University of Oulu

A Kaijalainen et al 2021 IOP Conf. Ser.: Mater. Sci. Eng. 1178 012026.

Effect of ageing on the mechanical properties of cold formed S700 rectangular hollow

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Author: Kaijalainen, A1; Mourujärvi, J1; Tulonen, J2;
Organizations: 1Materials and Mechanical Engineering, CASR, University of Oulu, Oulu, Finland
2SSAB Europe Oy, Hämeenlinna, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
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Language: English
Published: IOP Publishing, 2021
Publish Date: 2021-09-24


The aim of this work is to study the effect of ageing (250 °C for 1 h) on the mechanical properties of the cold formed S700 rectangular hollow section. The investigated hot rolled steel strip was produced thermomechanical rolling followed by direct quenching. The dimension of the investigated hollow section was 120 x 120 x 10 mm and the corner radii and the other tolerances compliant with EN 10219. Tensile properties and Charpy-V impact toughness were determined for the base material and flat and corner area of the hollow section. The results showed that the tensile strength in the corner was slightly higher in comparison with the flat side, revealing higher cold deformation rate in the corner. Ageing increased the strength level relatively higher than cold forming without losing any elongation properties. The impact energies were at the high level at −40°C and −60°C in cold formed and aged materials. Even at −80°C, the CV results were 118 J/cm². It is also notable that no difference in CV values between the flat and the corner samples were observed. Thus, the results showed that the flat side specimens testing provides sufficient information of mechanical properties of the cold formed rectangular hollow sections and no need demanding corner sample testing when the structural hollow section is produced by using the thermomechanical controlled and direct-quenched base material. Furthermore, results showed that cold formed S700 is excellent for offshore steels, as steels are used even colder conditions as before.

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Series: IOP conference series. Materials science and engineering
ISSN: 1757-8981
ISSN-E: 1757-899X
ISSN-L: 1757-8981
Volume: 1178
Article number: 012026
DOI: 10.1088/1757-899X/1178/1/012026
Host publication: 6th International Conference on Recent Trends in Structural Materials (COMAT 2020) 30th November - 4th December 2020, Pilsen, Czech Republic
Host publication editor: Džugan, Jan
Conference: Conference on Recent Trends in Structural Materials
Type of Publication: A4 Article in conference proceedings
Field of Science: 216 Materials engineering
Funding: The authors are grateful to Business Finland for financing this work as a part of the research project Steel Ecosystem for Focused Applications (StEFA).
Copyright information: © 2021 The Authors. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd