Dislocation Density
Dislocation density is the total length of all dislocation lines per unit volume in a crystal. It indicates how much a material has been plastically deformed and how much it work-hardens.
Physical-Chemical Mechanism of Action
Dislocation density describes the number and length of dislocation lines within a crystal. These lines are locations where the atomic lattice structure is disturbed. During plastic deformation, these dislocations move, leading to increased strength.
Metallurgical Relevance & Welding Risks
High dislocation density can strengthen the material, but also increases the risk of cracks and hot cracks. At too high values, the material can no longer deform plastically and instead breaks. This is especially dangerous when welding under pressure or high stresses.
Workshop Practice & Action Guidelines
To achieve optimal dislocation density, pay attention to proper cooling after welding. Too fast cooling can lead to excessively high dislocation density and make the material more crack-prone. For heavy materials like steel, controlled cooling in a furnace is recommended to increase strength and avoid cracks.