Corrosion resistance mechanism of electron beam W/Ni surface alloyed 45 steel for marine

To improve the corrosion resistance of 45 steel, a material widely used in marine engineering and shipbuilding but prone to corrosion failure in high salt, high humidity, and dry wet alternating environments, a W/Ni alloying layer was prepared on its surface via electron beam surface alloying technology. Microstructural analysis reveals a gradient structure in the alloyed layer. Electrochemical tests show that after alloying, self-corrosion potential shifts positively from -0.650 V to -0.589 V, current density decreases by 72% from 1.360×10-5 to 3.791×10-6 A/cm², and charge transfer resistance increases from 100.9 to 303.5 Ω·cm². The improved corrosion resistance arises from a synergistic effect: uniform Ni promotes a continuous Ni-rich oxide film, while W enrichment enhances film compactness and pitting resistance.