Research on long-term anti-corrosion technology for high-performance fasteners

Fastener bolts are prone to corrosion problems in both terrestrial atmospheric and marine environments, making the evaluation of protective coating crucial for durability enhancement. This study implements Dacromet coating technology on fasteners through a standardized process involving surface pre-treatment, controlled baking temperature, and coating application. A 3D bolt assembly model was developed in SolidWorks, with corrosion parameters and boundary conditions established through four-probe conductivity measurements to enable accurate corrosion modeling. Finite element simulations of the meshed bolt model reveal humidity-dependent corrosion behavior. Increasing relative humidity (RH) enhances oxygen solubility while diluting NaCl concentration, thereby reducing electrolyte conductivity by 18-22% and extending oxygen diffusion time by 25-30%. Concurrently, elevated oxygen concentration accelerates galvanic corrosion, with peak corrosion current density observed at the critical RH range of 0.86 and 0.92.