High-Temperature Oxidation Behavior of CrMoV, F91 and Mar-M247 Superalloys Exposed to Laboratory Air at 550 degrees C

摘要

The oxidation behavior of three commercial superalloys, CrMoV, F91 and Mar-M247, was studied at 550 degrees C in laboratory air for 1000h. Mar-M247 superalloy showed the best oxidation resistance, which is attributed to the formation of a scalerichin Cr2O3 and Al2O3, followed by F91 and CrMoV. A thick duplex oxide formed on CrMoV alloy and spallation was observed. The results for CrMoV alloy showed that calculated Fe diffusion in magnetite was 200 times faster than literature values for Fe diffusion in Fe3O4, which is attributed to grain-boundary diffusion and the effect of impurity on diffusion. F91 initially formed a protective chromium-rich oxide layer followed by formation nodules, leading breakaway oxidation. The oxide nodules consisted of a duplex structure with different morphologies and oxide phases from duplex oxide scale in CrMoV.