Change search
ReferencesLink to record
Permanent link

Direct link
Oxygen penetration in the protection shroud in steel casting
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.ORCID iD: 0000-0002-3548-8638
2010 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 81, no 11, 965-973 p.Article in journal (Refereed) Published
Abstract [en]

Physical modelling of argon shroud used in ingot casting was carried out using a 2D 1:1 scaled model in order to determine the oxygen distribution around the steel stream. The oxygen concentrations were measured by an oxygen sensor. Complementary PIV measurements were also carried out for a gas inlet configuration using dual (horizontal and vertical) gas inlet. The main findings were: (1) The oxygen concentrations were considerably high in the ordinary operation conditions. The oxygen contents were the highest in the case of vertical gas injection (higher than 11% in all cases). (2) A minimized distance between the ladle and the collar on the top of the vertical runner would reduce the oxygen entrainment by convection and diffusion, in the case of horizontal gas injection and a dual gas inlet configuration. (3) A modest flow rate of argon gas should be used. Further increase of the gas flow would not improve the protection. (4) A dual gas inlet configuration would be more effective than a single inlet, especially in the case of larger distances between the ladle and the runner.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2010. Vol. 81, no 11, 965-973 p.
Keyword [en]
argon shroud, ingot casting, reoxidation, cold model
National Category
Materials Engineering Metallurgy and Metallic Materials
URN: urn:nbn:se:kth:diva-13397DOI: 10.1002/srin.201000088ISI: 000284863500007ScopusID: 2-s2.0-84859585529OAI: diva2:325044

QC 20100617 Uppdaterat från submitted till published 20101223

Available from: 2010-06-17 Created: 2010-06-17 Last updated: 2016-07-19Bibliographically approved
In thesis
1. Formation of non-metallic inclusions and the possibility of their removal during ingot casting
Open this publication in new window or tab >>Formation of non-metallic inclusions and the possibility of their removal during ingot casting
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present study was carried out to investigate the formation and evolution of non-metallic inclusions during ingot casting. Emphasize have been on understanding the types of inclusions formed and developed through the casting process and on the development of already existing inclusions carried over from the ladle during casting. Industrial experiments carried on at Uddeholm Tooling together with laboratory work and Computational Fluid Dynamics (CFD) simulations.

Ingots of 5.8 tons have been sampled and the types of inclusions together with their distribution within the ingot have been characterized. Two new types of inclusions have been found. Type C1 is found originated from casting powder and in the size from a few μm to 30 μm. Type C2 is of macro inclusion type sizing up to 70 μm. The presence of C2 inclusions are few but very detrimental for the quality of the steel. Both types, C1 and C2 consist of alumina, indicating that reoxidation is the main reason for their existence.

The protecting argon shroud has been studied by the use of a 1:1 scaled 2D model. Both flow pattern and oxygen measurement have been carried out. CFD has also been used as an auxiliary tool. It has been found that the oxygen pickup through argon gas shroud depends mostly on the distance between the ladle and the collar placed on top of runner. Further increase of gas flow rate above 2.5 m3.h-1 had very little effect on the oxygen distribution since both the flushing effect and the entraining effect with respect to oxygen are enhanced by further increase of inert gas flow rate. In the case of dual gas inlet, the flow in the shroud was found much less diffused compared with either vertical or horizontal injection system. The oxygen content in this arrangement was also greatly reduced.

Studies of the runner after casting revealed a sparse non-metallic network structure around the periphery of the steel rod remained in the runner. The surface of the refractory had been severely attacked by the mechanical force from the streaming steel. The erosions of the centre stone and the end stone were on the other hand negligible. CFD calculations showed that the flow at those locations is almost stagnant. The surface of the refractory in contact with the steel was found to have an increased content of alumina. The source for the alumina could come from either exchange reaction of dissolved aluminium replaces the silica or reoxidation products origin from oxygen pick up during the transfer from the ladle to the vertical runner. Inclusions were also found entrapped in the steel refractory interface.

It was also found that a formation of a liquid slag film as early as possible during casting would increase the possibility to remove inclusions and especially inclusions generated by the casting powder.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. viii, 49 p.
Ingot casting, tool steel, inclusion, runner, refractory, erosion, casting powder, cold model, argon shroud, reoxidation, oxygen measurement, CFD, PIV
National Category
Metallurgy and Metallic Materials
urn:nbn:se:kth:diva-12458 (URN)978-91-7415-620-1 (ISBN)
Public defence
2010-04-30, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
QC 20100617Available from: 2010-04-23 Created: 2010-04-23 Last updated: 2011-02-08Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Ragnarsson, LarsDu, Sichen
By organisation
In the same journal
Steel Research International
Materials EngineeringMetallurgy and Metallic Materials

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 144 hits
ReferencesLink to record
Permanent link

Direct link