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The purpose of this paper is to study the corrosion of the coupling of two different types of stainless steel, austenitic and ferritic, used in the fabrication of water reservoirs in the solar energy industry.

Potentiodynamic polarization and gravimetric immersion tests were used to evaluate corrosion of the coupling of two different types of stainless steel, austenitic and ferritic.

The galvanic corrosion was not significant in the case of the coupling of AISI 304 and 444 steels. The difference of the open circuit potentials obtained for the AISI 304 and AISI 444 steels was 28 mV for the polished samples. The galvanic current density (i_g) was 55 nA/cm². The corrosion observed in the stainless steel couple was in the weld area.

The methodology used is adequate to evaluate generalized galvanic corrosion. The problem of the corrosion in the coupling of the stainless steels is a problem of localized corrosion and the observed 28 mV potential difference was lower than the dispersion of results usually obtained from readings of corrosion potentials in electrochemical cells.

The use of two different types of steel in contact with each other may lead to galvanic corrosion, and the welding of steel pieces may lead to several corrosion problems. Since the boiler may be used in different countries, subject to a great diversity of water quality, corrosion may be a significant problem.

Literature data of the AISI 444 steel corrosion behaviour are still scarce. The coupling of two different stainless steels (AISI 304 and 444) in the water reservoir manufacturing was a necessary requirement of the solar energy industry. The manufacturers of boilers must evaluate and quantify the corrosion processes, which occur in the equipment used in the solar energy industry. As the solar energy industry has matured in the last ten years, the corrosion of this equipment may be a significant problem in due course.

The purpose of this paper is to present a laboratory accelerated periodic immersion wet/dry cyclic corrosion test, reflecting the alternate wet/dry process during the atmospheric exposure of metallic materials, which can be applied to evaluate the atmospheric corrosion resistance (ACR) of weathering steels in a very short period.

This test method uses 0.01 M sodium bisulfite aqueous solution with pH 4.4 as the immersion medium, simulating the notable characteristics of sulfur dioxide pollutant in industrially polluted atmospheres. During the test process, the tested specimens are immersed into the solution for 12 minutes, immediately followed by the subsequent drying process for 48 minutes, and such alternate process consists of a cyclic period, i.e. 1 hour. As a result of this procedure, a relative corrosion rate is defined to determine the ACR. To determine a preferred test period, different test periods including 72 and 200 hours were compared.

Compared with several other commonly used test methods, it was confirmed that the relative ACR of various steels can be determined after testing for only 72 hours. The constituent of the corrosion products, i.e. the rust layer, was consistent with that formed after long-term exposure in a typical outdoor atmospheric environment.

The test method enables comparative testing for ranking the ACR of weathering steel during the development of new weathering steels.

The purpose of this study was to select an atmospheric corrosion evaluation methodology and to establish a range of relative corrosion penetration and/or progress values, which could be used as reference in the selection of materials for the civil construction industry.

Salt spray, field tests, accelerated cyclic tests and accelerated field tests were used to evaluate atmospheric corrosion resistance of civil construction materials. The cyclic accelerated test and the field test with saline solution spray were found to be appropriate for atmospheric corrosion resistance evaluation.

The corrosion resistance of aluminium killed mild steel, aluminium killed copper added steel, and electrogalvanized steels, all phosphatized and painted, were evaluated by field and accelerated corrosion tests. Of the materials studied, aluminium killed mild steel showed the least resistance to atmospheric corrosion. The use of aluminium killed copper added steel is recommended for material specification in the civil construction industry.

Salt sprays are not adequate to evaluate atmospheric corrosion resistance. There are other cyclic tests that could be tested in future work.

Brazilian technical standards, which specify the metallic materials used in the civil construction industry, will be changed in order to include the construction steel corrosion resistance evaluation methodology, which is proposed in this paper. As a result, the tendency of the construction materials lifetime is set to increase.

This paper contributes to the improvement of the Brazilian Technical Standard by the inclusion of an atmospheric corrosion resistance requirement.

