THE INFLUENCE OF CERIUM ON THE MICROSTRUCTURE OPTIMIZATION OF 42CrMo4 STEEL

The manufacturing program of the company VITKOVICE HEAVY MACHINERY a. s. comprises production of a wide range of structural steels for the high exposed machine parts, such as shafts of wind power stations, turbine shafts, gears, etc. Due to the ever increasing demands of customers to increase the service properties of steel while maintaining the reasonable prices it is necessary to look continuously for ways to improve the offered steel grades. One option is to optimise the microstructure by refinement of grain size and thus to achieve better mechanical properties. It is generally known for achievement of fine-grained microstructure of steels a suitable combination of microalloying elements and thermomechanical processing is used. In addition to standard microalloying elements, such as Al, V, Nb and Ti it is also possible to use cerium inclusions of which serve as good place for heterogeneous nucleation during solidification of steel. In this paper the influence of cerium on optimisation of microstructure of the 42CrMo4 steel was studied. A series of laboratory tests was performed, on the basis of the results of which an operational experiment was proposed and designed.