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Inclusion Motion under a Swirl Flow in the Continuous Casting Process and Wire Feeding in the Induction Furnace
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The thesis includes the studies of two phenomena related to continuous casting. One subject is the inclusion motion in the submerged entry nozzle (SEN) and mold when using a swirl flow. The swirl flow is generated in a SEN by using an electromagnetic swirl flow generator (EMSFG). The other subject is focused on FeSiRE particles (powder) that are added into the molten steel by using a wire feeding method, which in the future could be used in a continuous casting mold.

Firstly, two kinds of a full type and a half type EMSFG were designed based on mathematical modeling. Then, the distributions of the magnetic flux intensity and the Lorentz force were obtained for two types of EMSFG devices. Based on the results of the Lorentz force, the flow field, temperature field and inclusion motion in the SEN and the mold were studied by using a full type and a half type EMSFG. Moreover, a comparison from the above aspects was investigated between a full type EMSFG and a half type EMSFG. In addition, the effect of different inclusion parameters such as the densities, sizes and boundary conditions, on the inclusion behavior was studied. It was found that light Al2O inclusion moves towards the rotational center by a centrifugal force and that a swirl flow prevents nozzle clogging. The heavy CeO inclusion more or less moves outwards towards the SEN wall and they may stick to the wall. It was also found that the inclusion separation to a mold meniscus increased and that the inclusions being trapped into a solidified shell decreased when using a swirl flow compared to when not using a swirl flow.

A study of a wire feeding into molten steel in an induction furnace was done to determine the potential to implement wire feeding into a mold in the future. A major difference compared to a traditional solid wire is that the wire contains particles (powder). Firstly of all, the wire melting behavior in the molten steel was studied. More specially, the influence of the different wire materials (aluminum, copper and 316L stainless steel wires) on the dissolution time in the molten steel was modeled. Moreover, these simulation results were compared to experimental results. In addition, the FeSiRE particle (powder) motion in the induction furnace was also simulated. The results showed that the copper wire is more suitable to apply in the continuous casting mold when a small addition and a lower wire feeding speed are used. Conversely, if a large amount and a higher feeding speed are needed, the aluminum wire may be recommended for injections in the mold. The results also indicated that the thermal properties of particle (powder) have an influence on the wire melting behavior in the molten steel.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. , ix, 71 p.
Keyword [en]
inclusion motion, swirl flow, rotating magnetic field, electromagnetic swirl flow generator, full type, half type, submerged entry nozzle, mold, wire feeding, melting behavior, FeSiRE particle (powder) motion, induction furnace
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-175999ISBN: 978-91-7595-736-4 (print)OAI: oai:DiVA.org:kth-175999DiVA: diva2:865167
Public defence
2015-11-27, Sal D3, Lindstedtsvägen 5, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20150102

Available from: 2015-11-02 Created: 2015-10-27 Last updated: 2015-11-02Bibliographically approved
List of papers
1. Design of magnetic fields for half and full type electromagnetic swirl flow generators
Open this publication in new window or tab >>Design of magnetic fields for half and full type electromagnetic swirl flow generators
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2015 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 86, no 4, 361-374 p.Article in journal (Refereed) Published
Abstract [en]

In this work, the placement of an electromagnetic swirl flow generator (EMSFG) around a submerged entry nozzle (SEN) was proposed as a method for generating a rotating electromagnetic field in a continuous casting (CC) process of steel. First, two kinds of a full type EMSFG and a half type EMSFG were designed based on mathematical modeling. Then, distributions of magnetic flux intensity in an EMSFG as well as distributions of Lorentz force in molten steel were simulated. It was found that the EMSFG structure and electromagnetic parameters have an important effect on magnetic flux intensity and Lorentz force distributions. For both a full type and a half type EMSFG, the magnetic flux intensity and Lorentz force increases as the magnetomotive force increases. Especially, for a full type EMSFG, the magnetic flux intensity is distributed evenly in molten steel. Moreover, the Lorentz force increases along a radial direction in the molten steel in the SEN. However, for a half type EMSFG, the magnetic flux intensity and Lorentz force decreases gradually towards the region without an EMSFG. Consequently, a full type EMSFG with a 44 000 AT magnetomotive force and a 50 Hz frequency is more suitable to apply in the operation of an EMSFG under actual production conditions.

Place, publisher, year, edition, pages
John Wiley & Sons, 2015
Keyword
rotating magnetic field, electromagnetic swirl flow generator, full type, half type
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-143900 (URN)10.1002/srin.201300463 (DOI)000352712300004 ()2-s2.0-84926627883 (Scopus ID)
Note

QC 20150511. Updated from manuscript to article in journal.

