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 one of the easiest ways to identify stainless steel in daily life

The second is the nitric acid drop recognition method. Stainless steel has corrosion resistance to concentrated nitric acid and dilute nitric acid and has no reaction after dripping nitric acid solution. However high carbon types 420 and 440 are slightly corroded after dripping nitric acid solution. Carbon steel turns brown when it encounters concentrated nitric acid and causes strong corrosion when it encounters dilute nitric acid. Non-ferrous metals corrode immediately when they encounter concentrated nitric acid. This method requires your own nitric acid drops.

The third is to use the copper sulfate drip test identification method. This test method needs to do the first step: remove surface grease and impurities, polish a small area with a soft cloth, and then drip copper sulfate solution on the metal surface. If it is ordinary carbon steel and iron, after the copper sulfate solution drips on the surface, a layer of metallic copper will be formed on the surface. If the stainless steel surface encounters copper sulfate solution, no copper precipitation or copper color will be displayed.

The fourth is the spark test identification method. Using grinding on the grinding wheel, four different stainless steels can be identified by sparks from the stainless steel. If there are short reddish sparks with several forks, it is 302, 303, and 316 stainless steel. If there are very few dark red short sparks with several forks, it is 308, 309, 310, and 446 stainless steel. If there are long white sparks with several forks, it is 410, 414, 416, 430, 431. If it is a shimmering color spark with obvious flash or a long white spark, it is 420, 420f, and 440a stainless steel.

The last is the use of chemical elemental analysis. This method 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 enterprises.