Ověření možnosti zvýšení jakosti ocelových výkovků legováním kovy vzácných zemin

Abstract

The diploma thesis deals with verification of the possibility of increasing the quality of steel forgings of 42CrMo4 steel by addition of rare earth metals. The dominant element involved in alloying was cerium, which was in the form of mischmetal. Two identical ingots weighing about 24 tons were cast on one casting slab. The first ingot was longitudinally divided into two parts in order to accurately map the distribution of cerium across the section and subsequently analyzed. The second ingot was forgedinto round bar with three different diametersand was heat treated. The effects of cerium on mechanical properties, structure and microcleanness were evaluated on samples from different cross-sectional sites. The highest values of mechanical properties were found in the subsurface and the lowest in the center of the bar.