Stainless steel screws generally have good corrosion resistance, mainly due to the chromium element they contain. Chromium forms a dense chromium oxide protective film on the surface of the screws, preventing further intrusion of oxygen and moisture, thus effectively preventing rust. In general indoor or outdoor environments, such as under normal urban climate conditions, 304 stainless steel screws can be used for a long time without obvious corrosion, meeting the installation requirements of most solar panels.
The corrosion resistance of 316 stainless steel screws is even more outstanding, especially in harsh corrosive environments. It contains more nickel and molybdenum elements than 304 stainless steel. The molybdenum element enhances the screws' tolerance to chlorides. Therefore, in coastal areas where the air contains a large amount of salt, or in chemical industrial parks and other areas with chemical corrosion risks, 316 stainless steel screws can better resist the erosion of salt spray and chemical substances, ensuring the stable installation of solar panels.
To improve the corrosion resistance of carbon steel screws, surface treatment is usually carried out. Common treatment methods include galvanizing and nickel - plating. Galvanizing forms a zinc layer on the surface of the screws. Zinc is more reactive than iron, and during the corrosion process, zinc will be oxidized first, thus protecting the iron substrate. A general electro - galvanized layer can improve the corrosion resistance of the screws to a certain extent. However, in harsh environments, the zinc layer may gradually be corroded, and regular maintenance is still required. Nickel - plating can provide better corrosion resistance and decoration, but the cost is relatively high.
Carbon steel screws themselves have poor corrosion resistance. Their main component is iron, and they are prone to rusting in humid air. If directly exposed to the natural environment, carbon steel screws will be oxidized quickly, with rust appearing on the surface, which in turn affects their strength and connection stability.
