Corrosion Behavior Of Stainless Steel Research Articles

Stainless steel selection tool for water application: pitting engineering diagrams

Introduction: This work systematically investigates the effect of chloride level, temperature, and the water system’s oxidative power on the pitting corrosion performance of stainless steels in pH-neutral environments.Methods: Two test programs were set to a) develop a robust method for constructing the pitting engineering diagrams and b) construct the pitting engineering diagrams based on the obtained method from the first test program. The various electrochemical techniques were selected to assess and understand factors that affect the corrosion behavior of stainless steel. Extensive testing was performed with short-term electrochemical measurements and long-term immersion tests.Results and Discussion: The obtained results demonstrate that the electrochemical methods are sufficient to define pitting diagrams showing the boundaries between pitting and no pitting as a function of chloride concentration, temperature, and the water system’s oxidation potential. The laboratory long-term electrochemical test results correspond the best to real applications and clearly underline the importance of an induction time for pit initiation. Accordingly, two sets of pitting engineering diagrams were constructed based on the water system’s oxidation potential. Measurements at the applied potential of 150 mV vs. saturated calomel electrode (SCE) correspond to applications in sterile tap water, whereas the applied potential of 400 mV vs. SCE corresponds to slightly chlorinated water or water with some biological activity. Pitting engineering diagrams were proved to be very useful tools to aid material selection in water application. However, it is important to realize that additional factors, such as different surface conditions and the presence of other environmental species, crevice design, or weld will affect the exact position of the boundaries between pitting and no pitting.

Influence of electrochemical descaling treatment in simulated cooling water on the corrosion behavior of stainless steel

The electrochemical descaling treatment of circulating cooling water can effectively reduce the content of scaling ions, chloride ions and produce strong oxidizing substances with bactericidal properties in the water, which is beneficial for operation at high concentration ratio (N) of circulating water, meets the goal of clean production and has a good prospect. However, changes in ion concentration and type in water can have an impact on the corrosion behavior of metals. Currently, there is limited understanding of the impact of electrochemical treatment on the corrosion behavior of stainless steel, a commonly used material in cooling water systems, which increases the application risk of this technology. In this study, the effects of electrochemical treatment of simulated cooling water on the corrosion behavior and the passive film properties of Type 304 stainless steel with different N values were investigated by analysis of water composition, polarization curve and X-ray photoelectron spectroscopy. The results showed that the pitting potential of stainless steel decreased with the raise of N in untreated simulated water, while the pitting potential increased with the raise of N in electrochemically treated simulated water, and the highest pitting potential was observed when N was 10. The electrochemical treatment effectively reduced the Cl− content in the simulated water. With the increase of N, the concentration ratio of [Cl−]/[SO42−] decreased, and the content of ClO− generated by Cl− oxidation in the water increased, which affected the corrosion behavior of stainless steel. Appropriate concentrations of the ClO− can effectively inhibit pitting corrosion of the stainless steel in simulated water, and the best inhibitory effect observed when ClO− concentration was 50 mg⋅L−1. The inhibition of pitting corrosion by ClO− was attributed to the effective improvement of the Cr/Fe ratio and the oxides/hydroxides ratio in the passive film on the surface of stainless steel, thus the compactness and the protection performance of the passive film was enhanced. The results can provide reference for the design of electrochemical treatment devices and processes.

Study of the Corrosion Behavior of Stainless Steel in Food Industry.

AISI 304L stainless steel is widely used in the processing equipment and food and beverage handling industries due to its corrosion resistance, hygienic properties, and cost-effectiveness. However, it is prone to pitting and crevice corrosion phenomena, the development of which can be influenced by factors such as chloride concentration, temperature, humidity, and bacterial presence. Surface treatments, including roughness levels and residual tensile stress, can significantly affect the corrosion behavior and resistance of the material. This study aims to evaluate the impact of three different surface treatments on the durability of AISI 304L steel. The correlation between surface roughness resulting from pre-treatment and pitting potential values will be examined. Additionally, the influence of different concentrations of biocide additives on surface durability will be assessed to determine the maximum effective concentration for preventing pitting phenomena. Passivation processes will also be evaluated as a potential solution for improving the pitting potential and overall durability of the components. By optimizing surface treatments and biocide concentrations, improved corrosion resistance and durability can be achieved, ensuring the long-term performance and reliability of AISI 304L steel components in critical applications such as food processing and beverage handling.

