The present study focused on STRESS CORROSION CRACKING (SCC) and CORROSION behavior of ferritic stainless steel (grade 430) in activated methyl diethanolamine (aMDEA) solution, which is classified as a tertiary amine. In this regard, cyclic polarization and U-bend tests were performed in CO2 loaded aMDEA with different concentrations at 25 and 70 ° C to observe CORROSION behavior and also the possibility of crack initiation. Based on the obtained results, it was found that the CORROSION rate increased in concentrated amine solutions. Also, by increasing temperature from 25 to 70 ° C both CORROSION rate and susceptibility to SCC initiation were intensified. Increment of amine concentration and also increase in temperature led to more absorption of CO2, generating a more acidic solution. Overall it could be stated that while for the grade 430 stainless steel investigated in this study CORROSION and CRACKING was observed Therefore it could be concluded that in amine-containing environments this steel is not a very suitable alternative for carbon steels, which are commonly used in these environments.

Electrochemical Impedance Spectroscopy (EIS) is a powerful method for investigating various electrochemical systems. The technic involves application of a small amplitude alternative current (AC) perturbation to the electrochemical system and recording its response, and therefore it is considered a non-destructive monitoring technic. This article describes the scientific fundamentals for the EIS method, instrumentation of the method, especially different electrode configurations (2 or 3 electrode systems and comb-shaped or interdigitated electrodes), and also various fields where CORROSION monitoring and analysis has been carried out by EIS. These include: atmospheric CORROSION, concrete CORROSION, analysis of performance of surface films and coatings, study of inhibitors, high temperature CORROSION and oxidation, CORROSION in gas and oil industries, microbiologically influenced CORROSION (MIC) and STRESS CORROSION CRACKING (SCC). The most recently published literature has been surveyed and typical equivalent circuit models, capabilities of the EIS technic and limitations of the technic are highlighted for each application. This article is a free translation and re-composition of two chapters about IES from references [1] and [2].

STRESS CORROSION CRACKING behavior of X52 pipeline steel was investigated in a near neutral pH solution by slow strain rate test, potentiodynamic polarization and surface analysis technique. Potentiodynamic polarization tests were performed at fast and slow potential sweep rates, to simulate crack tip and crack wall roles in the SCC process. The results showed that the dominant mechanism of SCC at relatively low and moderate applied potentials is anodic dissolution mechanism. While, at more cathodic applied potentials hydrogen based mechanism was the dominant one.

An investigation of the electrochemical noise generation during STRESS CORROSION CRACKING (SCC) of 70-30 Brass in Mattson's solution was conducted. The fluctuations of potential and current were monitored. The relationship between potential and current fluctuations has been evaluated in time domain and the obtained data has been analyzed in the frequency domain using Power Spectral Density (PSD). It is shown that 70-30 Brass has characteristic noise behavior during SCC that is step-by-step change in current and potential up to the final stage of fracture, and this may be used for SCC monitoring.

Electrochemical impedance spectroscopy (EIS) was used to detect STRESS CORROSION CRACKING (SCC) in stainless steel 304 alloy exposed to an aqueous environment at 120 °C. Stainless steel 304 alloy as u-bend was tested in the solution that contains 40 weight percent of magnesium chloride. Ubended samples were prepared according to ASTM G30. EIS measurements were always performed simultaneously on u-bend samples under STRESS and non-STRESS conditions. The results indicate that changes in phase shift versus time could be related to the STRESS CORROSION CRACKING process. STRESS CORROSION CRACKING is detectable at a frequency of 23.95 Hz. EIS measurement can be used for SCC monitoring in u-bend samples. Finally, analysis of the fracture surface by using metallographic and SEM techniques confirmed the EIS results.

