磁场处理对微合金钢由奥氏体向铁素体的转变过程产生影响，主要体现在铁素体的形核率和晶粒长大速度两个方面．磁场处理增加了铁素体的形核率，同时也提高了晶粒的长大速度．由于磁场对铁素体形核率的影响效果显著，缩短了相变时间，最终得到细晶组织． The influence of the magnetic field treatment on the transformation of austenitic to ferritic microalloyed steel is mainly reflected in the nucleation rate of ferrite and the grain growth rate. Magnetic field treatment increases the rate of ferrite nucleation and also increases the grain growth rate. Due to the effect of the magnetic field on the nucleation rate of ferrite is remarkable, the phase transformation time is shortened and the fine grain structure is finally obtained.