Somthing about the food grade of stainless steel

1. The main components of stainless steel
The main components of stainless steel are iron, chromium, nickel, and a small amount of carbon and other elements

Second, the classification of stainless steel
According to material organization structure

Austenitic stainless steel
Martensitic stainless steel
Ferritic stainless steel
Austenitic-ferritic duplex stainless steel
Precipitation hardening stainless steel
The most common is austenitic stainless steel, the output of austenitic stainless steel accounts for about 75% to 80% of the total output of stainless steel.

Three, austenitic stainless steel
The classic first-generation austenitic stainless steel is called 18-8 steel (that is, our common 304 stainless steel, 18-8 means that the chromium content is about 18%, and the nickel 8%~10%), which is the most typical Representative steel, other austenites are all developed on the basis of 18-8.

The common components of austenitic stainless steel are:

2XX series (chromium-nickel-manganese austenitic stainless steel, the most common 201, 202)
3XX series (chromium-nickel austenitic stainless steel, the most common 304, 316)
The 2XX series originated from the Second World War. The use of nickel as a strategic material is strictly controlled in various countries (nickel is very expensive). In order to solve the dilemma of a serious shortage of nickel supply, the United States first developed the 2XX series stainless steel products with low nickel content. As an emergency and supplement to the 3XX series, the 2XX series was developed by adding manganese and (or) nitrogen to the steel to replace the precious metal nickel. The 2XX series is inferior to the 3XX series in corrosion resistance, but both are non-magnetic, so domestic Many unscrupulous merchants pretend to be 304 stainless steel with inferior 201 stainless steel, but excessive intake of manganese in the human body will cause damage to the nervous system, so the 2XX series cannot be used for tableware.

Fourth, what is the difference between 304, SUS304, 06Cr19Ni10, S30408
These 18-8 austenitic stainless steels are called differently in different countries, 304 (American standard, which is the American name), SUS304 (Japanese standard, which is also the Japanese name), 06Cr19Ni10 (Chinese standard, which is the Chinese name), S30408 ​​(S30408 ​​is the UNS number of 06Cr19Ni10, and the United States 304 also has a corresponding UNS number of S30400). Different national standards will be slightly different, but in the end, these can generally be regarded as the same material.

Five, 304 stainless steel or 316 stainless steel which is better
We usually say that 316 stainless steel refers to 316L, “L” is the abbreviation of “LOW” in English, which means “low carbon”. Compared with 304, 316 stainless steel has increased the content of nickel, reduced the content of carbon, and newly added molybdenum (no molybdenum in 304). The addition of nickel and molybdenum greatly enhances its corrosion resistance and high temperature resistance. Of course, the cost Also higher. 316 is mainly used in marine, high-temperature distillation, special medical equipment and other equipment that need corrosion resistance and high temperature resistance, so 304 is enough for ordinary food contact.

Six, what is food grade stainless steel
Food-grade stainless steel refers to stainless steel that meets the national mandatory standard GB4806.9-2016 “National Food Safety Standard and Metal Materials and Products for Food Contact”.

It can be seen from the above that the country has two main requirements for food-grade stainless steel: one is that raw materials must meet the requirements, and the other is that the precipitation of heavy metals in these raw materials must meet food-grade standards.

Many friends will ask if 304 stainless steel is food grade stainless steel?


The answer is: 304 stainless steel is “not equal to” food-grade stainless steel. 304 is an American standard. Naturally, it is impossible for the Chinese standard to use the word “304” as an American standard, but generally speaking, “specially treated 304 stainless steel” is food Grade stainless steel, ordinary 304 stainless steel is not food grade stainless steel, 304 stainless steel has a wide range of industrial uses, and most of them are not food grade.

Post time: Aug-24-2021

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