Subgrain Boundary Formation
Subgrain boundaries form through dislocation buildup during recovery, leading to crystal regions with small orientation differences.
Physical-chemical mechanism of action
During cooling and recovery of metals, dislocations form. These dislocations gather into parallel walls, forming subgrain boundaries. These boundaries separate crystal regions with slight orientation differences.
Metallurgical relevance & welding risks
Subgrain boundaries can lead to increased toughness and improved mechanical properties, as they prevent crack propagation. However, uncontrolled buildup of subgrain boundaries can result in a fine grain structure, which can weaken the weld and impair its toughness.
Workshop practice & instructions
To form subgrain boundaries in a controlled manner, it is important to carry out careful post-weld heat treatment. This involves setting cooling times and temperatures to ensure the metal has sufficient time to stabilize its crystal structure. Too rapid cooling can cause subgrain boundaries to form improperly and impair the mechanical properties of the weld.