Effect of Hot-Rolled Heavy Section Bars Post-Deformation Cooling on the Microstructure Refinement and Mechanical Properties of Microalloyed Steels

In the industrial practice—especially in reverse rolling mills—heavy section products with stable mechanical properties (YS, UTS) and ductility (A, Z) but an impact toughness (KV) at too low levels are often observed. The results presented present work concern relationship between parameters of cooling process rolled made microalloyed steels, different chemical compositions (such as Al-N, Al-N-V, Al-N-Ti) their properties. Special focus was put on composition, grain size subzero temperatures. It is shown, that by introducing restrictions towards more strict control Al, Ti, V, N, it can be ensured final not sensitive to variations which, hence, provides required especially impacts requirements for a wide range products. also found slight modifications microalloying elements proper parameters, possible replace commonly used normalizing annealing heat treatment after rolling.