The influence of the applied type of cooling after eight-stage hot compression test on the structure and mechanical properties of TRIPLEX type steels

The aim of the work was to analyse the impact of an eight-stage hot compression process carried out on the Gleeble3800 simulator, with three cooling variants after thermo-mechanical treatment of Fe-Mn-Al-C steels for their structure and mechanical properties. Performed research allowed to evaluate the impact on the structure and properties of simulation conditions for multi-stage rolling of difficult-to-treat thermomechanical steels for which this treatment is the final process of obtaining ready-to-use high-strength construction steels. Applied thermo-mechanical treatment causes that the main process of removing the effects of strain hardening is dynamic recovery, and static and metadynamic recrystallisation taking place after the last deformation but also between successive deformations, which was also confirmed on the basis of structural analysis of the tested steel after different cooling variants. As a result of the eight-stage hot compression test, the ferrite changed its distribution from fine grains occurring at the boundaries of austenite grains after forging, to elongated grains in a perpendicular direction to the compression direction. Isothermal heating at 850 degrees C for 30s resulted in obtaining a fine-grained structure, statically or metadynamically recrystallised. The maximum tensile strength of the tested steels is about 1250 MPa, and the total elongation value is about 27%.