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STEEL MANUFACTURE. 



STEEL MANUFACTURE. 



822 



terminates the operation. When the crucibles are cold, they are 

 broken, and small cakes of steel are obtained in the form in which it 

 comes to England. 



This making of cast-steel is a remarkable operation. The heat of the 

 furnaces is believed to be higher than any other known in English 

 manufactures. The ingots weigh from about 40 to 200 Ibs. each, 

 according to the purposes to which they are to be applied. No less 

 than four to five tons of coke are needed for smelting one ton of steel. 



The tilling of steel is a process of hammering, mostly for cast-steel. 

 The steel is heated to a certain temperature, and hammered all over 

 for a considerable time ; this closes the pores, and renders the metal 

 as close and compact as possible. The steel for the best articles is both 

 cast and tilted. Case-hardening is an operation whereby articles made 

 of malleable iron or cast-iron are superficially converted into steel by 

 heating them with charcoal in a crucible. 



Relations of Sled to Iron. The steel manufacture is just now in a 

 transitionary state ; several new processes of a highly curious nature 

 have been introduced by Heath, Clay, Bessemer, Uchatius, and others, 

 not fully successful, perhaps, but significant of the future. Most of 

 these depend on a study of the relations between iron and steel, in a 

 way which we shall briefly describe. 



With respect to the composition of steel and the nature of the 

 mixture necessary to constitute it, differences of opinion have long 

 existed. The question even now is considered by some as hardly 

 decided, whether carbon is indispensably necessary to its formation, 

 and whether certain substances or metals, especially silicon, may not 

 give rise to it ; and it is generally admitted that phosphorus is always 

 it. Berzelius mentions iron containing manganese as particularly 

 eligible, and yet analyses show that this metal is not present in steel 

 in most cases. An experiment performed by Mr. Pepys in 1815, seems 

 not only to prove the necessity of carbon, but also that the diamond is 

 capable of producing the same effect. In order to get rid of the objec- 

 nat the carbonaceous matter of a common fire might supply 

 carbon when irun and diamond were heated by means of it, he placed 



diaiu l-].ow<liT in a piece of pure soft iron wire ; and having properly 



I it, he heated it by means of voltaic electricity : after a few 

 minutes' heating, the diamond had disappeared, and the interior surface 

 of the iron was converted into perfect blistered steel, which, being 

 heated to redness and plunged into cold water, became so hard as to 

 resist the file and scratch glass. Some years since a method was dis- 

 covered by Mackintosh of converting iron into steel by means of the 

 carbon of carburetted hydrogen gas. Gay Lussac found that during 

 fusion steel loses much silicon and a little carbon. Brande has found 

 that when the carbon has fallen short of one per cent., the steel was 

 deficient in hardness ; and when it has exceeded this proportion, the 

 dies have split or not stood their work. He states, at the same time, 

 that minute quantities of other bodies appear to influence the quality 

 of steel ; and that unless it contain phosphorus it cannot be depended 

 on for the manufacture of dies in coining. Dr. Thomson examined 

 some cast-steel furnished him by Mr. Buttray, a steel-maker near 

 Glasgow. The general result of his trials gave hiiu a composition 

 which approaches 20 atoms of iron + 1 atom of carbon ; and this he 

 thinks likely to be the constitution of cast-steel, an opinion corrobo- 

 rated by the fact above stated by Mr. Brande. Mr. Faraday and Mr. 

 , Stodart published in the ' Phil. Trans.' for 1822 a valuable series of 

 experiments on alloys of steel, from which it appears that by combining 

 ith other metals its quality is improved. A very minute addi- 

 tion was found sufficient to produce a good effect : thus one 500th of 

 silver gave an alloy harder than cast-steel ; one 100th of nickel gave 

 a very hard alloy, susceptible of a fine polish ; alloys of rhodium and 

 platinum were also formed; and these, with the alloys of iridium, 

 osmium, and palladium, formed the most valuable compounds. 



Mr. Binks, in a paper read before the Society of Arts in 1857, on the 

 nature and properties of steel, described the experiments which had 

 led him to the following conclusions : That the substances whose appli- 

 cation to pure iron convert it into steel, all contain carbon and nitro- 

 gen ; or that nitrogen has access to the air during the process. That 

 carbon alone added or applied to pure iron, does not produce steel ; and 

 that neither does nitrogen alone produce it. That it is essential for 

 both carbon and nitrogen to be present. That both exist substantially 

 in steel after its conversion. That such presence is the real cause of 

 tinctivc physical properties of steel from those of iron. That 

 presumptively, though not demonstratively, the form of combination is 

 that of a triple alloy of iron, carbon, and nitrogen. 



It has for many years been believed in England, that Swedish iron 

 derives some of its valuable steel-making properties from the presence 

 of a small quantity of manganese; hence the question might not 

 manganese be profitably added to English iron ? Mr. Heath took up the 

 subject, spent a fortune upon it, greatly enriched Sheffield, and died 

 broken-hearted. In 1839 he devised a mode of combining carbon with 

 manganese, to produce a carburet, which converted English iron into 

 rery good steel. The manganese appeared to him to act as a sort of 

 detergent, taking away certain impurities from the iron. Unfortunately 

 for his interests, he improved the process ; he put into the furnace the 

 eleinenU of the carburet (carbon and manganese) instead of the carbu- 

 ret itself, thereby lessening the expense. He neglected to obtain a 

 second patent for this improvement; the Sheffield manufacturers saw 

 th<s flaw, made the new steel without paying him any royalty and 



defied him. The suit of Heath r. Unwin, carried on for eleven years, 

 in all the various forms known to English law and equity, ruined Mr. 

