Vliv mikrolegování kovy vzácných zemin na vlastnosti ocelových výkovků

Abstract

Bachelor thesis is focused on evaluation of properties of heavy steel forgings, which were alloyed with rare earth elements. The main alloying element was cerium in the form of mischmetal. In particular, its use was made to improve the quality of steel. Experiments were performed on two heats of 42CrMo4 steel. Due to verification of cerium distribution in the cross section of steel ingot, the ingot was longitudinally cutted and chemical analysis were carried out. Forgings were checked by ultrasonic testing, also microstructural and micropurity analysis and mechanical testing were carried out. By comparison with selected forgings of similar diameters and after a similar quality heat treatment regime it can be stated that the addition of cerium in the form of mischmetal probably influences the achieved level of mechanical properties. The positive effect can be seen especially in the increase in strength, while retaining very good plastic properties.