This study aims to report the CO₂ corrosion performance of 3Cr steel and 3Cr2Al steel and reveal the role of aluminum in mitigating corrosion of low-Cr steel.

Aluminum was added to 3Cr steel to prepare a new type of 3Cr2Al steel, and the effect of aluminum on the corrosion resistance of pipeline steel was studied using morphology observation and composition analysis, weight loss tests and electrochemical test.

In the CO₂/O₂ coexistence environment, the average corrosion rate of the 3Cr2Al steel was obviously lower than that of the 3Cr steel. The addition of aluminum expanded the range of prepassivation, and the dynamic potential polarization curve of 3Cr2Al steel showed duplex prepassivation phenomena. 3Cr steel underwent severe local corrosion, and 3Cr2Al steel underwent uniform corrosion. The addition of aluminum contributed to the formation of a dense corrosion product layer and greatly reduced the localized corrosion sensitivity.

The studies on CO₂ corrosion of aluminum containing low-Cr steel are quite rare. This study clarifies the role of aluminum by comparing the corrosion behavior of 3Cr2Al and 3Cr steel. The effect of aluminum on the growth of corrosion product film was discussed, and the duplex prepassivation phenomena of Cr and Al were revealed.

Comparative investigations of the corrosion resistance of different coated sheet steels in various fuel mixtures were carried out. Corrosion resistance has been studied on the following materials: Neuratern (electrolytically deposited terne‐coated steel, Thyssen Stahl AG, Germany); Ternesheet (hot‐dip terne‐coated steel, Nippon Steel, Japan); hot‐dip terne‐coated steel (Dnepropetrovsk, Ukraine); Neuralyt (Zn‐Ni electrolytically deposited steel, Thyssen Stahl AG, Germany); fal‐D (hot‐dip aluminized steel, Thyssen Stahl AG, Germany); hot‐dip aluminized steel (Cherepovets), Russia); Galvalume (hot‐dip Zn‐55 per cent Al steel, Cherepovets, Russia). Investigations were carried out in the following environments: commercial petrol without special additives + water; commercial petrol, 10 per cent ethylated spirit + water; commercial petrol, 15 per cent methylated spirit + water. Corrosion resistance was evaluated in terms of ratings and weight loss. To compare the behaviour of the different types of samples and various fuel mixtures over the test period rating curves were plotted as a function of the test time.

The purpose of this paper is to study the influence of moisture on corrosion behaviour of steel ground rods in mildly desertified soil and the mechanism behind it.

The specimens were used for weight loss corrosion experiments and polarization scans were taken at different moisture levels. Specimen surfaces were characterized using a scanning electron microscope, energy dispersive spectrometer, and using X‐ray diffraction.

The results indicated that the moisture content of the soil influenced steel corrosion considerably. The maximum corrosion of 20G and Q235 galvanised steels occurred at 10 per cent and 12.5 per cent soil moisture, respectively. The corrosion products of 20G steel were mostly Fe₂O₃ and Fe₃O₄, whereas that of Q235 galvanised steel was Zn₅(OH)₈Cl₂ · H₂O.

The paper provides information regarding the relationship between moisture and corrosion of steel ground rods, which is useful for understanding the mechanism of soil corrosion. The research results can provide theoretical guidelines for preventing the corrosion of steel ground rods buried in mildly desertified soil.

With the transition from supplying ships with direct current to alternating current, plus the increase in the number of electricity consumers within the coastline region, as well as with the construction of steel quays and docks and reinforced steel quays, the conditions have been created for the occurrence of wandering exchange currents in the sea. Corrosion due to these currents considerably exceeds all expectations. In this work, the rate of steel corrosion in synthetic sea‐water has been investigated in an alternating electric field. Electro‐chemical parameter measurements determining corrosion rate were performed on samples in sea‐water in an alternating current field and compared with the sample — applying a “blind test” — without an electric field. All measurements were performed at an electrolyte temperature of 20°C. Corrosion rate was investigated in dependence on the current density. The following factors were applied as measures of corrosion rate: specific concentration of Fe ions in the electrolyte and the change of potential of the steel electrode polarized within alternating electric field. Measurement results shown that in the sea‐water with an alternating electric field an increase in the corrosion of steel takes place, exceeding expected amounts. The change of steel potential in alternating current field is proportional to the corrosion rate and can be very simply applied for estimation of corrosion rate due to alternating currents.

