Evolution of properties of continuously cast AISI 321steel billet during pipe production on a continuous pipe rolling mill

This study investigates the evolution of the technological ductility of a continuous-cast billet (CCB) of AISI 321 steel during rolling across various stands of a continuous pipe rolling mill. Compression, tension, and torsion tests were conducted on samples taken from the billet and shell within the temperature range of 900–1250 °C using a multifunctional complex equipped with a Gleeble 3800 thermomechanical simulation system. The results showed that the maximum ductility of billets is achieved at 1200–1250 °C and the shell at 1150–1200 °C. Preliminary deformation (piercing) was shown to improve the ductility of the billet. Ductility diagrams that consider the influence of temperature and stress state were constructed to help optimize rolling regimes and improve the pipe quality. For the first time, the obtained data enabled the rolling of austenitic stainless steel pipes directly from continuous-cast billets at the Volzhsky Pipe Plant.