Improvements in the Manufacture of Cemented Armor Plates of Steel and Alloys of Steel, for Ships and other uses.

Реферат: 16,806. Marks, E. C. R., [Soc. Anon. Italiana, Gio. Ansaldo, Armstrong, & Co.]. Aug. 10. Cementation ; manganese steel.-A process of cementation, applicable to armour-plates and the like, consists in the employment of determined pressures of a carburizing-gas relatively to the temperature and the composition of the gas. The speed of penetration of the carbon, or the depth to which the carbon penetrates in a given time, increases as the pressure is increased provided that the temperature is varied in accordance with the following rules, When the decomposition of the carburizing-gas takes place with diminution of volume, the temperature is raised if the reaction is exothermic and lowered if it is endothermic. If tne reaction involves increase of volume, the relations are reversed. For example, a steel containing carbon À1 to À2 per cent, manganese À2 to À4 per cent, phosphorus À2 to À4 per cent, and traces of silicon and sulphur, may be cemented by means of carbon monoxide under ordinary pressure at 950-1000‹ C., while at a pressure of, say, over four atmospheres, the temperature should be raised to about 1100‹ C., as the reaction is exothermic and takes place vith diminution of volume. It is stated that by alternately increasing and diminishing the pressure and temperature, successive layers, each of a substantially uniform degree of carburization, may be produced, the degree of carburization of the successive layers increasing towards the outer surface. Steel articles may also be subjected to the action of gases under the conditions specified above, while immersed wholly or partly in solid carburizing-substances.