The relevant simulation techniques, influencing factors and mechanisms of crevice corrosion were summarized. The crevice corrosion issues of the nuclear-grade materials during service were reviewed. The status and main problems on crevice corrosion in high-temperature and high-pressure water environments have been discussed. The coming possible research topics and directions are also proposed.

Corrosion performance of candidate clad materials for fuel of supercritical water-cooled reactor (SCWR) is reviewed with emphasis on that of four typical candidate alloys. According to the results presented in this paper, it is noted that the austenitic stainless steels with high Cr content show excellent corrosion resistance. Therefore, this kind of steels should be good candidate clad material for the fuel of SCWR.

The corrosion of three Fe-Si alloys with approximately 5%, 9% and 13% (atomic fraction) Si was studied at 600 ℃ in H₂-CO₂ and H₂-H₂S-CO₂ mixtures providing oxygen and sulfur pressures of 10^-19 and 10^-3 Pa, respectively. Oxidation and oxidation-sulfidation experiments were carried out by continuous and discontinuous methods. The corrosion kinetics of the alloys in the two gas mixtures followed approximately the parabolic rate law with K_p values of the order of 10^-8 and 10^-10 g²cm^-4s^-1 for gases with and without sulfur. The scales formed in the oxidizing atmosphere were composed of an outermost layer of iron oxide, an intermediate complex layer containing a mixture of oxides of both elements and an internal oxidation zone of silicon. Conversely, the scales grown in oxidizing-sulfidizing atmosphere consisted of an outer multiple FeS layer plus an inner mixture of FeS and SiO₂. There was no external oxidation of silicon in the two gases. The corrosion rates of the alloys were extremely faster in the oxidizing-sulfidizing atmosphere than in the oxidizing gas due to the large quantities of FeS produced, providing a path for the rapid outward diffusion of iron ions due to its much higher defect concentration than the oxide of iron. The corrosion resistance of the base metal was clearly improved by the addition of silicon.

Hydrogen permeation behavior and its effect on cracking mechanism of X65 steel under cathodic polarization were studied in artificial seawater by means of electrochemical hydrogen permeation test and slow strain rate test (SSRT). Results show that the calcium magnesium deposits formed on the steel during cathodic polarization would significantly decrease the hydrogen diffusion coefficient; the effective hydrogen diffusion coefficient (D_eff) was calculated by Fourier method, modified Laplace method and time-lag method respectively, which give an average value 1.49×10^-7 cm²s^-1; the hydrogen concentration (C₀) in the sub-surface of the steel showed an exponential relationship with the polarized potential; the crack propagation was influenced by the synergistic effect of anodic dissolution and hydrogen evolution under the “soft” polarization conditions; however, if the polarized potentials were extremely negative, the concentration of hydrogen would increase sharply, as a result, the X65 steel became sensitive to hydrogen embrittlement.

The short-term corrosion behavior of the welded joint of X65 pipeline steel was comparatively studied in artificial laboratory environments, which aims to simulate the real environment of shallow and deep sea respectively, by using mass loss test, potentiodynamic polarization curve measurement and corrosion morphological observation by scanning electron microscopy (SEM). Results show that the corrosion rate of the welded joint in simulated shallow sea water was faster than that in the simulated deep sea environment. In the simulated shallow sea environment the weld joint exhibited mainly pitting corrosion; however in the simulated deep sea environment, relatively serious corrosion occurred near the fusion-line (FL) while non obvious corrosion could be observed on the welded zone. The corrosion potential of heat affected zone (HAZ) was lower than that of the welded zone and matrix of X65 pipeline steel both in simulated deep and shallow sea environments, which caused galvanic effect in welded zone and accelerated the corrosion rate of HAZ. Thereby the formed corrosion product film on HAZ was thicker with a larger charge-transfer resistance R_t.

The corrosion behavior of X52 and X80 steels in simulated seawater environments was investigated by immersion test, electrochemical impedance spectrums (EIS) measurement and surface examination by scanning electron microscope (SEM). It was demonstrated that when the solution was not deoxidized, which was the simulation of shallow sea environment, both of general corrosion and pitting corrosion would occur on the surface of X52 and X80 steels, the corrosion rate was relatively high; when the solution was deoxidized, which was the simulation of deep sea environment, there was mainly pitting corrosion occurred on the surface of X52 and X80 steels, the corrosion rate was slow. By comparison the corrosion behavior of X52 steel and X80 steel in the simulated seawaters in which oxygen concentration was mainly considered, it is clear that X80 steel is more suitable for deep sea environment.

The effectiveness of cathodic protection for X65 carbon steel in a simulated oilfield produced water was examined by means of measurements of polarization curve, constant potential cathodic polarization and weight loss. Then the morphology, composition and constituent of the corrosion products were characterized by SEM, EDS and XRD. The result indicates: in the simulated oilfield produced water, X65 carbon steel suffered from serious pitting corrosion with a great weight loss rate; the cathodic protection potential in a range -800 mV to -1000 mV exhibits obvious inhibition effect on corrosion of X65 in the environment; a sound scale of calcareous deposits can't formed on the surface of carbon steel by the potential of -800 mV, a dense and good adhesive scale of deposits may formed by -900 mV on the steel surface, resulting effectively in reduction of the cathodic protection current density. The deposits blister and easily spall off due to hydrogen evolution by potential -1000 mV. In comparison with the circumstance in seawater, hydrogen evolution potential of X65 carbon steel is much positive in the simulated oilfield produced water and the deposits do not contain magnesium hydroxide.

