Corrosion Of Stainless Steel Research Articles

Role of Hydrogen in Metal Oxidation—Implication to Irradiation Enhanced Corrosion of Ni-Based Alloys and Stainless Steels in High Temperature Water

Hydrogen plays various roles in metals or at metal–environment interfaces. Well known effects on metals are hydrogen embrittlement, hydrogen enhanced local plasticity, hydrogen enhanced strain-induced vacancy, hydrogen accelerated oxidation, hydrogen-induced creep, and their synergy. In this study, the potential roles of hydrogen in materials degradation are demonstrated and studied by two different tests. One is the high temperature oxidation of Ni-based alloy in various environments with hydrogen penetration, and the other is the effects of neutron flux/fluence on the oxidation kinetics and SCC of 316L and 316LN stainless steels, regarding a possible role of transmuted H from N. The results emphasize that the hydrogen either permeated into metals from surrounding environments, such as high temperature water or gaseous hydrogen, or generated in metals by nuclei transmutation, such as hydrogen transmuted from N atoms in metals, which can promote metal oxidation through multiple mechanisms. Apparently, the oxidation/corrosion phenomenon is a synergy of sub-mechanisms. For instance, dissolved hydrogen (DH) is usually believed to slow down the corrosion process for lowering the open circuit potential (OCP). However, H also facilitates the transport of the cations in oxide, thereby accelerating the corrosion process. In this bi-mechanism system, two different, contradictory mechanisms work and exist simultaneously. Therefore, whether the metallic materials are benefited or degraded by the H during its oxidation process depends on which sub-mechanism is dominant. Namely, hydrogen can play the role an oxidant in the metal and metal/oxide interface to pre-oxidize metal elements, such as Cr, Ni, and Fe, and possibly promote inward oxygen diffusion and the oxidation rate at the interface. Moreover, hydrogen may play a role as a reductant in oxides where existing oxides can be reduced. Then, the protective capability of oxides will be decreased to result in corrosion acceleration at the metal–oxide interface. These phenomena were observed in Ni-based alloy and possibly austenitic stainless steel containing N such as 316LN SS. This work demonstrates a part of the role of hydrogen on oxidation, and more extensive and systematic work is needed to delineate the role of hydrogen on oxidation with and without irradiation.

Dynamics of microbial communities on the corrosion behavior of steel in freshwater environment

In a freshwater environment, accelerated corrosion of carbon and stainless steels is frequently observed. Here, an immersion study was conducted using nine types of steels in a freshwater pool for 22 mo. Accelerated corrosion was observed in carbon and Cr-containing steels and cast iron, whereas no visible corrosion was observed in stainless steels, even after 22 mo. Microbial community analysis showed that, in general corrosion, Fe(II)-oxidizing bacteria were enriched in the early corrosion phase, Fe(III)-reducing bacteria increased in the corrosion-developing phase, and sulfate-reducing bacteria were enriched in the corrosion products during the final corrosion phase. In contrast, in the 9% Cr steel with localized corrosion, the family Beggiatocaea bacteria were particularly enriched. These microbial community compositions also differed from those in the water and sediment samples. Therefore, microbial communities are drastically altered with the progression of corrosion, and iron-dependent microbial energy metabolism contributes to an environment that enables the enrichment of other microorganisms.

Investigation on Effects of Avocado Extract as Eco-friendly Inhibitor for 201 Stainless Steel corrosion in Acidic Environment

Investigation on Effects of Avocado Extract as Eco-friendly Inhibitor for 201 Stainless Steel corrosion in Acidic Environment

The corrosion characteristics of SS316L stainless steel in a typical acid cleaning solution and its inhibition by 1-benzylimidazole: Weight loss, electrochemical and SEM characterizations

Acid cleaning, an inevitable industrial practice used to descale chemical reactors, usually causes serious corrosion attack on underlying alloy substrates. Ameliorating this phenomenon requires the addition of effective corrosion inhibitors into the acid solution. Current global regulations encourage environmentally–benign molecules as corrosion inhibitors. Consequently, 1-benzylimidazole has been investigated for its inhibitive characteristics against the corrosion of SS316L stainless steel in a typical acid cleaning solution containing 2 % HCl + 3.5 % NaCl. Weight loss measurements confirm that the corrosion inhibition property of 1-benzylimidazole increases with concentration but depreciates with increased temperature. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) measurements confirm that 1-benzylimidazole adsorb on the stainless steel surface to isolate its surface from the acid solution. 1-benzylimidazole is a mixed-type inhibitor with greater anodic influence, and its adsorption enhances the formation and protectiveness of a passive film. Weight loss and the electrochemical measurements agree to an average inhibition efficiency > 70 % at 1000 ppm. The inhibitor adsorbs via physisorption and obeys the Temkin isotherm model. SEM surface characterization confirm the ability of 1-benzylimidazole to protect the surface microstructure of the stainless steel during the corrosion.

