Degradation of low‐carbon MgO‐C refractory by high‐alumina stainless steel slags in VOD ladle slagline

Abstract

A new type of low‐carbon magnesia carbon refractory (LCMCR) substituting for MgO‐Cr2O3 refractory was successfully used in vacuum oxygen decarburization (VOD) ladle slagline, and the composition and microstructure of the used LCMCR were investigated. The results indicated that the decarburizing reaction (MgO‐C reaction) in the LCMCR under the VOD refining condition (high temperature, low pressure) was inhibited due to the low carbon content in the MgO‐C refractory and the dense layer formed between slag and original layer. The dense layer prevented the penetration of the external O2 into the LCMCR inside because of the lower permeability of this layer, and thus, the direct burnout of the C in the LCMCR was substantially restrained. On the other hand, the large size crystal and the ultra‐low inclusions (SiO2 and Fe2O3) content of the fused magnesia in the LCMCR made the magnesia more slag resistance, because the grain boundary in magnesia had higher slag penetration resistance and the contact area between the slag and the magnesia was reduced. The two aspects of the inhibited decarburizing reaction and the high quality magnesia synthetically contributed to the high slag resistance of the LCMCR.

Microstructure, properties, and application of low carbon Al2O3‐C refractories used as submerged entry nozzles

“…Undoubtedly, the adhesion of this viscous layer to the interface can inhibit the advance of the liquid slag and thus limit the slag corrosion. 36,37 For the traditional Al 2 O 3 -C refractory, however, the enrichment of Al 2 O 3 in the slag near the interface (containing 25.38 wt% CaO, 14.73 wt% Al 2 O 3 , 40.49 wt% SiO 2 , 1.93 wt% MgO, 8.40 wt% Na 2 O, 2.86 wt% Fe 2 O 3 , and 4.21 wt% F) was much less pronounced than that for LAC, failing to form a protective layer at the interface. This difference was mainly caused by the poor wear resistance of the oxidized layer, which would be easily eroded away by the flux.…”

Research on the corrosion behavior of low carbon mold flux on submerged nozzle refractory

“…Carbonaceous material is one of the main components controlling the melting rate of protective slag. [21][22][23][24] The carbon content of commonly used mold flux can reach 3%-5%. When smelting low-carbon steel or ultra-low-carbon steel, the mold flux with high carbon content is easy to increase the carbon content of molten steel and deteriorates the quality of steel.…”

“…In the process of continuous casting, mold flux has the functions of heat preservation, air isolation, lubrication, and adsorption of inclusions. Carbonaceous material is one of the main components controlling the melting rate of protective slag 21–24 . The carbon content of commonly used mold flux can reach 3%–5%.…”