Corrosion Rate Of Carbon Steel Research Articles

Dried Clove Leaf as Corrosion Inhibitor for Medium Carbon Steel in Acidic Media

Medium carbon steel is a widely used steel variant known for its susceptibility to mechanical property degradation due to corrosion. In order to decrease the corrosion rate of medium carbon steel, various protective measures are employed such as the addition of inhibitors. Dried Clove Leaf (DCL) extract was extracted and applied as an inhibitor for medium carbon steel AISI 1040 in different acidic environments. Fourier-transform infrared spectroscopy (FTIR) was conducted to analyze the compounds present in the clove leaf extract. Subsequently, corrosion rate and inhibitor efficiency were assessed to demonstrate the effectiveness of the clove leaf inhibitor. The parameters under this research included varying inhibitor concentrations for 0%, 5%, 10%, 15%, and acidic media using HCl and H2SO4. The successful extraction of DCL was confirmed by the presence of a C=C bond in the FTIR results, occurring at wavenumbers ranging from 1638 to 1514 cm-1, indicative of the presence of benzene rings corresponding to eugenol (a phenolic component). The inhibitor exhibited remarkable efficiency, reaching its peak at 96.51% when used with HCl media at a DCL concentration of 15%. This high efficiency is notably reflected in the significant reduction of the corrosion rate from 352.96 mpy to 12.31 mpy in the presence of HCl media.

The influence of addition maja fruit peel extract as inhibitor on the corrosion rate of stainless steel and carbon steel

Corrosion can cause serious damage, such as a piece of equipment or a decrease in tool life. The materials used in an industry, its use can be seen in factory flow pipes that carry a substance, which is one of the factors causing corrosion. The aim of this research is to determine the performance of maja rind extract as an inhibitor of stainless steel and carbon steel corrosion rates, to determine the inhibition efficiency of maja rind extract in controlling the corrosion rate of stainless steel and carbon steel. Method use in this reasearch extraction and polarization. The best concentration in controlling the corrosion rate of SS 304 was obtained at 100 ppm with a corrosion rate of 0.00963 mpy, for SS 316 it was obtained at 100 ppm with a corrosion rate of 0.00521 mpy, while on steel plate it was obtained at 100 ppm with a corrosion rate of 0.00774 mpy. The best inhibitor efficiency on SS 304 can reach 97.6% with the best concentration of 100 ppm, on SS 316 it can reach 99.4% with the best concentration of 100 ppm, and on steel plate it can reach 98.84% with the best concentration of 100 ppm.

Study of corrosion properties of carbon steel, 304 and 316L stainless steels in sulfuric acid and their degradation products

In this study, corrosion properties of carbon steel and stainless steels, and degradation of sulfuric acid by the corrosion mechanism are presented. Carbon steel (CS), 304 stainless steel (SS304), and 316L stainless steel (SS316L) specimens were analyzed through their electrochemical response by using a potentiostat measurement. The specimens were submerged in concentrated 98 wt.% of H2SO4 acid for 0 day to 60 day. The degradation of H2SO4 was determined by its volume change, turbidity, and color due to the corrosion mechanism. Corrosion rate of CS, SS304 and SS316L specimens are 43.237 mm/year, 0.420 mm/year and 0.086 mm/year, respectively. After 60 days, the weight-loss of CS, SS304 and SS316L specimens are 48 wt%, 33 wt% and 0.1 wt%, respectively. Corrosion resistance of the materials are influenced by the passive oxide layer that forms on its surface and associated with electrochemical activity or semiconductive composition. The degradation of H2SO4 acid was observed due to the corrosion process of specimens and related to the turbidity and volume increase while the wt% concentration of H2SO4 acid decreases. In order to make material choices that enable continuous and safe operation of the process, it is important to understand the corrosion mechanism changes.

Anticorrosion Agents for Carbon Steel in Acidic Environments: Synthesis and Quantum Chemical Analysis of New Schiff Base Compounds with Benzylidene.

