The porosity of P91 and P92 exposed to 500, 550℃/25 MPa supercritical water (SCW) environment have been investigated. The oxidized samples were characterized by scanning electron microscopy (SEM)/energy dispersion X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The oxide scale is composed of a dual-layer structure: the outer magnetite (Fe₃O₄) and the inner magnetite-chromite (Fe₃O₄-FeCr₂O₄). An innermost internal oxidation zone was also observed in P92. The formation of pores is related to the defect types present in the magnetite structure, there are two major defect types in magnetite, one is interstitial Fe²⁺, and another is vacancy which may collapse into pores when vacancy concentration is high enough in supercritical water.

Some elements such as Mg, Ti, Nb were added in Al alloy sacrificial anodes. The effects of these elements and correlated second phases on the properties of the anodes were investigated. In the studied anodes, Mg has two existing states which are solid solution and second phase separately. For the second phase, there are T-phase (Al₂Mg₃Zn₃) and $\eta$-phase (MgZn₂), which are anodic and dissolve preferentially related to the anode matrix in the chloride solution. The effects of some factors on the electrochemical properties and solubility behavior of anodes were discussed, which include the category, morphology, quantity and distribution of the second phases. The results confirmed that the homogeneous distribution, regular shape and proper quantity of second phases are beneficial to get best anode efficiency and surface dissolved state. The ideal content of Mg is about 2 % in all studied anode, at which  the anode efficiency would be close to 90 %. In this paper, the effects of trace Ti, Nb were discussed. The trace Ti, Nb is useful to get more fine grain microstructure and bigger anode efficiency, and the effect of independent Ti is better than that of Ti and Nb simultaneously. But for the anode surface dissolved state, the more fine grain microstructure was not corresponding to more uniform surface dissolution; because the trace Ti, Nb would cause the change of distribution, shape and quantity of second phases.

In order to clarify the fretting wear behavior of 304 stainless steel in Na₂SO₄ solution, the electrochemical approach is applied in this work. The potential pulse method is used to evaluate the relationship between the fresh surface produced by fretting wear and lost surface. The results shows as follows: wear volume is increased with the increase of potential; the fresh surface area is approximately one tenth of the wear scar area, and fretting corrosion wear is caused by electrochemical element.

Inhibition performance of three kinds of imidazoline derivative inhibitors for Q235-A steel in the simulated producing well water saturated with CO₂ at 85℃ were studied using weight loss and electrochemistry techniques including electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results of weight loss showed that the three kinds of imidazoline derivative inhibitors all had good inhibitor properties at concentration of 40 mg/L, the inhibition efficiency of inhibitor HSJ-3 was up to 80 %. The sharp decrease of anodic current density and positive shift of corrosion potential (E_corr) indicated that these imidazoline derivative inhibitors were all anodic inhibitors which worked as “negative catalysis”. The results of EIS showed that the film of inhibitor HSJ-1 with alkyl formed slowly; the film of inhibitor HSJ-2 with thiourido group formed fast and could be auto-repaired; the film of inhibitor HSJ-3 with phosphonic group also formed fast, but decayed in a short time.

The corrosion behavior of copper in the presence of 3-amino-5-mer capto-1,2,4-triazole (3-AMT) has been investigated in deionized water. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight-loss measurement were applied to analyze the effect of the organic compounds on the corrosion inhibition of copper. Results showed that the inhibition efficiency increased with increasing the inhibitor concentration and the compound acted at anodic-type inhibitor. The adsorption of 3-AMT has been found to occur on the surface of copper according to the Langmuir isotherm. 3-AMT is chemically adsorbed on the copper surface.

Corrosion performance of olive green film on LY12 Al alloy, prepared electrolytically in 0.2 mol/L NaOH at room temperature, is evaluated by electrochemical techniques including dynamical potential anodic polarization curve and polarization resistance. Good passivity of the color film in both acid and neural media and pitting resistance are demonstrated according to the results. Moreover, the color film also shows good long-term corrosion resistance in various aggressive corrosion solutions. The structure, composition and morphology of the color film are analyzed with the help of X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The color film, a little more 4 μm in thickness, is mainly composed by α-alumina based on XRD. The enrichment of O and other corrosion-resistance elements inside film benefits the corrosion performance of LY12 alloy, also helps the stabilization of film color.

The different microstructure of X80 steel was obtained by heat treatment, water quenching and air cooling. The pitting electrochemical behavior of X80 pipeline steel with three different microstructure in 0.5 mol/L Na₂CO₃+1 mol/L NaHCO₃ high pH soil simulative solution was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. The results indicated that the corrosion inhibition of X80 steel after heat treatment became worse compared with original microstructure, but passivated easily；the law of R_p and n of three microstructures steel varying with potential is same, and n is bigger or lower in different potential ranges; the difference of microstructure caused by heat treament and the uniformity of passive films should be responsible to the different electrochemical behavior. The conclusion from potentiodynamic polarization curve is the same to the conclusion reached by electrochemical impedance spectroscopy.

