Diffusion layer
The diffusion layer is a zone in the weld where penetrated elements are dissolved and the hardness continuously decreases toward the core. It forms through atomic exchange between the materials.
Physicochemical Mechanism
The diffusion layer forms through atomic exchange between the weld material and the base material. Some of the base material dissolves into the weld material, leading to a homogeneous mixture.
Metallurgical Relevance & Welding Risks
The diffusion layer affects the mechanical properties of the weld. A thin diffusion layer can increase hardness and improve toughness, while an excessively thick layer can lead to uneven hardness distribution, causing cracks and fractures.
Workshop Practice & Action Guidelines
To achieve an optimal diffusion layer, precisely control welding parameters such as temperature and time. Too high a temperature can result in a too-thick layer, while too low a temperature can make it too thin. Recommended values vary by material, but generally set parameters to achieve a homogeneous hardness distribution in the weld.