The crack growth rates of fatigue, stress corrosion and corrosion fatigue for 4340, 15 and A508 steels under various conditions were determined. A ligament model and computer program for corrosion fatigue crack propagation were presented after comparing the experimental results with predicted data from Linear Summation Model or Process Competition Model. The results showed that this simple model could predict curves of da/dN ～△K in reasonable agreement with measured data. The simplicity and convenience of this model are much helpful for engineering application.

The behavior and mechanism of corrosion fatigue for A508 steel in distilled water were stydied by means of a displacement controlled cantilever bend fatigue machine as well as by fractographic and eledtrochemical techniques. The fatigue tests were performed at R=0, f=0.5Hz in ambient air distilled water at various temperatures. It was showed that the fatigue crack growth rates of A508 steel in distilled water were 4 to 6 times faster than that in ambient air, and that they decreased with increase in water temperature at 15-80℃. This was precisely related to the reduction of dissolved oxygen contents, corrosion potential and quantity of Fe2O3 in oxide film, and this agreed closely with the decrease in percentage of I.G. fracture with increasing water temperature. According to these data, it was suggested that the fatigue of A508 steel in distilled water should be considered as a true corrosion fatigue since no stress corrosion cracking occured and that the crack propagation might be controlled by anodic dissolution and simple fatigue rupture. A possible model was proposed in that local attacks occured,at the fracture front and the ligaments between these areas experienced a higher effective △K, resulting in mechanical rupture. The measured data were in reasonable agreement with the predicted curves of da/dN ～△k from this ligament model, △keff = △Kapp/(1-αC).

Based on the EIS (Electrochemical Impedance Spectroscopy) displays of zinc rich coatings at various immersion time, two kinds of equivalent circuits were proposed as their physical models. The relation between impedance characteristics and structure and properties of coatings was discussed. The protective properties of two zinc rich coatings were evaluated in terms of calculated results of impedance data.

The effect of short period non-proportional overloading on environmental hydrogen induced fracture life of 42CrMo steel in 0.5 mol/L H2SO4solution was studied under continuous hydrogen charging condition.A weight loading system was employed in the study. Experimental results showed that non-proportional overloading might cause more severe retardation than proportional one. The mechanisms responsible for retardation of subsequent crack growth were discussed. The influence of overloading was dependent on integral effect of the following faCtors: (1) crack branching,which decreassed significantly the crack growth driving force; (2) residual compressive stresses existing in the overloading plastic zone, which reduced effective stress intensity factors; (3) effect of dislocation shielding on retarding hydrogen transportation as well as accumulation; and (4) overloading damage, which might shorten HIF life.

Effects of hydrogen and stress on anodic dissolution for mild steel in 1 mol/L NH4NO3 solution were investigated under various potentials corresponding to active, active-passive transition, passive and transpassive regions respectively on the polarization curve. The results showed that hydrogen decreased the dissolution rate in the active region but increased the rate in the passive and transpassive regions and increased the rate tremendously in the active-passive transition region. They were consistant with the effects of hydrogen on electrochemical impedance. Constant stress σ=1.1 σys increased the dissolution rate only by 2% in the active region but 30～70% in the active-passive transition region. The effects of hydrogen and stress on the dissolution rate were synergistic rather than simply additive and the effect in the transition region was far greater than that in the active region.

The inhibition efficiencies of imidazole and its derivatives, analgen, and amidopyrine for mild steel in hydrochloric acid were drtermined with weight loss method. The geometries of imidazole and its derivatives were optimized, and the energies and coefficients of their molecular orbitals were calculated using semiempirical MNDO method. Approximate ground-state electronic properties of analgen and amidopyrine were obtained by means of MNDO and CNDO/2 methods. It was found that the sum of net charges of five atoms in the ring for imidazole and its derivatives was well correlated with their inhibiting efficiencies.The mechanism of inhibition process was discussed with quantum chemistry.

The initial oxidation behavior of Ni3Al and Ni3Al-Cr alloys at a temperature range of 700-1100℃ was investigated using Setaram thermal anaysis instrument with sensitivity of 2 ug. At 700-900℃, the oxidation of Ni3Al in the first 5 minutes was accelerated markedly with increasing temperature. The weight gains of Ni3Al after xoidation for 0.5h at 800℃ and 900℃ was lower than that at 700℃. Addition of chromium into Ni3Al significantly reduced the oxidation rate of the alloy below 900℃, but increased its oxidation rate above 1000℃. The oxide scale was examined by EDS. The results indicated that no plain NiO phase region was observed on the oxide scale of Ni3Al-Cr alloy. Cr addition might decrease the lattice parameters of Ni3Al, increase the packing density and reject the surface diffusion of Ni.

