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Passivation Layers of Ultra-Advanced High Strength Steels and High Strength Steels / REBECCA DEWFALL

Swansea University Author: REBECCA DEWFALL

DOI (Published version): 10.23889/SUThesis.66885

Abstract

The fundamental ambition of this thesis is to assess the effects of chemical com-position, temperature and elapsed time reaction on scale formation. The control of oxidation rates and oxide morphology are focal points of interest along with the evolution and formation mechanisms of scale morphology...

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Published: Swansea University, Wales, UK 2024
Institution: Swansea University
Degree level: Doctoral
Degree name: EngD
Supervisor: Coleman, M.
URI: https://cronfa.swan.ac.uk/Record/cronfa66885
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spelling v2 66885 2024-06-24 Passivation Layers of Ultra-Advanced High Strength Steels and High Strength Steels 242feadd72d228c6087ab68a58411871 REBECCA DEWFALL REBECCA DEWFALL true false 2024-06-24 The fundamental ambition of this thesis is to assess the effects of chemical com-position, temperature and elapsed time reaction on scale formation. The control of oxidation rates and oxide morphology are focal points of interest along with the evolution and formation mechanisms of scale morphology with time and temperature.An approach using rapid alloy prototyping (RAP) was selected to help discern the effects of common alloying elements Mn, Si and Mo, on overall scale formation using a wt% comparable to that seen in high strength industrial grades. RAP was successfully used to investigate the formation of oxides associated with Mn, Si and Mo in isolation. The oxide thickness was shown to vary significantly depending on the alloying additions. A minimum fundamental addition of 1wt.% Si was requisite in order to produce a complete passivation layer.Industrial steel grades were investigated to predict the oxidation rates, scale formation and blister regimes that may form within the hot-strip mill. New and previously unidentified blister formation mechanisms were discovered. Blister upon cooling was discovered during air cooling and observed on a number of samples.Unique and new phenomena such as blister crown splitting and secondary blister were identified on DP800 due to the presence of a conglomerated spinel phase and hematite in the outer oxide.Plant trials were conducted with differing coiling temperatures after hot rolling to determine the effect on internal oxidation. It was discovered that coiling temperature had a significant impact on the depth of internal oxidation after hot rolling, with a strong negative correlation associated between temperature and depth of the internal oxidation zone. The recommended coiling temperature has been implemented in the United Kingdom, Netherlands and India, eliminating issues sur-rounding cleanliness after hot-band annealing.Analysis was conducted using; TGA, EBSD, EDS, WDS, FIB and FEG-SEM imaging. E-Thesis Swansea University, Wales, UK Passivation, Oxidation, Steel, RAP, Blister, Fayalite, Silicon 21 5 2024 2024-05-21 10.23889/SUThesis.66885 COLLEGE NANME COLLEGE CODE Swansea University Coleman, M. Doctoral EngD WEFO, ESPRC WEFO, ESPRC 2024-06-24T15:45:01.8986624 2024-06-24T15:13:09.4180260 Faculty of Science and Engineering School of Engineering and Applied Sciences - Materials Science and Engineering REBECCA DEWFALL 1 66885__30740__02f9f12f5c674a05a8b5da85bdc0fb15.pdf 2024_Dewfall.R.final.66885.pdf 2024-06-24T15:25:22.2705417 Output 218526540 application/pdf E-Thesis – open access true Copyright: The Author, Rebecca Dewfall, 2024 true eng
title Passivation Layers of Ultra-Advanced High Strength Steels and High Strength Steels
spellingShingle Passivation Layers of Ultra-Advanced High Strength Steels and High Strength Steels
REBECCA DEWFALL
title_short Passivation Layers of Ultra-Advanced High Strength Steels and High Strength Steels
title_full Passivation Layers of Ultra-Advanced High Strength Steels and High Strength Steels
title_fullStr Passivation Layers of Ultra-Advanced High Strength Steels and High Strength Steels
title_full_unstemmed Passivation Layers of Ultra-Advanced High Strength Steels and High Strength Steels
title_sort Passivation Layers of Ultra-Advanced High Strength Steels and High Strength Steels
author_id_str_mv 242feadd72d228c6087ab68a58411871
author_id_fullname_str_mv 242feadd72d228c6087ab68a58411871_***_REBECCA DEWFALL
author REBECCA DEWFALL
author2 REBECCA DEWFALL
format E-Thesis
publishDate 2024
institution Swansea University
doi_str_mv 10.23889/SUThesis.66885
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Materials Science and Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Materials Science and Engineering
document_store_str 1
active_str 0
description The fundamental ambition of this thesis is to assess the effects of chemical com-position, temperature and elapsed time reaction on scale formation. The control of oxidation rates and oxide morphology are focal points of interest along with the evolution and formation mechanisms of scale morphology with time and temperature.An approach using rapid alloy prototyping (RAP) was selected to help discern the effects of common alloying elements Mn, Si and Mo, on overall scale formation using a wt% comparable to that seen in high strength industrial grades. RAP was successfully used to investigate the formation of oxides associated with Mn, Si and Mo in isolation. The oxide thickness was shown to vary significantly depending on the alloying additions. A minimum fundamental addition of 1wt.% Si was requisite in order to produce a complete passivation layer.Industrial steel grades were investigated to predict the oxidation rates, scale formation and blister regimes that may form within the hot-strip mill. New and previously unidentified blister formation mechanisms were discovered. Blister upon cooling was discovered during air cooling and observed on a number of samples.Unique and new phenomena such as blister crown splitting and secondary blister were identified on DP800 due to the presence of a conglomerated spinel phase and hematite in the outer oxide.Plant trials were conducted with differing coiling temperatures after hot rolling to determine the effect on internal oxidation. It was discovered that coiling temperature had a significant impact on the depth of internal oxidation after hot rolling, with a strong negative correlation associated between temperature and depth of the internal oxidation zone. The recommended coiling temperature has been implemented in the United Kingdom, Netherlands and India, eliminating issues sur-rounding cleanliness after hot-band annealing.Analysis was conducted using; TGA, EBSD, EDS, WDS, FIB and FEG-SEM imaging.
published_date 2024-05-21T15:45:00Z
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score 11.012678

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