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This post was last edited by Wang Wei2 on 2020-4-28 at 10:58. For steel, corrosion is commonly referred to as “rusting,” which is what we mean by the corrosion of metals. The reasons for steel corrosion are as follows: One can explain it from the perspective of energy and energy levels. All matter in nature has a natural tendency to transition from higher energy states to lower energy states (just as water flows from high places to low places); this is a law of nature. Corrosion can be understood as the process in which a material, in an environment, undergoes a transition from a higher energy state to a lower energy state, and from an unstable state (metastable state) to a stable state, through physicochemical and electrochemical mechanisms. The second is to explain and understand the corrosion process from an oxidation-reduction perspective. Corrosion is an oxidation process: iron turns into iron oxide (rusting), plastics, rubber, and similar materials are oxidized (aging), and even the decay of organisms is related to oxidation processes. To vividly understand and explain the corrosion process of steel and the significance of corrosion control, iron ore (iron oxide in its stable state in nature) is transformed into steel (a metastable state) through smelting (which increases the energy level and consumes energy). Steel can be used as a structural material to meet mechanical requirements and the desired performance characteristics. However, in normal environments, steel in a metastable state is constantly transitioning to a lower-energy, stable state, eventually returning to its ore state (iron oxide, rust). Therefore, without protection or with inadequate protection, the lifespan of steel is short; however, by implementing corrosion control, the time it can remain in a stable state can be extended, allowing it to meet the expected service life requirements.