Available from: 2014-04-02 Created: 2014-04-02 Last updated: 2017-12-05Bibliographically approved
2. Inclusion Behavior under a Swirl Flow in a Submerged Entry Nozzle and Mold
Open this publication in new window or tab >>Inclusion Behavior under a Swirl Flow in a Submerged Entry Nozzle and Mold
2015 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 86, no 4, 341-360 p.Article in journal (Refereed) Published
Abstract [en]

Previous studies have verified that a swirl flow generated in a submerged entry nozzle (SEN) can effectively improve a flow pattern and a heat transfer in a continuous casting (CC) process. In order to obtain a further in-depth understanding with respect to the effect of a swirl flow on a CC process, the inclusion behavior in a SEN and a mold was studied in the present work. The flow field and the temperature field of molten steel as well as the inclusion behavior in a SEN and a square bloom mold were simulated under the influence of a rotating electromagnetic field (swirl generator). Also, the influence of different inclusion parameters such as the densities, sizes, and boundary conditions, on the inclusion behavior was studied. The results show that a flow pattern in a SEN can be characterized into three distinct flow regions: an accelerating flow of molten steel from an electromagnetic swirl flow generator (EMSFG) inlet to an EMSFG center, a decelerating flow of molten steel from an EMSFG center to an EMSFG outlet, and a recirculation flow of molten steel from an EMSFG outlet to an SEN outlet. In addition, it was found that light Al2O3 inclusion moves towards the rotational center by a centrifugal force, and that a swirl flow prevents nozzle clogging. Moreover, it was also found that the inclusion separation to a mold meniscus increased and that the inclusions trapped into a solidified shell wall decreased when using a swirl flow.

Keyword
inclusion behavior, mold, rotating magnetic field, submerged entry nozzle, swirl flow
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-166340 (URN)10.1002/srin.201300462 (DOI)000352712300003 ()2-s2.0-84926686756 (Scopus ID)
Note

QC 20150508

Available from: 2015-05-08 Created: 2015-05-07 Last updated: 2017-12-04Bibliographically approved
3. The Influence of Swirl Flow on the Flow Field, Temperature Field and Inclusion Behavior When Using a Half Type Electromagnetic Swirl Flow Generator in a Submerged Entry Nozzle and Mold
Open this publication in new window or tab >>The Influence of Swirl Flow on the Flow Field, Temperature Field and Inclusion Behavior When Using a Half Type Electromagnetic Swirl Flow Generator in a Submerged Entry Nozzle and Mold
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2015 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 86, no 11, 1312-1327 p.Article in journal (Refereed) Published
Abstract [en]

In the preceding work, the inclusion behavior in a submerged entry nozzle (SEN) and mold induced by using a swirl flow has been investigated. The results showed that a swirl flow can effectively promote the inclusions removal to the meniscus as well as reduce the inclusions entrapment at the solidified shell wall. Moreover, that the swirl flow was generated by using a full type electromagnetic swirl flow generator (EMSFG). In the present work, a kind of a half type EMSFG was investigated, since it is easier to implement in a production scale. The influence of the stirrer on the fluid flow, heat transfer, and inclusion behavior in the SEN and mold was studied. Furthermore, a comparison between these two types of EMSFG from the aspects of flow field, temperature field, and inclusion behavior was done. In addition, the effect of different magnetomotive forces, inclusion sizes, densities as well as boundary conditions on the inclusion behavior was studied. The results show that the effect of a half type EMSFG (88000 AT) on the molten steel is very close to a full type case (44000 AT). More specifically, the flow pattern, temperature distribution as well as inclusion behavior in the SEN and mold look very similar. Also, it was found that from the viewpoints of the inclusions separation to the mold meniscus and the inclusions trapping at the solidified shell wall, better results could be obtained for a “Trap” boundary condition when using half type EMSFGs.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2015
Keyword
Inclusion behavior, swirl flow, half type EMSFG, rotating magnetic field, submerged entry nozzle
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-175988 (URN)10.1002/srin.201400330 (DOI)000363679600010 ()2-s2.0-84945443211 (Scopus ID)
Note

QC 20151026

Available from: 2015-10-26 Created: 2015-10-26 Last updated: 2017-12-01Bibliographically approved
4. The Wire Feeding and Melting behavior in the Induction Furnace
Open this publication in new window or tab >>The Wire Feeding and Melting behavior in the Induction Furnace
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(English)Manuscript (preprint) (Other academic)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-176269 (URN)
Note

QS 2015

Available from: 2015-11-02 Created: 2015-11-02 Last updated: 2015-11-02Bibliographically approved

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