Failure Case Study Series Part Four: Investigation of the Failure Mechanism of the Connecting Rod in an Industrial Oxygen Compressor

Abstract

This investigation addresses the catastrophic fracture of a connecting rod in an oxygen compressor unit during steady‑state operation. Owing to its function in transmitting cyclic compressive and tensile loads between the crankshaft and the piston, the connecting rod it’s a critical structural element.
The assessment employed a systematic multi‑technique protocol. Macroscopic fractography was used to document crack morphology, fracture‑surface topography, and subsidiary failure‑related surface markers. Representative specimens were preserved for laboratory evaluation. Material conformance was verified through chemical composition analysis and hardness measurements benchmarked against applicable standards. The internal structure, including phase distribution, cleanliness, inclusion content, and thermal‑processing quality, was examined using optical metallography (OM). High‑resolution scanning electron microscopy (SEM) combined with energy‑dispersive spectroscopy (EDS) enabled the identification of crack‑initiation sites, fracture mechanisms, and local compositional anomalies.