Bolting failures typically occur at which locations?

• A. All of the above.
• B. The thread root area.
• C. The head to shank area.
• D. Nicks or gouges.

Answer: (A)

Bolting failures are often driven by stress concentration and surface imperfections. The thread root area is a well-known fatigue hotspot because the sharp corners of the thread create high local stresses under cyclic loading, so cracks commonly initiate there. The head-to-shank area is another transition region where geometry changes can concentrate stress, especially if the bolt is loaded in bending or shear or if seating is imperfect, making it a likely failure point. Nicks or gouges on the bolt surface act as notches that drastically raise local stress and serve as initiation sites for cracks or fracture. Since any of these locations can act as a starting point for failure depending on loading and conditions, bolting failures typically occur at all of the above.