Why do stainless steel bends become magnetic and can corrode?

Why do stainless steel bends become magnetic and can corrode???
Stainless steel is a type of alloy in which the components that determine sustainability, stainless are the components Nickel and Chromium.
Standard 304 stainless steel ratio Nickel 8% and Chromium 18%
Stainless steel itself has a layer of Oxide (Cr2O3) covering the surface to prevent factors that cause oxidation of the internal components, so in case the stainless steel product is deeply scratched, exposed to chemicals or detergents, it will cause damage. punctures and corrodes the protective oxide layer of stainless steel and accelerates the oxidation process of stainless steel, it is necessary to clean and process (polish) to regenerate the protective oxide layer of stainless steel.
In the case of bending and creating corners, it is necessary to clean the mold, use lubricating oil to reduce force (reduce magnetism and corrosion) and clean stainless steel before and after construction and product installation. .
(Especially with current bending machines, it will cause deep scratches on the surface of the product, so cleaning and polishing will return the smooth, bright surface of stainless steel)
Wherever force is applied, magnetism will arise and MAGNETISM DOES NOT AFFECT THE QUALITY OF THE PRODUCT.
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