Using OCC simulative test and indoor exposure test,the effect of pho sphoric segregation on pitting propagation of five rolling carbon steels with d ifferent metallurgical feature has been studied.The results showed that the pho sphoric segregation was the main cause of forming stair-shape corrosion on the wall of pits.Due to smaller corrosion inhibition of lower phosphoric zone in st eel and its quicker dissolution,phosphoric segregation and lower phosphorus con tent accelerated propagation of the pit.The extension of phosphoric segregation and inclusions along the rolling direction resulted in higher dissolving speed in the direction which was parallel to the plate surface than that in the direct ion which was vertical to.Consequently,the caliber of pits in carbon steels was generally larger than its depth.Exposure conditions had important effect on the action of phosphoric segregation.The effect of phosphoric segregation in a lternating immersion with dry and wet was stronger than that in stirring immersi on ,and that in quiet immersion was the weakest.The stronger oxygen depolarizat ion (i.e.more positive corrosion potential ) and the formation of typical rust tubercle (i.e.acid active region ) were the favorable conditions which enable p hosphoric segregation to act.

The oxidation of a silver-based alloy Ag-8Y was studied in 105 Pa and 10-1 5 Pa oxygen at 700℃.The oxidation rate under high P(O2) is very fast and f ollows approximately parabolic rate law,however under low P(O2) is much sl ower and quite irregular with large deviations from parabolic behavior.Under hig h P(O2) the alloy experiences only an internal oxidation of Y without any significant outward Y diffusion,as a result of a fast oxygen penetration.Under l ow P(O2)the alloy forms an almost continuous Y2O3 layer containing Ag particles,plus an internal oxidation zone of Y much thinner than under high P (O2).In both cases pure Ag metal appears on the top surface as a continuous layer for high P(O2) and as separate particles for low P(O2).The int ernal Y2O3 particles in the matrix change shape with depth,being small and g lobular close to the alloy surface but larger and acicular,elongated nearly perp endicularly to the alloy surface,at larger depths.

Theoretical analysis of inhomogeneity of corrosion poten tials with rust preventive oil film and conformity to discontinuous binomial dis t ribution is described.This paper is on the basis of Bailey and Ritchie's general electrochemical theory for the oxidation of metals.In general electrochemical t heory,oxidizing metal is viewed as a self-driving electrochemical cell in which the oxide acts as both ionic and electronic conductor.It is pointed out that the ory analysis results are coincident with experimental measurements.There exist t w o kinds of film in the rust preventive oil film,ionic film and electronic film,w hich lead to inhomogeneous corrosion potentials distribution on metal surface an d discontinuous binomial distribution.

Weight gain of hot dip aluminized 1Cr18Ni9Ti has me asured in high temperature oxidation test.Microstructure and oxide of diffusion layer have analyzed.The results show that the highest service temperature is 110 0℃ for hot dip aluminized 1Cr18Ni9Ti steel.The NiAl phase will show the anti-ox idation property with transform ationfrom the Fe2Al5 phase to FeAl phase at 1100℃.X-ray diffractometer analysis indicated that the formation of the α-Al 2O3 is the governing factor to the anti-oxidation properties of the hot dip al uminized 1Cr18Ni9Ti steel.

A nanocrystallized surface was fabricated on low ca rbon steel by using ultrasonic shot peening (USSP) technique.The grain size on t he top layer of surface nanocrystallized (SNC) low carbon steel was about 20 nm, which increased with the distance from the peening surface.The electrochemical c orrosion behaviors of SNC low carbon steels with different grain sizes were stud ied by electrochemical methods in 0.05 mol/L H2SO4+0.05 mol/L Na2SO4 aqu eous solution.There existed a grain size effect on the electrochemical corrosion of SNC low carbon steel when the grain size was lower than 35 nm.The corrosion rates of SNC low carbon steels increased with the decrease of the grain size.The rise of corrosion rate was attributed to the more active atoms on the grain bou ndary caused by SNC.

The electrochemical performance of Al-5Zn-0.05In-0. 1Sn-0.3RE and Al-5Zn-0.05In-0.1Sn-Mg-0.3RE alloy sacrificial anodes have been me asured with constant current method, and their microstructures have also been ex amined by metallography, scanning electron microscopy, and energy spectrum analy sis, Results showed that magnesium addition improved the performance of aluminum anode due to the change of the composition of segregation at grain boundary. Mg segregation at grain boundary decreased the corrosion of crystal grain boundary and dropping of crystal grain.

Studying the corrosion feature and corrosion produc t of test sample by way of soak test and with the aid of scanning electron micro scopy(SEM) and XRD,it is discovered that the corrosion feature of Desulfovibrioi desulfuricans(D.desulf) to petroleum tubular materials is pitting,and the corro sion product is Fe9S8.At the same time,studying the depolarization reaction of D.desulf.has both anode and cathode depolarization reaction.In the research o f growth feature of D.desulf.,it is discovered that the growth of D.desulf.exist s logarithm period,growing animated period,and decreasing period.

Surface Corrosion in damp air of the bimetal electr ical contact rivet head(Ag-CdO/Cu)used in low voltage electric apparatus was stu died in this paper. The surface of new contacts was covered with a film about 3 μm thick because of corrosion after laid in damp air for 40 days. The film colo ur of which was yellow, dark yellow or dark blue instead of keeping silver. On X PS, results showed that the film consisted of carbon, chloride and oxides, which made contact resistance larger and weldability worse.

High voltage anodization of aluminum in mixed elect rolytes of phosphoric acid and sodium tungstate could be divided into four stage s: conventional anodization stage,initial stage of anodic deposition,rapid growt h stage and slow growth stage.The film formed during the first stage was differe nt from that formed either in phosphoric acid or sodium tungstate electrolyte.SE M results showed that it had a woolenlike microstructure and quickly interlace d into a web in the second stage with the increase of the voltage.The electrolytic spe cies such as PO3-4、WO2-4 and et al,aggregated toward the gel fo rmed near the oxide and transformed to the noncrystalline film through concentra tion,coagulation,dehydration and refrigeration under the combined action of elec trochemical and Joule heat effects.

Stress corrosion cracking behavior of SiCw/p-Al、 SiCw/2024Al composite and 2024 alloy in 3.5%NaCl solution have been studied by using double-cantilever-beam method.The effect of whisker on stress corrosion c racking behavior of the composites was examined.The results presented that the p rese nce of whisker changed the characters of stress corrosion of composites.Whisker plays a special role in the processing of stress corrosion cracking of the comp osites，which is both promoting and hindering the crack propagation.

Multi-resolution analysis was used to treat the galvanostatic transient response signals of underground pipeline system ,the information was denoised with satis factory result.The continuous wavelet transformation was also introduced to corrosion electrochemistry measurement to pick up the useful information to diag nosis the defect of underground pipeline system from the response of small ampli tude sine current with high disturbance. It was shown that the wavelet transform ation has the good properties of retrieving the useful information from the dist urbed signal.

After the background and meanings of cavitation ero sion research,the two famous hypothesises for the fundamental theory,i.e. shock-wave and micro-jet impingement; the main test facilities,e.g.a rotating disk test rig and the vibratory cavitation erosion apparatus; characterization a nd evaluating indexes of cavitation erosion are introduced in this paper.The cho osing principles for the metallic materials to resist cavitation erosion as well as the several new kinds of cavitation erosion resistant metallic material s have been reviewed.The research focus of such metallic materials at present a nd the trend of its development in the future have also been pointed out.It is necessary to continue the research of fundamental theory of cavitation erosion, especially the research of the incubation period,and at the same time,developi ng new metallic materials to resolve practical problems is an urgent work.