The susceptible sites for pitting of 2Cr13 stainless steel have been stdied. Tests have proved that in sodium chloride solution the most susceptible sites of 2Cr13 for pits nucleation were at the duplex manganese-calcium-sulfide inclusions surrounding the particles of Al_2O_3. Such inclusions are called "active" inclusions.The influence of the contents of elements S, Mn, Al_(sol) and inclusions 1Al_2O_3, MnS on corrosion resistance has been studied. When the 2Cr13 stainaess steel is deoxidized by A1, the steel contains more such "active" inclusions. snd the corrosion resistance is lower, but when it is deoxidized by Si-Fe, uch "active" inclusions are less and the corrosion resistance of 2Cr13 is remarkably improved.

The corrosion resistance of Fe Cr8P13 B5 and FeCr8 P13 C7 alloys in different states have been investigated in the media containing chlorine ions by electrochemical measurement and total immersion test. Experimental results showed that: (1)The amorphotis Fe Cr8 P13 B5 and Fe Cr8 P13 C7 alloys have excellent corrosion resistance. The polarization curves of both amorphous corrosion resistant alloys are much similar measured in 3.5% NaCl at 30℃ by potentio-kinetic method. No breakdown potential(E_b) was observed within the measured region from-1.0 to+1.5 volts(SCE)and their anodic current densities maintain low level,less than 10μA/cm~2;The corrosion rates of both amorphous alloys are lower than 10~(-3)—10~(-4)mm/y in all immersion testing environments such as 3.5%0 NaCl at 60℃, 0.5—2.5N HCl at 30℃, 10% FeCl_3·6H_2O at 40 and 60℃ and 1M H_2S_O4+0.5MNaCl at 30℃. (2) After vacuum annealing treatment at 500℃ for 1 hour, the corrosion resistance of Fe Cr8 P13 C7 alloy dropped abruptly, while that of Fe Cr8 P13 B5 alloy remained as good as in the amorphous state. Electrochemical measurements and immersion test results agree very well.

The structures of the rust layers of two low alloy steels formed by localized corrosion in marine environment were investigated. Optical microscope, electron probe, EM and microelectrochemical testing show that although the low alloy steel corrodes faster than ordinary carbon steel, but when the rust layers formed are dense and enriched with alloying elements, the corrosion processes will be inhibited. These corrosion products can form sparingly soluble salts and cover the bottom of the pits, while outside the pits this phenomena will not occur and the corrosion processes turn to enlarge the radius of the pits, as can be confirmed by the difference of the microelectrochemical mv-d curves inside and outside the pits. From the types of steels investigated, Al-Cu-P steel has more typical above mentioned characteristic, and the localized corrosion behavior of the Ni-Cu-As steel is nearly the same as that of the carbon steel.

A corrosion equation of the oxygen concentration cell of low alloy steel in sea water is derived and proved. This equation shows that, the anodic processes overpotential difference between the anode and cathode is an important factor for the corrosion process. The corrosion current of the oxygen concentration cell increased with the increase of overpotential difference up to a limiting value, and the relationship between the logarithm of the corrosion current density and the logarithm of the proportion of cathodic to anodic area will turn to a linear relationship at the same time. According to this equation, the necessary condition for the local corrosion of low alloy steel in sea water by the oxygen concentration cell mechanism is that, the overpotential difference has to be greater than the difference between their respective equilibrium potential.

The application of complex-impedence graphical method to treat the corrosion systems with semi-circular type A. C. impedence graph, and the calculation of the optimum radius of the orbits by the least square method were reported. A BASIC language was also furnished. According to this proceduct, polarization resistance R and other parameters can be calculated directly from the graph. A Chinese made DJS-130 type electronic computer was used. An analytical treatment of the impedence measurement date of the system of corrosion of A_3 steel in3.5%NaCl solution is also presented in this paper.

The thermal fatigue resistance high temperature combustion gases of eight heat resistant steels and superalloys in fatigue properties were studied on test rigs heated by combustion flue gas. These alloys were selected for use in high speed Diesel engines preliminary, combustion chamber nozzles are studied. Fatigue cracks and fractographic characteristics were carefully analysed, and EM, SEM, Electro nprobe methods were also used to study the micro-and macro- structures as well as the corrosion produces in the cracks. Results of this research may be useful for solving fatigue problems in pratical serviee condition, i. e., in high temperature oxidizing enviornment, and for better selection and improvement of materials.

The mechanism of failure of The exhaust valves of internal combustion engine with domestic fuels and typical working parameters made by 21—4N and 4Cr10 Si2Mo steel was investigated with metallographic, SEM, X-ray diffration and electron probe methods. Especially~ the mophology, composition and the destruction process under cyclic stress of the surface corrosion protection layer were examined. Exhaust valves of both gasoline and Diesel engine are damaged by combine gas corrosion and fatigue stress, which caused the formation of pits. Experiments show that a surface treatment process forming a protective coating prevents the pit-formation and extends the service lives in se veral folds. The application of a type PSR-1 alloy coating by special coating equipment VF-79 can furnish economically very good anti-corrosion and antiwear properties service tests in land, river and sea transports pcove that this coating is good for both gasoline and Diesel engine valves and performs better than hard surfacing. This process has been commercialized recently.

The corrosion date of phenol formal dehyde GFRP are fakulated. These date show that this material is excellant for high temperature dilute sulphuric acid, and the corrosion resistance together with the quality of chemical equipments produced can be further improved by chemical treatment of glass fiber and by dry method for forming. With these improvements, the phenolic RP can be successfully used in the whole high temperature system for better corrosion resistance to dilute sulphurie acid in synthetic alcohol production plant. The authors hope that, more attention should be given to this improved traditional material.Table 6, Figure 8.