低碳钢铁素体相变析出行为

Precipitation behavior of ferrite transformation of low carbon steel

利用高温淬火相变仪测定了EH40级船板钢晶内铁素体的相变温度区间,又利用高温共聚焦显微镜对晶内针状铁素体的相变析出行为进行了原位观察。结果表明:能得到针状铁素体的最佳降温速率为10℃/s,升温过程中奥氏体开始相变温度Ac1=743℃,降温过程中奥氏体结束相变温度Ar1=546℃;针状铁素体的生长过程伴随着加速和减速现象;观察到针状铁素体的3种形核方式,分别为夹杂物诱导形核、在奥氏体晶界上感生形核析出以及在晶界铁素体上感生形核析出。最后揭示了从铁素体析出生长到形成连锁组织的作用机理。

The phase transition temperature range of intragranular ferrite in EH40 grade ship steel was measured by high temperature quenching phase change instrument.The phase change precipitation behavior of intragranular acicular ferrite was observed with the way of insitu by using high temperature confocal microscopy.The results show that the optimum cooling rate of acicular ferrite is 10℃/s,the austenite begins to change phase during heated is Ac1=743℃,and the austenite finish phase transition temperature during cooling is Ar1=546℃.The growth process of acicular ferrite is accompanied by acceleration and deceleration,and three nucleation modes of acicular ferrite are observed,which are inclusion-induced nucleation,nucleation induced on the austenite grain boundary,nucleation induced on the ferrite grain boundary,respectively.Finally,the mechanism from the precipitation and growth of ferrite to the formation of interlocking microstructure is revealed.