When the heavy metals migrated in the use of stainless steel products exceed the limit, it may endanger human health.
Therefore, the production of stainless steel cookware needs to find a balance between corrosion resistance and safety. If the content of nickel and chromium is high, the anti-corrosion function will be enhanced, but the subsequent precipitation of nickel and chromium will also increase, which means that the safety risk will increase.
Because of this, the national food safety standard of "Stainless Steel Products" (GB9684-2011) has made strict regulations on the precipitation indicators of various heavy metals such as chromium, cadmium, nickel and lead in cooking utensils.
Why does the national standard not specify the migration limit of manganese?
One reason is that with the increase of manganese content in stainless steel, it is accompanied by the loss of corrosion resistance and rust resistance of cookware. Once the manganese content reaches a certain value, this product cannot be used as cookware or can not be called stainless steel cookware. . But even such high levels of manganese generally do not have any health effects.
Therefore, although the national food safety standard does not stipulate the content of manganese, it clearly points out that the main part of the tableware container must be made of stainless steel that meets the national standard.
Food-grade stainless steel is stainless steel that meets the GB9684 standard.
304 stainless steel is a very common stainless steel, also known as 18-8 stainless steel in the industry. Its corrosion resistance is better than 430 stainless steel, corrosion resistance and high temperature resistance, and good processing performance, so it is widely used in industry and furniture decoration industry and food and medical industry, such as: some high-grade stainless steel tableware, bathroom kitchen utensils.
304 is a general purpose stainless steel that is widely used to make equipment and parts that require a good combination of properties (corrosion resistance and formability).
In order to maintain the inherent corrosion resistance of stainless steel, the steel must contain more than 17% chromium and more than 8% nickel.
Generally, 304 stainless steel is not food grade, and the special processed is food grade.
As we all know, stainless steel products related to "edible" must use 304 and 316 stainless steel. The price of 316 stainless steel is high, and it is mostly used in high-end equipment, such as aerospace, food machinery and other fields. The food-grade stainless steel used in daily necessities is mostly 304 stainless steel, which has good acid and alkali resistance and strong corrosion resistance.
In contrast, 201, 202 stainless steel (commonly known as high manganese steel) is generally used in industrial products and cannot be used as tableware because of:
● The nickel content is not up to the standard, the acid and alkali resistance is poor, and it is easy to rust;
● Excessive manganese content, excessive intake of manganese by the human body will cause damage to the nervous system.