Influence of Refractory-Steel Interfacial Reaction on the Formation Behavior of Inclusions in Ce-containing Stainless Steel

Abstract

Effect of Ce addition on the interfacial reaction between alumina refractory and 25wt%Cr-20wt%Ni-4wt%Si-0.5wt%Mn stainless steel deoxidized by Al at 1 873 K was investigated to understand the contribution of the refractory-steel reaction to the inclusion evolution processes. The oxygen content markedly decreased by Al deoxidation, followed by a sluggish decrease by Ce addition greater than 0.5 wt%. The Ce content continuously decreased, but the higher the initial Ce content, the lower the Ce-decreasing rate was obtained. The content of Al initially decreased due to the formation of Al-rich inclusions, followed by an abrupt increase mainly due to a reduction of alumina refractory by Ce at the steel-refractory interface. The content of Al decreased again because of the formation of CeAlO 3 compound not only as inclusions but also as refractory-steel reaction products. The CeAl 11 O 18 and CeAlO 3 were formed at the refractory side, while the Ce 2 O 3 and CeAlO 3 were formed at the steel side in the 0.5 wt% and 1.0 wt% Ce added systems. From the refractory-steel reaction mechanism, the process of inclusion evolution was proposed to three steps as follows. The initial SiO 2 -rich oxides are reduced by Al, resulting in the formation of aluminosilicates inclusions (Step 1). The Al 2 O 3 in the inclusions are reduced by cerium, resulting in the formation of Ce-rich oxides (Step 2). Because the Ce content continuously decreased due to the refractory-steel reaction, the inclusions transform from Ce-Al complex oxides to Al-rich aluminosilicates and from Ce 2 O 3 to Ce-Al complex oxides in the 0.1 wt% and 0.5 wt% Ce added systems (Step 3).

Transformation of Oxide Inclusions in Stainless Steel Containing Yttrium during Isothermal Heating at 1473 K

“…A similar result was also observed by Katsumata et al in 25 mass% Cr-6 mass% Ni stainless steel [8]. Kwon et al [9,10] investigated the evolution of inclusions in Al-killed stainless steel with Ce addition at 1873 K. Mn(Cr)-silicates were found to be the primary inclusions before Al addition. When Al was added without Ce addition, the initial Mn(Cr)-silicate changed to Al 2 O 3 -rich inclusions.…”

“…The influence of different REM on the behavior of inclusions at steelmaking temperature has been well investigated [7][8][9][10][11][12]. Dan et al [7] studied the deoxidation characteristic of Al-Ce and Al-Y complex deoxidizers in molten iron.…”

An <i>in situ</i> Study of the Formation of Rare Earth Inclusions in Arsenic High Carbon Steels

“…[7][8][9][10][11][12] Some side reactions between RE elements and crucibles were also investigated. 13,14) It was proved that RE-As even RE-O-S-As inclusions might form in arsenic RE steels. 15,16) What kinds of inclusions may form greatly depends on the chemical compositions of steel, especially the concentrations of RE, O and S; further, the formation of arsenic inclusions depends to a large extent on RE inclusions.…”

Roles of Inclusion, Texture and Grain Boundary in Corrosion Resistance of Low-Nickel Austenite Stainless Steel Containing Ce

“…3,4) Torkamani et al 5) found that rare earth elements could change the interaction between the inclusions and matrix during the solidification process, affecting the microstructural features. Kwon et al 6) reviewed that a decrease in Ce content was attributable to the formation of oxide inclusions, and the inclusion-steel interfacial area could be acted as the preferential site for initiation of pitting corrosion. Arenas et al 7) reported that not only the control of composition, size and morphology of Ce-containing inclusions in steel but also the high seg-regation of Ce element along grain boundaries were highly important for the corrosion behavior of steels.…”

“…2 O 3 can be transformed into Ce 2 O 2 S according to the relevant calculations. Similarly, CeS is calculated as follows: @ ......................... (6). ............…”