Why are stainless steel kitchen knives magnetic？

There are many kinds of stainless steel, such as martensite, austenite and so on (I don't explain in detail here, you can find it by searching on the Internet). People often think that the magnet adsorbs stainless steel material to verify its advantages and disadvantages and authenticity. It does not absorb and has no magnetism. It thinks that it is good, and the real price is real. If the absorber has magnetism, it is considered to be counterfeit. In fact, magnetism is used to determine whether it is stainless steel Steel is really one-sided and impractical method of error identification~
The tool is generally made of martensitic stainless steel, because the main performance of the tool is to have high hardness. The tool without hardness is useless. The trace elements with high hardness will be relatively high, such as chromium, molybdenum and nickel, which will be magnetic.
If the tool is made of austenitic material, the defect is that the cutter will have a notch and a rolling edge at most in a week. Even if there is no notch or rolling edge, it is very sharp at the beginning of use. After using it for a period of time, you will find that it can't be sharpened any more. This material is known as the so-called "real" stainless steel, but it has no hardness and magnetism, and there is not much hardness after heat treatment.