On the transformation of austentite to martensite and tempering process of martensite in iron-nitrogen system

The transformation of austenite to martensite and the tempering of martensite in iron-carbon system, have been investigated by several workers but very few studies have related to the problem in iron-nitrogen system, inspite of the fact that both nitrogen and carbon have similar atomic volumes and that a forced interstitial solid solution is formed in iron. In the present work the authors have studied the transformation of austenite to martensite based on statistical thermodynamics and crystallography using Fe-N alloys, and have compared the results to those Fe-N alloys, and have compared the results to those obtained with Fe-C alloys. Studies on tempering of martensite and austenite in Fe-N alloys were carried out by X-ray diffraction analysis. (Prof. Y. Imai, Messrs M. Izumiyama and M. Tsuchiya Metallurgical Research Institute, Tohuku University, Japan)