Effects of Nb and V on the Microstructure and Properties of Rolled Non-quenched and Tempered Steels

摘要

The property and microstructure of rolled non-quenched and tempered steels of Nb-V comprehensive micro alloying have been investigated.The mechanical properties and the load -displacement curves were measured respectively by using electron tension test machine and digital-impact test machine.The microstructure and fracture surface of impact samples were observed with SEM.The results show that micro-alloying Nb and V non-quenched and tempered steel behaves higher tension strength and toughness than that of only V micro-alloying one under the condition of about same plasticity.Improvement of the properties is related with that Nb can effectively make fine pearlite group and inter-lamella spacing at the impact fracture pearlite flakes.Corresponding relationship between various domain of fracture morphology and characteristics points at the curve of digital impact has been discussed.