Coarsening anneal
Coarse grain annealing is a process to coarsen the metal grain by targeted heating and cooling, to improve magnetic properties or high-temperature properties.
Physical-chemical mechanism
Coarse grain annealing refers to the targeted coarsening of the metal grain through a controlled temperature curve. During the annealing phase, the metal is held in an environment that causes its grain to coarsen. This happens through the diffusion of atoms and the formation of new crystals.
Metallurgical relevance & welding risks
The coarsening of the grain improves mechanical properties such as toughness and hardness, especially for high-temperature applications. However, uncontrolled coarse grain annealing can lead to too coarse a grain, which impairs the density and modulus of elasticity of the material. This can lead to cracks and damage in the metal.
Workshop practice & instructions
To successfully carry out coarse grain annealing, the metal must be heated in a protected environment to ensure a controlled temperature curve. The heating time and temperature must be precisely maintained to achieve the desired grain size. Uncontrolled or too rapid cooling can lead to too coarse a grain.