Types of stainless steel

Resistant to mechanical damage, scratches and dents, non-corrosive, easy to clean and to ensure work in hygiene – simply speaking – stainless steel. For many years, it has been at the forefront of materials used in the production of professional kitchen equipment and dishes.

Few people know, however, that two types of steel can be strikingly different. It turns out that this alloy can be very diverse, which is why steel is used in various industries. So how can you tell them apart?

Steel: 21/0, 18/0, 18/8, 18/10

The above numbers refer to the percentage value of two main elements added to steel – chromium and nickel. To use a concrete example, 21/0 means that this particular alloy contains 21% of chromium and 0% of nickel.

This information is crucial since a steel alloy can be called stainless if the content of the former element (chromium) is higher than 10.5%. The latter value (nickel) tells us about whether the alloy is magnetic or not. Then, if you see 18/8 alloy, it means that it does not have magnetic properties. By contrast, 18/0 alloy shows magnetic properties, which is reflected by 0 in the marking.

Nevertheless, for stainless steel, there is a more significant aspect of content values. Alloys of steel with 8-10% nickel content exhibits much higher resistance to corrosion (contrary to nickel-free alloys). Its content is also recognizable thanks to aesthetic qualities – nickel brings out the bright colour and high gloss.

The numbers mentioned here can most frequently be found in the food industry to produce cutlery, pots and high-quality kitchenware.

Advice #1: Alloys marked 21/0 and 18/0 do not exhibit high acid resistance. That is why you should avoid making sour dishes in it, e.g. based on vinegar, lime or lemon.

AISI steel

The second most popular classification for steel comes from the name American Iron and Steel Institute. This institute focused its efforts into a numbering system for steels into various series, including the ones used in professional kitchens. AISI/SAE or SAE steel grades belong to the same classification system.

300 Series belongs to austenitic alloys, i.e. with the addition of chromium accompanied by nickel or molybdenum. They are used in kitchens in our homes, just like 400 Series which are called ferritic and martensitic alloys. Their high hardness and strength go hand in hand with slightly lower corrosion resistance.

Advice #2: 300 and 400 Series alloys are used to produce professional kitchen equipment – countertops, work shelves, tables and storage racks.

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