INFLUENCE OF Cr, Mn AND Mo ON STRUCTURE AND PROPERTIES OF V MICROALLOYED MEDIUM CARBON FORGING STEELS

The influence of Cr, Mo and Mn on microstructure and mechanical properties of V-microalloyed medium-carbon steels has been studied by means of metallography and mechanical testing. Cr, Mn and Mo addition promotes the formation of bainitic sheaves suppressing the formation of ferrite-pearlite and acicular ferrite. The influence of Mn is somewhat masked by a low content of nitrogen. In a low nitrogen steel VN particles are not present and the nucleation of acicular ferrite is suppressed. The yield strength of Cr, Mo and Mn alloyed steels with bainite structures is lower in comparison to the base steel due to less pronounced precipitation strengthening effect. The presence of bainitic sheaves decreases the CVN20 impact energy in comparison to ferrite-pearlite and acicular ferrite microstructures.