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