Corrosion of Carbon Free and Bonded Refractories for Application in Steel Ingot Casting

Abstract

This phenomenological study investigates the corrosion of refractories by a highly corrosive steel (1.6587, 18CrNiMo7‐6) with a high aluminum content and casting temperature of 1580 °C. The applied refractory castables with matrices based on alumina, mullite, and zirconia/titania doped alumina (AZT) are carbon free or low carbon (4 wt%) containing with and without nanoscaled additives. The corrosion is analyzed mainly by microscopy after the corrosion tests. The carbon containing samples are negligibly corroded due to inhibited wetting. The nanoadditives in the carbon containing samples show no influence on the corrosion. The carbon free AZT is attacked most strongly with a corrosion layer of about 14 mm. In the alumina (corrosion layer about 6 mm) and AZT sample, compositions corresponding to manganese aluminates form with manganese from the steel. When also silicon diffuses into the refractory, compositions referring to manganese aluminosilicates form. In the mullite matrix crucible (corrosion layer about 1 mm) compositions corresponding to manganese aluminosilicates form directly with manganese from the steel resulting in a highly viscous melt at the interface which retard the further attack. For a future final evaluation, however, also the steel quality has to be taken into account as will be studied by an Aspex‐SEM.

Interactions between Carbon‐Bonded Alumina Filters and Molten Steel: Impact of a Titania‐Doped Filter Coating

“…The addition of titania did not lead to a provable formation of new phases: apart from α‐alumina, only rutile was identified in sample AC‐T. It is assumed that if any aluminum titanate phases were present before, they decomposed during heat treatment under reducing atmosphere, in line with results reported by Naghizadeh et al and Fruhstorfer et al…”

Effect of Crucible Material for Ingot Casting on Detrimental Non‐Metallic Inclusions and the Resulting Mechanical Properties of 18CrNiMo7‐6 Steel

“…[18] It is known that carbon-bonded crucible materials react with the steel melt, which causes aggregation of non-metallic inclusions at the crucible surface, [19] but also corrosion, erosion, or spalling of refractory material due to different thermal expansion coefficients. [1,20] Thus, both the chemical composition of casting material as well as the evolution of non-metallic inclusions are affected. [2] In particular, the generation of non-metallic inclusions during casting process through deoxidization in ladle and mold even as interaction between refractory and steel was investigated.…”

“…Table 1 summarizes the treatment parameters for the applied different crucible materials. Fruhstorfer et al [20] published details on the production of the crucibles. The temperature during melt treatment was measured using both pyrometer for surface temperature measurement and temperature/oxygen sensor (Celox, Type S, Heraeus) within the steel melt.…”

Corrosion mechanism of lightweight microporous alumina‐based refractory by molten steel

“…Many studies have been conducted to investigate the reaction between molten steel and dense refractories . Fruhstorfer et al investigated the reaction interfaces between alloy steel and various types of refractories, and found that the reaction between molten steel and refractories significantly affects not only the cleanliness of the produced steel, but also the service life of the metallurgical furnace lining . However, the molten steel corrosion to the lightweight refractories is still not been understood, despite their importance in developing lightweight wear lining materials.…”