Arsalan Ajami - Student. School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box ۱۱۱۵۵-۴۵۶۳, Tehran, Iran
Hamed Mirzadeh - Professor.School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran
Mostafa Najafi - Student. School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box ۱۱۱۵۵-۴۵۶۳, Tehran, Iran

The st37 steel and a modified version of this steel containing micro -addition of Cr and Mo were subjected to the martensite thermomechanical process (tempering of cold rolled martensite). It was found that the presence of Cr and Mo can result in the retardation of softening during tempering of cold rolled sheets, where the hardness of the modified steel at each tempering time was much higher compared to the st37 steel. Accordingly, the characteristic hardness fall related to the occurrence of continuous recrystallization postponed effectively. The micro-addition of Cr and Mo was found conductive to grain refinement via development of fine ferrite/carbide aggregate.

Martensite process; Microstructure; Grain refinement