Subgrain Boundary Formation
Subgrain boundary formation is the appearance of dislocations in energetically favorable walls during recovery, which divides the crystal lattice into smaller regions.
Physical-Chemical Mechanism of Action
During cooling and recovery of metals, dislocations form in the crystal lattice. They try to arrange themselves in energetically favorable patterns, which divides the lattice into smaller regions. This process forms subgrain boundaries.
Metallurgical Relevance & Welding Risks
Subgrain boundary formation can lead to an increased number of dislocations, which can impair the toughness and strength of the material. Too many dislocations can also cause cracks or hot cracks, especially if the material cools too quickly.
Shop Practice & Action Guidelines
To ensure optimal subgrain boundary formation, the weld material should be cooled in a controlled environment. This means the cooling position and rate must be precisely controlled. Too fast cooling can cause hot cracks, while too slow cooling can coarsen the material and reduce its toughness.