Study On The Strain Induced Transformation Of Cr-Mo Steels

This paper has studied the technics of grain refinement of the low-alloy steels 12Cr1MoV and 2.25Cr1Mo by the methods of heat treatment and deformation.The effect of rolling technology factors, such as heating temperature, strain rate deformation temperature and strain amount, deformation temperature and cooling rate in non-recrystallization region on the ferrite transformation behavior and microstructure were studied on a Gleeble 1500 thermo-mechanical simulator for the low-alloy steel 12CrlMoV. Optical microscopy and SEM observations showed that the grains fine down with increasing of strain rate, strain amount and cooling rate .At the same time, the precipitated second phase can restrain the occurrence of recrystalliztion by deformation in the non-recrystllization region, and the existence of second phase can not only hinder the movement of dislocation but also result in dislocation multiplication. Therefore, the mechanisms of grain refinement for low-alloyed steels which are different form the low carbon steel are due to strain induced ferrite recrystllization and precipitated second phase which hinder the growth of ferrite and makes grains refined.