Effect of fretting regimes on the fretting corrosion behavior of stainless steel in artificial crevices

Fretting crevice corrosion at the fastening interfaces of stainless-steel products is an unavoidable issue in the medical, marine, and nuclear industries. In this study, the effects of the fretting regimes on the fretting corrosion in artificial crevices were investigated, and the results showed that fretting initiated severe corrosion inside the crevice under the stick regime. Under the stick–slip and slip regimes, the volume loss was dominated by fretting corrosion, without initiating crevice corrosion.

Effects of minor alloying elements (Si, Mn and Al) on the corrosion behavior of stainless steels in molten carbonate fuel cell cathode environment

Abstract Effects of minor alloying elements (Si, Mn, and Al) on the corrosion resistance behaviors of stainless steel (SS) modified 310S used as a cathode current collector (CCC) material for molten carbonate fuel cells (MCFC) were examined in a mixture of 62 mol% Li2CO3–38 mol% K2CO3 at 650 °C by measuring the change in corrosion potential and the potentio-dynamic, potentio-static polarization responses. The corrosion potential of modified 310S gradually increased after 9 h of immersion due to an active to passive transition and that of SSs added with minor alloying elements drastically increased before 6 h of immersion due to the reactive alloys. Si, Mn, and Al addition to base SS led to a decrease in corrosion resistance due to the rapid corrosion rate at the cathode operation potential, −40 mV, of the MCFC. The steady state current densities of SSs added with minor alloying elements were higher than that of 310S and modified 310S. Addition of Si, Mn, and Al induced a decrease in corrosion resistance of CCC materials in molten carbonate fuel cell operating temperatures, 650 °C.

A protective role of Cl− ion in corrosion of stainless steel

Corrosion behaviour of stainless steel was comparatively explored in 0.6 M KCl, KBr and their mixed solution. If Cl− and Br− ions simultaneously exist, Cl− ions were found to be less susceptible to metastable pitting corrosion and they can inhibit pit corrosion, which attributes Cl− ions have low adsorption coefficient or adsorption site to reduce pit growth from metastable to stable state. Pits will initiate at the locations where surface inclusions exist, which express morphological diversity during corrosion. This study expects to provide a new insight into the role of Cl− ion in corrosion of steel.

Tensile Effect on Sensitization and Corrosion Resistance of Stainless Steels

The purpose of this research is to investigate cold work effect on corrosion behavior of stainless steels of type AISI 304, AISI 316L and AISI 2101. The specimen were processed through cold work simulated by the tensile test at various percentages elongation and then tempered at 600°C for different time intervals. Two electrochemical techniques and hardness test were utilized in this investigation. The first technique was the double loop electrochemical potentiokinetic reactivation (DL-EPR) that yields the values of degrees of sensitization (DOS). The second one was the cyclic potentiodynamic polarization (CPP) to study the ability of the metals to build or repair the damaged films under localized corrosion. The DOS values from the DL-EPR tests of the samples under the same heating conditions suggested that specimens drawn at higher percentage elongation tend to have more chromium depleted areas. Also, the test specimens with more exposure time to heat were more prone to chromium deficiencies. As for the ability of the metal to create or repair damaged film after corrosion has occurred, it was found that AISI 316L had hihger corrosion resistance than AISI 304. However, AISI 2101 stainless steel had highest corrosion resistance. In this study, it was also found that AISI 2101 did not exhibit pitting corrosion, but the crevice corrosion. This could be due the fact that AISI 2101 which is a duplex stainless steel has high corrosion resistance and could trigger the crevice corrosion take place before the pitting initiation.

Influence of Organic Acids and Related Organic Compounds on Corrosion Behavior of Stainless Steel—A Critical Review

Stainless steel is one of the most commonly used structural materials in industry for the transportation of liquids such as water, acids, and organic compounds. Corrosion is a major concern in industry due to the use of strong mineral acids, feedstock contamination, flow, aqueous environments, and high temperatures. Stainless steel is the most commonly used material in the petrochemical industry because of its characteristics of self-protectiveness, offered by thin passive oxides, and its metallurgical composition. However, chlorides and mineral acids attack the stainless steel continuously, consequently breaking down the passivation film, causing a continuous challenge from corrosion. The corrosion in stainless steel is influenced by many factors including flow rate, temperature, pressure, ethanol concentration, and chloride ion content. This review describes the impact of organic compounds and organic acids on the degradation behavior of stainless steel. The review also summarizes the commonly used organic compounds and their applications. It has been demonstrated that organic acid concentration, temperature, and halide impurities have significant effects on susceptibility to pitting corrosion by damaging the passivation film. The phenomenon of corrosion in stainless steel is quite different in immersion tests and electrochemical potentiodynamic polarization. This review article discusses the importance of organic compounds and their corrosion behavior on steel. The article also puts emphasis on the roles of corrosion inhibitors, monitoring methods, corrosion management, and forms of corrosion.

