Intercrystalline Grain Boundary Segregation
Intergranular segregation is the enrichment of foreign atoms or impurities at the grain boundaries. This increases hot cracking susceptibility and brittleness.
Physical-Chemical Mechanism of Action
Intergranular segregation occurs when foreign atoms or impurities are concentrated in the boundary regions between grains. This happens due to thermodynamic driving forces that cause these atoms to gather at the most stable sites in the crystal lattice.
Metallurgical Relevance & Welding Risks
This segregation can increase hot cracking susceptibility, as it makes the structure more brittle and distributes hardness unevenly. This leads to an increased susceptibility to cracking and deformation at temperatures near the melting point.
Workshop Practice & Action Instructions
To minimize intergranular segregation, the following should be done:
• Cool the weld as quickly as possible (t8/5 ≤ 10 s) to avoid martensite formation.
• Use a good shielding gas to keep foreign atoms and impurities away from the weld pool.
• Adhere to welding parameters such as voltage and temperature to control the structure uniformly.