Speaker
Description
A very fine ferritic structure is important for achieving the required mechanical properties for high-strength pipe steels during hot strip rolling. Pipe steels are usually produced by thermomechanical rolling with low rolling temperatures during finishing. This rolling practice is demanding on capacity and equipment.
To overcome this problem, an advanced rolling strategy for high-strength pipe steels as hot strip was established based on numerical metallurgical modelling of microstructure and mechanical properties. In conjunction with a simultaneous adjustment of the cooling strategy with increased cooling rates, roughing and especially finishing can be carried out more gently.
Therefore, it is possible to achieve at least unchanged product properties with high homogeneity while at the same time increasing rolling performance and protecting the mill stand.
The intended paper will introduce the setup, metallurgical mechanism and modes of operation of the advanced rolling strategy. As an overview the main aim is to show that through consistent usage of Nb and the associated metallurgical mechanism recrystallization and transformation during rolling the novel process leads to an increase in the performance of the hot strip mill compared to classic thermomechanical rolling and that the set microstructure ensures consistent product performance in terms of strength and brittle fracture resistance for high-strength pipe steels in various thicknesses.