 Heath, who died in 1850. His widow succeeded in obtaining a small 

 interest arising out of the patent, but quite disproportionate to the 

 importance of the invention. Mr. Webster has stated that, between 

 1839 and 1855, buyers of Sheffield cast-steel goods benefited to the 

 extent of tiro million} sterling by the lowering of prices due to Mr. 

 Heath's process. 



Steel is of a lighter gray than iron. It is susceptible of receiving a 

 very high polish, and this is greater as the grain is finer. When steel 

 is hardened its volume is increased. When heated to redness, and 

 slowly cooled, it is scarcely harder than iron ; but by very rapid cooling 

 it becomes hard, and so brittle as to be readily broken. The fracture 

 is usually fine grained. In ductility and malleability it is much infe- 

 rior to iron, but exceeds it greatly in elasticity and sonorousness. It 

 may be subjected to a full red heat, or 2786 Fahr., without melting, 

 and is therefore less fusible than cast-iron, but much more so than 

 wrought-iron. Pieces of steel which have not been cast may be readily 

 welded together or with iron ; but after casting, the operation is more 

 difficult. In order to give to steel the different degrees of hardness 

 required for various purposes to which it is applied, it is subjected to 

 the process of tempering. The higher the temperature to which it is 

 raised, and the more sudden the cooling, the greater is the hardness. 

 Thus when immersed in mercury the hardness is greatest, on account 

 of the good conducting power of the metal, and its consequent ready 

 abstraction of heat. After this comes acidulated water, salt water, 

 common water, and lastly oily or fatty bodies. It is found that, 

 according to the degree to which steel is tempered, it assumes various 

 colours, and formerly these colours served as guides to the workman ; 

 now, however, a thermometer, with a bath of mercury or of oil, is 

 employed, and the operation is performed with a much greater degree 

 of certainty. Into this bath the articles to be tempered are put, with 

 the bulb of the thermometer graduated up to the boiling-point of 

 mercury. The tempering heat varies from 430 Fahr. (for lancets) to 

 600* (for pit saws). 



Pitdtlled and Jletsemtr Sted. Arising out of the inquiries concerning 

 the relations between iron and steel, several new modes of making steel 

 have recently been introduced or proposed. Hitherto, most English 

 steel has been made by the converting process, already described; but 

 on the Continent it is more usual to adopt what is called the raw 

 method, puddling the metal in a charcoal furnace. The English 

 method raises the amount of carbon in or with bar-iron up to about 

 1 per cent. ; the Continental method lowers the amount of carbon in or 

 with pig-iion from 4 to 1 per cent. Riepe's method, patented in 

 1850, and worked some time by the Low Moor Iron Company and the 

 Mersey Steel Company, is for making a kind of steely iron by the 

 puddling process, good enough for most common purposes hard and 

 unyielding, or soft and silky, according to the extent to which the 

 process is carried. To produce this steel, pig-iron is thrown into a 

 puddling-furnaco [FURNACE; IRON MANUFACTURE], together with a 

 little iron slag, salt, clay, and oxide of manganese ; the molten metal is 

 worked or puddled beneath the scum, and is worked up into balls or 

 blooms at a certain stage. Captain Uchatius, engineer of the Imperial 

 Arsenal at Vienna, has devised a method of making steel in which (as he 

 thinks) English iron would suit as well as Swedish or Russian. He brings 

 the iron to a granular state, by running it from a furnace into agitated 

 cold water. These grains are mixed with some cheap oxygen-yielding 

 material, such as spathose iron-ore, put into a crucible, and melted 

 in a cast-steel furnace. The pig-iron gives up some of its carbon and 

 its earthy impurities to the oxygen, and becomes steel. The smaller 

 the granules, the softer the steel. Uchatius produces 25 Ibs. of steel 

 from 24 Ibs. of granulated iron, 4 Ibs. of spathose ore, 4 Ibs. of oxide 

 of manganese, and a little clay. Sir F. Knowles has introduced ,1 

 method in which a retort instead of a crucible is used ; while the crude 

 iron is mixed with hot gases rich in carbon. The processes of Uchatius 

 and Knowles seem better adapted for the laboratory than for largo 

 manufacturing operations. Other modes of producing steel directly 

 from the crude iron have been introduced, with varying success, by 

 Clay, Saunderson, Plant, Nasmyth, Mortier, and others. 



But of all the novelties connected with the Rteel manufacture, those 

 by Mr. Bessemer have attracted the most notice within the last few 

 years. He has taken out five or six fpatents on the subject. In his 

 hands the difference between iron and steel is simply one of degree, for 

 it is not easy to say where Bessemer iron ends and Bessemer steel 

 begins. It was at the Cheltenham meeting of the British Association, 

 in 1856, that the process first attracted attention. Mr. Bessemer con- 

 ceived that pig-iron might be converted into malleable iron, and then 

 into steel, without any additional consumption of fuel. Pig-iron 

 contains more carbon than the others ; and if oxygen could be made to 

 burn a portion of this away, the object would be accomplished. How, 

 then, to expose molten pig-iron to the action of oxygen ? He decided 

 that a blast would best effect this. He formed a fire-brick furnace of 

 small size, with tuyire holes near the bottom, and two larger holes 

 half-way up. Molten pig-iron flowed at once from a blast-furnace to 

 this small furnace or cylinder, and a blast was driven into the cylinder. 

 A violent commotion ensued, and an intense heat resulted from the 

 0'iiiliination of the oxygen in the blast with the carbon in the molten 

 mass. Volumes of flame and a few sparks were produced, and then a 



