METALLURGY. 



523 



say, only 45 per cent, of chromium. By the 

 use of this chromium pig-iron and open-hearth 

 steel can be produced which will compete in 

 every respect with tlie best English crucible 

 steel, and in many cases even excel it. Chro- 

 mium steel is harder than ordinary steel with 

 the same percentage of carbon, but it is more 

 difficult to harden. If the carbon is kept 0'2 

 per cent, lower than would be used if no chro- 

 mium were present, and that amount of chro- 

 mium is added which will give the requisite 

 degree of hardness, a steel can be obtained that 

 will stand a much greater welding heat than 

 ordinary carbon steel, and will be at the same 

 time both tougher and harder. The percentage 

 of carbon in a chrome steel should never ex- 

 ceed 0-9. The percentage of chromium need 

 rarely exceed 1/5 per cent. If it is desired to 

 produce a harder steel than that containing 0'9 

 per cent, of carbon and 2 per cent, of chro- 

 mium, 0'2 per cent, of silicon must be present 

 to insure freedom from blow-holes, and the 

 phosphorus, on account of the presence of sili- 

 con, should be kept below - 3 per cent. 



A new direct method, applied by the Car- 

 bon Iron Company of Pittsburg, for making 

 wrought-iron from the ore, is based upon the 

 use, as a reducing agent, of a new kind of 

 graphite from Rhode Island, which also pro- 

 tects the iron from reoxidation. This, having 

 been ground very tine and mixed, previous to 

 roasting, with water, is mingled with the ore 

 in the proportion of one to tour by weight. 



In Huchavel's method of producing wrought- 

 iron and steel direct from the ore, the main 

 feature of the furnace consists of a movable 

 hearth fitted to a blast-furnace constructed 

 partly of ca-^t-iron and partly of wrought-iron 

 plates, the latter of which form a double skin 

 to the body of the furnace, while the space 

 between the skins is used to heat the blast. 

 The furnace, the inventor represents, has been 

 gradually developed from the simplest form of 

 cold-blast furnace, under the stress of difficul- 

 ties which were from time to time encountered. 

 The fuel used is wood charcoal. From mag- 

 netic ore containing 58 per cent, of iron, the 

 author obtains 52-4 per cent, of steel ; and the 

 loss in producing wrought-iron is said to be no 

 greater than it is in a puddling-furnace. 



In a paper on " Silicon and Sulphur in Cast- 

 iron," Mr. T. Turner reaches the conclusion 

 that, in the blast-furnace, three chief agencies 

 are at work tending to eliminate sulphur, of 

 which in Cleveland practice not more than 

 one twentieth passes into the iron: 1. A high 

 temperature tends to prevent the absorption of 

 sulphur by iron ; 2. A slag rich in lime readily 

 combines with sulphur: and 3. The amount of 

 sulphur actually retained by the metal is influ- 

 enced by the proportion of silicon, and prob- 

 ably certain other elements present in the iron 

 the more silicon the less sulphur. 



The " rapid " steel-making process of B. H. 

 Thwaite and A. Stewart is intended to com- 

 bine the best features and avoid the defects of 



the Bessemer and Siemens-Martin processes. 

 The pig-metal is melted in a " rapid " cupola 

 and collected in a receiver, from which it is 

 run into a vertical converter, and thence drawn 

 off in the ladle. In its passage through the 

 converter the mass is subjected to the blast 

 from the cupola-blower. As soon as the iron 

 is collected in the ladle, the latter is : 

 from its trunnions and rapidly revolved. Stir- 

 rers effectually mix the metal, and the steel !> 

 then ready for the mold. The system can be 

 applied to existing open-hearth furn;. 



A practical demonstration has been given at 

 the Lambeth works of Messrs. Brin of the di- 

 rect conversion, by a new process, of iron into 

 steel containing two per cent, of aluminum. 

 The charge consisted of about forty pounds of 

 broken cast-iron, which was smeared with clay 

 the source of the aluminum and a special 

 flux. This charge was placed in a small 

 foundry-furnace, and was speedily transformed 

 into excellent steel. Other metals can be simi- 

 larly treated, and any percentage of aluminum 

 can be alloyed with them. The plating of iron 

 with aluminum by means of the blow-pipe was 

 shown on the same occasion. 



A second report has been made by the com- 

 mittee appointed by the British Association to 

 investigate the influence of silicon on the prop- 

 erties of steel. While in the series of experi- 

 ments previously reported upon the committee 

 had used specially pure iron, in the present 

 series it had taken ordinary basic iron, in the 

 condition in which it would be sent into com- 

 merce, added definite quantities of silicon, and 

 examined the product chemically and mechan- 

 ically. The general results of the investigation 

 are summarized as follow : On adding silicon 

 to ingot iron containing manganese the metal 

 rolls well, and does not show any signs of red- 

 shortness; it welds perfectly well with all pro- 

 portions of silicon, and (with one somewhat 

 doubtful exception containing 0'5 per ctnt.) is 

 not brittle when cold. With less than about 

 0'15 per cent, of silicon, the limit of elasticity, 

 the breaking load, the extension, and reduction 

 of area are but little, if at all, appreciably af- 

 fected by the presence of silicon ; but with 

 more than 0'15 per cent, of silicon the limit 

 of elasticity and breaking load are increased, 

 while the extension and reduction of area are 

 distinctly decreased by the presence of silicon. 

 The effect exerted by silicon in increasing the 

 tenacity of ingot iron is not nearly so great as 

 that of carbon. The relative hardness is very 

 slightly affected by the proportions of silicon 

 used in these experiments. On account of the 

 small scale on which the experiments were 

 conducted, it was not practicable to perform 

 tests with reference to resistance to shock. 



The Carlsson modification of the Bessemer 

 process is employed in Sweden in the treat- 

 ment of a charcoal pig-iron about 1'5 per cent, 

 of silicon, 0-1 to 0'15 of manganese, 3'9 of 

 graphite, and O'l of combined carbon. The 

 slag resultant from the production of this pig- 



