Edge dislocation

Dislocations are lattice defects in metal that move during plastic deformation. Welding creates many of them due to rapid temperature changes, making the material hard and brittle. When they pile up at grain boundaries, stress peaks occur that can lead to cracks, especially in the heat-affected zone. To keep this under control, you need to manage heat input, use low-hydrogen filler, and stress-relieve anneal critical steels after welding. This relieves internal stresses and prevents cracking.