Stainless Steel In Seawater Research Articles

Exploring the Effect of Lanthanum on the Corrosion Resistance and Antimicrobial Properties of Fe–20Cr–18Ni–6Mo–0.8Cu–0.2N Stainless Steel in Seawater

This study investigates the effects of lanthanum (La) on the microstructure and corrosion resistance of Fe–20Cr–18Ni–6Mo–0.8Cu stainless steel in seawater. Microstructural analysis shows that La addition refines grain size and alters precipitated phases. X‐ray diffraction confirms austenitic structures, while transmission electron microscopy reveals the formation of Cu5La compounds and ferrite/σ phases. Electrochemical tests indicate that the sample without La has the highest open‐circuit potential and best corrosion resistance in nonseawater conditions. However, after 16 days of seawater exposure, the 0.5 wt% La sample exhibits superior corrosion resistance with a corrosion rate of 0.0175 mm/a, while higher La contents (1.0 wt% and 1.5 wt%) leads to poor corrosion resistance and large corrosion craters. Scanning electron microscopy confirms minimal surface corrosion for the 0.5 wt% La sample. In sulfate‐reducing bacteria environments, La enhances corrosion resistance, except for pitting corrosion observed in the 1.5 wt% sample. Scanning Kelvin probe force microscopy shows minimal surface potential fluctuation (from −30 to 10 mV) for the 0 wt% La sample, indicating the best corrosion resistance. This study provides insights into the role of rare earth elements in super austenitic stainless steels.

Effect of Surface Roughness on the Corrosion Behavior of 304 Stainless Steel in Seawater

Effect of Surface Roughness on the Corrosion Behavior of 304 Stainless Steel in Seawater

Numerical Analysis of Stainless Steel of Crevice Corrosion Initiation Behavior with Varying External Potentials and Initial Crevice Gaps

The potential, current density, pH, and crevice profile distribution within the crevice structure of stainless steel in seawater were numerically analyzed. The crevice corrosion phenomena were mathematically modeled with the initial boundary value problem of diffusion and static electrical field, respectively. This initial boundary value problem was discretized using a finite difference method. The predicts of the crevice corrosion behaviors, set for various external potentials and initial crevice gaps, were classified into three categories: the pitting type, the active type, and no corrosion. The pitting type crevice corrosion was predicted to occur in conditions where the external potentials were noble and the initial crevice gaps were narrow. The active type crevice corrosion was predicted to occur in conditions where the external potentials were less noble and the initial crevice gaps were narrow. The range of external potential conditions where crevice corrosion was predicted not to occur increased in conditions with wide initial crevice gaps. Crevice corrosion was predicted to occur at all external potentials in conditions where the initial crevice gaps were 2 μm or less.

REASON OF PITTING CORROSION OF MARTENSITIC STEELIN SEA WATER

Abstract. The assumption that corrosion of products from X17 martensitic stainless steel in seawater occurs due to incomplete oxidation of chromium atoms in cells on the surface of the products is made in the presented work. Incomplete oxidation of chromium atoms occurs in the cells of X17 steel. This is due to the fact that oxygen molecules at temperatures up to 350 °C not having enough energy for chemical interaction with trivalent chromium atoms entering the cubic body-centeredcells of martensitic stainless steel. There is a significant decrease in the corrosion rate after placing X17 stainless steel products in 5% iodine solution in ethanol after pre-treatment of the product surface with active forms of oxygen. The treatment was carried out during 12 hours with chemically active forms of oxygen (ozone and singlet oxygen) at a temperature of 350 °С. Most of the chromium atoms on the surface of X17 steel samples were completely oxidized as a result of 12 hours exposure to highly active forms of oxygen. The density of the oxide passivation layer on the surface of the products increased significantly as a result of the formation of new bonds CHROMIUM -OXYGEN -CHROMIUM. This resulted in increased corrosion resistance. The rate of interaction with an alcohol solution containing halogen ions was reduced by 71% for the samples with the oxide passivation layer compared to samples of untreated X17 steel.

