Nosov Magnitogorsk State Technical University (Magnitogorsk, Russia):

A. G. Korchunov, Dr. Eng., Prof., Vice-Rector for International Affairs, e-mail: international@magtu.ru
M. A. Polyakova, Dr. Eng., Prof., Dept. of Material Processing Technologies, e-mail: m.polyakova@magtu.ru
D. V. Konstantinov, Cand. Eng., e-mail: magstu.international@gmail.com

University of Padova (Padova, Italy):
M. Dabalá, Dr. Eng., Prof., Dept. of Industrial Engineering, e-mail: manuele.dabala@unipd.it

This paper examines the mechanical properties of high-strength (1,770 MPa) 7-wire prestressing strands and how they tend to change under thermo-mechanical treatment involving short-term induction tempering under high tension. The change dynamics of the following properties was monitored for 12.5 mm strands: tensile strength, yield strength, full elongation at maximum tension force and modulus of elasticity in the temperature range from 360 to 400 °С, the process speed range from 50 to 65 m/min, and at the tension force of 64 kN. The authors found a quantitative increase of the mechanical properties of prestressing strands for all the studied regimes of thermo-mechanical treatment. Thermo-mechanical treatment resulted in a significant growth in yield strength — from 28 to 36%, and in full elongation at maximum tension force, which demonstrated a higher than double growth. The paper shows how the temperature and rate of thermo-mechanical processing influence the mechanical properties of prestressing strands and their change dynamics.

This research was funded by the Ministry of Science and Higher Education of the Russian Federation as part of a comprehensive project aimed at establishing a hightechnology production line with support from a higher educational institution (Contract No. 02.G25.31.0178 dated 01/12/2015; No. МК204895 dated 27/07/2015).
The authors would like to thank the foundation Fondazione Cariparo for their support of the Visiting Program TIP-STEP project.

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