[Back]

H. Radlwimmer, P. Wiehoff, T. Wojcik, J. Six, S. Ilie, E. Kozeschnik:
"Influence of different cooling regimes on the hot ductility of continuously cast micro-alloyed steel";
Talk: EUROMAT 2017, THESSALONIKI; 2017-09-17 - 2017-09-22.

Influence of different cooling regimes on the hot ductility of continuously casted micro-alloyed steel
H. Radlwimmer1,*, P. Wiehoff1, T. Wojczik1, J. Six2, S. Ilie2, E. Kozeschnik1
1 TU Wien - Institute of Materials Science and Technology
Getreidemarkt 9, 1060 Vienna, Austria
2 voestalpine Stahl GmbH,
Voest-Alpine-Straße 3, 4031 Linz, Austria
*harald.radlwimmer@tuwien.ac.at
Keywords: hot ductility, steel, micro-alloyed
Since many decades, continuous casting is the most commonly used process in steel production. A major focus of investigation is on the straightening operation, which often leads to effects causing rejection and/or repair of the slab. Straightening usually takes part in a region of reduced ductility, which typically occurs between 1200 °C and 600 °C. In this work, we present two series of hot tensile tests. Both series only differ in their cooling regime. Austenitization temperature, austenitization time, as well as strain rate are the same for all tests. The cooling regimes investigated here are (1) constant cooling rate, and (2) constant cooling time. In literature, variations of test regime (1) are commonly described. However, this choice has to be scrutinized for two reason; (a) the dimensions of a continuous caster are unchangeable, (b) the casting velocity may only be adapted within narrow margins during operation. Hence, as length and velocity in the casting device are constants, also the cooling time must be constant. Therefore, the cooling rate is only determined by the straightening operation temperature. On a laboratory scale, we investigated the hot ductility of both test series with a micro-alloyed steel grade. Hot tensile tests are conducted with a Gleeble 1500 thermo-mechanical testing machine. The fracture surface reduction of area is used to quantify the degree of hot ductility. For further conclusions, metallographic specimen are investigated and the results are presented herein.

hot ductility, steel, micro-alloyed