, the blast of air playing upon them during the time. ”

“ The decarburization is effected by the addition of oxide of iron produced during rolling, and partially by the air which enters the furnace as the metal melts slowly down; manganese is added during the process. It is important that the temperature should be kept low. It is difficult to weld this steel perfectly, because, probably, the temperature at which it has to be worked is too low to make the cinder sufficiently liquid to enable it to be squeezed out under the hammer to the same extent that it is in the case of malleable iron. ”

“ In consequence of the extremely high temperature which we can command, either in the Bessemer or open-hearth process, it is possible to obtain in a molten state a metal practically free from carbon, or containing carbon to any required amount. All of the products have been called steel, although they constitute in effect a new metal, having qualities considerably different from those of steel. ”

“ The principle which regulates the production of steel by these methods is taken advantage of in the Uchatius process, in which pig iron is first granulated by running it while molten into cold water. The granulated metal is then mixed with about twenty per cent, of roasted spathic ore, crushed fine; the mixture, to which a little flux has been added, if necessary, is then fused in clay crucibles. If very soft steel is required, some wrought-iron scrap is added. ”

“ When these chambers have become heated to a high temperature, the waste gases are made to pass through two other similar chambers, and the air and gas necessary for combustion in the furnace are caused to pass through the highly heated regenerators. By causing the ingoing gases to pass alternately, at suitable intervals of time, through each pair of regenerators, a very high and, at the same time, uniform temperature can be obtained in the furnace, without any greater consumption of fuel than in the older methods. ”

“ The result of the application has been, that phosphorus has been converted from an enemy into a friend, and aids in producing and maintaining the temperature that is needed. Silicon is also useful as a combustible, and in preventing the metal from becoming honeycombed by escaping gases while solidifying. This it does by combining with oxygen and preventing the latter substance from combining with carbon and forming a gaseous product. ”