Abstract: Alumina inclusions with high melting point and poor deformability were found as the main type of inclusions in Q345D steel produced by a Chinese plant. The stoichiometric ratio of CaO/Al2O3 was about 1:6 during refining and casting, which was detrimental to the castability of molten steel and the property of steel products. Therefore, the modification of inclusions was studied. Field experiments were taken out followed by full process analysis of the composition, amount and size of inclusions. Calcium treatment was proved to be effective. However, the phenomenon of CaO/Al2O3 decreasing from 3:1 to 1:2 was also discovered. Thus, argon blowing was studied aiming at reoxidation prevention. Satisfied modification of inclusions in Q345D steel was achieved under these measures.
Authors: Yi Wang, Lifeng Zhang, Wen Yang, Qiang Ren, Dongteng Pan, Xincheng Wang, and Libin Sun
Keywords: Q345D Steel, Inclusions, Calcium Treatment, Reoxidation, CaO/Al2O3