Doctoral Dissertations

Alternative Title

Inclusion engineering in Manganese-Silicon de-oxidized steel for thin-strip casting

Keywords and Phrases

Ferro-alloy dissolution; Inclusions; Steelmaking; Thermodynamic-modeling; Thin-strip casting

Abstract

"The focus of this research was to understand inclusion formation and evolution in Mn-Si de-oxidized steels used in thin-strip casting. Inclusions formation and evolution in ultra-low carbon low-alloyed steels were studied. Inclusion engineering can be used to remove or modify detrimental inclusions, which cause casting issues.

The first part of this study focused on inclusion formation as a result of ferro-alloy addition. De-oxidation reaction in steels are the primary source of the typical oxide inclusion formed in steel. For Mn-Si de-oxidized steels ferro-silicon and ferro-manganese are the two ferro-alloys used for de-oxidation. Inclusion formation and evolution during the early stages of dissolution of these ferro-alloys was experimentally studied. The mechanism for inclusion formation in their transient phase was proposed.

The second part of this study shows the results of modification of inclusions observed in Mn-Si killed steel as a result of ferro-titanium addition. MnO-SiO2-Al2O3 based inclusions were modified by ferro-titanium addition to form inclusions of lower melting points. These inclusions would cause fewer issues during casting.

In the third part of this study a comprehensive dynamic model for vacuum tank degasser (VTD) was developed. VTD is used in the industry to obtain ultra-low carbon steels. Further, VTD processing typically removes gaseous species from liquid steel which is essential for thin-strip casting. Inclusion content in the steel is further reduced by this process. The VTD model calculated thermodynamic equilibrium under different conditions within steel in a ladle during VTD processing. The model successfully predicted composition change in steel over time under VTD processing."--Abstract, page iv.

Advisor(s)

Smith, Jeffrey D.

Committee Member(s)

Robertson, D. G. C.
Lekakh, S. N. (Semen Naumovich)
O'Malley, Ronald J.
Fahrenholtz, William

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Materials Science and Engineering

Sponsor(s)

NUCOR Castrip

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2015

Journal article titles appearing in thesis/dissertation

  • Transient inclusion formation and evolution in silicon-killed steels
  • Inclusion modification in Si-Mn killed steels using titanium addition
  • A kinetic model for vacuum tank degassing

Pagination

xiv, 163 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2015 Vivek Thapliyal, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Library of Congress Subject Headings

Steel -- Deoxidizing
Manganese-silicon alloys
Degassing of metals
Steel -- Metallurgy

Thesis Number

T 10727

Electronic OCLC #

913410445

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