X20Cr13 / 1.4021

1.4021, also known as X20Cr13 or AISI 420, is a martensitic, hardenable steel for use where moderate corrosion resistance is required.

Steel 1.4021 usually contains about 12-14% chromium and 0.16-0.25% carbon, together with small amounts of other elements such as manganese (Mn) and silicon (Si). This composition contributes to its hardness and corrosion resistance.

1.4021 belongs to the group of martensitic stainless steels characterised by a martensitic microstructure formed by quenching and tempering processes. This structure gives the steel high strength, hardness and wear resistance.

One of the defining characteristics of steel 1.4021 is its high hardness. It can achieve hardness levels up to HRC 50-55 after heat treatment, making it suitable for applications that require wear resistance and cutting ability.

Although this steel is not as corrosion resistant as austenitic stainless steels, 1.4021 offers moderate corrosion resistance in mild environments. Its chromium content provides some resistance to corrosion, but it can be susceptible to corrosion in aggressive environments such as those containing chlorides.

Martensitic stainless steels such as 1.4021 are generally magnetic under all conditions, which can be advantageous in applications where magnetic properties are desired, such as in magnetic bearings or certain industrial applications.

Due to its hardness and wear resistance, steel 1.4021 is often used for cutting tools, surgical instruments and knives. It is also used in industries such as food processing, automotive and aerospace for components that require strength and corrosion resistance. It can be polished to a very fine finish as optimum corrosion resistance is achieved after polishing. Preheating of the material before welding is recommended