1. When a tensile stress is applied to a single crystal, the shear stress exerts a force F = τ*b on the dislocation line, which is pinned at both ends. This could occur if the two ends were nodes where the dislocation in the plane of the paper intersects dislocations in the other slip planes, or the pinning could be caused by existing precipitates.

3. The shear stress reaches a maximum when the segment becomes a semicircle.

5. The loop continues to expand, and a new dislocation line is formed. The process can repeat itself sending out many loops. "