Research On Dynamic Mechanical Properties And Deep Sea Corrosion Resistance Of 10Ni5CrMoV Steel

Efficient exploitation and conservation of the deep oceans proposed great challenges for mechanical properties and corrosion resistance of structural materials.10Ni5CrMoV steel was widely used as deep ocean structures. It is of great significance to study the mechanical properties and corrosion resistance of 10Ni5CrMoV steel.The dynamic mechanical properties of 10Ni5CrMoV steel were investigated by Split Hopkinson Pressure Bar. The results showed that rate effects of 10Ni5CrMoV steel comprised three different regions:insensitive zone, transitional zone and sensitive zone with the corresponding rate flow controlling mechanisms:friction stress, thermally activated and phonon drag. The fracture of 10Ni5CrMoV steel showed characteristic of ductile fracture during quasi-static tensile and dynamic tensile.Effect of hydrostatic pressure on the corrosion behaviour of 10Ni5CrMoV steel was discussed by simulating deep sea environment. The results demonstrated that corrosion resistance of 10Ni5CrMoV steel was deteriorated with the increase of hydrostatic pressure. The corrosion morphologies of 10Ni5CrMoV steel could be described as shallow-disk localized corrosion at atmosphere pressure and uniform corrosion at 6 MPa. The reason was explained based on recurrence plot and finite element analysis (FEA). Growth of pit under high hydrostatic pressure showed anisotropic behavior. Significant higher growth rate was found in the direction perpendicular to load axis. FEA indicated that localized plastic strain played an important role on pit growth, which resulted in the coalescences of pits and further the formation of uniform corrosion.Effect of grain ultra-fining got by cycle quenching on dynamic mechanical properties and corrosion resistance of 10Ni5CrMoV steel was studied. Strain effects and fracture characteristic of 10Ni5CrMoV steel were unchanged before and after grain ultra-fining and the yield strength value added resulting from grain refining increased with the increase of strain rate. Moreover, the corrosion resistance of 10Ni5CrMoV steel was enhanced by grain ultra-fining.