How to distinguish food stainless steel from technical stainless steel

Each type of stainless steel is used in specific conditions. Depending on where the specific alloy is used, stainless steel can be heat-resistant, acid-resistant, technical and food grade. It is the last variety that ordinary users most often encounter. As you know, the performance characteristics of any brand of steel depend on its chemical composition. Various alloying additives give the metal special properties. For example, food grade stainless steel has an increased content of chromium and nickel in its composition. Thanks to chromium, the steel is resistant to corrosion, and the addition of nickel makes the alloy resistant to nitric acid and several other acids. Other elements also affect the operational characteristics of the alloy. Let's find out what features food grade stainless steel has. And we will also find out how to determine that before us is such an alloy, and not a technical grade of steel.

The chemical composition is the basis of all bases

In addition to chromium and nickel, food-grade stainless alloys also contain a number of other chemical elements. Each of them brings new useful properties to the characteristics of steel. For example, molybdenum makes it possible to use rolled metal and its products in contact with acetic and sulfuric acids. Silicon helps stainless steel to be resistant not only to sulfuric acid, but also to hydrochloric acid. The addition of copper increases the tensile strength of the metal and additionally increases resistance to corrosion.

If you compare food-grade stainless steel with technical stainless steel, then this kind of chemical composition differs primarily from the fact that nickel is absent here. Technical grades of steel are distinguished by increased anti-corrosion resistance, ease of processing (for example, good weldability) and significant mechanical strength. Therefore, they are used in the construction industry, as well as in many branches of industry, in particular in mechanical engineering.

Since food-grade stainless steel contains a large amount of nickel and little carbon, such steel should not react to a magnet in any way. However, this household method of distinguishing a technical alloy from a food grade is, of course, not very accurate. In order to reliably determine the chemical composition and, accordingly, the grade of steel, it is necessary to conduct a spectral analysis of the sample in the laboratory.

In household conditions, stainless products are not too strongly affected by aggressive substances with a high percentage of chlorides. Steel grades such as AISI 304 (an analogue of 08Х18Н10 according to GOST), AISI 430 and AISI 410, AISI 321 and 12Х18Н10Т are used for the manufacture of dishes and other kitchen utensils. But in equipment for the production of food products, in food pipelines and other similar products used in the food industry, metal is constantly exposed to aggressive environments. For example, solutions of sulfamic acid and caustic soda, which are used at temperatures from +75°C to +90°C, are used for washing such equipment. AISI 316 stainless steel (08Х17Н13М2) will be the most suitable option for operation in similar conditions.

What properties should food grade stainless steel have?

Food grade stainless steel has the following characteristics:

1. Resistance to aggressive media, increased anti-corrosion properties.

1. Chemical inertness - products made of such grades of steel should not react with the media and substances in contact with them to avoid harm to people's health.

2. High mechanical strength - for example, professional kitchen equipment and utensils must be reliable and not "fit" against mechanical influences.

3. Good weldability - otherwise you won't be able to make products and parts of a complex shape.

4. Resistance to temperature changes and high pressure.