What is a common method for preventing corrosion on carbon steels?

Using chemical coatings is a well-established method for preventing corrosion on carbon steels. These coatings create a barrier between the steel and corrosive environmental factors such as moisture, oxygen, and salts, which are primary contributors to corrosion. By applying a chemical coating, such as paints, galvanization, or other protective paints, the underlying metal is shielded, significantly reducing the rate at which it will oxidize or corrode.

Increased humidity exposure can actually exacerbate corrosion issues rather than prevent them. High humidity levels provide moisture that can facilitate the corrosion process.

Thermal expansion treatments are not specifically designed to prevent corrosion; instead, they can help manage the physical stresses within materials due to temperature changes but do not provide a protective barrier against corrosion itself.

Electrical insulation might be useful in specific instances where galvanic corrosion is a concern, but it does not generally serve as a primary corrosion prevention methodology for carbon steels.

Thus, the most effective and commonly used method among the options given is the application of chemical coatings, which directly address the risk of corrosion.