Papers by Author: Hong Zhou Lu

Abstract: 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.

Abstract: The effect of morphology and distribution of sulfides on tensile, impact and bending fatigue properties of non-quenched and tempered steel 49MnVS3 has been investigated in this paper. Microscopic structure and morphology of sulfides are observed, and impact fracture and fatigue fracture have been analyzed by SEM. The results show that the morphology of sulfides is mostly strip and distributes in ferrite, which affects mechanical properties and fatigue life. The length direction of sulfide strip is parallel to the rolling direction of steel. When the length of sulfide is short relatively and is approximate to the shape of particles. The impact properties and bending fatigue performance of 49MnVS3 are higher. Under those conditions, there are more ductile characteristics in their impact fracture and the fatigue fracture. The reasons for the effect of sulfide morphology on the mechanical and fatigue properties are explained.