Open Access Conference Proceedings

High-strength low-alloy (HSLA) steels are low-carbon steels, making them an excellent construction material for automotive applications, transportation of media such as oil and gas, or responsible marine structures often operating in the harsh weather conditions of northern seas. These steels gain unique properties from micro-additives of Nb, V or Ti (up to 0.15 wt%) and can, for example, reduce the weight of structures by up to 40 % compared with the classic S235JR steel. The only place in Poland where HSLA steel strips can be produced is the ArcelorMittal Poland Hot Rolling Mill in Krakow. These steels are investigated by many research institutes, but due to the restricted number of places where they are produced and the high cost of industrial research, there is still a need for the investigations related to mass-scale production. In this study, the authors examined two selected steels produced at the ArcelorMittal Hot Rolling Mill in Krakow. Dilatometric analyses and strain dilatometry investigations were carried out within this study. The research enabled a good characterization of the material in terms of the phase transformations taking place during controlled cooling as well as the analysis of the material microstructural changes. The obtained results may contribute to more precise control of the material cooling conditions and, consequently, to obtaining the expected mechanical properties meeting customer expectations.

Keywords: HSLA steels, thermomechanical hot rolling, dilatometry, phase transformation, microstructure

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