Corrosion of steel

Steel is a ferrous metal, and ferrous metals tend to form rust. You can read in this post what conditions are necessary and how to prevent rusting. You will also learn why stainless steel grades can rust as well and what types of corrosion must be considered for all types of steel.

Production of steel

Steel is a particularly hard and pure iron material. Essentially, steel is made of iron and carbon. The rust susceptibility of unalloyed steels is therefore just as high as with iron. Depending on the alloy, however, steel may also be made of stainless steel.

By incorporating certain other metals in the manufacturing process, steel, like all non-ferrous metals, then forms an oxide layer on the surface that protects it from corrosion.

Each alloy offers special properties, and also has a different rust resistance.

Types of corrosion against which all steels are susceptible

Apart from a few special steels, all steels are susceptible to high temperature corrosion.

In addition, contact corrosion and crevice corrosion must be considered in all steel constructions. No metal is protected against these types of corrosion.

Individual alloys may also be susceptible to stress corrosion cracking or transcrystalline corrosion. But that does not apply to all steels and steel grades. Ferritic steels have some advantages in terms of stress corrosion cracking, but disadvantages in other areas.

corrosion protection

For steel, both active and passive corrosion protection measures are used. Often one finds the hot dip galvanizing as passive corrosion protection. The steel tanks of boilers are always protected from corrosion by sacrificial anodes or external current anodes because they constantly come into contact with water.

The only steel that does not require corrosion protection is Corten steel. It forms a stable layer of rust that protects it from further corrosion.

Tips & Tricks

Always use suitable steel grades for the respective application. Otherwise, corrosion and strength losses in steel construction can threaten. There is always an optimally suitable steel grade for every application.

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