Abstract
A more powerful and simplified method of case hardening as well as of bright annealing by the use of town-gas has been proposed. The method was to make the case hardening power of modified town gas more effective by utilizing the cyanide salts and the oxidizing constituents in a closed vessel. A new gaseous constituent C2 N2 O was theoretically estimated to be its important one, being illustrated by comprehensive experiments.
Steels wese oxidized by heating in the atmosphere of town-gas, but were bright-annealed or case-hardend by addition of the K4Fe(CN)6 over 0.5gr per litre town-gas. Carbonitriding power became maximum at 3gr. K4Fe(NC)6 per litre town-gas, and was reduced by addition over it, the reason being that the concentration of C2N2O gas, having vital effect in case hardening, became maximum at 3gr./lr.
