A Morphological Comparison between Inclusions in Aluminium Killed Steels and Deposits in Submerged Entry Nozzle

Dekkers, Rob; Blanpain, Bart; Wollants, P; Haers, F; Gommers, B; Vercruyssen, Carina

doi:10.1002/srin.200300197

Cited by 41 publications

(28 citation statements)

References 12 publications

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“…Inclusions in LCAK steel after deoxidation are mainly alumina‐based. Large alumina‐based inclusions have a detrimental effect on the castability of the molten steel27–29 and the surface quality of the steel sheet30–32. Currently, large alumina‐based inclusions are either modified into low melting ones by calcium treatment,9, 33, 34 or removed by flow transport,35, 36 or become defects of the steel product 26…”

Section: Resultsmentioning

confidence: 99%

Cleanliness of Low Carbon Aluminum‐Killed Steels during Secondary Refining Processes

Yang

Wang

Zhang

et al. 2012

steel research int.

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Efficient secondary refining process is necessary for massive and stable production of low carbon aluminum-killed (LCAK) steels. Plant trials were performed to investigate the cleanliness of steels. Characteristics of composition, cleanliness, and inclusions of LCAK steel during different secondary refining processes, including LF, CAS, RH-LIT, and RH, were studied and compared. The results showed that CAS, RH-LIT, and RH processes had better control of low carbon, silicon, and nitrogen than LF process. High cleanliness of LCAK steels could be achieved by all the mentioned refining processes. It was concluded that the total oxygen (T.O.) should be <35 ppm to reduce the amount of inclusions and reach the level of clean steels. The removal rate of inclusions during RH-LIT and RH processes was much higher than that of LF and CAS. The T.O. content and the amounts of inclusions during CAS, RH-LIT, and RH could be quickly decreased to a low value within 10 min. The results showed that CAS and RH-LIT as well as RH refining processes can produce LCAK steels that meet the requirements of high efficient, low cost, clean, and stable production, while LF is more suitable for the heats with poor control of end point of BOF, and for the process with calcium treatment to control sulfur content and lower the clogging of Submerged Entry Nozzle during thin slab continuous casting.

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Section: Resultsmentioning

confidence: 99%

Cleanliness of Low Carbon Aluminum‐Killed Steels during Secondary Refining Processes

Yang

Wang

Zhang

et al. 2012

steel research int.

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“…The relation between the side length of the rombicubeoctahedron D and the sphere radius of a sphere with the same extension is shown in equation (8) D~R 1z2 1=2 (8) The drag force F d on a sphere surrounded by a fluid flowing with velocity v can be expressed as 37 shown in equation (9) F d~Cd A rv 2 2 (9) where C d is the drag coefficient and A is the crosssectional area of the sphere. The value of C d depends on the flow characteristics.…”

Section: Appendixmentioning

confidence: 99%

Pilot plant study of nozzle clogging mechanisms during casting of REM treated stainless steels

Kojola

Ekerot

Andersson

et al. 2011

Ironmaking & Steelmaking

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A pilot scale bottom teemed high frequency furnace with a nominal capacity of 600 kg and an adjustable nozzle temperature was used to study clogging of rare earth metal (REM) treated stainless steels. The influence of the following variables on the clogging was studied: amount of REM, fraction of oxide clusters, total oxygen content in the steel, reoxidation, aluminium additions before REM additions and silicon additions during casting. Overall, the results show that, during the present experimental conditions, mainly two typical clogging rates could be identified, fast and slow clogging. Two main differences could be detected between the fast and slow clogging rates. Steel containing mainly small single inclusions clogged faster than steel containing mainly large inclusion clusters. The reason was believed to be that the small inclusions could stick to the nozzle wall at narrow passages where the steel flow velocity was high while the larger ones could not. The source of the small inclusions was believed to be reoxidation. It was also found that the main part of the nozzle accretion was caused by agglomeration of inclusions and inclusion clusters, while only a thin oxide film along the nozzle wall was caused by oxide precipitation at the nozzle wall.

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“…This deposition of alumina inclusions can disturb and eventually block the fluid flow of the steel melt and therefore cause an interruption in the production . Based on their investigation of inclusion morphologies, Dekkers et al suggested that the deposition consisted of reoxidation products. However, the results of these kinds of investigations are strongly dependent on the steelmaking process and the casting conditions.…”

Section: Introductionmentioning

confidence: 99%

A Study of Cluster Characteristics in Liquid Stainless Steel and in a Clogged Nozzle

Janis

Karasev

Inoue

et al. 2015

steel research int.

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Clusters of Al2O3 inclusions in a liquid stainless steel (18/8) and in a clogged ZrO2 nozzle after casting were studied during a pilot plant trial. Samples were taken from the melt at different holding times after an addition of 0.1 mass% Al. The characteristics (composition, size, number, and morphology) of clusters and clustered inclusions in the steel samples and in the clogged nozzle were investigated after electrolytic extraction and etching by using SEM. It was found that the Al2O3 inclusions in the clusters are transformed from a spherical into irregular and regular (with sharp edges) shape during the holding time. Most of the inclusions in the clusters (>80%) after a 6 min holding time are regular inclusions, which have sharp edges and flat faces. The size of the inclusions in clusters in the melt increased on average from 1.0 μm at a 1 min to 5.2 μm at a 12 min holding time. While the sizes of different types of inclusions in the clogged nozzle correspond to those present in the liquid steel at respective time, the frequency of spherical inclusions in the clogged nozzle is about 2–4 times larger (particularly near the nozzle wall) compared to that in the melt. Growth and transformation of Al2O3 clusters in the liquid steel at different holding times after an addition of Al and during casting were considered based on the obtained results.

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A Morphological Comparison between Inclusions in Aluminium Killed Steels and Deposits in Submerged Entry Nozzle

Cited by 41 publications

References 12 publications

Cleanliness of Low Carbon Aluminum‐Killed Steels during Secondary Refining Processes

Cleanliness of Low Carbon Aluminum‐Killed Steels during Secondary Refining Processes

Pilot plant study of nozzle clogging mechanisms during casting of REM treated stainless steels

A Study of Cluster Characteristics in Liquid Stainless Steel and in a Clogged Nozzle

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