A rectangle crevice assembly was used to study the crevice corrosion behaviors of X70 steels in Na₂SO₄ solutions under cathodic polarization condition. Effects of bulk solution concentration, pH, dissolved oxygen concentration on the electrochemical and chemical environments under the simulated disbanded coating were analyzed. It is shown that the higher bulk solution concentration was in favor of the cathodic current flowing into the crevice. However, the passivation film on the steel was attacked and corrosion occurred. The pH values of the solution under the disbonded coating with the alkaline bulk solution hardly changed while it changed rapidly with the acidic one and the steel at the opening was corroded. The available cathodic protection distance decreased with the dissolved oxygen being removed in bulk solution. The switching off of the applied potential led to the solution acidification and a free corrosion state of the X70 steel.

The AZ91D magnesium alloy was treated by modulated passivation technique. The optimal parameter of modulated passivation for the AZ91D magnesium alloy was determined by the orthogonal experiments. The surface morphology was observed by scanning electron microscopy (SEM). An investigation on the corrosion resistance of the magnesium alloy was discussed through potentiodynamic polarization curve, electrochemical impedance spectroscopy, Mott-Schottky curve and scanning electrochemical microscopy (SECM) measurements. The experiment results suggested that a stable film was formed after modulated passivation. The corrosion resistance of the AZ91D magnesium alloy was improved greatly after modulated passivation.

Corrosion characteristic of X70 pipeline steel in a high saliferous and alkaline soil environment, named Ku'erle soil, was investigated by burying tests both in lab and nature field, micro-morphology analyses and electrochemical polarization technique. The X70 pipeline steel would form a protective corrosion product film, leading to a relative low dissolution current, however, the anodic current in local corrosion area, or in fresh surface without film covering, is much more intensive than the usual metal surface covered with productive film, indicating that X70 pipeline steel is susceptible to local corrosion. The characteristic of these localizing corrosion is non-uniform corrosion and visible corrosion pits observed in a magnifying scale, and in a mode of intergranular corrosion under micro scale observation.

Corrosion behavior of mild steel was studied in atmosphere containing 0.4×10^-6 and 1×10^-6 volume fraction of SO₂ with indoor simulated test. Corrosion morphologies were investigated by means of optical microscope (OM) and scanning electron microscopy (SEM), meanwhile corrosion products were analyzed by X-ray diffraction (XRD). The results showed that the corrosion rate of mild steel increased with increasing SO₂ concentration. The atmospheric corrosion process of mild steel was divided into two stages in atmosphere containing 0.4×10^-6  volume fraction of SO₂  which both agreed with exponential growth law, while in atmosphere containing 1×10^-6 volume fraction of SO₂, it was divided into three stages which respectively followed exponential growth, linear growth and exponential decay law. It can be indicated from the observation of macroscopic surface that the growth rate of corrosion products was relatively quicker and the rust layer was thin in the condition of 0.4×10^-6  volume fraction SO₂, while in atmosphere containing 1×10^-6  volume fraction of SO₂, the rust layer grew outward slowly and the layer was thick. Atmospheric corrosion of mild steel had filiform corrosion characteristics in atmosphere containing SO₂, filiform corrosion products which initiated from grain boundaries and surface active area spread along the grain boundaries and ferrite. At the same time, cellular products grew on the filiform corrosion products. Sulfur mainly concentrated in the cellular products. Cellular products grew faster with the increasing content of SO_2.

The corrosion behavior of Fe-Al alloys below KCl-ZnCl₂ deposits in air was investigated at 500℃. Compared to their oxidation in air without salt deposits, all the examined alloys below chloride deposits experienced accelerated corrosion characterized by formation of porous corrosion products plus internal attack of matrix, particularly the degradation of alumina on Fe-25Al alloy. The enhanced corrosion was attributed to then formation of chlorine from the reaction of chlorides in the deposit with the oxide scale of alloy. The corrosion rate decreased with increasing Al content. The possible reactions between alloy component and chloride compounds were predicted on basis of phasestability diagrams and the mechanism on accelerated corrosion was also interpreted.

The corrosion behaviors of the cold-sprayed Zn-50Al coatings in seawater were characterized by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The X-ray diffraction (XRD) results of corrosion products and scanning electron microscopy (SEM) analysis of corrosion surface were used to comparatively investigate the corrosion properties of Zn/Al coatings, and to study the self-sealing mechanism. The results indicated that the better corrosion resistance of cold-sprayed Zn-50Al coatings compared with Zn coatings due to the better self-sealing effect which effectively prevents further seawater corrosion. It has more appropriate cathodal protection potential than Al coatings and low corrosion rate than Zn coatings, the corrosion rate of the Zn-50Al coatings retained a low level with time.