Wear, Corrosion, and Biocompatibility of 316L Stainless Steel Modified by Well-Adhered Ta Coatings

Wear, Corrosion, and Biocompatibility of 316L Stainless Steel Modified by Well-Adhered Ta Coatings

Effect of test media on the crevice corrosion of stainless steel by sulfate reducing bacteria

The potential for crevice corrosion of UNS30400 stainless steel in the presence of sulfate-reducing bacteria (SRB) was studied in different media. Immersion studies found crevice corrosion to occur in test media supplemented with high chloride levels and SRB present for crevice gaps of ~3 μm. Electrochemical measurements showed high susceptibility to corrosion in this particular medium, demonstrated by a negative shift of open circuit potential, increased corrosion current and the lowest passivity breakdown potential. Overall, the results showed that test media can play a critical role in the crevice corrosion of stainless steel in the presence of SRB.

Inhibition Efficiency of Erdosteine Drug for 304L Stainless Steel Corrosion and Its Solvation Thermodynamic Parameters

Inhibition Efficiency of Erdosteine Drug for 304L Stainless Steel Corrosion and Its Solvation Thermodynamic Parameters

Direct microbial electron uptake as a mechanism for stainless steel corrosion in aerobic environments

Shewanella oneidensis MR-1 is an attractive model microbe for elucidating the biofilm-metal interactions that contribute to the billions of dollars in corrosion damage to industrial applications each year. Multiple mechanisms for S. oneidensis-enhanced corrosion have been proposed, but none of these mechanisms have previously been rigorously investigated with methods that rule out alternative routes for electron transfer. We found that S. oneidensis grown under aerobic conditions formed thick biofilms (∼50 µm) on stainless steel coupons, accelerating corrosion over sterile controls. H2 and flavins were ruled out as intermediary electron carriers because stainless steel did not reduce riboflavin and previous studies have demonstrated stainless does not generate H2. Strain ∆mtrCBA, in which the genes for the most abundant porin-cytochrome conduit in S. oneidensis were deleted, corroded stainless steel substantially less than wild-type in aerobic cultures. Wild-type biofilms readily reduced nitrate with stainless steel as the sole electron donor under anaerobic conditions, but strain ∆mtrCBA did not. These results demonstrate that S. oneidensis can directly consume electrons from iron-containing metals and illustrate how direct metal-to-microbe electron transfer can be an important route for corrosion, even in aerobic environments.

Corrosion susceptibility behavior in 12Cr–1Mo martensitic stainless steel welded by SAW process and the effect of δ-ferrite in the HAZ

Pitting corrosion in stainless steel (SS) is a punctual defect that promotes fatigue and cracks propagation. Martensitic steel of steam turbine is exposed to the thermal cycle of welding, high pressures, and corrosive environments in the heat-affected zone (HAZ). The presence of δ-ferrite in HAZ causes crystalline grain boundaries sensitization and reduces corrosion resistance. This research evaluated the corrosive effect of NaCl, NaOH, and H2SO4 in critical welding regions (BM, HAZ, FZ) by analyzing potentiodynamic curves, EIS, and mass loss calculation. The δ-ferrite in the HAZ promotes an increase in the corrosion rate in the NaCl and H2SO4 derivatives of the corrosion products formed. Furthermore, the mass loss in the HAZ was more significant than that in the BM and FZ. Despite having a lower Cr content in the FZ.

Effect of hydrostatic pressure on the pitting corrosion of 17-4PH martensitic stainless steel

The effects of hydrostatic pressure on the performance of passive film and the pitting growth process of 17-4PH martensitic stainless steel (17-4PH SS) were investigated by electrochemical measurements and stochastic theory. The results revealed that the growth rate and compactness of the passive film were changed by hydrostatic pressure, which inhibited the diffusion of point defects in the passive film and enhanced the protection performance of the passive film. The change of the performance of the passive film affects the pitting nucleation, metastable pitting process and reduces the transition probability from the metastable pitting to the stable pitting, which eventually leads to the decrease of pitting sensitivity of 17-4PH martensitic stainless steel.

