Doctoral Dissertations

Richard Osei

Keywords and Phrases

Descaling; Oxidation Kinetics; Oxide Phases; Reheating; Scale Structure; Water Jet Impact Factor

Abstract

During continuous castings, reheating, and hot rolling, slab surfaces are exposed to atmospheres containing oxidizing gases which results in scale formation. Inefficient removal of the formed scale during reheating affects product surface quality. The effect of steel composition and operating parameters on scale formation and scale removal efficiencies were investigated. Experimental investigations were carried out using a thermogravimetric (TGA) apparatus designed to replicate the combustion gas atmosphere and temperature in actual industrial slab reheat furnaces. Report on oxidation kinetics, scale structure and properties, and descaling were conducted on laboratory cast and industrial samples. Different characterization techniques were used to analyze in-depth formed scale structure.

Results on scale formation studies showed that sample chemistry, reheating parameters and sample surface condition significantly affected the development of scale structure and its properties particularly in the subsurface scale layer region. The studies showed that major alloying elements (Mn, Si,), micro alloying (Al) elements, and impurities (Cu, Ni, Cr) modified the properties of the formed scale and its kinetics mechanism. Complexity of scale formation due to alloying elements and impurities in steel and cast slab surface condition affected its efficient removal using hydraulic descaling. Samples with high alloying elements of Si and Mn were characterized by strong adhesion and complex root penetrations in the subsurface scale region which decreased descaling efficiency. Descaling hydraulic parameters and surface pretreatment that improved scale removal efficiency were suggested”--Abstract, page iv.

Advisor(s)

O'Malley, Ronald J.

Committee Member(s)

Lekakh, S. N. (Semen Naumovich)
Bartlett, Laura
Miller, F. Scott, 1956-
Adaba, Obinna

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Materials Science and Engineering

Comments

This study is supported by Kent Peaslee Steel Manufacturing Research Center, and the authors express their appreciation to partner industrial members of this project for supplying material for this study.

Research Center/Lab(s)

Peaslee Steel Manufacturing Research Center

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2022

Journal article titles appearing in thesis/dissertation

  • Scale formation on 430 stainless steel in a simulated slab combustion reheat furnace atmosphere
  • Effect of Al additions on scale structure and oxidation kinetics of 430-ferritic stainless steel reheated in a combustion atmosphere
  • Thermodynamic prediction and experimental verification of multi-phase composition of scale formed on reheated alloy steels
  • Descaling of medium C and high SI, MN steels
  • Effect of Cu additions on scale structure and descaling efficiency of low C steel reheated in a combustion gas atmosphere
  • Effect of mold powder residue on thin cast slab scale structure evolution during reheating and descaling

Pagination

xix, 185 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2022 Richard Oise, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12127

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Included in

Metallurgy Commons

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