Effects of Alloying Elements on Mechanical Properties and Corrosion Resistance of Weathering Steel for Transmission Tower

This study aims to optimize the corrosion resistance and mechanical properties of angle steel used in transmission towers. It systematically explores the influence of C, Mn, Nb, V, Ti strengthening elements and Cr, Ni corrosion resistant elements on the comprehensive performance of 420 MPa weathering steel. Seven sets of experimental steels were prepared using vacuum melting combined with controlled rolling process. The mechanism of alloy elements on microstructure evolution, mechanical properties, and corrosion behavior was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical testing. The results showed that the experimental steels exhibited a dual phase structure of ferrite and pearlite, and the strength was significantly improved by the precipitation strengthening of V element through carbonitride (yield strength reached 420-441.5 MPa). The synergistic regulation of C-Mn can effectively optimize the carbon equivalent to balance weldability. In the cyclic infiltration test simulating acid rain environment, the alloy ratio of Cr≥0.45% and Ni≥0.15% can reduce the relative corrosion rate to below 50% of conventional Q420 angle steel. Microscopic analysis reveals that the content of α-FeOOH in the dense rust layer formed on the surface of weathering steel is over 95%, significantly higher than the 49.4% of conventional steel. This stable rust layer effectively improves the corrosion resistance by suppressing the anodic dissolution process. This study provides theoretical basis and process parameters for the composition design of weathering angle steel for transmission towers.