Study on Stress Corrosion Properties of 1Cr17Ni2 Stainless Steel

1Cr17Ni2 stainless steel is used in aviation, ships, machinery, and other fields. However, stress corrosion will lead to its strength reduction, thus failure. In this paper, we studied the stress corrosion resistance of 1Cr17Ni2 stainless steel bolts and nuts using fasteners’ stress corrosion test method and fasteners’ stress corrosion test method in a simulated environment with the accelerated stress corrosion test method of fasteners. The influence of seawater concentration, temperature, stress, test duration, and other parameters was fully considered during the test. The test results showed that 1Cr17Ni2 stainless steel would appear to stress corrosion crack under a specific corrosive environment, but the occurrence probability was not high. Therefore, in the complex seawater salt fog environment, the stress corrosion of 1Cr17Ni2 stainless steel cannot be ignored, which provides a practical reference for applying 1Cr17Ni2 stainless steel in a complex environment.

Numerical Simulation of Crevice Corrosion of Stainless Steel–Titanium in NaCl Solution

A multiphysics model based on the finite element method was adopted, emphasizing a deeper insight into the rarely studied crevice corrosion behavior of stainless steel and titanium overlapping. The model takes into account damage due to corrosion inside the crevice, different species transportation, local electrochemical reactions, homogeneous reactions in the electrolyte, and formation of a corrosion product and its influence on electrochemical reaction. The simulation results show that the location of the greatest attack for stainless steel is at the crevice opening; this finding is consistent with the IR drop theory. The potential increases gradually from the tip to the opening of the crevice, and the current changes smoothly following a sharp rise at the opening. The minimum and maximum values of pH and Cl− concentration are both in the middle and opening of the crevice. The influence of the crevice size on corrosion is also discussed in detail.

Corrosion and antimicrobial behavior of stainless steel prepared by one-step electrodeposition of silver at the grain boundaries

Introducing Ag to the surface is a common means to obtain an antibacterial product. However, the poor adhesion between coating and substrate often results in a non-durable antibacterial performance. Herein, we developed a simple one-step pulse-reverse electrodeposition method to introduce Ag particles into the grain boundaries of 304 stainless steel (304 SS) surface for a stable and long-acting antibacterial application. In the present method, the grain boundary was preferentially corroded as the potential “seat” for Ag particles, and the surface content of Ag upgraded to 0.57 at.% by optimizing the electrolyte, electrodeposition temperature, reaction time, and current density. Without deteriorating the corrosion resistance of the substrate, the 304 SS with Ag particles demonstrated considerable antibacterial properties against Escherichia coli and Staphylococcus aureus even after ultrasonic treatment or accelerated abrasion. Consequently, the current study proposes a facile strategy for the production of durable antibacterial stainless steel.

Influence of Nickel on Niobium Nitride Formation in As-Cast Stainless Steels

The influence of the nickel content and cooling rate on niobium nitride precipitation in as-cast stainless steels were analysed. Niobium microalloying is important for mechanical properties and the prevention of intergranular corrosion in stainless steels. However, coarse precipitates can negatively affect steel properties. The precipitation of NbN depends on thermodynamic conditions, which are dictated by the chemical composition and temperature. The thermodynamic computations were used to estimate niobium nitride precipitation. Additionally, segregation models were used to predict precipitation. Three steel batches with different nickel contents (9 wt.%, 4.7 wt.%, and 0.16 wt.%) were prepared in an induction furnace and cast into sand moulds. The polished and etched samples were examined with an optical microscope, followed by a more detailed examination using a scanning electron microscope. An automatic scanning electron microscope analysis of the niobium particles was performed to obtain particle number and size distribution. Primary niobium carbonitrides, eutectic phases, and heterogenous nucleations on MnS inclusions were observed. As the proportion of nickel in the solution decreased, the solubility of nitrogen in the melt increased, which is manifested by a lower formation of primary and eutectic niobium carbonitrides, while MnS non-metallic inclusions played an important role in the heterogeneous nucleation.

THE INFLUENCE OF THIN MULTI-LAYER OXIDE COATINGS MADE BY EB-PVD, ON THE CORROSION OF 316 L STAINLESS STEEL

Corrosion is a process of destroying metals (alloys) under the chemical or electrochemical action of the environment. A valuable method to improve the corrosion resistance of metals and alloys working under extreme environments based on protecting the metal substrate with different ceramic materials has been proposed. Experiments were performed by Electron Beam – Physical Vapor Deposition (EB-PVD), for deposition of multi-thin oxide layers of the type: Al2O3 / ZrO2 doped with Y2O3 / La2Zr2O7 / ZrO2 doped with Ce2O3, on 316L stainless steel laminated sheet substrates. The influence of multi-layer oxide coatings on the corrosion of 316L stainless steel was studied by electrochemical corrosion experiments (linear polarization) in NaCl solution of different concentrations (from 0.06M to 0.6M). To highlight the microstructural aspects on the elec-trochemically corroded samples, scanning electron microscopy (SEM) analyses were performed. The coating adhesion was evaluated by scratch test. Complex multi-layer oxide coatings improve the corrosion resistance of stainless steel in dilute NaCl electrolyte solutions (0.06M and 0.2M). In contrast, for more concentrated NaCl solutions (0.4M and 0.6M), these thin multi-layer oxide coatings are more susceptible to corrosion than simple alumina coatings which have higher po-larization resistance and lower corrosion rates.

