Connecting Rod That Fractured Because of a Forging Fold
A motorboat engine connecting rod forged from carbon steel fractured in two places and cracked at the small end during service. The analysis (visual inspection, 50x micrographs of sections etched with 2% nital, magnetic-particle inspection, and metallographic examination) supported the conclusion that the connecting rods were rendered susceptible to fatigue-crack initiation and propagation by the notch effect of coarse folds formed during the forging operation. One fracture was caused by fatigue resulting from operating stresses, and the other was a secondary tensile fracture. No recommendations were made.
Connecting Rod That Fractured Because of a Forging Fold, ASM Failure Analysis Case Histories: Offshore, Shipbuilding, and Marine Equipment, ASM International, 2019, https://doi.org/10.31399/asm.fach.marine.c0047151
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