A Sound Weld Can Still Fracture Where Its Load Path Becomes Too Thin

What the evidence preview establishes

Residual stress fractured the weld through its section of minimum thickness. The thin section acted as a hinge between the joined components even though fusion was sound and no porosity or other weld defect sufficient to explain failure was found.

Why this case matters

Weld quality requires adequate geometry as well as sound fusion. Section across the load path, compare minimum weld thickness with adjoining walls, and assess structural restraint before blaming porosity or isolated brittle features on the fracture surface.