Lower temperature aluminizing and its effect on improving corrosion resistance of iron treated by surface mechanical attrition treatment

Abstract

An ultrafine-grained surface layer with the average grain size of about 28 nm in the surface layer was fabricated on a pure Fe plate by the surface mechanical attrition treatment (SMAT). Lower temperature aluminizing treatments of the SMAT samples were investigated by scanning electron microscope and X-ray energy dispersive spectroscope. The electrochemical corrosion behavior of the aluminized SMAT sample was studied in 0.05 mol/L Na 2 SO 4 + 0.05 mol/L H 2 SO 4 solution, in comparison with the original SMAT and the coarse-grained sample. The results showed that SMAT had a negative effect on the corrosion resistance of Fe. An aluminized surface layer was formed on SMAT sample by aluminizing treatment at 400°C, which was much lower than that of the conventional aluminizing treatment. A successive lower temperature aluminizing process made the aluminized layer thicker and continuous. The SMAT sample treated by a successive lower temperature aluminizing had much higher corrosion resistance and exhibited passive behavior, which was due to the formation of a protective passive film.

Improve oxidation resistance at high temperature by nanocrystalline surface layer

“…So oxidation rates of the nanocrystalline specimens are significantly accelerated in the initial stage. Increase of the oxidation rate with decreasing grain size is attributed to the larger grain-boundary area, which result in an increase in the short circuit diffusion paths 17 .The similar results showed that SMAT had a negative effect on the corrosion resistance of Fe 18 . In contrast, after the formation of a protective (Fe, Cr) 2 O 3 layer, due to its higher density of grain boundaries in the nanocrystalline surface layer, a higher flux of Cr goes towards the (Fe, Cr) 2 O 3 -the alloy interface, while the spinel (Fe, Cr) 2 O 3 and FeCr 2 O 4 layer inhabits Cr and O/Fe diffusion through it.…”

Protective diffusion coatings on magnesium alloys: A review of recent developments

“…For example, the nitriding process for pure Fe after SMAT can be achieved at a temperature as low as 300 • C, which is 200 • C lower than that of the conventional nitriding process [43]. Similarly, the treatment temperature of chromizing and aluminizing of the Fe and carbon steel can also be markedly reduced by SMAT [46][47][48].…”

Electrochemical noise analysis of duplex stainless steel 2101 exposed to different corrosive solutions

“…14,15 Each of the corrosion processes occurring on a metal surface was believed to give distinct noise characteristics in the time domain. 11 From the time records, parameters like noise resistance , localisation index (LI) and roll-off slopes of [16][17][18][19][20][21][22][23][24][25] However, these re- 26,27 The aim of the present work was to analyse the EN signals from DSS 2101 electrodes immersed in various environments to characterise the mechanisms of different types of corrosion. Results of analysis were also compared with those of linear polarisation (LP) and electrochemical impedance spectroscopy (EIS).…”

“…14,15 Each of the corrosion processes occurring on a metal surface was believed to give distinct noise characteristics in the time domain. 11 From the time records, parameters like noise resistance , localisation index (LI) and roll-off slopes of [16][17][18][19][20][21][22][23][24][25] However, these re-…”