On the Use of Machine Learning Algorithms to Predict the Corrosion Behavior of Stainless Steels in Lactic Acid

Predicting the corrosion behavior of materials in specific environmental conditions is important for establishing a sustainable manufacturing system while reducing the need for time-consuming experimental investigations. Recent studies started to explore the application of supervised Machine Learning (ML) techniques to forecast corrosion behavior in various conditions. However, there is currently a research gap in utilizing classification ML techniques specifically for predicting the corrosion behavior of stainless steel (SS) material in lactic acid-based environments, which are extensively used in the pharmaceutical and food industry. This study presents a ML-based prediction model for corrosion behavior of SSs in different lactic acid environmental conditions, using a database that described the corrosion behavior by qualitative labels. Decision tree (DT), random forest (RF) and support vector machine (SVM) algorithms were applied for classification. Training and testing accuracies of, respectively 97.5% and 92.5% were achieved using the DT classifier. Four SS alloy composition elements (C, Cr, Ni, Mo), acid concentration, and temperature were found sufficient to consider as input data for corrosion prediction. The developed models are reliable for predicting corrosion degradation and, as such, contribute to avoiding failures and catastrophes in industry.

Tribological behavior of 316H stainless steel in NaNO3-KNO3 molten salt at elevated temperature

The corrosion behaviors of stainless steels in various high-temperature molten salt have been extensively investigated. However, the tribological behavior of the alloys acting as moving parts in the molten salt is rarely reported. In this work, 316H stainless steel was selected to comparatively study its high-temperature tribo-corrosion performance in molten solar salt (60% NaNO3+40% KNO3, wt.). Under the drying sliding condition, the wear rate increases at 500 °C though the friction coefficient decreases compared to that at room temperature. In contrast, compared to the 500 °C dry sliding condition, the wear resistance of 316H at 500 °C in molten nitrate salt is remarkably improved owing to the lubrication effect of the molten salt and the enhanced oxidation tendency on the worn surface.

Improving the electrochemical corrosion behavior of stainless steel (316L) through the deposition of tantalum-based thin films

Austenitic 316L stainless steel (SS) is commonly used as a biomaterial for human implant applications. However, its clinical uses are limited due to its relatively high corrosion rate in physiological conditions. Various surface modifications, including coatings, have been developed to enhance its performance. In this study, a thin layer of Tantalum (Ta) was applied to the surface of 316L stainless steel using a DC Magnetron Sputtering (DCMS) system; the thickness of the coating varied from 1.504 to 6.083 µm, achieved by deposition times ranging from 15 to 60 min. The aim was to examine the electrochemical corrosion characteristics of the uncoated 316L SS and the Ta-coated 316L SS, followed by Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscopy, and Open Circuit Potential tests. These tests were conducted for 10 min, 60 min, and 90 min to assess their performance over time. The PDP measurements took place in a simulated body fluid (SBF) at a pH of 7.8 ± 0.25 and a temperature of 40 °C, with varying coating durations. The PDP test outcomes revealed that the Ta-coated 316L stainless steel exhibited enhanced resistance to corrosion compared to the uncoated 316L stainless steel sample. The efficacy of Ta coatings on the 316L stainless steel samples was assessed through several techniques, including Optical microscopes, Energy Dispersive X-ray Spectroscopy, Scanning Electron Microscopy, and X-ray Photoelectron Spectroscopy. The findings from SEM and EDS verified the successful application of the Ta coating onto the stainless steel. The composition of the surface oxide film of Ta, the substrate, and the thickness of the coating were determined using the XPS technique, which confirms the effectiveness of the Ta coating in safeguarding 316L stainless steel against electrochemical corrosion, particularly for biomedical applications.

Localized Corrosion of Stainless Steel Triggered by Typical Inclusions in NaCl Solution: Oxy-Sulfide and MnS.

