The Works Of Messrs. Schneider And Co.

42 MESSRS. SCHNEIDER AND CO.’S WORKS. it nécessitâtes a very important and costly plant, the results obtained repay the outlay and trouble involved. Uses of Siemens-Martin Steel.—Until 1880 Messrs. Schneider and Co. manufactured only acid steel by the scrap process, with material obtained from pure pig iron made in the Creusot blast-furnaces, with Mokta, Bilbao or Allevard ore. To arrive at a greater degree of purity they tried the same material in a basic hearth, in a small experimental Siemens-Martin furnace, during the months of November and December, 1879. It was found from these experiments that they could obtain steel practically free from sulphur and phosphorus, and of a milder quality the acid process. However, by the present methods of gun construction, such heavy ingots for this purpose are rarely necessary. Ingots for making shells, for locomotive tyres, for springs, &c., are made from acid steel, while basic steel is cast for armour-plates, engine shafts, plates, sections, various tyres &c. Messrs. Schneider and Co., only manufacture in their Siemens-Martin plant, steel of strengths from 35 to 100 kilogrammes per square millimétré (22.22 to 63.50 tons per square inch). The lower-grade steel, such as that for rails, joists, &c., is made in the Bessemer plant. There are, as a rule, two heats per twenty-four hours. With certain Fig. 95. First Compressed-Steel Ingot Made by Messrs. Schneider and Go. Fig. 96. Diagrams Showing Results of Analyses of the First Compressecl- Steel Ingot Made by Messrs. Schneider and Co. MANGANESE than the softest steel made by the acid process. On January 20, 1880, one of the 20-ton furnaces was trans- formée! and fitted with a dolomite hearth ; it produced steel equal in quality and purity to the best Swedish iron. Other furnaces were transformée! later on, and gave extra mild steel, préférable to that obtained by the acid process, for the construction of marine boiler furnaces. The actual plant consists of three furnaces with a basic hearth, and one with an acid hearth ; the latter is used exclusively for the manufacture of steel for guns. For large guns that require an ingot heavier than the charge of this furnace, those adjacent are temporarily modifiée! for grades, three heats can be obtained. For gun steel, how- ever, the heat lasts about fourteen to sixteen hours. The shape of ingot moulds varies according to the purpose for whicli the ingots are intended. Thus, ingots for axles and tyres are cast in octagonal moulds ; rolled plates and bars are made from ingots cast in square or rectangular moulds. The scrap process is still employée!. The material used consists of superior quality hématite pig, puddled iron obtained with this same pig iron, and steel scrap. For the manufacture of gun steel, Swedish and South of France (Landes) charcoal pig is used, together with hématite pig, the charge being entirely made up with puddled iron. The total output of the Siemens-Martin plant is now