Suitable Humidity: Humidity has a significant impact on the rust layer stabilization of weathering steel. Excessively humid environments can easily form liquid films on the surface of weathering steel, accelerating the electrochemical corrosion rate of the steel matrix. Relatively dry and well-ventilated environments are more conducive to the formation of stable rust layers. For example, in an inland semi-arid climate, the rust layer of weathering steel is more likely to stabilize.
Appropriate Concentration of Aggressive Media
Chloride Ions: Chloride ions (Cl⁻) are commonly found in coastal areas and regions where de-icing salts are frequently used in winter. High concentrations of Cl⁻ can easily penetrate the porous outer rust layer of weathering steel, accelerating the electrochemical corrosion reaction inside the rust layer and increasing the corrosion weight loss of the steel matrix. Therefore, a low Cl⁻ concentration environment is beneficial for the stabilization of the rust layer.
Sulfur Dioxide: In an industrial atmospheric environment, sulfur dioxide (SO₂) can react with oxygen (O₂) to cause the corrosion of weathering steel. Although high concentrations of SO₂ have an adverse effect on the stable rust layer, studies have found that weathering steel can form a uniform and dense rust layer under certain SO₂ concentration conditions, which has a certain self-healing function and is conducive to the formation of a stable rust layer.
Sufficient Light and Ventilation: Sufficient light and good ventilation conditions are conducive to the formation of stable rust layers. For example, the south-facing sunny side of the main beam of a bridge is more likely to generate stable rust layers than the north-facing shaded side because sufficient light is conducive to the occurrence of electrochemical reactions in the rust layer, promoting the transformation of rust layer components into more stable forms. At the same time, good ventilation can timely remove corrosive gas products and water vapor, maintaining a relatively stable environment on the surface of the rust layer.
Appropriate Temperature: Temperature also affects the rust layer stabilization process of weathering steel to a certain extent. Generally, moderate temperatures are more conducive to the formation and stabilization of rust layers. Although there is no particularly clear and specific temperature range regulation, extreme high or low temperatures may affect the rate and quality of rust layer formation. For example, in extremely cold environments, the activity of electrochemical reactions decreases, which may slow down the formation rate of rust layers; while in extremely high-temperature environments, the structure and composition of rust layers may be affected, making them less stable.
