Effect of chemical composition on the phase transformation temperature during the hot rolling of profiles with a given level of mechanical properties

This study explores the modeling of structural transformations and the development of optimal microstructures in steels subjected to advanced heat treatment processes. The mathematical description of phase transformations is based on the theory of nucleation and grain growth, with thermokinetic diagrams serving as a foundation for predicting microstructural evolution. Special attention is given to the Quenching-and-Partitioning (Q&P) process, which facilitates the formation of multi-phase microstructures with a balanced ratio of martensite and retained austenite. The research highlights the significance of cooling methods in achieving desired properties. Among these, water-air spray cooling is shown to effectively enhance heat dissipation while adapting to complex component geometries. Experiments demonstrate that Q&P-treated 22MnB5 steel achieves improved strength (Rm = 1045 MPa) and elongation (A = 10.8 %) compared to conventional processes, with lower alloying element content.