Novel Schiff bases (SBs), namely, N1,N2-bis(2-(((E)-4-chlorobenzylidene)amino)ethyl)ethane-1,2-diamine (I), N1,N2-bis(2-(((E)-4-(dimethylamino)benzylidene)amino)ethyl)ethane-1,2-diamine (II), and N1,N'1-(ethane-1,2-diyl)bis(N2-((((Z)-4-dimethylamino)benzylidene) amino)methylethane-1,2-diamine) (III), were prepared and characterized by using elemental analysis, IR, and 1H NMR spectroscopy. For assessing carbon steel in diverse settings, with and without inhibitors at varying concentrations, electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PP) techniques were employed. The results showed that the synthesized inhibitors effectively decreased the corrosion rate of carbon steel in acidic media and the inhibition efficiency reached up to 93% for compound III at a concentration of 250 ppm. In addition, all prepared compounds were successful as anticorrosion agents, and the inhibition mechanism followed chemisorption from the Langmuir isotherm. The data obtained from the theoretical analysis show that the efficiency of the prepared compounds was in the order III < II < I. Furthermore, quantum chemical calculations were performed to gain insight into the electronic structure of the compounds. The analysis of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) showed that compound III had the highest surface coverage due to its specific molecular structure and spacer. This observation agreed well with the Langmuir adsorption data.

Effects of Ca2+ Ions on the Localized Corrosion of Carbon Steel Influence of the Associated Anion

The corrosion rate of carbon steel under the attack of electrolytic mediums saturated by CO2 at a working temperature of 65 °C under dynamic conditions is studied in this paper. The effect of Ca2+ ions on corrosion rates and their dependency on the associated anion (Cl− or CO32−) with respect to the Ca2+ cation and Na+ are also assessed. A potentiostat/galvanostat associated with a rotor stator in an AISI 1040 steel-ring configuration, rotating at 600 rpm, was used. A linear polarization-resistance technique was applied to calculate the corrosion rate. It is found that the corrosion rate depends not only on the presence of Ca2+, but also on the salt anion added to the electrolytic medium. There was a strong inhibitory effect of the corrosion in the presence of Ca2+ in chloride-free mediums because of an ankerite deposition with a lower solubility compared to siderite. Moreover, it was observed that, even if the corrosion rate increased together with the Cl− concentration, its value depended on the cation introducing the anion. It was higher when Cl− was associated with Na+ compared to when it was associated with Ca2+. We found the following decreasing order in the carbon steel corrosion rate: 2% NaCl + 1380 ppm CaCl2 &gt; 2% NaCl &gt; 2% NaCl + 1360 ppm Na2CO3 &gt; 2% NaCl + 1.25 g/L CaCO3 &gt; 1450 ppm of NaCl &gt; 1380 ppm CaCl2 &gt; 1360 ppm Na2CO3 &gt; 500 ppm CaCl2 &gt; 424 ppm Na2CO3 &gt;&gt; 1.250 g/L CaCO3.

Biodegradable polysaccharide grafted polyacrylamide inhibitor for corrosion in CO2- saturated saline solution

A biodegradable polysaccharide-based inhibitor is grafted with polyacrylamide (PAM) for oilfields’ sweet corrosion. The green properties of agar and PAM were incorporated to synthesize an agar-grafted-PAM (AGGPAM) inhibitor. Electrochemical tests of Tafel and AC impedance, were used to determine the corrosion rate of carbon steel (C-steel) and protection efficiency in CO2-saturated 3.5 wt% NaCl solution. The surface morphology was characterized using FESEM coupled with EDX. Results demonstrated the promising performance of AGGPAM in improving steel resistivity, achieving 85% efficiency at 500 mg L−1 and reducing the corrosion rate from 33 to 4.9 mils per year at 25 °C. The electrochemical tests classified AGGPAM as a mixed-type inhibitor, yet with a larger potential to inhibit the cathodic hydrogen evolution. Kinetics study at a temperature of 50 °C revealed a deteriorated AGGPAM inhibition attributed to electrolyte diffusion through the weakly adsorbed AGGPAM film. Nevertheless, the AGGPAM-inhibited solution exhibited a corrosion rate of 26.7 mils per year at 50 °C, which is still lower than that of blank at 25 °C. The steel resistance was diminished from 1436 to 355 Ω cm2 at 50 °C. Implementing AGGPAM coating reduced the steel corrosion rate to 9.6 mils per year, achieving 71% efficiency. AGGPAM inhibitor toxicity was evaluated using ADMETlab, which predicted negligible hazardous impacts. Lastly, potentiostatic testing of steel with AGGPAM at an applied potential of 50 mV illustrated surface protection and decreased current over a prolonged time. Herein, the experimental investigation revealed the promising capabilities of AGGPAM as an efficient corrosion inhibitor in oilfields.

