The Secrets of Stainless Steel in Steel Pipe Knowledge
2013-07-18
All metals react with oxygen in the atmosphere to form an oxide film on their surface. However, the iron oxide formed on ordinary carbon steel continues to oxidize, causing rust to expand and eventually form holes. Paint or oxidation-resistant metals can be used for electroplating to protect the surface of carbon steel, but as is known, this protection is merely a thin film. If the protective layer is damaged, the underlying steel will begin to rust.
The corrosion resistance of stainless steel depends on chromium, but since chromium is one of the components of steel, the protection methods vary. When the amount of chromium reaches 10.5%, the atmospheric corrosion resistance of steel significantly increases; however, when the chromium content is higher, although corrosion resistance can still be improved, it is not significant. The reason is that when alloying steel with chromium, the type of surface oxide changes to resemble that formed on pure chromium metal. This tightly adhered chromium-rich oxide protects the surface and prevents further oxidation. This oxide layer is extremely thin, allowing the natural luster of the steel surface to be seen through it, giving stainless steel its unique appearance. Moreover, if the surface layer is damaged, the exposed steel surface will react with the atmosphere to self-repair and re-form this oxide 'passivation film', continuing its protective function.
Therefore, all stainless steel elements share a common characteristic: their chromium content is above 10.5%.
Shenyang Tengfei Iron Corporation
Shenyang Tengfei Steel Pipe Co., Ltd.
Address: No.6 A 3, No.13 Road, Economic and Technological Development Zone, Shenyang City, Liaoning Province
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