Steel In Acidic Chloride Solution Research Articles

Effects of hydrogen and surface dislocation on active dissolution of deformed 304 austenitic stainless steel in acid chloride solution

The mechanochemical effects between dissolved hydrogen and deformation on active dissolution of 304 stainless steel in acid chloride solution were investigated by use of constant loading test method. A theoretical model was proposed in terms of the stored strain energy and electron work function. Results indicated that active dissolution was affected mainly by Gibbs free energy produced by the part of plastic deformation and surface dislocation structure. A good agreement between the prediction and test results revealed that the synergistic effect of stress and dissolved hydrogen only promoted the process of active dissolution.

ChemInform Abstract: The Effect of Copper on the Anodic Dissolution Behavior of Austenitic Stainless Steel in Acidic Chloride Solution.

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Electrochemical behaviour of carbon steel in acid chloride solution in the presence of dodecyl cysteine hydrochloride self-assembled on gold nanoparticles

In this work, the dodecyl cysteine hydrochloride surfactant was synthesized. The surface properties of this surfactant were studied using surface tension technique. The nanostructure of this surfactant with the prepared gold nanoparticles was investigated using TEM technique. The synthesized surfactant and its nanostructure with the prepared gold nanoparticles were examined as non-toxic corrosion inhibitors for carbon steel in 2 M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The results show that the percentage inhibition efficiency (η%) for each inhibitor increases with increasing concentration until critical micelle concentration (CMC) is reached. The maximum inhibition efficiency approached 76.6% in the presence of 175 ppm of dodecyl cysteine and 90.8% in the presence of the same concentration of dodecyl cysteine hydrochloride self-assembled on gold nanoparticles. Polarization data indicate that the selected additives act as mixed type inhibitors. The slopes of the cathodic and anodic Tafel lines (βc and βa) are approximately constant and independent of the inhibitor concentration. Analysis of the impedance spectra indicates that the charge transfer process mainly controls the corrosion process of carbon steel in 2 M HCl solution both in the absence and presence of the inhibitors. Adsorption of these inhibitors on carbon steel surface is found to obey the Langmuir adsorption isotherm. From the adsorption isotherms the values of adsorption equilibrium constants (Kads) were calculated. The relatively high value of (Kads) in case of dodecyl cysteine hydrochloride self-assembled on gold nanoparticles reveals a strong interaction between the inhibitor molecules and the metal surface.

Electrochemical behaviour of high nitrogen bearing stainless steel in acidic chloride solution: Effects of oxygen, acid concentration and surface roughness

The effects of oxygen, H 2SO 4 concentration and surface roughness on the electrochemical behaviour of high nitrogen bearing stainless steel (HNS) in acidified 0.5 M NaCl solution were investigated using potentiodynamic polarization method. The results revealed three corrosion potentials indicating an unstable system. The number of the potentials was influenced by H 2SO 4 concentration. Three potentials existed above 0.011 M H 2SO 4, two between 0.011 and 0.0065 M H 2SO 4 and one below 0.0065 M H 2SO 4. Oxygen increased the number of corrosion potential at 0.005 M H 2SO 4 + 0.5 M NaCl solution while surface roughness had no noticeable influence on the number of potentials but increased the values of the corrosion potentials and passivation current densities with increase in the surface roughness. The corrosion mechanism has been discussed using the ideal polarization curve models.

Effect of Delta Ferrite on Corrosion Resistance of Type 316L Stainless Steel in Acidic Chloride Solution by Micro-Droplet Cell

More than 2% δ-ferrite phase is presented in type 316L stainless steels due to improvement of hot workability or welding process. In order to clarify the mechanism on how the δ-ferrite affects the corrosion resistance, electrochemical tests in a micro-droplet cell were conducted and microstructures were analyzed by TEM-EDS and SEM-EDS. Especially, the micro-droplet cell was modified at our laboratory to observe the polarization behavior of δ-ferrite phase in an acidic chloride solution. The anodic polarization behavior in both active zone and passive zone was affected by δ-ferrite. The degradation of corrosion resistance in the low potential zone with δ-ferrite phase is due to the preferential dissolution of a matrix, γ phase. It is explained with the fact that the formation of δ-ferrite lowers the concentrations of chromium and molybdenum in γ phase. It is also confirmed by potentiostatic test, EDS analyses and phase-equilibrium prediction. In addition, the micro-droplet cell and EDS analysis reveled that the pitting potential in the neutral pH solution was affected by Ca containing inclusion rather than δ-ferrite phase.

Corrosion inhibition of carbon steel in acid chloride solution using ethoxylated fatty alkyl amine surfactants

Four novel non-ionic ethoxylated fatty alkyl amine surfactants (I–IV) were synthesised and investigated as corrosion inhibitors of carbon steel in 1 M hydrochloric acid solution using gravimetric, open circuit potential and potentiostatic polarisation techniques. The percentage inhibition efficiency (η%) for each inhibitor increased with increasing concentration until the critical micelle concentration (cmc) was reached. The maximum inhibition efficiency approached 95.1% in the presence of 400 ppm of the inhibitor (IV). It was found that the adsorption of the surfactants on carbon steel followed the Langmuir adsorption isotherm. Potentiostatic polarisation data indicated that these surfactants act as mixed type inhibitors. The values of activation energy (Ea*) of carbon steel dissolution in 1 M HCl were calculated in the absence and presence of 400 ppm of each inhibitor. Finally, scanning electron microscopy (SEM) was used to examine the surface morphology of polished carbon steel surfaces and those immersed in 1 M HCl in the absence and presence of 400 ppm of inhibitor (IV).