ОЦЕНКА ЭФФЕКТИВНОСТИ ИНГИБИРОВАННОГО РАПСОВОГО МАСЛА ДЛЯ ЗАЩИТЫ СЕЛЬСКОХОЗЯЙСТВЕННОЙ ТЕХНИКИ В ПРИСУТСТВИИ ДИОКСИДА СЕРЫ В АТМОСФЕРЕ

Sulfur dioxide, present in the atmospheres of agricultural production, is an active stimulator of corrosion processes. We studied the protective effectiveness of compositions based on rapeseed oil (RM) and Emulgin as a corrosion inhibitor (CI) in the corrosion of carbon steel St3 in a 0.5 M NaCl solution in equilibrium with sulfur dioxide depending on the exposure time of the electrodes in the working environment. Model atmospheres were created in sealed plastic containers. The initial concentration of sulfur dioxide in the range from 0.1 to 10 vol.%, the ratio of the volumes of the gas and liquid phases, equal to 1.4 were chosen. It has been established from viscosity-temperature curves that Emulgin has a thickening effect in relation to PM, due to the formation of micellar structures. It has been established that the mass transfer of moisture through the oil films of RM with Emulgin increases with an increase in the SO2 concentration and the duration of the experiment and decreases with an increase in the Emulgin concentration. The corrosion rate of carbon steel in the gas and liquid phases increases with an increase in the initial concentration of sulfur dioxide in the air. It has been established that films of non-inhibited PM provide the protective effectiveness of carbon steel in a 0.5 M NaCl solution in equilibrium with the gas phase, containing up to 0.001 vol.% sulfur dioxide, in 92-93%. 7 - 10 wt.% Emulgin, it is advisable to introduce into the protective film at an equilibrium concentration of sulfur dioxide in the gas phase of more than 0.001 vol. %.

Laju Korosi Logam Baja Karbon Rendah di Larutan Garam pada Berbagai Konsentrasi Inhibitor Korosi dari Ekstrak Daun Pepaya

Papaya leaf extract could be used as an organic corrosion inhibitor. Corrosion inhibitors were used as a method to reduce corrosion rate. The most corrosive environment was the marine environment. The purpose of this study was to determine the best concentration of papaya (Carica papaya) leaf extract inhibitor which could reduce the corrosion rate of low carbon steel in a 3.56% NaCl solution environment. The maceration process was carried out for 24 hours with 70% ethanol solvent with a solute:solvent ratio of 1:8 (w/v) at room temperature. Inhibitor extracts were analyzed qualitatively with the phytochemical method. The addition of FeCl3 was carried out on the inhibitor extract from papaya leaves. The color change occurred from blackish brown to greenish black which indicated the presence of tannin compounds in the papaya leaf extract. Corrosion testing was carried out with hot stream temperature setting at 45⁰C to 55⁰C and concentrations of inhibitor extracts at 300, 600, and 900 ppm. The test was conducted for 36 hours with a span of metal mass every 6 hours. Corrosion rate calculation is done by weight loss method. The results showed that papaya leaf extract inhibitors positive contained corrosion inhibitor and could reduce the corrosion rate in 3.56% NaCl solution. The corrosion rate without inhibitor is 1.023 mmpy. Corrosion rates with inhibitor concentrations of 300, 600, and 900 ppm were 0.755, 0.585, and 0.438 mmpy, respectively.

The Effect of Immersion Time on Corrosion Rate on St37 Carbon Steel in 3% NaCl Corrosive Medium Using Waru Leaves Extract Inhibitor

The research of effect of immersion time on the corrosion rate of St37 carbon steel has been conducted in a 3% NaCl corrosive medium using a hibiscus leaves extract inhibitor. The samples of carbon steel St37 were immersed in a corrosive medium of NaCl 3% without being given and given the inhibitor of hibiscus leaf extract with a concentration of 15% for 3, 6, 9, and 12 days. Calculation of reduction in corrosion rate is carried out by the weight loss method. The results showed that adding the hibiscus leaves extract inhibitor effectively reduced the sample's corrosion rate with the most excellent efficiency at nine days immersion, which was equal to 78,48%. The results of XRD characterization show that the phase formed is pure Fe is a corrosion product. The results of SEM characterization showed that the surface microstructure of the sample after immersion was cracks, holes, and lumps, which indicated that the sample had been corroded. The results of EDS characterization show that in the soaked sample, there were corrosion products in the form of FeO compounds whose magnitude increased with every immersion.

