Microstructure

Microstructure is the term used to refer to the crystal structure of a solid, polycrystalline material. In metallurgy, a distinction is made between primary and secondary microstructures. Primary microstructures are created during primary Forming. Secondary microstructures, on the other hand, depend on the production processes used.

During crystallisation, the microstructure is primarily determined by the number of nuclei and the cooling rate. Faster cooling and a larger number of crystal nuclei result in fine-grained microstructures (fine grain), while slow cooling with few nuclei produces a coarse microstructure (coarse grain). Extremely rapid cooling, for example during solidification on cooled rollers, creates amorphous Metals called metallic glasses with no crystalline structures.

The crystallites' axes are normally arranged randomly in polycrystalline microstructures, but their orientation (texture) can also be defined by shaping so that they point in a preferred direction. The Material then has anisotropic properties. The microstructure's orientation can also be defined, for example, by slag particles during hot forming, during which they are stretched into thin fibres in the microstructure and give it different properties lengthways and crossways. The microstructure (granulation, grain) can be influenced by reheating during thermal treatment processes.