Failure analysis on two austenitic stainless steels applied in cyclone separators of catalytic cracking unit

In this paper, several experiment approaches to the macro-mechanical properties, microstructural morphology, phase identification, etc. were used for the failure analysis on two austenitic stainless steels applied in cyclone separator of catalytic cracking unit. The results show that the damage of material (310Cb) applied in cyclone separators within second regenerator (CSSR) is more serious than the material (0Cr19Ni9) applied in cyclone separators within first regenerator (CSFR). The damage of CSSR is mainly manifested as material embrittlement so that fracture occurs. However, its main damage causes do not result from carburizing or sulfurizing, but the precipitation of harmful σ phases and Cr23C6 phases. Resulting in such phenomena, the internal cause is the high chromium (25 wt.%) of material, while external cause is the cyclone separators subjected to high temperature (>700 °C). It can be concluded that the material selection of CSSR is not more appropriate than CSFR. Assuming that the CSSR has the same lifetime as CSFR through taking some measures, the lifetime of the whole set regenerating system can be extended a lot. Because the main causes of failure are recognized, the corresponding measures to improve the lifetime of the whole set regenerating system can be given.