SS sheet can be roughly divided into three categories: 200 series, 300 series and 400 series, of which 300 series is the most commonly used, 200 series and 400 series are a substitute for 300 series on a certain course, and strictly speaking, 400 series is not called stainless steel , Called stainless iron, because it does not contain nickel, so it can be attracted by magnets. The 200 series and 300 series have nickel, so they are non-magnetic and cannot absorb iron.