Embrittlement of a FeCrAlMo alloy exposed to high temperature

• Embrittlement failures in purge lines made of a FeCrAlMo alloys are studied.
• The failures are attributed to the formation of Mo-rich precipitates.
• The origin of the failures is related to high temperature aging of the alloy.

A metallurgical evaluation of a FeCrAlMo alloy was carried out after observing low temperature fracture in several purge lines made of this material. The unexpected material embrittlement was attributed to high temperature phase transformations occurred during a previous exposure of the components at 800 °C. The microstructural analysis showed extensive Mo-rich precipitates and Cr-rich carbides at grain boundaries associated with the failed components. The study also showed by means of compression tests carried out at room temperature evident loss of ductility in the samples exposed at high temperatures as a consequence of the material aging.