Sintering Behavior of New Chromite-Alumina Mixed Ladle Filler Sands for High Mn-High Al Steel Grades

Developing novel filler sands has garnered significant interest in improving the ladle’s free‐opening rate and enhancing the cleanliness of high‐Mn and high‐Al steel. Laboratory studies explored the effect of adding Cr2O3 powder on the sintering behavior of chromite‐based ladle filler sands. Furthermore, interfacial phenomena were examined between the sands and high‐Mn and high‐Al steel grades, varying in Mn contents. The results demonstrate that adding Cr2O3 power played a role in inhibiting the liquid phase formation in the filler sand. With a 16% addition, the steel (Mn mass%=30) reacted with the sand, leading to the shape of a spinel phase (SP), specifically (Mn, Fe, Mg)O·(Al, Cr)2O3, which facilitated the separation of the liquid phase. The reduction of FeO to Fe by Mn, Al, and C in steel, especially Al, was hindered by adding Cr2O3, resulting in a suitable sintering degree that ultimately benefited ladle free‐opening. SiO2 is crucial for forming the liquid phase during the sintering process. The SiO2 content of the sand should be about 20% to achieve optimal sintering effects. Chromite sand for casting is not suitable for the high‐Mn and high‐Al steels. The mixed sand composition presented in the current study demonstrates potential as a suitable filler sand material for high‐Mn and high‐Al (20 ≤ Mn mass% ≤ 30) steel.This article is protected by copyright. All rights reserved.

Section: Resultssupporting

confidence: 89%

“…[10,[12][13][14][15]17] Similar conclusions have been drawn in previous studies, albeit with the difference that no liquid phase was detected in foundrygrade chromite sand. [17]…”

Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Effect Of Fe In the Steelmentioning

confidence: 99%

Section: Effect Of Sio 2 In the Sandmentioning

confidence: 99%

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Effect of Cr₂O₃ Addition on Sintering Behavior of Novel Chromite‐Based Ladle Filler Sand

Li,

Kong,

Zang

2023

Effect of Carbon on Sintering Behavior of Chromite‐Based Ladle Filler Sands

Yuan,

Deng,

Zhu

2024

Self Cite

To investigate the effect of carbon on the sintering behavior of ladle filler sands, laboratory experiments are carried out using chromite‐based filler sands and carbon (graphite) powders as well as liquid steel in an inert atmosphere at 1600 °C. It is found that the fine carbon powders result in an increase in angle of repose before sintering. After sintering, the apparent porosity increases with the carbon content in the sands, while the bulk density declines. During sintering with and without liquid steel, the carbon powders in the sands will react with the sand grains, leading to the generation of some gases (CO and CO2) and the increase of liquid phase in the sands. The acceleration of the formation of the liquid phase in the sands would enhance the sintering of the sands. The generated gases can result in many large holes in the sands, and liquid steel is very possible to infiltrate into the sands. To obtain a higher ladle free opening rate, special attention should be paid to carbon addition in ladle filler sands.

A Novel Nonmetallic Inclusion in High‐Mn and High‐Al Steel Caused by the Interfacial Reaction Between Steel and Ladle Filler Sand

Li,

Zang,

Zhang

et al. 2024

The influence of chromium‐bearing filler sand on the transformation of inclusions in high‐Mn and high‐Al steel under various reaction times and Mn content levels is studied, and the mechanism of filler sand intrusion into the steel matrix is analyzed. It is demonstrated that an inclusion containing Cr2O3 is discovered. The evolution pathway of oxide inclusions is identified as Al2O3–MnO → Al2O3–MnO–SiO2 → Al2O3–MnO–SiO2–Cr2O3(Cr2O3 + MnO–SiO2) → Al2O3–MnO–Cr2O3–MgO·Al2O3. It is noteworthy that Cr2O3 inclusions tend to diffuse from the outside inward, but the internal content remains almost unchanged, which is due to the strong diffusion hindrance of SiO2. The formation of a liquid phase in the filler sand is a necessary condition for its infiltration into the steel matrix. The critical liquid‐phase content that results in the formation of Cr2O3 inclusions is 42%, which contains 5–8% of Cr2O3. The formation of pore channels provides favorable conditions for sand penetration, with the maximum penetration depth reaching up to 29 mm. Large sand inclusion particles reach millimeter scale in size and are distributed quite randomly. Chemical reactions at the steel/sand interface can lead to an increase in the total oxygen (T.O) content in the steel. The reaction time has little effect on the T.O content, while the Mn content in the steel has a significant impact, with an increase of up to 41 ppm. During the smelting stage, the filler sand can enter the molten steel, thereby affecting the quality of the product.