A Thermodynamic Study on the Inclusion Formation in Ferritic Stainless Steel Melt

• Published in: ISIJ International Vol. 44; no. 7; pp. 1134 - 1139
• Main Authors: Cha, Woo-Yeol, Kim, Dong-Sik, Lee, Yong-Deuk, Pak, Jong-Jin
• Format: Journal Article
• Language: English
• Published: Tokyo The Iron and Steel Institute of Japan 01.01.2004; Iron and Steel Institute of Japan
• Subjects: AOD slag; Applied sciences; Exact sciences and technology; inclusion; Metals. Metallurgy; MgO · Al2O3 spinel; secondary deoxidation; stainless steel; Non metallic inclusion; Ferritic stainless steel; Thermodynamics; Ferritic steel; Microstructure; Stainless steel
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.44.1134

A type 430 stainless steel melt containing different Al levels was equilibrated with an AOD type slag saturated with Al2O3 or MgO to clarify the formation mechanism of slag-type inclusions containing MgO · Al2O3 spinel. The Al-O deoxidation equilibrium in the stainless steel melt was examined as a function of melt temperature to check the validity of available thermodynamic data, and to estimate the secondary deoxidation by Al picked up from the ladle slag. During the temperature drop from AOD to tundish, a small amount of entrapped AOD slag particles in molten steel can easily change their composition to a level where the MgO · Al2O3 spinel can crystallize. The refractory material, MgO or Al2O3 for a ladle, is one of critical factors to affect the Al level in the melt, and hence the formation of MgO · Al2O3 spinel inclusions in the final products.