The corrosion behavior of HSn70-1copper alloy in sulfate-reducing bacteria (SRB) containing medium in the absence and presence of a static magnetic field (SMF) respectively was investigated by means of weight loss method, electrochemical measurement and surface analysis method. The results showed that the corrosion weight loss and the corrosion current density of the alloy was higher in the inoculated SRB medium in the absence of SMF rather than those in the presence of SMF. Thus the presence of a SMF can suppress effectively the corrosion of copper alloy. The results of SEM/EDS, XRD and XPS analysis showed that in the inoculated SRB medium a compact and uniform film formed on the surface of copper alloy in the presence of SMF, the corrosion products were cuprous sulfide; however in the absence of SMF the formed corrosion product on the alloy was loose and consisted of cupric sulfide. In fact the compact corrosion scale of cuprous sulfide could effectively suppress the SRB induced corrosion of copper alloy.

Electrochemical characteristics of sulphate-reducing bacteria (SRB) induced corrosion of X80 pipeline steel were studied in an acid soil solution by mean of microbiological test methods and electrochemical techniques. The results showed that there exist a period for the newly-inoculated bacteria to be acclimatized to the new environment, during which death of large quantity of bacteria did occur; the open circuit potential of the steel is always lower in the inoculated soil solution than that in the sterile environment; SRB inhibits the corrosion process of the steel in the early stage and accelerates the corrosion process in the later stage during the experiment; while the activity of SRB alters the dielectric of the metal/solution interface, which is responsible for the increase of the corrosion rate of the pipeline steel in the later stage of the experiment.

In most cases, microbiologically induced corrosion (MIC) of pipeline was investigated in near neutral culture-media, however, the particular and new environments in which pipeline services were ignored. In this paper, morphology and composition of corrosion productsinduced by sulphate-reducing bacteria (SRB) in an acid soil solution of X80 pipeline steel were examined by X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The results showed that the activities of SRB have little influence on the structure of the corrosion product on the steel surface, while it facilitates the transformation of sulfur from oxidation states into redox status and thereby, the deposition of sulfide and phosphuret, altering the composition of the corrosion product. In the presence of SRB, the sensitivity to local corrosion of the steel is increased notably, and the metabolite of SRB and the direct electron transfer (DET) from the steel to SRB may be responsible for the increase.

The influence of sodium azide NaN₃ on cathodic oxygen reduction induced by microbe-assisted catalysis on the surface of 316LSS in seawater was studied in order to reveal the possible use of sodium azide (NaN₃) as an agent to inhibit the activity of cytochrome c oxidase in microbial respiration. For such action, the adopted critical concentration of NaN₃ was evaluated by fluorescence microscopic technology, and cyclic voltammograms and AC impedance were used to study the variations of electrochemical properties of the electrodes in seawater aerated with oxygen and nitrogen atmosphere respectively. Results showed that biofilm on the surface of the stainless steel could increase the intensity of reduction peak current density; however, it decreased obviously when stainless steel samples were disposed with NaN₃, meanwhile, the peak potentials shifted negatively. According to the results of AC impedance, microbial respiration could directly promote the transfer of electrons to the final electron acceptor (oxygen); simultaneously reduce the tendency to corrosion of the stainless steel. It was suggested that the microbial adhesion on 316L stainless steel could change the traditional way of electron transfer of cathodic oxygen reduction in natural seawater, accelerating the transfer of electron to oxygen and finally catalyzing the reduction of oxygen.

A new corrosion inhibitor, diethylammonium O,O '-di(2-phenylethyl)dithiophosphate (EPP), was synthesized and characterized by elemental analysis and IR spectrum. Its inhibitive effect, adsorption behavior, and influence factors for Q235 steel in HCl solution were evaluated by weight loss measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy. The results showed that EPP was a mixed type inhibitor, the inhibitive efficiency increased gradually with the increase of inhibitor concentration, but decreased slowly with temperature of corrosion system. The inhibitive efficiency was up to 98.48% at the inhibitor concentration of 60 mgL^-1 in 1.0 molL^-1 HCl at 30 ℃. The adsorption of EPP on Q235 steel surface was consistent with the Langmuir adsorption isotherm and belonged to chemisorptions. The quantum chemical calculations showed that the coordination bond and back-donating bond could be easily formed between inhibitor molecules and metal Fe atoms, and thereby the multicenter, stable chemical adsorption could be formed.

Corrosion behavior of LY12 aluminum alloy electrodes coated with silicone-epoxy hybrid coating in 5%NaCl solution was investigated by means of electrochemical impedance spectroscopy (EIS) measurement, while impedance models related to different immersion stages were also proposed. The results indicated that the reaction process of the coating during immersion presented three stages: the initial stage, water was absorbed in the silicone-epoxy hybrid coating; the middle stage, the hydrolysis and poly-condensation of alkoxy-silicone occurred in the coating; and then the coating acted as a protective barrier in the third stage. Analysis of the impedance parameters revealed that the silicone hydrolysis and poly-condensation enhanced the density and the degree of crosslinking of the coating. Therefore, during immersion the coating systems exhibited characteristics of inherent repairing or re-healing.

The degradation behavior of two kind of fusion bonded epoxy coatings on Q235 carbon steel in 1.5 mol/L NaCl solution was investigated by electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM) with energy dispersive spectrometer (EDS). The results showed that corrosive species (Cl^- etc) could penetrate through the coating and then arrive at the interface of coating/Q235 carbon steel ,which then induced corrosion reaction there, resulting corrosion products composed mainly of iron oxide and iron chloride. Finally a three step process was proposed to describe the electrochemical process of the coating degradation.