Effects of Hydrogen on Semiconductivity of Passive Films and Corrosion Behavior of 310 Stainless Steel

Abstract

Hydrogen damage is a severe problem that refers to the degradation of mechanical properties of a metal caused by the presence of, or interaction with, hydrogen. The reduction of hydrogen ions is a source of atomic hydrogen. Hence, corrosion reactions, the application of cathodic protection and electroplating, etc., are major sources for introducing hydrogen into metals. During these hydrogen-generating processes, some of the reduced hydrogen may be absorbed on the metal surface and diffuse into the metals. [1][2][3][4][5] The presence of hydrogen in metals has a significant influence on the mechanical properties and electrochemical behavior of metals. For instance, increased hydrogen content results in the low stress fracture and plastic reduction of steels. 6,7 Dissolution of hydrogen in metals was proven to affect the general corrosion of metals 1,8 and to induce stress corrosion cracking 9,10 and pitting corrosion. 11,12 It is known that the nature of passive films on metals and alloys is an ultimate factor which controls their corrosion behavior. 13,14 Therefore, knowledge about electronic structure of the passive film is required for better understanding of the corrosion process. For this reason, much work has been devoted to the study of the electronic properties and chemical composites of passive films on metals and alloys. 13,[15][16][17][18][19] Most passive films formed on stainless steels behave like semiconductors. Based on the fact that the potential-dependent transpassive dissolution varies with the electronic properties of the passive film, Sato 20 proposed a breakdown mechanism of the passive film on metals: the electrochemical stability of a passive film strongly depends on the electron energy band structure in the film. Bohni, et al. 21 studied the semiconductive properties of the passive films on 304 SS using Mott-Schottky analysis and photoelectrochemical methods. They found the coincidence of the onset potential for pit nucleation with the flatband potential of passive film. Bianchi et al. 14 concluded that the high susceptibility of stainless steel to pitting nucleation was connected to n-type conductivity of the oxide film. Nevertheless, the reason for the existence of this correlation is still not clear, and little research has been done to investigate the effect of hydrogen dissolved in metals on electronic structures of passive films on metals. 22 In this work, the new experimental results on the reversion of the electronic properties of passive film induced by hydrogen dissolved in AISI 310 SS were presented. The experimental results were analyzed by taking into account the susceptibility of specimens to pitting corrosion with or without hydrogen and were interpreted by the band model of different conductivity types of passive films. ExperimentalThe test material was commercial 310 SS foil, 0.01 cm thick. The main composition (wt %) was 23.5 Cr, 18.4 Ni, 1.76 Mn, 0.70 Si, 0.15 Mo, 0.16 Cu, 0.09 Ti, 0.02 Nb, 0.06 C, 0.02 P, 0.02 S, and Fe in balance. The solution for hydrogen charging wa...

Corrosion Behavior of Alloy 600 Coupled with Electrodeposited Magnetite in Simulated Secondary Water of PWRs

“…Taking the half-height of the oxygen in Fig. 6 as an estimate of the film/substrate steel interface, 22) the passivated films formed on the non-coupled and coupled Alloy 600 with the magnetite require approximately 24 and 17 s of etching, respectively. This indicates that galvanic coupling between Alloy 600 and the magnetite formed the thinner and less protective passive film of Alloy 600.…”

pH Effect on Sulfur-Induced Passivity Degradation of Alloy 800 in Simulated Crevice Chemistries

“…Yang found that the susceptibility of 310 SS to pitting is strongly influenced by hydrogen present in the specimens. 52 The presence of hydrogen in 310 SS causes an inversion of a surface film conductivity type from p to n-type. 52 The susceptibility of 310 SS to pitting can be correlated to the electronic properties and chemical composition of the passive film.…”

“…52 The presence of hydrogen in 310 SS causes an inversion of a surface film conductivity type from p to n-type. 52 The susceptibility of 310 SS to pitting can be correlated to the electronic properties and chemical composition of the passive film. The high susceptibility of the charged specimens to pitting corresponds to the n-type conductivity of the passive film, while low susceptibility is connected to p-type conductivity and high chromium and nickel oxide content.…”

Improvement in the Corrosion Resistance of Austenitic Stainless Steel 316L by Ion Implantation

“…This is likely due to the change in the composition and thickness of the passive film. The structure of passive film resembles that of a semiconductor (21) (28) . The iron oxides which act as dopants to chromium oxide in the native passive film are selectively dissolved during the potentiostatic test, and consequently results in decreased conductivity.…”