Erosion-Corrosion Of Fe- And Ni-Based Alloys At 550 deg C

The erosion-corrosion behaviour of four steels (Fe2.25Cr1Mo, Fe9Cr1Mo, AISI 304, 353 MA) and one Ni-based super alloy (Inconel 625) was investigated. The alloys were exposed in a test rig at 550 deg C in air for 1 day, 1 and 3 weeks. The particle velocity was 1.2 m/s. The measured wastage of the alloys was in the range 58-270 mu m/1000 h. Auger electron spectroscopy was used to analyse the oxide products. The oxide formed during erosion was up to 30 times thicker than the oxide formed during pure oxidation. The cation content of the oxides formed on the eroded samples resembled the alloy composition. The enhanced oxidation during erosion was caused by inward transport of molecular oxygen through cracks and other defects created by the particle bombardment. The oxidation takes place at the oxide/metal interface; the adhesion of the oxide to the metal thereby becomes strong.