Chemical nature of radioactive elements
1913
Journal of the Franklin Institute
CURRENT TOPICS. Influence of Sulphur on Cast Iron. H. I. COE. (Proc. Brit. Foundrymen's Assoc., 1911-1912.)--A series of test bars was prepared from pure materials and was examined chemically, physically, and metallographically. The results show that: (a) With low silicon content a small amount of sulphur causes nearly all the carbon to become combined. With high silicon content the effect of sulphur in this respect is much less marked. (b) There appears to be a critical point, which varies
more »
... the silicon content, at which the effect of sulphur changes suddenly. (c) The addition of sulphur increases tenacity, transverse strength, and hardness. This influence is due partly to its effect oal the condition of the carbon, partly to its modifying the dendritic character of the silicious irons. (d) Manganese neutralizes the influence of sulphur on the condition of the carbon, and, if in excess, eliminates sulphur by separation as manganese sulphide. Sulphur is most dangerous in irons low in silicon and manganese. These results were obtained in the absence of phosphorus, and probably y¢ould be modified in the case of commercial pig iron. Cast iron is desulphurized either by the addition of ferromanganese or by Saniter's process, which consists in mixing burnt lime and calcium chloride with the molten charge, thus producing calcium sulphide. For malleable cast iron, if the R6aumur process is employed, o.2 to 0.4 per cent. of sulphur may be present, but for " Blackheart" castings o.o5 per cent. is the maximum permissible, since in the Rfaumur process the annealing is oxidizing, and the stability of the carbide as regards decomposition into iron and graphite is of little importance, while the production of " Blackheart" castings depends essentially on the decomposition of iron earbide. As sulphur prevents this decomposition, it is therefore harmful.
doi:10.1016/s0016-0032(13)91002-4
fatcat:m4pjuoxegbeffmqd6zyyrshjxa