亚快速凝固下磷对铁素体体积分数与形态的影响

Influence of P on Volume Fraction and Morphology of Ferrite Under Sub-rapid Solidification

通过金相组织观察,分析了不同磷含量双辊连铸薄带中的铁素体.实验结果表明,与同样磷含量的铸锭相比,铸带中的铁素体体积分数明显增大;对于同一个铸带,表层内铁素体体积分数小于中心区域,且磷含量越低表层内铁素体体积分数越小;随着磷含量的升高,铸带中的铁素体形态逐渐由针状向表面圆滑的块状转变.通过理论分析得出,快速冷却有利于钢中铁素体的稳定;表面圆滑的块状铁素体是由钢液中直接析出的,而针状铁素体是由固态奥氏体中析出的.

The ferrite in twin-roll cast strips with different P contents was analyzed by the observation of the microstructure. The results showed that the volume fraction of ferrite in the cast strip was obviously more than that in the cast billet with the same P content. In a cast strip, the volume fraction of ferrite in the surface layer was less than that in the center area, and the ferrite in the surface layer was reduced with the reduction of the P content. The morpology of the ferrite in the cast strip was gradually transformed from the acicular form into the polygonal form with smooth surface with the increase of the P content. Through the theoretical analysis, it was shown that the rapid cooling favored ferrite stabilizing in steels, and the polygonal ferrite with smooth surface directly precipitated from the liquid steel while the acicular ferrite precipitated from the solid austenite.