Effect of calcium treatment on inclusions in Si-Mn-killed 304 stainless steels

• Main Authors: Yi Wang, Xiaohui Sun, Lifeng Zhang, Ying Ren
• Format: Article
• Language: English
• Published: Elsevier 2020-09-01
• Series: Journal of Materials Research and Technology
• Subjects: Calcium treatment; Inclusions; Si-Mn deoxidation; Stainless steels; Ladle refining; Deformation
• Online Access: http://www.sciencedirect.com/science/article/pii/S2238785420316252

In the current study, two plant trials for the ladle refining process without and with the calcium treatment were compared to investigate the effect of the calcium treatment on the inclusion deformation in Si-Mn-killed 18Cr-8Ni stainless steels. The total aluminum rose from 10 ppm to 25 ppm due to the slag and steel reaction, increasing the Al2O3 in inclusions during the ladle refining process. Without the calcium treatment, inclusions changed from Al2O3-SiO2-MnO-CaO with about 20% MnO to Al2O3-MgO-SiO2-CaO with about 10% MnO. The calcium treatment obviously lowered Al2O3 and MnO in inclusions and led to the formation of CaO-rich inclusions. Inclusions changed from Al2O3-SiO2-CaO-MnO to SiO2-CaO-Al2O3 after the calcium treatment of Si-Mn-killed stainless steels. Calculations showed that the calcium treatment of 15−25 ppm lowered the melting temperature of inclusions but further additions increased the melting temperature. Calculations also showed that calcium addition lowered Young’s modulus. Calcium treatment was an effective method to improve the deformability of inclusions in Si-Mn-killed stainless steel during the cold rolling process.