强磁场下Fe-C合金中碳的质量分数对先共析铁素体形貌的影响

选用高纯Fe-0.12C,Fe-0.36C,Fe-0.52C及Fe-0.76C合金为实验材料,研究了强磁场退火条件下碳质量分数对Fe-C合金先共析铁素体晶粒形状和尺寸的影响规律.结果表明:随着碳的质量分数增加,先共析铁素体晶粒不但逐渐减小,而且沿强磁场方向伸长并呈链式排列的趋势不断减弱.产生上述现象不仅与Fe-C合金的碳质量分数相关,而且与先共析铁素体晶粒的形成过程和演变机理密不可分.并由此提出一种碳质量分数较低的Fe-C合金在先共析铁素体转变初期或碳含量接近共析成分的Fe-C合金中先共析铁素体晶核距离较远的情况下适用的磁偶极子模型.

Effect of Carbon Content on Morphology of Proeutectoid Ferrite Grains in Fe-C Alloy in High Magnetic Field

The effect of carbon content on the morphology of proeutectoid ferrite grains in Fe-C alloys annealed in high magnetic field was investigated,especially in high-purity Fe-0.12C,Fe-0.36C,Fe-0.52C and Fe-0.76C alloys.The results showed that the grain size of the proeutectoid ferrite gradually decreases with increasing carbon content and the trend to elongating the grains in the magnetic field direction to form chain-like arrangement becomes weaker.This phenomenon is not only attributed to the different carbon contents of the Fe-C alloys,but also closely related to the formation process and evolution mechanism of the proeutectoid ferrite grains.Consequently,a magnetic dipole model is proposed applicable to the early stage of proeutectoid ferrite transformation in low carbon Fe-C alloys or in case the distance between proeutectoid ferrite nucleus is relatively long in the Fe-C alloys in which the carbon content approaches the eutectoid composition.