The weather in the Arabian Gulf region constitutes an environment that is corrosive to carbon steel. In the Gulf region, atmospheric corrosion is aggravated further by the high salinity of Gulf sea‐water. In addition, sulphur dioxide and deposits from combustion products tend to make the atmosphere in the Gulf region even more corrosive. Various inhibitors are reported in the literature that can help in the prevention of metal corrosion in aqueous environments. Among these, sodium dihydrogen orthophosphate, sodium benzoate, sodium nitrite and sodium nitrate were obtained and the effectiveness of certain corrosion inhibitors on carbon steel specimens was examined in a simulated atmospheric corrosion environment containing 2% NaCl and 1% Na₂SO₄ with various inhibitor concentrations. Test specimens were prepared from locally produced carbon steel reinforcing bars. It was found as a result of the test programme that treatment of the steel with 10 or 100mM sodium dihydrogen orthophosphate for one day at room temperature resulted in the best inhibition of corrosion. The results also demonstrated that inhibitors such as sodium benzoate and sodium nitrite were only similarly effective, as was sodium nitrate. Plans further study to examine the inhibition performance of sodium dihydrogen orthophosphate under actual atmospheric conditions.

The purpose of this study was to investigate the corrosion of rusted carbon steel in dilute NaCl solution, with the purpose of exploring the effect of the rust layer on metal corrosion and establishing a corrosion model for rusted iron.

The corrosion behavior of rusted carbon steel in dilute NaCl solution was studied by means of weight-loss determinations, scanning electron microscopy, Raman spectrometry and electrochemical techniques.

The results indicated that carbon steel had a similar corrosion behavior in all three NaCl solutions. The iron rust, which consisted of a thin γ-FeOOH layer and a thick Fe₃O₄ layer, can facilitate the corrosion process of carbon steel via reduction of γ-FeOOH and the large area cathode of Fe₃O₄. Hence, the corrosion rate of carbon steel was accelerated significantly and finally was determined by the limiting diffusion rate of oxygen.

A corrosion model of rusted carbon steel was established, suggesting that iron rust formed in all slightly acidic waters with low alkalinity probably promotes the corrosion of carbon steel. Anti-corrosion measures for iron in this type of solution, such as desalination water, should be aimed to reduce the promotional effect of the rust layer on metal corrosion.

The purpose of this paper is to explore the long‐term corrosion behavior of carbon steel in 3% NaCl solution and evaluate the effect of rust layer on the corrosion process.

The corrosion behavior of rusted carbon steel in 3% NaCl solution was studied by means of infrared spectroscopy (IR) and electrochemical impedance spectroscopy (EIS).

The results indicated that the corrosion of carbon steel was affected by chloride ion in initial immersion and then controlled by the rust layer. The rust layer consisted of a thin outer layer (γ‐FeOOH layer) and a thick inner layer (Fe₃O₄ layer). The outer rust layer facilitated the cathodic process via reduction of γ‐FeOOH, while the inner rust layer provided a large cathode area and oxygen could be reduced on its surface. As a result, the corrosion rate of carbon steel was determined by the limiting diffusion rate of oxygen and stabilized at a high value.

The corrosion model of rusted carbon steel in 3% NaCl solution was established. It is probable that the iron rust in all slightly acidic water with low alkalinity can promote the corrosion process via reduction of γ‐FeOOH. Anti‐corrosion measures for iron in this type of solutions should be aimed to reduce the promoting effect of rust layer on the metal corrosion. The NaCl solution prepared from tap water is more suitable for the substitution of artificial water than that prepared from deionized water.