the chemical composition of stainless steel includes carbon, Cr (Cr), Ni, Ti, Mn, N, Nb, Mo, Si, Cu and other elements.

the corrosion resistance of stainless steel decreases with the increase of carbon content. therefore, the carbon content of most stainless steels is low, and the maximum is less than 1.2%. the ωc (carbon content) of some steels is even lower than .3% (such as Cr12).

the main alloying element in stainless steel is Cr (chromium). Only when the Cr content reaches a certain value, the steel has corrosion resistance. Therefore, the general Cr content of stainless steel is at least 1.5%. Stainless steel also contains elements such as Ni, Ti, Mn, N, Nb, Mo, Si and Cu.

extended information

during the manufacturing process of stainless steel equipment, there will be performance damage, defects and some substances that affect the surface, such as dust, floating iron powder or embedded iron, hot tempering color and other oxide layers, rust spots, grinding burrs, welding arc marks, welding spatter, flux, welding defects, oil and grease, residual adhesive and paint, chalk and marking pen marks. Most of them don't pay attention or do well because they ignore their harmful effects.

once the protective film is damaged, thinned or changed by other methods, the underlying stainless steel will begin to corrode. Corrosion is generally not all over the surface, but at or around the defect. This kind of local corrosion is usually pitting corrosion or crevice corrosion, and these two kinds of corrosion will develop to depth and breadth, while most surfaces are not corroded.

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