Effect of selected green corrosion inhibitors on SO2 removal during carbon steel corrosion in aqueous solutions of ammonia and histidine

To understand the feasibility of using carbon steel in the flue gas desulfurization process, the corrosion protection of carbon steel was investigated by adding four green corrosion inhibitors (12-aminolauric acid; 4-carboxyphenylboronic acid; 1,2,3-benzotriazole; and L-methionine) to an ammonia solution containing histidine as the SO2 absorbent. The effects of the corrosion inhibitors on the corrosion rates of carbon steel and SO2 absorption performance were investigated. We observed that 1,2,3-benzotriazole was the most effective corrosion inhibitor, reducing the corrosion rate by 73 % and increasing the SO2 absorption loading by 8.3 % compared to other corrosion inhibitors. Scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray diffraction studies were conducted to understand the corrosion inhibition behavior of 1,2,3-benzotriazole. The formation of the Fen-(SO2-BTA)m complex and its subsequent adsorption on the carbon steel surface blocked active sites and inhibited corrosion. This study demonstrated the feasibility of effectively using carbon steel under harsh environmental conditions such as in desulfurization.

CATHODIC PROTECTION OF CARBON STEEL IN 0.1N NaCl SOLUTION UNDER FLOW CONDITIONS USING ROTATING CYLINDER ELECTRODE

The effect of applied current on protection of carbon steel in 0.1N NaCl solution (pH=7) was investigated under flow conditions (0-0.262 m/s) for a range of temperatures (35-55°C) using rotating cylinder electrode. Various values of currents were applied to protect steel from corrosion, these were Iapp.=Icorr., Iapp.=2Icorr. and Iapp.=2.4Icorr. under stationary and flow conditions. Corrosion current was measured by weight loss method. The variation of protection potential with time and rotation velocity at various applied currents was assessed. It is found that the corrosion rate of carbon steel increases with rotation velocity andhas unstable trend with temperature. The protection current required varies with temperature and it increases considerably when the rotation velocity was increased. The protection potential decreases appreciably (shifts to more negative) with time and with increasing rotation velocity. Also it shifts to more positive with increasing temperature.

Carbon steel corrosion in a bentonite buffer: A comparison between in situ exposure and lab based experiments

AbstractIn this paper, carbon steel corrosion rates from experiments performed in situ (performed in an underground rock laboratory) and ex situ (performed in a conventional laboratory) test methods in anaerobic saturated bentonite are compared. The results indicate that the long‐term corrosion rate follows a power law decay curve, with a higher initial rate and greater rate of decay at higher temperature. In compacted bentonite blocks, varying the density has no significant effect on the corrosion rate measured during in situ testing, whereas granular bentonite of an equal dry density leads to a higher corrosion rate. Precorrosion of test specimens in an aerated solution at room temperature has a negligible effect on the subsequent anaerobic corrosion rate when tested ex situ for durations up to 11.8 years. The main difference between in situ and ex situ tests is the formation of silicon‐rich corrosion products in the ex situ tests but not in the in situ tests. Despite these differences, the corrosion rates in both tests exhibit the same general temporal evolution and similar magnitudes, suggesting that the main steel degradation processes are maintained in both configurations.

Experimental Investigation of Electric Arc Welding Variables on the Corrosion Behaviour of Steel Welds in Acidic Medium

This work investigated the effects of power input and welding speed on the corrosion rate of low carbon steel welds in one molar tetraoxosulphate (VI) acid (H2SO4) solution. Locally available low carbon steel rod (Ø12mm) used for this study was cut into twenty four samples Ø12mm × 50mm with the aid of hacksaw for both plane face and double V shape. The samples were further processed through machining to get twelve samples for plane face and double-V edge shape respectively. Electric arc welding was used for welding the samples to produce six welded joints for each of plane face and double V shape at different power input and welding speed. Weight loss method was employed to evaluate the corrosion rate of the welded joints in the tested medium. It was discovered from the study that welding speed and power input have significant roles to play in either lowering or increasing the corrosion rate of the low carbon steel welded joints in one molar tetraoxosulphate (VI) acid solution. The plane face and double-V edge low carbon steel welded joints corrodes less at power input and welding speed of 16.5kW and 12cm/min respectively. Their corrosion rate is more aggressive at higher power input and welding speed.

