In addition to iron, 304 stainless steel also contains chromium, nickel, aluminum, silicon, and other components. Scientists have found that the more uniform the internal structure of steel, the closer the various components are connected, making it more difficult for corrosive substances to invade. Generally speaking, steel with a chromium content of 10.5% is less prone to rusting. The higher the content of chromium and nickel, the better the corrosion resistance. For example, the nickel content required for 304 material is 8-10%, and the chromium content reaches 18-20%. Such 304 stainless steel will not rust after welding.

In addition, there is a layer of oxide protective film attached to the surface, just like putting armor on steel, which naturally makes it less prone to rusting. Stainless steel has the ability to resist corrosion by forming a thin, strong, and stable chromium rich oxide film (protective film) on its surface, which prevents oxygen atoms from continuing to infiltrate and oxidize. Once for some reason, this thin film is constantly damaged, and oxygen atoms in air or liquid will continuously infiltrate or iron atoms in the metal will continuously separate, forming loose iron oxide, and the metal surface will also be continuously corroded. This kind of surface facial mask is damaged in many ways, and the following are common:

1. The surface of stainless steel accumulates dust or foreign metal particles containing other metal elements. In humid air, the condensed water between the attachments and the stainless steel forms a micro battery, triggering an electrochemical reaction that damages the protective film, known as electrochemical corrosion.

2. Organic substances such as vegetables, soup, and phlegm adhere to the surface of stainless steel, forming organic acids in the presence of water and oxygen. Over time, these organic acids can corrode the metal surface.

3. The surface of stainless steel adheres to substances containing acids, alkalis, and salts (such as alkali water and lime water sprayed on decorated walls), causing local corrosion.