Depth of Hardened Layer
The case hardening depth is the layer thickness in which a certain hardness is achieved, starting from the surface layer. It indicates how deep the hardness penetrates into the material wall.
Physical-chemical mechanism of action
The case hardening depth describes how deep a certain hardness (e.g., 50 HRC) penetrates into the metal core of the weld. This process depends on the cooling load and the cooling behavior of the metal.
Metallurgical relevance & risks in welding
A too shallow case hardening depth can lead to insufficient hardness in the core of the weld, affecting mechanical properties and toughness. A too deep case hardening depth can lead to a brittle grain structure and increased risk of cracks and hot cracks.
Workshop practice & instructions
To control the case hardening depth, it is important to optimize the cooling load and the cooling behavior of the metal. This can be done by careful selection of the welding technique (e.g., TIG welding) and adjustment of the cooling jets. A typical goal is a hardness of 50-60 HRC in the surface layer, with a case hardening depth of about 1-2 mm.