Experimental and numerical study on the degradation law of mechanical properties of stress-corrosion steel wire for bridge cables

In this paper, the stress corrosion and monotonic tensile test of corroded steel wire were carried out. The effects of different corrosion ages and stress levels on failure modes, stress-strain curve and mechanical properties of corroded steel wire were discussed. Then, a finite element model of steel wire considering real surface morphology was established, and the surface stress distribution and the failure of steel wire under different corrosion degrees were compared. The relationship between stress triaxiality and critical equivalent plastic strain to different corrosion parameters was given. Finally, the degradation model of mechanical properties of corroded steel wires was established. The results showed that the failure patterns of steel wires with different degrees of corrosion were mainly divided into three types: cup cone shape, milling cutter shape and splitting shape. The shear lip zone of fracture section basically disappeared with the increase of stress corrosion, and the location of fiber area was transferred from the inside to the surface of steel wire. The decrease in strength and elastic modulus of the specimen under stress corrosion was four times and three times greater than that under non-stress corrosion, respectively. In addition, the crack position of specimen changed from the inside of section to the location of corrosion pit with the increase of corrosion degree. The fracture equivalent plastic strain decreased gradually, while the stress triaxiality increased. When the degree of corrosion reached 19.53%, the fracture equivalent plastic strain decreased by 55.41% from 0.314 to 0.140, and the stress triaxiality increased by 23.53% from 0.390 to 0.510. The influence of uniform thickness loss on the stress triaxiality was less than that of pit depth-width ratio. The larger the depth-width ratio, the larger the maximum stress triaxiality corresponding to the failure element. The constitutive model proposed in this paper could reflect the degradation law of mechanical properties of corroded steel wires.