Grains
Grains are microscopic crystals in metals separated by grain boundaries. Their size and orientation affect strength and toughness.
Physical-Chemical Mechanism of Action
Grains are microscopic single-crystal areas within a polycrystalline material, separated by grain boundaries. Each crystal has a specific orientation and size that affects the mechanical properties of the material.
Metallurgical Relevance & Welding Risks
The grain size (grain size) and orientation (grain structure) significantly influence mechanical properties like yield strength and toughness. Grains that are too large or irregular can lead to cracks and deformation, while too small grains increase hardness but limit ductility.
Workshop Practice & Action Instructions
To optimize the grain structure, control temperature and time during welding. For steel welding, it's important that the material doesn't cool too fast (t8/5 > 25 s) to avoid grains growing too large and causing cracks. For a finer grain structure, use slow cooling or special welding methods like high-pressure welding (HDS).