Corrosion protection in steel

Steel as iron metal must be absolutely protected against corrosion. For this purpose, various means are suitable. What you can use, which types of steel do not need additional protection and which disadvantages some protective measures can have, you will find in detail in this article.

Stainless steels

Stainless steels do not need special protection. Like all non-ferrous metals, they form an oxide layer that protects them from corrosion agents from the environment.

Stainless steels are made of special alloys. Depending on the type of alloy, the oxide layer is more or less stable. Not all stainless steels and stainless steels are equally resistant to corrosion. The most resistant to corrosion are high-alloyed steels with a high chromium or nickel content.

There are also some particularly resistant steel grades such as Inox or Nirosta. In fact, they are hardly affected by corrosion even under difficult conditions.

Stainless steel is also very resistant to corrosion in most cases. This is especially true for high-alloy stainless steels.

Passive corrosion protection

Passive corrosion protection is usually achieved by galvanizing steel. Hot-dip galvanizing is a very effective method because it produces much higher layer thicknesses than other processes.

Conventional zinc coatings are also used for unalloyed steel. In addition, painting also represents a passive corrosion protection, which is often used in steel. Often several methods are combined.

Active corrosion protection

In boilers, which have a steel container, sacrificial anodes are always used. The result is that not the steel corrodes, but instead the sacrificial anode, because it consists of a less noble metal, mostly magnesium. This protection is necessary because steel, which is constantly in contact with water, would otherwise rust after a short time.

Alternatively, one can also use a so-called external current anode. It does not have to be renewed on an ongoing basis, since the current does not come from the anode, but from an external source. This represents an advance.

Tips & Tricks

Always make sure that steel screws can cause contact corrosion when used with other metals. You may then need to make sure that the screws are really completely isolated from the other metals and sealed well enough. But you can also choose better compatible screws for mounting.

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