日本金属学会誌

J. Japan Inst. Metals, Vol. 14, No. 3 (1950),
pp. 57-60

An Investigation on Boron-Treated Steels (2nd Rept) The effects of Boron-addition to the Corelation between the Nitride's and Carbide's Precipitations at Austempering

Yunoshin Imai and Hikotaro Imai


Abstract:

Using 0.2∼.3%C-steels added to 0.01∼0.05%B,the corelation of precipitations of nitride and carbide on tempring was studied by measuring the change of magnetic coercive-force.The corelation of the beginning time of precipitations of nitride and carbide during austempering,in temperature range 040∼50°C,was also determined by microscopic observation.
From the results, the mechanism for increase of hardness by addition of small amount of Boron was elucidated,that is, boron accelerates the precipitation of nitride at the relatively low temperature(near the Ar''point) on quenching, while its tabilizes the supersaturated carbon and supress Ar' transformation and assists the martensitization.


(Received 1949/7/30)

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