1、Why does stainless steel have magnetism?

Answer: Often, people use magnets to test the quality of stainless steel. If a magnet doesn't attract and has no magnetism, it is considered genuine and of good quality. On the contrary, it is regarded as a fake. In fact, this is an extremely one-sided and impractical wrong way of discrimination.

Austenitic stainless steel is non-magnetic or weakly magnetic. Martensitic or ferritic stainless steel is magnetic. However, after cold working of austenitic stainless steel, the microstructure of the processed area will also transform into martensite. The greater the degree of processing deformation, the more martensite transformation occurs and the greater the magnetic property. The material of the product will not change. More professional methods should be adopted to test the material of stainless steel. (Spectral detection, stainless steel identification solution detection).

2. Why does stainless steel rust?

Answer: A. Dust containing other metal elements or particles of dissimilar metals accumulate on the surface of stainless steel. In a humid environment, the condensation water between the adherents and the stainless steel forms a micro-battery, triggering an electrochemical reaction and damaging the protective film. This is called electrochemical corrosion.

b. When organic substances such as vegetable juice, noodle soup, and phlegm adhere to the surface of stainless steel, in the presence of water and oxygen, they form organic acids. Over a long period of time, these organic acids will corrode the metal surface.

c. The surface of stainless steel adheres to substances containing acids, alkalis, and salts (such as splashed alkali water and lime water during wall decoration), causing local corrosion.

d. In polluted air (such as that containing large amounts of sulfides, carbon oxides, and nitrogen oxides), upon encountering condensation water, liquid spots of sulfuric acid, nitric acid, and acetic acid are formed, causing chemical corrosion.