Failure Analysis of Turboexpander

摘要

This article describes an investigation into a failure of a turboexpander wheel driving a compressor. Some of the wheel blades were completely cracked and detached, while others had cracks of varying lengths running parallel to the root of the blade. Detailed failure investigation using different characterization techniques such as visual examination, chemical analysis, fractography, metallography, SEM/EDX, hardness testing, modal impact testing, and FEA showed that the cracks and fractures in the turboexpander wheel were caused by fatigue which progressed from multiple origins on concave blade side surfaces, near the hub. The fatigue performance of the turboexpander wheel was degraded significantly by the presence of the anodized layer on the wheel surface. Corrective measures to avoid similar failures are suggested and discussed.