University of Oulu

Antti Kaijalainen, Vili Kesti, Lars Troive, Anna-Maija Arola, Tommi Liimatainen, Mikko Hemmilä, Jukka Kömi, David Porter, Superior bendability of direct-quenched 960 MPa strip steels, Procedia Manufacturing, Volume 15, 2018, Pages 676-683, ISSN 2351-9789,

Superior bendability of direct-quenched 960 MPa strip steels

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Author: Kaijalainen, Antti1; Kesti, Vili2; Troive, Lars2;
Organizations: 1Materials and Production Engineering, University of Oulu, Oulu 90014, Finland
2SSAB Europe Oy, Rautaruukintie 155, Raahe 92101, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.3 MB)
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Language: English
Published: Elsevier, 2018
Publish Date: 2018-08-29


The present paper shows the effect of microstructure on the press brake and frictionless 3-point bending of 6 mm thick ultrahigh-strength steel strips with a yield strength of 960 MPa. With a traditional press brake machine the minimum bending radii of the studied steels varied from 1.3 times the thickness to 3.0 times the thickness for the bend axis perpendicular to the rolling direction and in the range 2.0–3.5 times the thickness for the bend axis parallel to the rolling direction. The frictionless 3-point bending-equipment incorporating rotatable die-rollers has been applied to characterize the material work hardening behavior in a way relevant to the bending process, i.e. by using measured punch force vs. position data to derive the bending moment and the evolution of the flow stress and the strip curvature during the bending process. The main aim of the present paper is to establish an understanding of how bendability can be significantly improved and made more isotropic by modifying the subsurface microstructure to include a relatively soft polygonal ferrite and granular bainite layer and why the subsurface microstructure plays such a dominant role.

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Series: Procedia manufacturing
ISSN: 2351-9789
ISSN-E: 2351-9789
ISSN-L: 2351-9789
Volume: 15
Pages: 676 - 683
DOI: 10.1016/j.promfg.2018.07.300
Conference: International Conference on Metal Forming, Metal Forming 2018, 16-19 September 2018, Toyohashi, Japan
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Copyright information: © 2018 The Author(s). Published by Elsevier B.V. Creative Commons license BY-NC-ND.