The localized corrosion behavior of stainless steel (SS) induced by typical inclusion such as MnS and oxy-sulfide in NaCl solution was investigated by immersion tests and microelectrochemical tests. Oxy-sulfide consists of an internal polygonal oxide part and an external sulfide part. The surface Volta potential of the sulfide part is always lower than that of the surrounding matrix, as in the case of individual MnS, while the potential of the oxide part is indistinguishable from that of the surrounding matrix. Sulfides are soluble, while oxides are almost insoluble. Oxy-sulfide exhibits a complex electrochemical behavior in the passive region, which can be attributed to its complex composition and multi-interface coupling effects. It was found that both MnS and oxy-sulfide increase the susceptibility of the local area to pitting corrosion.

Micro/nanostructured amorphous TiNbZr films to enhance the adhesion strength and corrosion behavior of stainless steel

To improve the corrosion resistance of key components and ensure the service safety of marine equipment, here we combined femtosecond (fs) laser fabrication and magnetron sputtering deposition to develop micro/nanostructured amorphous TiNbZr films. Analysis of the compositional, microstructural, corrosion, and mechanical properties was conducted. The results showed that the TiNbZr films were amorphous, and spherical TiNbZr nanoparticles uniformly covered the fs laser-induced periodic fringe structure. A complex hierarchical micro/nanostructure was formed that was hydrophobic and showed enhanced adhesion strength. The TiNbZr films deposited on fs laser-treated substrates provided the best corrosion resistance, showing a self-corrosion current density of 116 nA/cm2, excellent passive ability, and pitting resistance. The microscratch test revealed that the micro/nanostructures doubled the binding strength of the TiNbZr/316L interface due to the compositional and structural gradients induced by an approximately 20 nm transition layer formed during fs laser processing. This work provides a new method for obtaining anti-corrosion films with a high adhesion strength for marine applications.

Corrosion Behavior of Stainless Steel in Seawater in the Presence of Sulfide

The effect of temperature (from 288 to 308 K) and concentration of sulfide ions (up to 40 ppm) on the corrosion behavior of AISI 304L and AISI 316L stainless steels in seawater was studied with measurements of open-circuit potential, linear and potentiodynamic polarization, and electrochemical impedance spectroscopy. An increase in temperature and pollutant concentration negatively affects the corrosion stability of stainless steels at the open circuit (the resistance, compactness, and thickness of the surface layer decrease and the corrosion current increases), in the passive region (the passivation current increases, the depassivation potential decreases, and the passive potential region narrows), and in the transpassive potential region (the rate of metal dissolution increases). The occurrence of pitting corrosion on the surface of the samples was confirmed with optical microscopy and a non-contact 3D profilometer. A few large pits (depth 80–100 μm and width 100 μm) were formed on the surface of AISI 304L steel, while several smaller pits (depth 40–50 μm and width 50 μm) were formed on the surface of AISI 316L steel. With increasing temperature and sulfide ion concentration, the width, depth, and density of the pits increased on both steel samples. In the studied temperature and concentration range of sulfide ions, the AISI 316L steels exhibited higher corrosion resistance. Overall, the influence of sulfide ions on steel corrosion was more pronounced than the influence of temperature.

Solar thermal irradiation cycles and their influence on the corrosion behaviour of stainless steels with molten salt used in concentrated solar power plants

Solar thermal irradiation cycles and their influence on the corrosion behaviour of stainless steels with molten salt used in concentrated solar power plants

Crevice Corrosion Behavior of Stainless Steels in a Flue Gas Desulfurization Environment

Crevice Corrosion Behavior of Stainless Steels in a Flue Gas Desulfurization Environment

Effect of oxidizing ions on the corrosion behavior of SiN stainless steel in high-temperature nitric acid solution

The oxidizing ions, abundantly existing in spent fuel reprocessing process, play a vital role in the corrosion behavior of stainless steels due to the inherently high electrode potential. However, the systematic research on the effect of these ions on the corrosion mechanism of stainless steels in high-temperature nitric acid media is rarely reported. Herein, the electrochemical behavior and the passive film characteristics of SiN stainless steel in hot nitric acid solution containing different ions with various concentrations were investigated. The oxidizing Cr6+, V5+ and Ce4+ affected both the anodic and the cathodic reactions, while the non-oxidizing Fe3+ only changed the cathodic reactions. Meanwhile, the passive film characteristics of SiN stainless steel are partly altered with the change in ion concentration, and the passive film primarily consisted of Fe2O3, Cr2O3, Cr(OH)3 and silicate. The existence of silicate with high chemical stability improved the protection of passive film, displaying a high resistance to intergranular corrosion in the transpassive domain. In addition, a critical concentration phenomenon was observed in nitric acid with oxidizing ions, and the deposition theory was proposed to reveal the mechanism of critical concentration phenomenon.