EFFECT OF MICRO-TEXTURES AND CrAlSiN COATINGS ON THE FRICTION AND WEAR PROPERTIES OF 316L STAINLESS STEELS IN SEAWATER

This paper aims to provide a method for improving the tribological properties of 316L stainless steels in seawater. During the experimental process, laser texturing technology was used to create biomimetic micro-textures inspired by turtle shell patterns on the 316L stainless steel surfaces. Then, CrAlSiN coating was deposited on the textured surface using the physical vapor deposition (PVD) technique, allowing us to study the frictional properties of the samples in both atmospheric and seawater environments. The results showed that, compared to polished 316L stainless steel, the specimens treated with micro-texture and CrAlSiN coating exhibited a reduction in wear rate by 52.1% and 71.8% under atmospheric and seawater friction conditions, respectively. Under atmospheric friction conditions, the micro-textures had a limited effect on reducing the friction of the 316L stainless steel substrate. However, the CrAlSiN coating, due to its excellent mechanical properties, significantly improved the wear resistance of the 316L stainless steel. Under seawater friction conditions, the continuous CrAlSiN coating played a role in reducing 316L stainless steel wear and seawater corrosion. At the same time, the micro-textures acted as reservoirs for wear debris and seawater, forming a more stable seawater lubricating film and reducing the friction coefficient. Therefore, the synergistic effect of the CrAlSiN coating and biomimetic micro-textures demonstrated remarkable improvement in the tribological performance of 316L stainless steel in seawater environments.

Crevice Corrosion of High-Grade Stainless Steels in Seawater: A Comparison Between Temperate and Tropical Locations

The corrosion risk for stainless steel components is not the same in all seawaters, with more failures generally reported in tropical seas. In this study, the influence of biofilm on electrochemical behavior and corrosion resistance of passive films of high-grade alloys was studied in different seawaters, including temperate seawater (France-Brest, North Atlantic Ocean), tropical seawater (Malaysia-Kelatan, Meridional China Sea), and intermediate conditions in terms of temperature (Brazil-Arraial do Cabo, South Atlantic Ocean). The stabilized open-circuit potentials and the polarization behavior of high-grade stainless steels were measured as a function of temperature in all of the tested field marine stations, providing quantified data and direct comparison of the biofilm-enhanced corrosion risks. Significant differences were measured in tropical and in temperate seawaters in heated conditions. Above 37°C, the biofilm activity was much more pronounced in tropical seawater compared to Atlantic Ocean sites, leading to much higher localized corrosion risk. Crevice corrosion of eight high-grades passive alloys was also studied with the use of crevice formers specifically developed for tube geometries. Duplex UNS S32205, superduplex UNS S32750, hyperduplex UNS S33207 and S32707, and 6Mo stainless steels UNS S31266 have been evaluated together with Ni-based alloys UNS N06845 and N06625. In the more severe conditions, the high-grade alloys UNS S32707 and the 6%Mo UNS S31266, both with pitting resistant equivalent number (PREN) around 50, showed better performance than commonly used superduplex UNS S32750 and UNS S39274 (PREN 40). The corrosion results are discussed regarding the monitored biofilm-induced depolarization measured in the different test conditions.

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.

Fretting Wear Characteristics of SLM-Formed 316L Stainless Steel in Seawater

The fretting wear characteristics of two different energy density 316L stainless steels formed by selective laser melting (SLM) under different friction conditions are studied. The image method was used to study the porosity of two samples with different energy densities (46.88 J/mm3, 98.96 J/mm3) formed by SLM. The dynamic wear test, respectively, evaluates its wear morphology and wear depth under three conditions: dry friction, distilled water, and an 3.5% NaCl solution. The porosity of the samples with SLM forming an energy density of 46.88 J/mm3 and 98.96 J/mm3 are 7.66% and 1.00%, respectively. Under the three conditions, the friction coefficient and wear depth of the samples with high energy density are smaller than those of the samples with low energy density; the friction of the samples with two energy densities in aqueous solution is faster than dry friction in air and tends to be stable. The friction coefficient in 3.5% NaCl solution is the smallest; when the energy density is constant, the wear depth of the fretting wear is the largest under dry friction and the smallest in distilled water. Under dry-friction conditions, the wear mechanisms of fretting wear are mainly oxidative wear and adhesive wear. In the fretting wear in the distilled water and the 3.5% NaCl solution, both wear mechanisms are abrasive wear and fatigue wear.

Effect of Cu2+ on Corrosion Behavior of A106B Carbon Steel and 304L Stainless Steels in Seawater.

The corrosion behaviors of A106B carbon steel and 304L stainless steel (SS) in seawater with different Cu2+ concentrations were studied by the immersion test and the potentiodynamic polarization test. The results showed that with the increasing Cu2+ concentration, the mass lot rates of A106B and 304L SS all increased in the immersion test, and compared with A106B, the mass lot rates of 304L SS were all smaller. In the potentiodynamic polarization test, following the concentration of Cu2+ increased, the corrosion potential of A106B firstly shifted negatively; then, when Cu2+ increased to 100 ppm, the polarization curve moved to the upper right direction; namely, both the corrosion potential and corrosion electrical density increased. The corrosion potential of 304L SS increased with the increasing Cu2+, and the passive region was reduced; the pitting sensitivity improved.

