Influence of Polishing-Induced Surface Hardening on the Adhesion of Oxide Scales Grown on a Ferritic Stainless Steel

Abstract

International audienceThe influence of surface preparation on the stress and adhesion of oxide scales formed on the ferritic stainless steel AISI 441 was studied. Steel coupons were surface-finished to different degrees of surface roughness from 400-grit SiC through to 1-micron diamond, and were also electropolished to remove the work hardened surface. Initial metal roughness was measured by optical profilometry. Oxidation was carried out at 800 degrees C under synthetic air for 100 h. Oxide residual stress was derived from the Raman shift of the main chromia line, and adhesion of oxide scales was quantitatively obtained using forced spallation by tensile straining. The results show that surface hardening is the most influential factor on adhesion, with the high dislocation-containing mirror-polished samples exhibiting the lowest adhesion energy (similar to 4 J m(-2)), and the electropolished samples with non-mechanically affected surface exhibiting the highest adhesion energy (17 J m(-2)). Recrystallisation of the subsurface zone during heating to the oxidation temperature is thought to be the most influential factor reducing scale adhesi

Local stress determination in chromia-former thanks to micro-Raman spectroscopy: A way to investigate spontaneous delamination processes

“…The shift of this peak allows, taking into account a specific calibration procedure, to determine the residual stress magnitude in the scale. 3,5,8,10,11 Thus, the relation between stress and peak shift is given by r ¼ ÀD Â 0:307 6 0:005;…”

Impact of Sample Geometry and Surface Finish on VM12-SHC Ferritic–Martensitic Steel Under Cyclic Steam Atmosphere Operating Conditions

“…The growth of oxides on curved substrate surfaces leads in many cases to "growth stresses," which do not occur on flat surfaces and therefore arise from the geometry. Sufficient amounts of chromium must be supplied by fast diffusion to the steel surface [20], and the diffusion can be enhanced by surface treatments [21][22][23][24][25]; surface deformation, e.g., by grinding, creates a high density of dislocations that act as fast diffusion paths for metal and enhances the diffusion of the selectively oxidized elements Cr, Si and Mn, favoring the formation of a Cr-rich protective oxide [20]. The importance of minor elements on the steam oxidation such as Si, Co, Mn, Mo and W has been reported, indicating that the critical Cr content of the alloy required to form a protective oxide depends on the presence of these minor alloying elements, as well as the microstructure and the service temperature [26].…”

Modeling of Trilayered Oxide Thermally Grown on 441 Ferritic Stainless Steel at 900 °C in Synthetic Air

“…Ferritic stainless steel (AISI 441) is used in many industrial applications such as solid oxide fuel cell (SOFC) technology, gas manifold, etc. At high temperature, oxidation of AISI 441 has already been widely studied [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] with oxide growth being shown to depend on many factors such as composition, preparation surface [9,14], atmosphere [10,13], temperature and time [3].…”