1. Magnetic detection:
   Test the material with a magnet. If it has strong magnetism (excluding weak magnetism), it can be preliminarily ruled out as 304 or 316 material. If it has no magnetism or weak magnetism, it can be preliminarily ruled out as 416, 430, 443, etc. This is a simple method for initial judgment.

2. Portable spectrometer:
   Use a portable spectrometer (a small and portable instrument) to excite the material with high-voltage electricity and generate a spectrum. This can qualitatively distinguish the types of steel elements and the approximate content.

3. Chemical reagent:
   There is a specialized reagent called nickel qualitative solution (mainly used to detect the content of nickel, an important element in stainless steel). When dropped on the surface of stainless steel and energized, it will instantly oxidize. If a pale white or light yellow color is produced, it indicates that the stainless steel does not contain nickel. If a pale rose-red color is produced and immediately fades to dark yellow, it indicates that the stainless steel contains about 1%-2% nickel. If a rose-red color is produced and does not fade, it indicates that the stainless steel contains more than 4% nickel. The brighter the rose-red color, the higher the nickel content.

4. Color and luster:
   For stainless steel that has undergone acid pickling: 300 series stainless steel has a silver-white color with a jade-like sheen; 400 series stainless steel is white with a slightly grayish hue and weaker gloss; 200 series stainless steel has a similar color to 300 series stainless steel, but slightly lighter. For stainless steel that has not undergone acid pickling: 300 series stainless steel is a brownish-white color; 400 series stainless steel is a brownish-black color; 200 series stainless steel is black.

5. Spark test:
   The spark test involves grinding the stainless steel on a grinding wheel and observing the sparks. If the sparks are streamlined with many dense nodes, it indicates that the stainless steel is of the 200 series with a higher manganese content. If there are no nodes, it indicates that the stainless steel is of the 300 or 400 series.

The above methods are simple and convenient for identification, but there may be some errors, especially the third and fourth methods, which rely heavily on visual judgment and may have larger errors. The most accurate method is still the inspection report issued by a qualified inspection agency.