The regression equation of internal rarefaction grades is acquired by processing the experimental data in the experiment of porous void by USTB,based on the mathematical theory of statistics.

• 应用数理统计学理论对北京科技大学所做实验的心部疏松实验数据进行处理,得到轧件心部疏松等级的回归方程,经检验,方程拟合良好且显著。