Corrosion behavior of carbon steel under NaCl liquid layer is investigated by inductive resistance probe(IRP). Average corrosion rate over the wet period, short for IFACR, is calculated by integration filter algorithm (IFA) with controlled environment factors including time of immersion (TOI), temperature and relative humidity (RH). A data-standardization approach is proposed in order to improve the accuracy of correlation of IFACR with the 3 control factors modeled by a linear equation. Two sets of corrosion kinetics parameters, corrosion current density I_corr, polarization resistance and anodic and cathodic Tafel constants, of Q235 steel in 1，5，10 mmol/L NaCl are measured by various electrochemical techniques including polarization curve, dynamic potential scan and potential step with an intention to benefit the understanding of corrosion under thin liquid layer. The results indicate that temperature has positive correlation with IFACR and TOI and RH show negative correlation. The contribution of RH to IFACR is maximum among three control factors, TOI is minimum and temperature is in middle. A changed contribution to IFACR of the factors, around 24 ℃ and RH 70% called threshold, is identified and specified. Also, this threshold is consistent with that of TOW (Time of Wetness) measurements done previously. The roles of Cl^- in the changed contribution and the specific threshold are analyzed. The detailed discussion on the dependences of IFACR and total corrosion loss on TOI, temperature and RH is presented with the help of electrochemical measurements.

Atmospheric corrosion of aluminium deposited with desert dust was simulated using a laboratory-accelerated test of cyclic wet-dry. Effects of the soluble salts in desert dust on atmospheric corrosion of aluminium were studied through mass loss, scanning electron microscope (SEM) and atmosphere corrosion monitor (ACM). The results demonstrated that the soluble salts in dust can widen the scope of relative humidity in which atmospheric corrosion occurs. Atmospheric corrosion of aluminium was getting more seriously with the increasing of the salt content in desert dust. MgCl₂ in desert dust had the strongest influence on atmospheric corrosion of aluminium, then did NaCl, MgSO₄ and Na₂SO₄ had the smaller influence.

orrosion resistance of welding joints of 310L(NAG) stainless steel in boiling nitric acid with different Cr⁶⁺ ions contents was investigated. It is shown that Cr⁶⁺ ions can remarkably enhance corrosion attack on welding joints, and with intergranular attack in heat affected zone and weld metal. The weld metal was suffered more severely corrosion attack, but in pure boiling nitric acid, welding joints exhibit strong corrosion resistance.

The susceptibility of  921A steel to hydrogen embrittlement was investigated by slow strain rate test and electrochemical study at different cathodic polarization potentials. Fracture surfaces observation were made by three-dimension microscope and scanning electron microscope (SEM). The results showed that the elongation, time-to-fracture, and fracture energy ratio decreased and hydrogen embrittlement coefficient increased with shifting potential in the negative direction. The elongation, time-to-fracture, and fracture energy ratio displayed uniform variance trend and exhibited the highest values when polarization potential was -0.710 V_SCE. when the polarization potentials were negative to -0.960 V _SCE, the hydrogen embrittlement coefficient suddenly increased  and the fracture surfaces exhibited quasi-cleavage fracture. The brittle fracture was observed by three-dimension microscope when the polarization potential was -1.110 V_SCE. The resistance of hydrogen embrittlement decreased when the polarization potential reached -0.960 V_SCE.

Tensile tests were used to investigate the mechanical behaviors of 5Cr tubing after electrochemical hydrogen charging. The experiment results show that the tensile strength and the plasticity decreased with the increase of pre-charging time and pre-charging density. Analysis on the fracture morphology by scanning electron microscope（SEM） indicated that the fracture surfaces of 5Cr tubing were characteristic of ductile dimple fracture pattern after electrochemical hydrogen charging. The diameter and depth of ductile dimple were smaller than the specimen without charging, but the number of ductile dimple was increased, which means that the loss of plastic properties was increased. When the hydrogen concentration reached a certain value, the fracture mode was changed from ductile fracture to brittle fracture.

A retired navy aircraft had serviced for more than twenty years in a southeast coastal airport, where the environment is high temperature, high humidity and high salt fog. The aircraft was torn down and then inspected, and it was found that its corrosion damage was serious. The aluminum structure was partly disassembled, clean and nondestructive inspected. The corrosion damage size, shape parameter and distribution characteristic were gained. Based on distribution parameter obtained through statistics analysis, a probabilistic model to predict corrosion damage growth under service environment was established, with considering of the randomness during corrosion process of aircraft structure. The results show that the theoretical model is very precise.