CRACKING of the concrete cover due to CORROSION is defined as the serviceability limit state of reinforced concrete structures. This study evaluated the influence of a mineral admixture i. e. nano wollastonite on CORROSION performance and serviceability of reinforced concrete structures by performing an accelerated CORROSION test on ten reinforced concrete beams under a sustained load. To do so, five concrete beams were treated with nano wollastonite (NCW), while the others were normal concrete beams (NC). The results were discussed in terms of CORROSION crack patterns, crack width, half-cell potentials, rebar mass loss, and rebar diameter degradation at different CORROSION levels. The results showed that the incorporation of nano wollastonite in reinforced concrete beams increased the service life by increasing the initial CRACKING time, decreasing the CORROSION crack growth rate and rebar mass loss. Given the maximum 0. 3 mm CORROSION crack width as limit state criteria, the lifetime of the NCW reinforced beams was 3. 6 times longer than that of Group NC. The experimental results were compared with existing models. However, these models were unreliable in predicting the steel cross-section loss based on crack width. To solve this problem, a GMDH-type neural network model was developed and evaluated using obtained experimental data for NC and NCW beams.

High strength aluminum alloy pipes (AA7075-T6) has been widely used in various industries due to their favorable properties, Such as high strength to weight ratio, excellent machinability and proper forming. On the other hand, according to the susceptible to phenomenon of STRESS CORROSION CRACKING, the evaluation and monitoring of mechanisms related to this issue is of considerable importance in the industry. In this research, Fuzzy clustering method (FCM) has been used to detect acoustic emission signals related to STRESS CORROSION CRACKING mechanisms of aluminum pipe. Using this method, while revealing the clusters in an unsupervised method, leads to more appropriate classification and separation of data. In this regard, a laboratory system including waveguide, corrosive solution chamber, and arc-shaped aluminum samples according to ASTM-E399 standard along with acoustic emission equipment was designed and prepared. Then, using the slow strain rate test (SSRT) and receiving AE signals simultaneously, the AA7075-T6 aluminum sample was placed in two corrosive environments (HCL9% and HCL33%) to identify the two main mechanisms of STRESS CORROSION CRACKING, including anodic dissolution and hydrogen embrittlement (cathodic). Five descriptive acoustic parameters including rise time, count, energy, amplitude and duration were used to analyze the obtained signals. In order to select the most effective acoustic characteristics and reduce the amount of information, principal component analysis was used. Subsequently, with the fuzzy method (FCM clustering) based on the optimized data from the analysis of the main components, it was possible to distinguish and separate these two types of CORROSION mechanisms. According to the obtained results, it was found that the dominant mechanism in the phenomenon of STRESS CORROSION CRACKING in HCL corrosive solution is the anodic dissolution mechanism, which in addition to increasing the CORROSION current density, increases the dependence of STRESS CORROSION on this mechanism by increasing the concentration of H+ and C- ions.

STRESS-CORROSION CRACKING (SCC) tests were conducted in the near-neutral pH standard solution, NS4, and in an actual soil solution, using four-point bending ala high STRESS ratio and low frequency conditions very similar to those of operational pipelines. Pitting incubation appeared first and then pitting initiated and grew in both solutions although. there were many more pits on the specimen tested in soil purged with 5% CO2 +95% N2 than in the Specimen tested in NS4 Solution purged with the same gas. These observations show that samples in soil solution are more susceptible to pitting than those in NS4 solution. When the pit reached a critical size, the increased STRESS concentration around the, pits, resulted in transition to a crack.

CORROSION of reinforcement due to frequently applied deicing salts is the major source of deterioration of concrete bridge decks, e.g. severe CRACKING and spalling of the concrete cover. Since crack width is easily recordable in routine visual inspections there is a motivation to use it as an appropriate indicator of condition of RC bridge elements in decision making process of bridge management. While few existing research in literature dealing with spatial variation of CORROSION-induced CRACKING of RC structures is based on empirical models, in this paper the extent and likelihood of severe CRACKING of a hypothetical bridge deck during its lifetime is calculated based on a recently proposed analytical model for CORROSION-induced crack width. Random field theory has been utilized to account for spatial variations of surface chloride concentration, as environmental parameter, and concrete compressive strength and cover depth as design parameters. This analysis enables to track evolution of CRACKING process, spatially and temporally, and predict the time for the first repair of bridge deck based on acceptable extent of cracked area. Furthermore based on a sensitivity analysis it is concluded that increasing cover depth has a very promising effect in delaying CORROSION phenomenon and extension of the service life of bridge decks.