Is there no sign 304 to use in the thermos?

The thermos can't be used without the 304 sign. Because 304 is stainless steel material number, other stainless steels contain heavy metals harmful to human body. I want to use a special stainless steel inspection reagent to test whether 304 stainless steel can drop on the surface of stainless steel and see if its color will change. If it is 304 stainless steel, it will not change color, otherwise it will change color.

Extended data:

304 stainless steel is a common material in stainless steel, with a density of 7.93 g/cm, also known as 18/8 stainless steel in the industry. High temperature resistance of 800℃, good processability and high toughness, widely used in industry, furniture decoration industry and food and medical industry.

Common marking methods in the market are 06Cr 19Ni 10 and SUS304, in which 06Cr 19Ni 10 generally represents national standard production, 304 generally represents ASTM standard production and SUS 304 represents Japanese standard production.

304 is a general-purpose stainless steel, which is widely used to manufacture equipment and parts that require good comprehensive performance (corrosion resistance and formability). In order to maintain the inherent corrosion resistance of stainless steel, steel must contain more than 18% chromium and more than 8% nickel. 304 stainless steel is a stainless steel brand produced according to American ASTM standard.