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Design, thermomechanical processing and induction hardening of a new medium-carbon steel microalloyed with niobium |
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| Author: | Javaheri, Vahid1,2 |
| Organizations: |
1University of Oulu Graduate School 2University of Oulu, Faculty of Technology, Mechanical Engineering |
| Format: | ebook |
| Version: | published version |
| Access: | open |
| Online Access: | PDF Full Text (PDF, 22.4 MB) |
| Persistent link: | http://urn.fi/urn:isbn:9789526223582 |
| Language: | English |
| Published: |
Oulu : University of Oulu,
2019
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| Publish Date: | 2019-10-22 |
| Thesis type: | Doctoral Dissertation |
| Defence Note: | Academic dissertation to be presented with the assent of the Doctoral Training Committee of Technology and Natural Sciences of the University of Oulu for public defence in the OP auditorium (L10), Linnanmaa, on 1 November 2019, at 12 noon |
| Tutor: |
Professor David Porter |
| Reviewer: |
Professor Pasi Peura Professor Annika Borgenstam |
| Opponent: |
Professor Hans-Olof Andrén Professor Pasi Peura |
| Description: |
AbstractThis thesis has been made within the European Industrial Doctorate (EID) project called Mathematics and Materials Science for Steel Production and Manufacturing, abbreviated as MIMESIS, which has five partners: EFD Induction in Norway; SSAB, Outokumpu, and the University of Oulu in Finland; and Weierstrass Institute for Applied Analysis and Stochastics (WIAS) in Germany. The main aim of this work was to develop a steel composition and processing route suitable for making a slurry transportation pipeline with the aid of induction hardening, and to characterize the phase transformations and microstructures involved in the various stages of the processing route. A novel steel chemistry was designed based on metallurgical principles assisted by computational thermodynamics and kinetics. The designed composition is a medium-carbon, low-alloy steel microalloyed with niobium, in wt.% 0.40 C, 0.20 Si, 0.25 Mn, 0.50 Mo, 0.90 Cr, and 0.012 Nb. This was subsequently cast, thermomechanically rolled on a laboratory rolling mill to two bainitic microstructures, and finally subjected to the thermal cycles predicted to be encountered with the internal induction hardening of a typical pipe geometry. The phase transformations and microstructures found at various stages of the simulated production process have been characterized and algorithms developed to enable the optimization of microstructure and hardness through the pipe wall thickness. see all
TiivistelmäTämä väitöskirja on tehty osana Euroopan teollisuustohtori (European Industrial Doctorate, EID) -ohjelmaa projektissa eli Matematiikka ja materiaalitiede teräksen valmistuksessa ja käytössä (Mathematics and Materials Science for Steel Production and Manufacturing, MIMESIS). Ohjelmassa on viisi partneria: EFD Induction Norjasta; SSAB, Outokumpu ja Oulun yliopisto Suomesta; ja Weierstrass Institute for Applied Analysis and Stochastics (WIAS) Saksasta. Työn päätavoitteina oli kehittää teräksen koostumusta ja prosessointireittiä, jotka soveltuvat lietteen kuljetusputken valmistukseen induktiokarkaisun avulla, sekä karakterisoida prosessin eri vaiheiden aikana tapahtuvat faasimuutokset ja mikrorakenteet. Uusi teräskoostumus suunniteltiin metallurgisten periaatteiden pohjalta hyödyntämällä laskennallista termodynamiikkaa ja kinetiikkaa. Suunniteltu teräs on niobilla mikroseostettu, matalaseosteinen ja keskihiilinen, eli painoprosentteina 0,40 C, 0,20 Si, 0,25 Mn, 0,50 Mo, 0,90 Cr ja 0,012 Nb. Teräs valettiin, valssattiin ja jäähdytettiin termomekaanisesti laboratoriovalssaimella kahdeksi bainiittiseksi mikrorakenteeksi ja lopulta altistettiin lämpösykleille, joiden ennustettiin olevan tyypillisiä sisäisesti induktiokarkaistulle teräsputkelle. Simuloidun tuotantoprosessin eri vaiheissa havaitut faasimuutokset ja mikrorakenteet on karakterisoitu. Sen lisäksi on kehitetty algoritmit, jotka mahdollistavat mikrorakenteen ja kovuuden optimoinnin putken seinämän paksuuden läpi. see all
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| Series: |
Acta Universitatis Ouluensis. C, Technica |
| ISSN: | 0355-3213 |
| ISSN-E: | 1796-2226 |
| ISSN-L: | 0355-3213 |
| ISBN: | 978-952-62-2358-2 |
| ISBN Print: | 978-952-62-2357-5 |
| Issue: | 713 |
| Type of Publication: |
G5 Doctoral dissertation (articles) |
| Field of Science: |
216 Materials engineering |
| Subjects: | |
| Copyright information: |
© University of Oulu, 2019. This publication is copyrighted. You may download, display and print it for your own personal use. Commercial use is prohibited. |