Grain Boundary Segregation
The enrichment of alloying elements or impurities at grain boundaries leads to local strengths and weaknesses in the material structure.
Physicochemical Mechanism of Action
Grain boundary segregation is a process where certain chemical elements or impurities concentrate at the boundaries between different crystal grains during cooling of metals. This happens due to the different solubility of these elements in the various phases of the material.
Metallurgical Relevance & Risks in Welding
This segregation can impair local corrosion resistance because certain impurities or alloying elements are concentrated at the grain boundaries. It can also lead to mechanical weaknesses, such as increased hardness and reduced toughness in these areas. This can lead to cracks or wear problems in the weld joint.
Workshop Practice & Action Instructions
To minimize grain boundary segregation, it is important to ensure controlled cooling and a homogeneous weld pool. Use materials with low segregation tendency when selecting weld joints. For highly critical applications, diffusion treatments or the use of stabilized alloys may be recommended.