Effect of Surface Roughness on Static Corrosion Behavior of J55 Carbon Steel in CO2-Containing Geothermal Water at 65 °C

The influence of surface roughness on the static corrosion behavior of J55 carbon steel in CO2-containing geothermal water environment was investigated with respect to average corrosion rate, morphology, chemical composition, corrosion depth, and the cross section of corrosion products. The influence of surface roughness on the CO2 corrosion of J55 carbon steel was then proposed based on the understanding of corrosion at 65 °C. The results show that the static corrosion rate of J55 carbon steel in CO2-containing geothermal water increases with increasing surface roughness. The surface roughness of J55 carbon steel increases 5.3-fold and the CO2 corrosion rate increases by 1.4-fold under different exposure times. The static corrosion rate of J55 carbon steel in CO2-containing geothermal water changes with exposure time. The corrosion rate of J55 carbon steel decreases with the increase in exposure time, and there is little change in the corrosion rate after immersion for 2 days. At the initial stage of corrosion, the corrosion rate of J55 carbon steel was mainly affected by surface roughness. The greater the roughness, the greater the corrosion driving force and the corrosion reaction surface area and therefore the greater the corrosion rate of J55 carbon steel. After immersion for 2 days, a continuous corrosion product layer was formed on the surface of J55 carbon steel and the corrosion rate was mainly affected by the corrosion product layer. The corrosion products of J55 carbon steel are not altered by surface roughness in a CO2-containing geothermal water environment. The corrosion products of J55 carbon steel are FeCO3 and a minute amount of CaCO3.

Investigation of carbon steel corrosion rate in different acidic environments

This study focused on evaluating the rate of carbon steel corrosion in one molarity of HNO3 H2SO4 and HCl in various acidic conditions. The twenty-day exposure of carbon steel specimens to acidic conditions was investigated and followed by the evaluation of corrosion penetration rate and mils per year. The results showed that the 1 M HNO3 solution was the most damaging to carbon steel due to its oxidizing character. Among the tested acidic media HNO3 was the most harmful followed by H2SO4 and HCl. Carbon steel metal's corrosion behaviour was affected by acid medium strength and exposure duration. Dissolving of carbon steel increased with increasing corrosive media severity and exposure time. Concept of passive behaviour in metals has been proposed as the primary reason for this effect. The corrosion penetration rate values for carbon steel used in the present investigation followed the order of HNO3 > H2SO4 > HCl when exposed to the three acidic environments. The maximum corrosion penetration rate values for carbon steel metal subjected to HCl H2SO4 and HNO3 were determined to be 0.008952 (2nd day) 0.03095 (1st day) and 0.039373 (1st day) respectively. In addition corrosion penetration rate values steadily dropped throughout the final days of immersion eventually becoming essentially constant in all acidic media. As a result of the greater impact of all the acidic media used in this investigation corrosion pitting occur on carbon steel consistently. By intensifying the acid medium these effects were exacerbated.

Research on 1,10-phenanthroline quaternary ammonium salt composite corrosion inhibitors for oilfield acidizing at high temperatures and high HCl concentrations

1-Benzyl-1,10-phenanthrolin-1-ium bromide (PQBr) was synthesized as a corrosion inhibitor for N80 steel, and its corrosion inhibition at high temperatures and high HCl concentrations was investigated via the weight-loss method. The addition of PQBr other additives reduced the corrosion rate of N80 carbon steel in 20% HCl at 453 K and 3 MPa to 59.93 g·(m2·h)−1. The adsorption of PQBr onto the surface of N80 carbon steel was evaluated by SEM, EIS, and PDP. An adsorption model and kinetic parameters of PQBr had been generated and determined. DFT calculations were performed to analyze the effect of the PQBr structure on adsorption.

Study on emergency treatment of minor oil leakage of closed circulation cooling water system

With the increasing shortage of water resources and the requirements of environmental protection, the closed circulation cooling water system will inevitably usher in a larger application space. However, when the leakage of the system, especially minor oil leakage, occurs, which is common and inevitable, the water quality of closed circulation cooling water will be deteriorated, and the cooling efficiency of the system will be affected due to the limited drainage and water refill. In view of such situations, this paper focuses on the slight oil leakage in the closed circulation cooling water system of Shaanxi Natural Gas General Plant, through the analysis of the water quality of the closed circulation cooling water system and the system basket filter intercepts in the case of slight oil leakage, with the experimental device of rotary hanging piece method and the inoculation of fresh intercepts to simulate the field conditions of slight oil leakage, the treatment effects of different treating agents are studied. The results show that: In the case of slight oil leakage in the closed circulation cooling water system, the corrosion of carbon steel and stainless steel increases and the corrosion of carbon steel is more serious than that of stainless steel. The metal material attached to the system is mainly corrosion products, and the bactericidal stripping agent SW-01 has almost no effect on the stripping effect of corrosion products, with excellent bactericidal effect. After 6 days of , 3.0g/L of the corrosion inhibition stripping agent HS-01 was added, the peeling effect of corrosion products was obvious, and the peeling effect of 0.3g/L biological dispersant was improved to a certain extent, but not particularly obvious. The peeling effect of the fixtures could be completed on the 9th day. This treatment method can make the corrosion rate of carbon steel and stainless steel fully meet the requirements of circulating cooling water under the condition of little drainage and large water refill, and the peeling effect of the fixtures is obvious. The effect can meet emergency handling requirements.

