Doctoral Dissertations

Abstract

"Alloying is required for the production of all steel products from small castings to large beams. Addition of large quantities of bulk alloys can result in alloy segregation and inconsistent alloy recovery. The objective of this research was to better understand alloy dissolution in liquid steel especially as it relates to Missouri S&Ts' patented continuous steelmaking process. A 45-kilogram capacity ladle with a single porous plug was used to evaluate the effect of four experimental factors on alloy dissolution: alloy species, alloy size or form, argon flow rate, and furnace tap temperature. Four alloys were tested experimentally including Class I low carbon ferromanganese, nickel and tin (as a surrogate for low melting alloys) and Class II ferroniobium. The alloys ranged in size and form from granular to 30 mm diameter lumps. Experimental results were evaluated using a theoretically based numerical model for the steel shell period, alloy mixing (Class I) and alloy dissolution (Class II). A CFD model of the experimental ladle was used to understand steel motion in the ladle and to provide steel velocity magnitudes for the numerical steel shell model. Experiments and modeling confirmed that smaller sized alloys have shorter steel shell periods and homogenize faster than larger particles. Increasing the argon flow rate shortened mixing times and reduced the delay between alloy addition and the first appearance of alloy in the melt. In addition, for every five degree increase in steel bath temperature the steel shell period was shortened by approximately four percent. Class II ferroniobium alloy dissolution was an order of magnitude slower than Class I alloy mixing"--Abstract, page iii.

Advisor(s)

Peaslee, Kent D., 1956-2013
Richards, Von

Committee Member(s)

Sharma, V. K.
Lekakh, S. N. (Semen Naumovich)
Fahrenholtz, William

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Metallurgical Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2011

Pagination

xv, 164 pages

Note about bibliography

Includes bibliographical references (pages 151-163).

Rights

© 2011 Darryl Scott Webber, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Alloys -- MetallurgyArgonLadle metallurgyMechanical alloyingSteel founding

Thesis Number

T 9908

Print OCLC #

794779279

Electronic OCLC #

763371868

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