By kinetic tests with double cantilever beam (DCB) specimens and slow strain rate tension (SSRT)tests,the stress corrosion cracking (SCC) behavior of SiC. (10pm,15 vo1%)/2024 aluminium mains composite in NaCl solution was investigated. The effect of particulate reinforcement on SCC behavior of this material was discussed. SCC did not occur in both tests in the open circuit condition. However, SCC was observed in the SSRT test under small anodic polarization. Introduction of the particulate reinforcement did not alter the SCC mechanism of intergranular anodic dissolution. The composite exhibited significantly higher SCC resistance than the similarly produced 2024 aluminium alloy. This could be attributed to: 1)the finer grains of matrix of the composite; 2) the strain concentration effect in the mains adjacent to SiC particulates; 3) the hindering effect of the particulates located at the grain boundaries from growing of the intergranular SCC crack.

The general characters of some film covered electrodes were analysed, and different electrochemical behaviour of the electrode systems was compared and discussed from an electrochemical point of view.The study indicated that the corrosion electrochemisty is a powerful tool for the investigation of film covered electrode even though some of the systems may be extremely complicated. It should be mentioned that differences of some steps of reaction and transferring processes occurred within the systems may lead to entirely different electrochemical behaviour.

The process of colored hot dip galvanizing and the corrosion resistance of the galvanized coatings were studied. Two types of melted zinc alloy bath (Zn-Mn-Cu) were developed for producing smooth, uniform and gaily-colored coatings.The golden, purple, blue and iridescent coatings were obtained at proper bath temperature and under suitable cooling conditions.Higher bath temperature and longer cooling time in air before quenching in water would thicken the oxide film on coatings, which resulted in changing the color of the Zn-Ti-Ni coating from golden to purple and blue, but with little effect on the iridescent color of the Zn-Mn-Cu coating. The salt spray tests showed that the colored galvanized coatings had excellent corrosion resistance, and their corrosion weight loss was only half of that for the conventional galvanized coatings. In addition, the colored coatings provided better adhesion to paint.

According to the results of 2-4 years' exposure tests of carbon steel samples in Hainan Province, the influences of meteorological factors and Cl- on atmospheric corrosion were investigated. The feature of atmospheric corrosion in this area was summarized. A corrosivity map for the province was drawn. The corrosion products on carbon steel at some typical places were analyzed by XRD and XPS.

The pitting potentials Eb of Al-Zn-In-Si and Al-Zn-In-Si-Mg alloys were measured in NaCl solutions.Influence of chloride ion concentration and temperature on pitting corrosion susceptibility was examined.Results showed that with the increase in Cl- concentration and temperature, the Eb decreased and pitting corrosion became more severe. From the standpiont of pitting corrosion, Al-Zn-In-Si-Mg alloy used for sacrificial anode was superior to Al-Zn-In-Si alloy. The corrosion morphology and EPA line scan analysis showed that the content of indium and silicon at pit bottom was much higher than the average content in alloy and that pitting corrosion mainly occurred around in and St-rich "islands".

The inhibitive effect of (P-NO2C6H4)N(C6H5)3Br(NPTPHB) and (p-NO2C6H4)P(C6H5)3Br(NPTPPB (CH5-C6H4) P(C6H5)aBr(MPTPPB) and [CH3(CH2)3CH2-C6H4]P(C6H5)3 Br(PPTPPB) on corrosion of aluminium in 1 mol/L Al(ClO4)3 solution at 15～35℃ and the effect of molecular structure of phosphonium salts on inhibitive efficiency were studied by using the differential polarization resistance and electrochemical impedance techniques. The results showed that all the three phosphonium salts inhibited the corrosion of aluminium. The inhibitive effect of the phosphonium salt was greater than that of the quaternary ammonium salt with similar structure. The inhibitive efficiency of the phosphonium salt which has substitution radical of long carbon chain on benzene ring was higher than that for short carbon chain.Their inhibitive efficiencies increased with rising temperature. The phosphonium salts adsorbed chemically on aluminium surface in Al(ClO4)3 solution and their adsorption followed Langmuir isotherm. Possible models of adsorption of MPTPPB and PPTPPB were proposed.