Failure of a Pump Shaft Ascribed to Accidental Local Heating
The broken end of a shaft from a centrifugal pump had a smooth fracture surface characteristic of failure from fatigue. Failure occurred in the plane of the keyway end and followed a slightly helical path, indicating that combined bending and torsional stresses were responsible. The material was a Cr-Mo-Ni alloy steel of the En 19 type in the hardened and tempered condition and of satisfactory quality. The assembly also included a copper sleeve attached by a circumferential braze behind the plane of fracture. The cracks were examined for the presence of copper, thinking that penetration by molten copper may have played a role, but no evidence was seen. An absence of chromium plating at the region of the heat-affected zone was also observed but could not be explained. Unfortunately, the end portion of the shaft was not available for examination.
Failure of a Pump Shaft Ascribed to Accidental Local Heating, ASM Failure Analysis Case Histories: Chemical Processing Equipment, ASM International, 2019, https://doi.org/10.31399/asm.fach.chem.c9001478
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