Recent progress on stress corrosion cracking (SCC) crack growth behavior of dissimilar metal welds between reactor pressure vessel and reactor coolant piping is reviewed in this paper. The worldwide studies concerning the effect of materials, stress and environmental conditions on SCC crack growth behavior are described. Meanwhile, the direction of further research is also forecasted.

In this paper, anode materials used for organic compounds containing aqueous electrolyte were introduced. Further, their failure characteristics were analyzed in terms of surface fouling and accelerated dissolution. Meanwhile, the strategies for failure prevention, including the optimization of chemical composition and anodic re-activation of electrode, were reviewed in details. Finally, the investigation of anode materials in organic compounds containing electrolyte was also prospected.

The stress corrosion cracking behavior of forged 316L stainless steel used for the main pipe of pressured water reactors was investigated in sodium hydroxide solution at 330 ^oC using U-bent samples. The results showed that, after immersion for 720 h, obvious stress corrosion cracks were found on the sample surfaces. The formed surface oxide film consisted of an inner layer rich in Fe, a middle layer rich in Ni and an outmost layer of oxide particles rich in Fe and Ni, which could not protect the base metal from further corrosion. EBSD and fracture morphology observation showed that the steel suffered mainly from intergranular cracking and the fractured surface exhibitedmainly rock candy-like patternwith partly river-like pattern and quasi-cleavage steps. The cracks were propagated by the brittle fracture of grain boundary oxides rich in Fe and Ni under the external stress. The stress corrosion cracking mechanism was ascribed to anodic dissolution-brittle fracture of grain boundary oxides by the applied stress.

The low cycle fatigue behavior of alloy 690 steam generator tubes in three different environments was investigated, i.e. in air at ambient temperature and 325 ℃ respectively as well as in simulated PWR primary water at 325 ℃. Meanwhile, the influence of dissolved oxygen and strain rate on fatigue life was considered. The results show that the design related with the fatigue life for the alloy 690 steam generator tube is very conservative, and the effect of PWR coolant environment is limited; while the corrosion fatigue life of the alloy 690 is not susceptible to the effect of the dissolve oxygen and strain rate under this test condition. Therefore, it is conferred that the corrosion fatigue behavior may be controlled by film rupture slip/dissolution mechanism.

The carbon capture and storage (CCS) in geological reservoirs is now considered to be one of the main options for achieving deep reductions in CO₂ emissions. Generally, the purity of captured CO₂ is only about 95% and can contain trace gases such as O₂, CO, SO_x and NO_x. In the presence of a water phase, these trace gases can contribute to the corrosiveness of high pressure-high temperature CO₂ (supercritical CO₂) systems. In this study, corrosion experiments of supercritical CO₂ with various amounts of O₂ were carried out to study the effect of small concentrations of O₂ on the corrosion rate of two kinds of carbon steels C75 and X65 and three kinds of stainless steels 13Cr, 2205 and 904L in aqueous supercritical CO₂ at 80 ℃ under 12 MPa. The decay kinetics of small starting O₂ concentrations were investigated and used for the experiments with continuous replenishment of used-up O₂. The results indicated that constant O₂ concentrations in supercritical CO₂, even trace of O₂ (1.50×10^-6), could enhance the corrosion rate of carbon steels tremendously (more than 100 mm/a). Under this condition, even the corrosion rate of 13Cr stainless steel obviously increased. However, surprisingly, with high O₂ concentrations seemed to exhibit passivation effect and the corrosion rates for carbon steels and 13Cr stainless steel were relatively low. The 2205 and 904L stainless steels were unaffected by addition of O₂ and showed high resistance (<0.01 mm/a) to the aqueous supercritical CO₂ corrosion.

Corrosion of X80 pipeline steel in an acidic red soil collected from Yingtan area of Southeast China was studied in a temperature range 20~75 ℃ by electrochemical impedance spectroscopy (EIS). Theory concerning corrosion dynamics and transition state was applied to analyze the process and kinetics of the corrosion reaction. The results show that EIS of X80 steel in the red soil contains a capacitive arc related with soil at the high frequency region and a capacitive arc from the interface process at low frequency region. With increasing temperature, the soil resistivity and charge transfer resistance decrease, and the corrosion rate increases. Kinetics analysis shows that corrosion of X80 steel in the acidic red soil is an endothermic reaction system companied with decrease of disorder degree.

The cyclic method of hot air oxidation/immersion in condensates was adopted to simulate the internal service conditions of automotive mufflers. The galvanic corrosion between type 409 and 304 stainless steels was investigated during the condensates immersion by using electrochemical measurements. The results of coupling potential and current indicate that the galvanic corrosion effect is very weak between these two steels without suffered from hot air oxidation. This means that 304 stainless steel can hardly accelerate the corrosion of 409 stainless steel as they contact directly in the condensate solutions. During the cyclic tests, the two steels show relatively higher values for the coupling current in the low coupling potential cases. Hot air oxidation will enhance the galvanic corrosion tendency between the two steels. However, they show small coupling current densities after cyclic oxidation at 250 ℃, with weak galvanic corrosion effect between them. Whereas they display large coupling current densities (i.e. strong galvanic corrosion effect) with the occurrence of localized corrosion after cyclic oxidation at 400 ℃.

