Study On Stress Corrosion Properties Of Steel Wires For Ultra-high Strength Bridge Cables

As the strength of the steel wire increases,its susceptibility to stress corrosion also increases.In this paper,the cold-drawn pearlitic steel wire after hot-dip plating was taken as the research object,and the effect of hot-dip plating on the microstructure and properties of the cold-drawn steel wire was studied.Using the constant load stress corrosion test method,combined with electrochemical test,the influence of different influencing factors on the stress corrosion performance of decoated steel wire was studied,the effect of loading stress and stress corrosion time on the microstructure of the steel wire coating was studied,and the ultra-high strength was discussed.Stress corrosion susceptibility of steel wires for bridge cables,and the effects of composition design and production process on the stress corrosion performance of steel wires.The hot-dip plating treatment changes the microstructure and mechanical properties of the cold-drawn steel wire.After hot dip plating,the pearlite structure of the steel wire still maintains the state of fiber layer as a whole,but some cementite is spheroidized,which makes the tensile strength of the steel wire.The strength decreased slightly,while the plasticity recovered to some extent.The stress corrosion properties of stripped steel wire were studied.The results show that the smaller the diameter of the steel wire,the greater the surface roughness,the shorter the breaking time of the steel wire with transverse notch,and the worse the stress corrosion performance;the greater the applied stress and the higher the corrosion temperature,the worse the stress corrosion performance of the steel wire;The effect of corrosive medium concentration on the stress corrosion performance of steel wire is only significant at low temperature.With the extension of the stress corrosion time,the corrosion resistance of the decoated steel wire becomes worse and the steel wire becomes brittle,but its tensile strength does not change significantly with the extension of the stress corrosion time.The stripped steel wire is fractured mainly by hydrogen-induced delayed fracture,supplemented by anodic dissolution fracture.In the early stage of stress corrosion,the stripped steel wire mainly produces Fe₂O₃;with the extension of the stress corrosion time,Fe S is mainly formed inside the stripped steel wire.The stress corrosion properties of hot-dip coated steel wire were studied.The results show that the greater the loading stress,the worse the corrosion resistance of the coated steel wire.Dipping the galvanized layer on the surface of the steel wire can effectively prolong the time for stress corrosion cracking of the bridge steel wire.The main occurrence of hot-dip galvanized steel wire in the early stage of stress corrosion is anodic dissolution fracture,and the corrosion products are mainly Zn S and Zn O.When the coating partially peels off and the fresh steel substrate is exposed,the cathodic protection will fail even if the coating is still largely attached to the surface of the steel wire,and the fracture mechanism will change from anodic dissolution fracture to hydrogen-induced delayed fracture.The stress corrosion susceptibility of steel wires for ultra-high strength bridge cables and the effects of composition design and production process on the stress corrosion performance of steel wires are discussed.The results show that the trend of hydrogen embrittlement susceptibility of ultra-high strength steel wire has not yet appeared an inflection point.Appropriately increasing the content of C,Si and Cr can improve the strength of the steel wire while reducing the sensitivity to stress corrosion;by improving the production process,increasing the diameter of the steel wire and reducing surface defects can effectively improve the stress corrosion performance of the steel wire.