Decarburized Rim
The decarburized zone is a near-surface depletion of carbon in the steel due to reaction with oxidizing furnace atmospheres, resulting in a pure ferritic structure at the surface. This can reduce hardness and strength.
Physicochemical mechanism of action
In the decarburized zone, the steel reacts with oxidizing gases in the furnace, especially oxygen and nitrogen. Carbon is bound at the surface and displaced by these gases. This leads to a depletion of carbon in the steel and the formation of a pure ferritic structure.
Metallurgical relevance & risks in welding
The decarburized zone can reduce the hardness and strength of the surface, which can lead to increased susceptibility to cracking and corrosion. During welding, this can cause weaknesses or inconsistencies in the weld.
Workshop practice & instructions
To minimize the risk of decarburized zones, the furnace atmosphere should be controlled. A lower carbon content and proper temperature control in the furnace are crucial. When welding, it is important to ensure that the weld does not fall into a decarburized zone by controlling temperatures and times.