Improving Cleanliness of 95CrMo Drill Rod Steel by Slag Refining

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Vol. 47; no. 1; pp. 99 - 107
• Main Authors: Wang, Linzhu, Yang, Shufeng, Li, Jingshe, Wu, Tuo, Liu, Wei, Xiong, Jiaze
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.02.2016; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Cleanliness; Inclusions; Iron and steel making; Materials Science; Mathematical models; Metallic Materials; Metallurgy; Nanotechnology; Refining; Slag; Slags; Steel; Steels; Structural Materials; Surfaces and Interfaces; Thin Films; Tool steels; Molten Steel; Refining Process; Slag Composition; Inclusion Size; Interfacial Tension
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-015-0481-0

Industrial experiments were performed to improve the cleanliness of 95CrMo drill rod steel by slag refining. Higher steel cleanliness, lower corrosion, and small inclusions were obtained using the optimal slag composition (pctCaO/pctSiO 2  = 3.7 to 4, pctCaO/pctAl 2 O 3  = 6 to 8). Layered composite inclusions formed during vacuum decarburizing refining. CaS first precipitated around the spinel and subsequently formed inclusions in which solid CaS-CaO wrapped around the Al 2 O 3 -MgO-SiO 2 -CaO system as the modification and diffusion progressed. The thermodynamic equilibrium between slag and liquid 95CrMo steel at 1873 K (1600 °C) was also studied to understand the effect of slag composition on the oxygen content and absorption capacity for Al 2 O 3 . A mathematical model based on an investigation of slag viscosity and the interfacial tension between slag and inclusions was used to predict the size of critical inclusions for different slags. The evolution of typical inclusions is discussed in terms of the study of reactions between slag and steel.