Abstract
Following the last paper (Tetsu-to-Hagane, Vo. 39, 1953, No. 12, p. 1336), an atmosphere obtained by addition of the cyanide salt of optimum amount in a closed vessel pre-filled with air or oxygen instead of town gas was examined and found to be cheap and more powerful in the case-hardening of rimmed steel as well as of killed steel: the richer the concentration of C2N2O gas in the atmosphere, the more powerful its case-hardening ability.
The concentration of C2N2O became maximum by addition of the K4Fe(CN)6 6gr per litre when air was used, and 33 gr per litre when oxygen is used. At these amount of the addition, the carbonitriding power became maximum in both cases. The mechanism of the carbonitriding on steels was also discussed.
