Effect of Nb-V Microalloying on Microstructures and Mechanical Properties of Medium Carbon Non-quenched and Tempered Steel

摘要

Based on optical microscope(OM), transmission electron microscope(TEM) and mechanical performance measurement, the microstructures and mechanical properties of Nb-V micro-alloying non-quenched and tempered steels have been studied. The results showed that the microstructure consists of ferrite and pearlite, in which there exists a lot of intragranular ferrite. Niobium carbide is the main form of carbonitrides, Nb-enriched carbonitrides refine grains, V-enriched carbonitrides have precipitation strengthening effect, which promotes the toughness of the studied steel. The mechanical properties for steels 1#, 2# and 3# have met the standards required by high load automobile crankshaft, in which the comprehensive property for 2# is the best.