Using Magnets
Chromium stainless steel has strong magnetism and can be attracted by magnets in any state, whereas chromium-nickel stainless steel is non-magnetic when annealed but becomes magnetic after cooling. High manganese steel, due to its high manganese content, is non-magnetic. This identification method is convenient and does not require additional supplies.
Observing Color
There is a noticeable difference in the color of stainless steel surfaces after being cleaned with acid. For example, chromium-nickel stainless steel has a silver-white color, while chromium stainless steel appears grayish-white. The color difference between chromium-manganese-nitrogen stainless steel and chromium-nickel stainless steel is minimal. Stainless steel that has not undergone acid cleaning displays different colors: chromium-nickel steel appears brown-white, chromium steel brown-black, and chromium-manganese-nitrogen steel black.
Using Copper Sulfate
First, remove the oxide layer from the surface of the stainless steel, then apply a drop of water. If the surface is rubbed with copper sulfate, the stainless steel will turn purple-red, indicating it is high manganese steel. Ordinary steel or low-alloy steel will show magnetic properties when subjected to this test.
