Lattice coherence
Lattice coherence is the state where the lattice of a newly formed particle transitions continuously into the surrounding lattice. This leads to high elastic stress and strengthens the material.
Physical-chemical mechanism of action
Lattice coherence occurs when the crystal structure of the newly formed particle at the phase boundary is identical to that of the surrounding metal. The lattice planes transition continuously, leading to high elastic stress.
Metallurgical relevance & risks in welding
Lattice coherence can contribute to increased toughness and strength of the material. However, it can also lead to increased crack growth and hot cracking if stresses are not properly relieved. This can occur particularly at high welding speeds and strong stress fields.
Workshop practice & instructions
To minimize lattice coherence and reduce risks, the following measures should be taken:
• Use speed-controlled welding (VCC).
• Keep the maximum welding speed below 10 mm/s.
• Ensure that the surrounding lattice is properly relaxed by controlling cooling steps and adhering to required time intervals.