The effect of zinc addition on corrosion behavior of stainless steels with different phases in simulated PWR primary water

In this study, corrosion behaviors of commercial austenitic, ferritic stainless steels, and duplex stainless steel with B2-NiAl were investigated in simulated PWR primary water environments with and without zinc addition. In addition, electrochemical methods such as EIS and Mott-Schottky analyses were utilized to investigate oxide layers. Zinc was incorporated mainly into chromium-rich spinel. For austenitic stainless steel, improvement on corrosion was observed, however other stainless steels showed less effects by zinc addition. It was found that beneficial effect of zinc addition depends on chromium content of matrix and the presence of low chromium-containing phase reduced beneficial effect.

Tailoring surface properties, biocompatibility and corrosion behavior of stainless steel by laser induced periodic surface treatment towards developing biomimetic stents

Laser-Induced Periodic Surface Structures (LIPSS) holds great potential for regenerative biomedicine. Creating highly precise LIPSS enables to generate biomimetic implant surfaces with improved properties. The present study focuses on the fabrication and investigation of laser-treated stainless steel samples with applied linear LIPSS patterns with grooves made by means of a picosecond laser system using wavelengths of 1064 nm and 532 nm. To investigate properties of the laser-treated surfaces and to understand the basics of cell-surface interactions between the LIPSS and human Umbilical Cord Mesenchymal Stem Cells (UCMSC), flat stainless steel samples with various applied nanopatterns were used. Such LIPSSs demonstrated higher surface roughness, good biocompatibility, lower wettability and higher corrosion resistance compared to the untreated (polished) specimens. The surface roughness of laser-treated samples was in microscale that enabled adhesion and migration of endothelial cells, thus increasing the likelihood for endothelialisation. This thereby could reduce the chances for the development of Late Stent Thrombosis (LST) and In-Stent Restenosis (ISR). Furthermore, laser textured surfaces demonstrated an environment supportive for cell attachment, proliferation and alignment with the nanogroves. Therefore, application of the biomimetic nanopatterns could help to overcome frequent post-surgery complications after the stent implantation.

Understanding the Mechanism of Cs Accumulation on Stainless Steel Suspended in Nuclear High-Level Liquid Waste.

In a nuclear facility, the surface of stainless steels (SS) was found to be contaminated during the processing of radioactive liquid waste. Their safe and secure disposal is highly challenging to the nuclear industry. If the fundamental property of steel corrosion could be evaluated, successful decontamination and effective decommissioning strategies could be planned. Although individual radionuclide contamination behavior on SS metal was studied, till date, SS contamination behavior under the exposure of high-level liquid waste (HLLW) was unexplored. In view of this, investigations were carried out to understand the nature of contamination in SS 304L alloy under the exposure of simulated HLLW (SHLLW). For understanding of radionuclide adsorption behavior on structural materials, scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy have been utilized for SS 304L. The solutions were analyzed using inductively coupled plasma optical emission spectroscopy to calculate the changes in the elemental composition of the solution and corrosion behavior of SS. The passivation of SS coupons was observed in the presence of HNO3 due to enrichment of Cr at the surface. The deposition of Cs and Mo was noticed, while SS coupons were exposed to SHLLW. At 3 M HNO3 and room temperature, the SS surface is mildly passivated by Cr enrichment by formation of a Cr oxide layer on the SS surface. However, the passive layer was not thick enough to attenuate the signal from the substrate below the passivated layer. Hence, Fe0 and Cr0 were also found along with Cr3+ and Fe3+ (in small quantity). When temperature was elevated to 70 °C, the SS surface was completely covered with the Cr oxide layer, and hence no Cr0 signal was observed. The small signal of Fe0 indicated that the signal from the substrate surface is present below the passive layer. During the passivation process, Cr diffused toward the passive layer, thereby producing a Cr-depleted layer below the passive layer (Cr0 signal was not seen). In the case of SHLLW at 70 °C, the surface was fully covered by Cr3+, Mo6+, and Cs+. Fe and Ni were not observed at all. This finding will help to design an effective corrosion inhibitor and suitable decontamination agent. In addition to that, this information was found to be useful in designing high-performance novel and modern age reactor materials with improved characteristics.