1) The first is the magnetic test identification method. Carbon steel, ferritic stainless steel, and martensitic stainless steel are magnetic. Austenitic stainless steel is generally non-magnetic. This method is the easiest way to identify stainless steel every day.

2) The second is the nitric acid drop identification method. Stainless steel has corrosion resistance to concentrated nitric acid and dilute nitric acid and has no reaction after dropping nitric acid solution. However, high carbon types 420 and 440 are slightly corroded after dropping nitric acid. Carbon steel turns brown when exposed to concentrated nitric acid, and causes strong corrosion when exposed to dilute nitric acid. Non-ferrous metals corrode immediately when exposed to concentrated nitric acid. This method requires you to prepare your nitric acid drops.

3) The third method is to use the copper sulfate drip test identification method. What needs to be done in this test method, the first step is to remove surface grease and impurities. Then polish a small area with a soft cloth after that drip copper sulfate solution on the metal surface. If it is ordinary carbon steel and iron, after copper sulfate liquid is dripped on the surface, a layer of metallic copper will form on the surface. If the stainless steel surface encounters copper sulfate liquid, it will not produce copper precipitation or show copper color.

4) The fourth is the spark test identification method. Four different stainless steels can be identified by grinding on the grinding wheel and according to the sparks emitted by the stainless steel. If there are short reddish sparks with several crosses, it is 302, 303, and 316 stainless steel. If there are long white sparks with several crosses, they are 410, 414, 416, 430, 431. If it is a shimmer-colored spark with obvious flash or a long white spark, it is 420, 420f, or 440a stainless.

5) The last one is to use chemical elemental analysis. This is relatively scientific. Using a few grams of drill cuttings for chemical analysis, the normal content of various chemical elements in stainless steel can be obtained. This is a common method used by various companies.