Microstructure and mechanical properties of V-Nb microalloyed steel for heavy-duty gear

The microstructure and mechanical properties of Cr-Ni-Mo case hardening steel with or without V-Nb microalloying for heavy-duty gear were investigated.Results show that V-Nb microalloying is effective to promote the properties of the Cr-Ni-Mo steel by refining the austenite grain size significantly,which resulted in an increase of its impact energy.The V-Nb microalloyed steel could not show abnormal coarsening of austenite grain when it is held in the temperature range of carburization for 10 h,and the mechanical properties of the carburizing case are also improved.