University of Oulu

Kaijalainen, A., Vähäkuopus, N., Somani, M., Mehtonen, S., Porter, D., Kömi, J. (2017) The Effects of Finish Rolling Temperature and Niobium Microalloying on the Microstructure and Properties of a Direct Quenched High-Strength Steel. Archives of Metallurgy and Materials, 62 (2), 619-626.

The effects of finish rolling temperature and niobium microalloying on the microstructure and properties of a direct quenched high-strength steel

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Author: Kaijalainen, A.1; Vähäkuopus, N.1; Somani, M.1;
Organizations: 1University of Oulu, Materials Engineering and Production Technology, Oulu, Finland
2SSAB Europe OY, Raahe, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.9 MB)
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Language: English
Published: Polish Academy of Sciences, 2017
Publish Date: 2021-03-01


This paper comprehends the effects of finish rolling temperature (FRT) and Nb-microalloying on the microstructural evolu-tion and resultant properties of a low carbon direct quenched steel in the yield strength category of ≥900 MPa. Results indicate that a decrease in FRT close to Ar3 temperature significantly influenced the microstructure following phase transformation, especially at the subsurface (~50–400 μm) of the rolled strip. On decreasing the FRT, the subsurface microstructure revealed a fine mixture of ferrite and bainite obviously as a result of strain-induced transformation, whereas the structure at the centreline remained es-sentially martensitic. Further, Nb-microalloying promoted the formation of ferrite and bainite even at higher FRTs, thus influencing the mechanical properties. The microstructures of the hot-rolled strips were further corroborated with the aid of CCT diagrams.

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Series: Archives of metallurgy and materials
ISSN: 1733-3490
ISSN-E: 2300-1909
ISSN-L: 1733-3490
Volume: 62
Issue: 2
Pages: 619 - 626
DOI: 10.1515/amm-2017-0091
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: The financial support of the Finnish Funding Agency for Technology and Innovation (Tekes) in the Breakthrough Steels and Applications Program of the Finnish Metals and Engineering Competence Cluster (FIMECC Ltd) is gratefully acknowledged.
Copyright information: This article is printed in an open access and distributed under the terms of the Creative Commons Attribution-NonCommercial (CC BY-NC 4.0, This license allows authors to copy and redistribute the material in any medium or format, remix, transform, and build upon the material. Authors may not use the material for commercial purposes. However, this condition does not include dependent works (they may be covered by another license).