The corrosion behavior of 5083 Al-alloy in seawater was studied by electrochemical methods, and the influence of Cl^- concentration on its pitting behavior was investigated. The results showed that the pitting potential of 5083 Al-alloy in seawater was -690 mV and the corresponding protective potential was -720 mV. Cl^- is the main active ion for pitting corrosion of 5083 Al-alloy. For the solutions with the same ion strength but varied Cl^- concentration in a range of 0~0.1 mol/kg, the pitting potential decreased quickly with the increasing Cl^- concentration. When Cl^- concentration exceeded 0.1 mol/kg, the pitting corrosion potential would no longer change obviously. In the meanwhile, the cathodic protection potential for 5083 Al-alloy was validated in a range of -800~-1000 mV by polarization experiment, which provides the basis for its protection while used in seawater.

The corrosion behavior of ZK60 magnesium alloy in 3.5% sodium halides NaX (X =F, Cl, Br and I) solutions was studied by means of static immersion methods, potentiodynamic polarization measurement and SEM observation. The results showed that, the open circuit potential (OCP) of ZK60 alloy in 3.5% sodium halides solutions increased first and then became flat to a steady state. The corrosion behavior of ZK60 alloy was related to the halogen ions in the solutions: i.e. it was passivated in 3.5%NaF solution, while it was corroded in 3.5%NaCl, 3.5%NaBr and 3.5%NaI solutions and its corrosion rate decreased with immersion time, which may be ascribed to the formed protective corrosion products with the increasing pH value of the solutions.

In order to simulate the carbon steel corrosion in oil-gas field produced water containing H₂S, a proper artificial water was poured into an autoclave and then into which H₂S gas was introduced respectively in two different ways: directly inducing H₂S from a pressed H₂S gas cylinder and generating H₂S gas in-situ during the corrosion process through chemical reaction of desired reagents pre-set in the water. The corrosion rates of 20# steel were comparatively studied for two different ways of introducing H₂S gas, while the other parameters kept the same, by weight loss technique, electrochemical measurement and scanning electron microscopy with energy dispersive spectrometer. It has been found that the 20# steel in the water with in-situ generating H₂S exhibits a corrosion rate 0.1077 mm/a and a coarse and porous corrosion product film. Whereas, those by inducing H₂S from gas cylinder are a corrosion rate 0.0518 mm/a and a uniform and compact corrosion product film respectively. It is also noted that the results of the former one are better accorded with those observed in oil/gas fields practice. Therefore, the way of directly inducing H₂S from gas cylinder into the waters should be suitable to simulate the relevant corrosion performance of metallic materials in oil-gas field produced waters.

A model was proposed to describe the swell-cracking of concrete induced by non-uniform rusting of re-bar versus time by consideration of regulations of the re-bar rusting process and the non-uniform distribution of the rust products on the re-bar. Then the distribution of displacement of the non-uniform rust-swelling of concrete at different moment could be deduced through the proposed model by using time discrete method. Thereafter, from the rust-swelling displacement, the ABAQUS swelling finite element model could deduce the overall cracking process. By comparison between the two overall swell-cracking processes induced by uniform and non-uniform rust induced swellings respectively, it follows that there exists large difference between the two cracking processes, while a prediction of much higher crack propagation rate by the later one is fairly well agree with the situation of engineering practice. Therefore, the model of non-uniform rust-swelling of concrete induced by non-uniform rusting of re-bar shows good prospect to be adopted in the study of corrosion behavior of steel re-bar reinforced concrete.

Applying volatile corrosion inhibitors is an effective way to protect cast iron relics. Herewith several new formulas of compounds of cyclohexylamine carbonate (CHC) with various kinds of inhibitors were designed and prepared for cast iron. Then their performance of corrosion inhibition was studied by means of electrochemical measurements and XPS. Results show among others that CHC with methenamine exhibits significant synergistic effect, i.e. a compound of mixed methenamine and CHC with a mass ratio 1∶4 exhibits the highest inhibition efficiency up to 96.61%. This mix-type compound inhibitor, which mainly suppressed the anodic reaction, could be chemically absorbed on the cast iron surface to act as a well-functioned protective film for cast iron relics.

The atmospheric corrosion behavior of carbon steel and galvanized steel was investigated by exposure for one and three years respectively at four test spots with different local-environmental conditions in a test site at Dujiangyan city of Sichuan province, and then the corrosion morphology, corrosion rate and corrosion products of the two steels were carefully examined. The results showed that due to the significant differences in local temperature and relative humidity the corrosion rates of the two steels were different at the four test spots. In general, the corrosion rates of the two steels reduced with the increasing corrosion time. Zn coating could effectively protect the steel substrate, i.e. suppress the environmental corrosion in the test spots. The relative humidity, time of wetness and the fluctuation of relative humidity were important affecting factors on the corrosion of the steels.

Influence of Yb additions on resistance to exfoliation corrosion of aluminum alloy 2519A was investigated in EXCO solution at ambient temperature, while the alloys were characterized by means of hardness test, tensile test, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that, with the addition of 0.2%Yb, the amount of the coarse phases AlCu phase and AlCuFeMn decreased in the alloy due to the formation of phases of Yb compounds with Al, Cu, Fe and Mn, of which the chemical activity was inferior to that of the phases AlCu and AlCuFeMn. Meantime, the Yb addition could also refine the θ ′ phase and increase its area fraction, as a result, the continuous precipitation of θ (Al₂Cu) phase at grain boundaries could be prevented, and the width of the precipitation free zone (PFZ) was shrunken at grain boundaries,therefore the resistance to exfoliation corrosion of the alloy could be improved. However an excessive addition of Yb might deteriorate the mechanical properties and the resistance to exfoliation corrosion of the alloys.