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Slag inclusion formation during solidification of steel alloys and in cast iron
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis explores the formation of segregation and inclusions during solidification of steel and cast iron. A better understanding of the formation mechanism should result in decreasing fraction of defects during solidification of ingot and strand material.

Density driven macrosegregation was studied both experimentally and theoretically to see the effect of channel segregation on the total segregation. Formation of these pencil-like segregations is due to natural convection in the solidifying metal caused by liquid enrichment of elements with lower density compared to the bulk. It is suggested to change the composition to compensate for this density difference.

Inclusion precipitation can be finite by limitations in segregation. Saturated liquid is found in the last solidified areas, often between dendrites. Here the enrichment of the liquid is possible due to microsegregation. Meanwhile crystals form and solidify the elements with low solubility in the solid is pushed out in the remaining liquid. Soon the liquid is saturated to the level where spontaneous formation of inclusions occurs. Microstructure studies by aid of SEM and micro-probe measurements are analysed to find at what point during solidification process the inclusions start to form. In steel making this formation has a detrimental effect on the mechanical properties in contrary to the production of nodular cast iron where the inclusions have a beneficial effect on the graphite formation.

Inoculation of cast iron aims at reaching higher number density of graphite nodules, nodule morphology modification and control of nodule distribution during solidification. Late precipitation of nucleation sites has shown to have a positive impact on preventing chill. To find the most potent inoculation agent different additives were tested. Special effort has been made to analyse the effect of oxides and sulphides as nucleation sites.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , 21 p.
Series
ISSN KTH/MSE-07/10-SE+CER/AVH
Keyword [en]
solidification, segregation, precipitation, inclusions, inoculation, EMPA
National Category
Other Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4371ISBN: 978-91-7178-624-1 (print)OAI: oai:DiVA.org:kth-4371DiVA: diva2:11994
Presentation
2007-05-11, Rum B1, MSE, KTH, Brinellvägen 23, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101102Available from: 2007-05-14 Created: 2007-05-14 Last updated: 2010-11-02Bibliographically approved
List of papers
1. Crack formation during continuous casting of tool steel
Open this publication in new window or tab >>Crack formation during continuous casting of tool steel
2005 (English)In: Transactions of the Indian Institute of Metals, ISSN 0019-493X, Vol. 58, no 4, 671-678 p.Article in journal (Refereed) Published
Abstract [en]

The formation of cracks has been studied during continuous casting of a tool steel. Experimental work was performed in a continuous slab caster and the position of the cracks was determined as a function of distance from the cooling surface. Numerically calculated temperatures and elastic stresses were combined with experimentally determined thermomechanical data of the cast material in order to predict crack positions. The model was extended to include the effect on the strain from both thermal shrinkage and the shrinkage caused by condensation of vacancies during the solidification process.

Keyword
SOLIDIFICATION PROCESS, ALLOYS, VACANCIES, ALUMINUM, BEHAVIOR
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-7083 (URN)000232332700024 ()2-s2.0-33644672764 (Scopus ID)
Note
QC 20100907Available from: 2007-05-14 Created: 2007-05-14 Last updated: 2010-09-07Bibliographically approved
2. Macrosegregation In Ingot Cast Tool Steel
Open this publication in new window or tab >>Macrosegregation In Ingot Cast Tool Steel
2004 (English)Report (Other academic)
Place, publisher, year, edition, pages
Stockholm: KTH, 2004. 22 p.
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-7084 (URN)KTH-MG-INR-04:09 SE (ISRN)
Note
QC 20101102Available from: 2007-05-14 Created: 2007-05-14 Last updated: 2010-12-20Bibliographically approved
3. A thermodynamic analysis of the inoculation process in cast iron.
Open this publication in new window or tab >>A thermodynamic analysis of the inoculation process in cast iron.
2006 (English)Report (Other academic)
Publisher
21 p.
Series
Trita-MG, ISSN 1104-7127 ; 2006:03
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-7085 (URN)KTH-MG-INR-06:03 SE (ISRN)
Note
20100602Available from: 2007-05-14 Created: 2007-05-14 Last updated: 2010-11-02Bibliographically approved
4. MnS precipitation during solidification in presence of oxide nuclei
Open this publication in new window or tab >>MnS precipitation during solidification in presence of oxide nuclei
2007 (English)Conference paper, Published paper (Other academic)
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-7086 (URN)
Conference
5th Decennial International Conference on Solidification Processing, 23-25th July 2007, University of Sheffield, UK
Note

QC 20101102

Available from: 2007-05-14 Created: 2007-05-14 Last updated: 2012-08-23Bibliographically approved

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CiteExportLink to record
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Citation style
  • apa
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  • Other locale
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Output format
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