Effectiveness of some non ionic surfactants as corrosion inhibitors for carbon steel pipelines in oil fields

The ability of new synthesized non ionic surfactants (I and II) to protect carbon steel in acid chloride solution was investigated using potentiostatic polarization, open circuit potential, weight loss and surface tension measurements. The experimental results showed that these inhibitors revealed a very good corrosion inhibition even at low concentrations. The percentage inhibition efficiency ( η%) increases by increasing the inhibitor concentration until the critical micelle concentration (cmc) is reached. It was found that, the adsorption ability of the surfactant molecules on carbon steel surface increased with the increase of the molecular size of the surfactant. Potentiostatic polarization curves indicate that the inhibitors under investigation act as mixed type. Finally, the mechanism of carbon steel dissolution in acidic medium was discussed both in absence and presence of the inhibitor molecules.

The synergy between deformation and anodic dissolution of an austenitic stainless steel in acidic chloride solution

AbstractIn corrosion medium, metals can deform under tensile stress and form a new active surface with the anodic dissolution of the metals being accelerated. At the same time, the anodic dissolution may accelerate the deformation of the metals. The synergy can lead to crack nucleation and development and shorten the service life of the component. Austenitic stainless steel in acidic chloride solution was in active dissolution condition when stress corrosion cracking (SCC) occurred. It is reasonable to assume that the anodic dissolution play an important role, so it's necessary to study the synergy between anodic dissolution and deformation of austenitic stainless steels. The synergy between deformation and anodic dissolution of AISI 321 austenitic stainless steel in an acidic chloride solution was studied in this paper. The corrosion rate of the steel increased remarkably due to the deformation‐accelerated anodic and cathodic processes. The creep rate was increased while the yield strength was reduced by anodic dissolution. The analysis by thermal activation theory of deformation showed a linear relationship between the logarithm of creep rate and the logarithm of anodic current. Besides, the reciprocal of yield strength was also linearly dependent on the logarithm of anodic current. The theoretical deductions were in good agreement with experimental results.

Effect of Strain Rate and Potential on the Propagation of Stress Corrosion Crack

On the basis of the model of slip-bare metal dissolution-repassivation and crack-tip strain analysis, a theoretical equation of stress corrosion crack propagation rate as a function of crack-tip strain rate and potential for 304L stainless steel in acidic chloride solution was deduced. The theoretical prediction showed that there are two regions in the curve of crack propagation rate with the crack-tip strain rate. In region I, the crack growth rate increased with increasing crack-tip strain rate. In region 11, the crack propagation rate was independence of the crack-tip strain rate. The crack propagation rate of 304L stainless steel in acidic chloride solution has been measured by slow strain rate testing (SSRT) technique. The crack propagation rate calculated theoretically was consistent with the experimental results in region 11 when potential was controlled in anodic region.

Stress corrosion cracking of AISI 321 stainless steel in acidic chloride solution

The stress corrosion cracking (SCC) of AISI 321 stainless steel in acidic chloride solution was studied by slow strain rate (SSR) technique and fracture mechanics method. The fractured surface was characterized by cleavage fracture. In order to clarify the SCC mechanism, the effects of inhibitor KI on SCC behaviour were also included in this paper. A study showed that the inhibition effects of KI on SCC were mainly attributed to the anodic reaction of the corrosion process. The results of strain distribution in front of the crack tip of the fatigue pre-cracked plate specimens in air, in the blank solution (acidic chloride solution without inhibitor KI) and in the solution added with KI measured by speckle interferometry (SPI) support the unified mechanism of SCC and corrosion fatigue cracking (CFC).

Inhibitive effect of benzotriazole on the stress corrosion cracking of 18cr-9ni-ti stainless steel in acidic chloride solution

The SCC susceptibility of 18Cr-9Ni-Ti austenitic stainless steel in 0.5 mol · dm −3 HCl+0.5 mol · dm −3 NaCl solution and the inhibiting effect of benzotriazole (BTA) on SCC and general corrosion were investigated by slow strain rate testing (SSRT), transient current measurements during fast strain rate testing (FSRT) under potentiostatic condition, scanning electron microscopy (SEM), potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS) measurements. The results indicated that the inhibitive action of BTA can be attributed to its adsorption and inhibiting the anodic dissolution of the metal by the effect of blocking the active sites on the metal surface.

The inhibition properties of some non‐ionic surfactants on steel in chloride acid solution

The inhibition effect of some non‐ionic surfactants Tween 20, Tween 40, Tween 60, Tween 80 and O1 (EO)20 on steel in acidic chloride solution has been investigated by studying their adsorption behaviour and the use of the gravimetric method in order to determine the inhibition efficiency. The results obtained show that these compounds are very good inhibitors. High inhibition efficiency is observed around their critical micelle concentrations (CMC), and it increases with the number of carbon atoms in the chain length of their molecules.

The effect of copper on the anodic dissolution behaviour of austenitic stainless steel in acidic chloride solution

The effect of Cu on the anodic dissolution behaviour of 18Cr-10Ni austenitic stainless steel in acidic 3.5% NaCl solution at 80°C was studied by electrochemical and AES techniques. The results indicated that Cu decreased the active dissolution. Cu was detrimental to the passivity of stainless steel. The growth kinetics of passive film were changed by Cu, which was related to the change of the initial dissolution behaviour of stainless steel during passivation process.

The corrosion of single pits on stainless steel in acidic chloride solution

A new method was developed for creating single corrosion pits on Type 304 stainless steel surfaces that otherwise exhibit very low dissolution rates. Single pits were grown by masking specimens with photoresist except for a region of 100 μm diameter, and then exposing them to 1 N H2SO4 and 0.1 N NaCl at 0.6 V (SCE). By measurement of current and surface area during pit growth, it was found that the dissolution current density decreases with the square root of time. These results support quantitatively the hypothesis that the corrosion rate is controlled by dissolution of an Fe SO4 salt film.