**3.2 Steel wire corrosion fatigue damage phenomenon**

After the test of each batch of steel wire specimens placed in the corrosion test chamber, take them out to observe the morphology of corrosion products, and then remove the corrosion products. Wait for the drying of the steel wire and then observe its surface morphology, and preliminarily analyze the experimental phenomenon (**Figure 3**) [13], the conclusions are as follows:


#### **Figure 3.**

*Apparent condition of steel wire with different corrosion times [13] (a) 120 h (b) 480 h (c) 840 h (d) 1200 h.*

and depth of the corrosion pits increase. After removing the corrosion products, the galvanized layer was covered with black oxide at the location of the corrosion pits, whose composition was mainly Fe(OH)3, Fe2O3–H2O and Fe2(SO4)3–8H2O. The surface of the steel wire in the uncorroded area around the corrosion pit is still relatively bright, and the degree of corrosion of the steel wire is relatively mild. Through these phenomena, it can be proved that the corrosion type of galvanized steel wire is anodic dissolution type, in which the exposed iron matrix reacts electrochemically with the surrounding corrosion products and H+ is reduced to atomic hydrogen, and gradually migrates to the deeper layer of the matrix through concentration diffusion (**Figure 3b**).

