Effects of Nitrogen on Passivity of Nickel-Free Stainless Steels by Electrochemical Impedance Spectroscopy Analysis

Abstract

The effects of different nitrogen contents on the passivity of nickel-free stainless steels in 0.5 M sulfuric acid + 0.5 M sodium chloride solution were investigated by electrochemical impedance spectroscopy in the potential ranges of active dissolution and active-passive transition. A simplified reaction model containing adsorbed intermediates involved dissolution process, and passivation process was proposed to explain the impedance characteristics. Based on both equivalent circuit and mathematical model analysis, the effects of nitrogen on the passivity of stainless steels are discussed.

Effect of nitrogen content on corrosion behavior of high-nitrogen austenitic stainless steel

“…At a higher N content, the R p value was larger, indicating a higher protective ability of passive film and a lower corrosion rate 55 . It is in accordance with the results conducted by Wu et al 56 that the addition of N improved the stability of passive film and thus enhanced the passivation of austenitic steel.…”

Effect of nitrogen content on corrosion behavior of a high nitrogen austenitic stainless steel

“…At a higher nitrogen content, the R p value was larger, indicating a higher protective ability of passive film and a lower corrosion rate [49]. It is in accordance with the results conducted by Wu [50] et al that the addition of N improved the stability of passive film and thus enhanced passivation of austenite steel.…”

Passivity and Semiconducting Behavior of a High Nitrogen Stainless Steel in Acidic NaCl Solution

“…In the passivated film obtained in the tested solution, the signals corresponding to the Cr 2p3/2 spectra show that there exist three constituent peaks representing metallic state of (Cr 0 ), Cr(OH) 3 /CrOOH, and Cr 2 O 3 [8,14,[36][37][38]. Similar structures of (Cr(OH) 3 + Cr 2 O 3 ) can be observed in the films formed on stainless steel in the strong (pH 0.8) and weak (pH 5) acid solutions [17].…”

“…It has been reported that the addition of nitrogen could drastically increase both the yield strength and ultimate tensile strength without sacrificing the ductility and toughness [2][3][4][5][6]. Moreover, the addition of nitrogen could also improve the corrosion, corrosion fatigue, and stress corrosion cracking resistance of stainless steels [5,[7][8][9][10][11][12][13]. Therefore, nitrogen is a strong austenite stabilizing element and is expected to substitute for relatively expensive element of nickel to make HNSS a resource-saving materials.…”

“…Passive films formed on surfaces of stainless steels have been described as a bilayer structure of (Cr(III) and Fe(III)) mixed inner layer enriched with Cr 2 O 3 and Cr-hydroxide outer layer. Previous results revealed that the passive films on stainless steels were mainly composed of Cr 2 O 3 , Cr(OH) 3 , MoO 2 , MoO 3 , Fe 2 O 3 , Fe 3 O 4 , FeOOH, and so forth, which was caused by either cation transport through interstitial diffusion or anion diffusion inwards the metal [8,12,[14][15][16][17][18]. However, the composition of films are influenced by both the chemical composition [8] and pH value of the solution [12,16,19].…”