Effects of Zinc alloy layer on corrosion and service life of galvanized reinforcing steels in chloride-contaminated concrete

Corrosion of reinforcing steel affects the service life of structures. A chloride environment exposed to reinforced concrete structures accelerates the corrosion process. Hot-dipped galvanized steel was used as reinforcing steel instead of bare carbon steel to provide better protection against corrosion. The coating layers of galvanized steel have different compositions which can affect corrosion behavior. When galvanized steel has been corroded, it will expose the zinc-alloy layer that has a different composition than the top pure zinc layer. A comparative study on electrochemical properties such as concrete resistivity, polarization resistance, corrosion current density, anodic Tafel slope, cathodic Tafel slope, and corrosion rate of bare carbon steel (BS), galvanized steel (GS), and corroded galvanized steel (CGS) was conducted. The BS, GS, and CGS were embedded in concrete with different mix proportions by varying water-to-binder ratios, chloride contents, and types of binder. The electrochemical properties data were measured by the Wenner four-probe, linear polarization resistance (LPR), and potentiodynamic polarization resistance (PPR) tests. The measurement results show that the resistivity of 0.4 w/b concrete is higher than 0.6 w/b concrete. Corroded galvanized steel's polarization resistance is lower than bare carbon steel's and galvanized steel's. The corrosion rate calculated from the Stern-Geary equation of corroded galvanized steel is higher than bare carbon steel and galvanized steel. Based on the calculation results, the specimens with galvanized steel have a longer crack-initiating life than the bare carbon steel. The crack-initiating life of the reinforced concrete structures using galvanized steel can be more precisely predicted by considering the corroded galvanized layer.

Optimization of low carbon steel coating with corrosion inhibitor method based on siwalan (Borassus flabellifer) fiber extract

Siwalan fiber waste (SFW) has the potential as a source of lignin (7-25%) which is used as a green inhibitor to inhibit the corrosion rate of low carbon steel (LCS). The aims of this study were: (1) determine the optimum conditions (types of HCl and H2SO4, Cinhibitor and Cmedia, inhibition temperature, and coating time) for LCS coating process using the inhibitory method using lignin extract from SFW, and (2) knowing the resistance of LCS coated with inhibitor at optimum conditions. Empirical research through laboratory experiments explains the relation between variables by analyzing numerical data. 185g of SFW produced 52.289g (28.26%) fine brown powder. IR spectrum analysis on extract showed the wavelength was almost the same as the standard. IR spectrum analysis was also carried out on the extracted compounds that were adsorbed, and the absorption peaks confirmed the presence of lignin in the adsorbed compounds. Based on the results of the analysis of the weighing data of the specimen before and after inhibition, the inhibitor concentration of 0.2–0.3 g/L in H2SO4 at 313K is the optimum condition to suppress the corrosion rate on the surface of LCS by 76.2%.

Study on rust layers of carbon steel, weathering steel and alloy steel exposed to Shanghai atmosphere for three years

The corrosion results of four steels (including carbon steel, weathering steels and alloy steel) exposed to atmospheric environment in Baoshan District of Shanghai for three years were systematically analyzed by means of corrosion weight loss, intelligent digital microscope, scanning electron microscope, energy dispersive spectrometer, confocal microscopy Raman spectrometer, etc. The rust layers on skyward surfaces of corrosion samples were characterized. The results showed that the atmospheric corrosion rate of carbon steel was the highest, and the rust layer exfoliated more. The rust layers of weathering steels and alloy steel exfoliated less, and Cr was enriched in the inner layers, which promoted the formation of compact and protective rust layers, prevented rust exfoliation and oxygen infiltration, contributed to crack restoration, and thus improved atmospheric corrosion resistance.