Volume fraction effect of stainless steel on microstructure, interface, corrosion and wear behavior of stainless steel / aluminum bimetal composites

304 stainless steel (SS)/A356 aluminum bimetal composites were manufactured by vacuum-assisted melt infiltration casting successfully. SS chips with different volume fractions of 35%, 50%, 60%, and 65% were used in a composite structure. Low-cost, environmentally friendly production was achieved by using chips as reinforcing material. Dry sliding ball-on-disc tests were performed against Al2O3 ball under a load of 10 N. Potentiodynamic polarization analysis was carried out in 3.5% NaCl solution. θ (Fe4Al13) and η (Fe2Al5) phases developed at the SS/Al interfaces. Abrasive and adhesive wear predominated worn surfaces, whereas galvanic and pitting corrosion mechanisms originated during potentiodynamic polarization tests. Lower volume fractions of SS chips resulted in microploughing, while their higher amounts caused microcutting during sliding. Moreover, the samples containing 60% and 65% SS failed in the corrosion tests due to the lack of passivation. The most suitable SS ratio was determined to be 50%, considering microstructural, interfacial, tribological, and anti-corrosion features of SS/Al bimetal composites.

Improved saline corrosion and hydrogen embrittlement resistances of superaustenitic stainless steel by PIII nitriding

PIII nitriding was applied to superaustenitic steel to improve wear resistance without compromising pitting and hydrogen embrittlement corrosion resistance. Nitriding at temperatures between 300 °C and 400 °C produced modified layers rich in γN phase and with thicknesses ranging from 1.2 ± 0.1 μm to 4.2 ± 0.1 μm. Nanoindentation tests indicated an increase in hardness up to ∼4 times compared to the untreated sample. The potentiodynamic polarization curves indicated an increase in pitting and crevice corrosion resistance after nitriding. In the PIII 350 °C nitrided sample, Ecorr and Epit increased 50% and 14%, respectively, while current densities icorr and ip decreased by 80% and 77% and crevice volume decreased by 93% when compared to the untreated sample. However, in the nitriding condition at 400 °C, the improvement the resistance to saline corrosion is not so marked was observed as a result of the increased passive current density due to formation of CrN The micrographs of surfaces after cathodic hydrogenation also indicated reduction in hydrogen embrittlement in the PIII 300 °C sample. In the PIII 400 °C sample, the hydrogen embrittlement was identified by the delamination and cracking of the modified layer. Thus, the formation of chromium nitrides must be avoided and only the γN phase must be formed to improve the resistance to hydrogen embrittlement and saline corrosion.

Simultaneous In Situ Imaging of pH and Surface Roughening during the Progress of Crevice Corrosion of Stainless Steel.

Stainless steel plays an important role in industry due to its anti-corrosion characteristic. It is known, however, that local corrosion can damage stainless steel under certain conditions. In this study, we developed a novel measurement system to observe crevice corrosion, which is a local corrosion that occurs inside a narrow gap. In addition to pH imaging inside the crevice, another imaging technique using an infrared light was combined to simultaneously visualize surface roughening of the test piece. According to experimental results, the lowering of local pH propagated inside the crevice, and after that, the surface roughening started and expanded due to propagation of corrosion. The real-time measurement of the pH distribution and the surface roughness can be a powerful tool to investigate the crevice corrosion.

Physical and chemical properties of sea salt deliquescent brines as a function of temperature and relative humidity

Thermodynamic modeling has been used to predict chemical compositions of brines formed by the deliquescence of sea salt aerosols. Representative brines have been mixed, and physical and chemical properties have been measured over a range of temperatures. Brine properties are discussed in terms of atmospheric corrosion of austenitic stainless steel, using spent nuclear fuel dry storage canisters as an example. After initial loading with spent fuel, during dry storage, the canisters cool over time, leading to increased surface relative humidities and evolving brine chemistries and properties. These parameters affect corrosion kinetics and damage distributions, and may offer important constraints on the expected timing, rate, and long-term impacts of canister corrosion.

The Role of Micro Pits in the Initiation Process of Crevice Corrosion of SUS304 Stainless Steel in an Aqueous Chloride Solution

The Role of Micro Pits in the Initiation Process of Crevice Corrosion of SUS304 Stainless Steel in an Aqueous Chloride Solution