If there is a problem with rust, either uses a non-corrosive metal or coat a corroded metal. Metal that does not rust will have a cost loss, and usually, there will be a performance loss. The coating allows you to use cheaper metals, which are often easier to work with. Paint is the first coating to protect mild steel when seen, but it will not last long. This leads to the problem of galvanizing. The million-dollar question is: Will galvanized steel rust?
The short answer is yes and no. Galvanizing is a zinc coating applied to the surface of the steel. It protects against rust and corrosion for a much longer time than paint, usually for 50 years or more, but brown rot will eventually appear.
How to prevent rust from galvanizing
Let's start with some definitions. Corrosion is the way the metal decomposes when oxygen erodes the metal surface. Rust is a special type of corrosion experienced by iron. Oxygen produces iron oxide, which is stripped from the metal body, exposing the fresh metal to oxygen.
Metals that do not rust, such as aluminum and stainless steel, form an oxide layer on the surface. This prevents further corrosion. Another metal that oxidizes and does not rust is zinc. Zinc is interesting because it bonds well to steel.
So, if you want to give steel a coating that lasts longer than paint, you can cover it with a layer of zinc. This is electroplating.
Zinc prevents oxygen and water from reaching the steel below. It first forms a layer of zinc oxide on the surface. When moisture is present, it becomes zinc carbonate. This makes the metal dark gray, insoluble in water, and prevents any further chemical changes.
Factors affecting the quality of galvanized steel sheet
When you consider using galvanized steel, it is important to consider local conditions. More specifically, consider:
High or low humidity, exposure to salt, acid, or industrial pollutants. (Desert Air: No problem. Tropical city: Potential problem.)
Buried galvanized steel sheets in the soil (such as the bottom of a fence post) will expose it to more moisture. However, the magnitude of the impact largely depends on the type of soil and the overall conditions, (muddy and wet or sandy and dry.)
As long as the melting point of zinc is lower than 787 °f (420 °c), the high temperature itself will not decompose zinc. However, when combined with corrosive factors such as humidity and industrial pollution, it is an accelerating factor. Low temperature has no effect on the galvanized layer.
Will galvanized steel rust? The answer is yes, but the speed is very slow. In fact, being slow is usually not a problem. This is why galvanized steel has been used for 2000 years and why it may be accepted in your application.