Corrosion Characteristics Of Steel Research Articles

Prediction of corrosion behaviour of reinforced concrete with manufactured sand using artificial neural network

The present study focuses on evaluating the corrosion performance characteristics of steel embedded in concrete, in which Manufactured Sand (M-Sand) is utilized as a fractional and full replacement for natural sand. Corrosion characteristics of steel that is fixed in concrete are analysed by accelerated corrosion test for M40 grade concrete supplanted with 60% manufactured sand for river sand which is found optimum. The modelling of corrosion currents is done using feed forward Artificial Neural Network. The test results exhibits that the durability property of concrete against the effect of corrosion is enhanced, by the partial substitution of 60 % M-Sand. Accurate modelling results for corrosion currents was obtained using Artificial Neural Network (ANN). The test results exhibits that ANN structures produced close prediction current values to that of experimental results.

Corrosion characteristics of steel in seawater containing various chloride concentrations generated by electrochemical method

The electro-clean system (ECS), a ballast water management system that eliminates harmful aquatic organisms in ship ballast water via electrochemically produced chloride, was developed. The current density for potentiostatic experiments subjected to seawater with an applied potential (−0.1 V) at various TRC concentrations (2×10 −6, 6×10 −6, 10×10 −6, and 15×10 −6) have similar results. The current density at −0.1 V has the highest value compared with that at −0.7 V and −0.4 V. For all concentrations, the current density increases with increasing applied potential.

Corrosion characteristics of steel in solutions derived from cements and blended cements

Potentiodynamic Anodic Polarization techniques were used to investigate the corrosion characteristics of steel in solutions. The solutions were prepared by mixing different cements at a water-binder ratio of 2.0 and extraction after 3 and 7 days. Cements used in this investigation included an OPC with low C 3A content, an OPC with high C 3A content, a Slag Cement and a Fly Ash Cement. Results indicate that in the absence of chloride ions, the corrosion characteristics of steel in these solutions are very similar to those of steel in lime-saturated water. Despite differences in the rest potentials found in solutions made with the range of binder materials, steel passivation could be observed in all solutions. Passivation imparted to the steel by binder solutions was found to vary in the presence of increasing levels of chloride. A threshold chloride ion concentration for depassivation was established for each binder solution tested. Solutions made from the High C 3A Cement and the Slag Cement displayed the best steel passivation characteristics, white the Low C 3A Cement solution rated worst.

濃硫酸中における耐候性鋼の腐食特性

The atmospheric corrosion of steel is thought to proceed in a concentrated sulfuric acid environment, because ferrous sulfate probably formed by its reaction with SO2 in atmosphere exists under the rust layer and is not oxidized immediately by oxygen supplied through the rust layer. Thus the corrosion characteristics of low-alloy steel in 98% sulfuric acid was investigated in comparison with carbon steel. The conclusions obtained were as follows:(1) The results of the rotating immersion test in 98% sulfuric acid showed that the corrosion rate of low-alloy steel was remarkably lowered with the lapse of time after four weeks of immersion. This behavior is quite different from that of carbon steel.(2) The anodic polarization of low-alloy steel was nearly the same as that of carbon steel in the early stage of immersion. However, as the corrosion progressed, the anodic reaction of low-alloy steel was suppressed more remarkably than that of carbon steel.(3) Corrosion products of both low-alloy steel and carbon steel were FeSO4 n H2O. However, from the analytical results by the X-ray microanalyzer, it was found for low-alloy steel that there was a very thin oxide film containing chromium, copper and other alloying elements in high concentrations at the alloy/iron sulfate interface.(4) Addition of Cl− ion into 98% sulfuric acid lowered the anodic polarization of steel. The role of Cl− ion is thought to destruct the stability of the passive oxide films. The passive film formed on low-alloy steel is more stable than that of carbon steel.From the above experimental results, the corrosion characteristics of steel in concentrated sulfuric acid is quite similar to that of atmospheric corrosion. It is certain that the very thin oxide film existing between the iron sulfate layer and the substrate metal plays a predominant role in the corrosion of steels.