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Dalian-builds-a-world-class-iron-ore-mixing-and-distribution-center
Dalian builds a world-class iron ore mixing and distribution center
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Knowledge Of Stainless Steel
Knowledge Of Stainless Steel
2021-10-15

Food grade stainless steel knowledge

1. What is stainless steel?

According to the definition in GB/T20878-2007, stainless steel is a steel with rust resistance and corrosion resistance as its main characteristics, with a chromium content of at least 10.5% and a maximum carbon content of 1.2%.

Stainless steel is the abbreviation of stainless and acid-resistant steel. Steels that are resistant to weak corrosive media such as air, steam, and water or are stainless steel are called stainless steel; The steel grade is called acid-resistant steel.

Due to the difference in chemical composition between the two, their corrosion resistance is different. Ordinary stainless steel is generally not resistant to chemical media corrosion, while acid-resistant steel is generally non-corrosive. The term “stainless steel” refers to a single type of stainless steel and refers to more than one hundred industrial stainless steel. Each stainless steel developed has good performance in its specific application field. The key to success is to understand the purpose first, and then determine the correct steel grade. There are usually only six types of steel related to the application of building construction. They all contain 17-22% chromium, and better steel grades also contain nickel. The addition of molybdenum can further improve atmospheric corrosion, especially the corrosion resistance of the chloride-containing atmosphere.

Food grade stainless steel knowledge

2. Classification of stainless steel

Stainless steel is often divided into martensitic steel, ferritic steel, austenitic steel, austenitic-ferritic (duplex) stainless steel and precipitation hardening stainless steel according to the state of organization. In addition, it can be divided into chromium stainless steel, chromium nickel stainless steel and chromium manganese nitrogen stainless steel according to the composition.

3.What is food-grade stainless steel

Food grade stainless steel refers to the stainless steel conforming to the national mandatory standard gb4806.9-2016 national food safety standard metal materials and products for food contact.

There are two main national requirements for food-grade stainless steel: one is that the raw materials should meet the requirements, and the other is that the precipitation of heavy metals in these raw materials should meet the food-grade standards.

Many friends will ask whether 304 stainless steel is food-grade stainless steel?

The answer is: 304 stainless steel is “not equal to” food-grade stainless steel, but generally speaking, “304 stainless steel after special treatment” 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.

4.How to make sure that what you buy is food grade stainless steel?

Taking the electric kettle as an example, the main body of the part in contact with water shall be food-grade stainless steel. Because the national mandatory standard gb4806.9-2016 is “mandatory”, buying regular large brand products meets the food-grade requirements.

Look at the appearance and product identification, including enterprise name, address, specification, model, trademark, etc; Try to choose products with material description, such as PP and other plastic materials, 304 or 430, and other stainless steel materials.

Looking at the “CCC” mark, electric food processing appliances are products subject to national compulsory certification (3C certification), so consumers must see whether the purchased electric food processing appliances are marked with CCC certification mark and whether they have obtained the “CCC” certification certificate.

Depending on the material, good stainless steel surfaces are mostly mirrors or processed into uniform lines. Wash with water and flow down into streams. Poor stainless steel surface processing is mostly rough, disordered lines, inconsistent color, and so on. The plastic material should be smooth, rigid, not deformed, and free of peculiar smell. It is best not to choose a plastic electric kettle with bright color.

5.Why does some stainless steel cutlery have a peculiar smell?

Sometimes when our hands touch metal, there will be a metallic smell on the hands, mainly because when the skin touches the surface of the metal, the oxidized fat on the skin is catalyzed by the trace metal ions of the metal to decompose into small molecules of aldehydes and ketones. You smell it. In fact, it is similar to the smell of blood and iron.

In the production process of stainless steel tableware, in order to make the product have certain special properties, such as anti-corrosion or anti-acid and alkali, after being shaped and condensed, it will be poured and polished by mechanical processing. Especially the oil and other substances attached to the finishing process after molding will produce “odor”. If you use food-grade stainless steel tableware such as 304 and 316, there is still an obvious “odor” after cleaning, indicating the quality of stainless steel is not standard.

6.How to clean stainless steel cookware?

Food grade stainless steel knowledge

Stainless steel is one of the most suitable materials for cooking utensils because it is very durable and beautiful. But unlike non-stick pans, if used improperly, stainless steel cookware will stick to dirt, which is difficult to remove. It is important to clean your cookware regularly and learn how to effectively remove stubborn dirt. At the same time, you can also do some surface treatment on the stainless steel pot to make the surface difficult to adhere to the cooked food, so that it is much easier to clean.