Weld-Adjacent Stress Risers Can Drive Spring Vibration Fatigue

What the evidence preview establishes

The springs failed by vibration-fatigue crack growth at the highest-stress weld-adjacent location, followed by ductile rupture of the remaining section. The repeated geometry indicated loads or displacement beyond the design capability rather than a material or welding defect.

Why this case matters

Repeated fatigue origins at one geometric transition point to a structural stress problem. Combine fractography with load-cycle requirements, S-N data, stress analysis, and an engineering safety factor before redesigning the spring.