Effect of Surface Finish on High-Temperature Oxidation of Steels in CO2, Supercritical CO2, and Air

On the role of surface deformation in the oxidation of NiCr alloys at 340–600 °C

“…Reducing the grain size may then have adverse consequences, as grain boundaries are fast diffusion paths for O as well as for Cr. In these conditions, grain refinement and cold work have generally been found to be beneficial to higher Cr grades, and to have either little effect or some detrimental effect on lower Cr grades [18,[21][22][23].…”

Corrosion Behaviors of Heat-Resisting Alloys in High Temperature Carbon Dioxide

“…As shown in Figure 11a and b [75], when the surface had been polished, a little thin chromia scale with many thick Fe-rich oxide nodules could form on the surface of austenitic steel 347H in 550 • C/20 MPa S-CO 2 for 1500 h. When the surface had been ground by 600-grit silicon carbide sandpaper, a continuously thin chromia layer with very small Fe-rich oxide nodules was formed on the surface (Figure 11c,d) [75]. Further comparison reveals that the increase in surface roughness slows down the oxidation rate of austenitic steel 347H.…”

“…However, another study revealed that the cold-working effect was not uniform, resulting in occasional nodules nucleation on the surface of the protective chromia scale [66]. However, the results from FMs Grade 91 exposed to 550 • C/1 bar CO 2 showed that a polished surface was more resistant to oxidation than the one treated by 600-grit sandpaper (Figure 11e,f) [75]. It is believed that the potential effects of the surface finish will be a competition between the fast diffusion paths created by subsurface structural defects and the resulting surface roughness that can act as stress concentrators during oxide growth.…”

Development of an Open-source Alloy Selection and Lifetime Assessment Tool for Structural Components in CSP

“…Essential corrosion data for model development and validation should include measured concentration profiles after exposures at the temperatures of interest (700-800°C) for different times. For exposures in sCO 2 , depletion of the alloying element forming the protective oxide can be correlated to the temporal evolution of specific mass change measurements for the three alloys (740H, 282 and 625), since these alloys have been reported to form compact and protective Cr-rich Cr 2 O 3 scales up to 800°C [2,4,[18][19][20][21][22][23][24][25]. However, for exposures in molten chloride salts, a combination of the extremely low fraction of species reacting in the boundary regions (a few microns) between phases or molecular regions and nonequilibrium reaction kinetics provide challenges in identifying corrosion products.…”