Plastometrická simulace řízeného válcování a ochlazování bezešvých trubek z oceli 42CrMo4

Abstract

This bachelor thesis deals with physical simulation of controlled rolling and cooling of the seamless tubes from steel 42CrMo4. The aim was to simulate the thermomechanical conditions during piercing as well as rolling in a pilger mill of the seamless tubes with the final diameter of 273 mm with the wall thickness from 6.3 to 40 mm and evaluate the influence of the finish rolling temperatures on microstructural and mechanical properties of the investigated steel. These physical simulations were performed with using of Hot Deformation Simulator HDS-20. Increasing the hardness of the investigated steel due to lower finish rolling temperatures significantly manifested especially in the case of the finish rolling temperature 820 °C, but only for samples simulating the tube wall thickness of 6.3 mm and 20 mm. Microstructure of these plastometricaly tested samples was formed by majority share of martenzite and minority share of bainite. Chosen finish rolling temperatures fundamentally did not influence the microstructure and hardness of samples, which simulated rolling of seamless tubes with the wall thickness 40 mm.