A Pin Can Fail in Few Bending Cycles Without an Origin Defect

What the evidence preview establishes

Fracture markings indicate a surface-origin low-cycle fatigue failure under bending, with slower initial growth followed by rapid final fracture. No obvious local material defect was found at the origin.

Why this case matters

Use fracture markings to locate the true origin before assigning a metallurgical cause. A clean origin in a low-cycle bending failure shifts attention toward loading, geometry, and material selection without proving which one controlled life.