Anticorrosive and Microbial Inhibition Performance of a Coating Loaded with Andrographis paniculata on Stainless Steel in Seawater.

With the trend for green technology, the study focused on utilizing a forgotten herb to produce an eco-friendly coating. Andrographis paniculata or the kalmegh leaves extract (KLE) has been investigated for its abilities in retarding the corrosion process due to its excellent anti-oxidative and antimicrobial properties. Here, KLE was employed as a novel additive in coatings and formulations were made by varying its wt%: 0, 3, 6, 9, and 12. These were applied to stainless steel 316L immersed in seawater for up to 50 days. The samples were characterized and analyzed to measure effectiveness of inhibition of corrosion and microbial growth. The best concentration was revealed to be 6 wt% KLE; it exhibited the highest performance in improving the ionic resistance of the coating and reducing the growth of bacteria.

Effect of sliding wear and electrochemical potential on tribocorrosion behaviour of AISI 316 stainless steel in seawater

Sliding tribocorrosion behaviours of AISI 316 stainless steel were investigated against alumina ball in natural seawater environment (SWE) under 5 N loads. OCP (open circuit potential), potentiostatic (−1 V and 0.3 V) and potentiodynamic measurements were enforced to understand the influence of the sliding wear and electrochemical potential on tribocorrosion behaviours of AISI 316 stainless steel in SWE. Tribocorrosion experiments were conducted with a ball-on-disk type reciprocating tribometer integrated with the three-electrode potentiostat. The wear track surfaces were examined by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and optical profilometry. Mechanical effects reduced corrosion potential under both OCP and potentiodynamic scans in tribocorrosion conditions. Ploughing effects on the wear track were evident at the OCP and −1 V potential because of the predominance of mechanical effects. Pits were determined to develop due to the formation of the galvanic couple between worn and unworn surfaces after the tribocorrosion test, which was conducted under 0.3 V potential. The reduction of the contact area because of the pits and the lubricating effect of the oxides on the surface caused the lowest coefficient of friction (COF) in the wear zone at 0.3 V potential. Besides, COF obtained under −1 V cathodic protection potential (0.35) was less than in OCP condition (0.37) since it only occurred by the wear effects. The study also revealed that material loss from the wear track increased from cathodic potential towards anodic potential.

Reduction of potential ennoblement of stainless steel in natural seawater by an ecofriendly biopolymer

The effect of biofilm formation on passive stainless steel in seawater environments is of primary importance since it leads to potential ennoblement of surfaces and subsequently to localized corrosion such as pitting and crevice corrosion. This study aims at developing an ecofriendly alginate biopolymer containing both non-toxic calcium and a limited amount of biocidal zinc ions which inhibits this effect. For this purpose, calcium alginate containing less than 1 % of zinc ions localized in the vicinity of the steel surface in natural and renewed seawater is demonstrated to reduce significantly the ennoblement process of steel. After 1 month of immersion, a mass loss of only 4 % of the active material is observed authorizing thereby long-term protection of steel in real environment.

Influence of dissolved oxygen content on the bacteria‐induced ennoblement of stainless steels in seawater and its consequence on the localized corrosion risk

AbstractThe ennoblement of stainless steel (e.g., the increase of open circuit potential [OCP]) is associated with bacterial colonization. This increases the risk of localized corrosion as the critical pitting/crevice potential can be overcome, especially for lower grade stainless steel. In this study, we assessed the influence of dissolved oxygen content (DOC) on the crevice corrosion of duplex and super duplex stainless steels. In addition, we used DNA amplicon sequencing to identify the bacteria most likely associated with the ennoblement. Above approximately 100 parts per billion (ppb) of dissolved oxygen, the ennoblement of OCP was observed leading to an increased risk of localized corrosion. Below approximately 100 ppb of dissolved oxygen, no ennoblement occurred and the risk of localized corrosion was reduced. We identified certain hydrocarbon‐degrading bacteria whose presence correlated with the ennoblement of super duplex stainless steel at saturated DOC. The role of these bacteria is not clear yet, but their distribution indicates a possible involvement in stainless steel ennoblement in seawater.

The Corrosion of Cast Duplex Stainless Steels in Seawater and Sour Brines

Modern duplex stainless steels have been in use since the early 1970s and cast versions of the wrought alloys were soon in demand for pumps and valves. Since that time a range of cast duplex stainless steels have been developed with a wide range of compositions, but all with approximately 50/50 austenite/ferrite phase balance and deliberate additions of nitrogen. This paper presents some comparative corrosion data on a range of cast duplex stainless steels, mainly in seawater. The differences in performance related to composition and microstructure are discussed. Corrosion data in lower chloride brines are also presented to show the limits of use of some lower alloyed duplex materials. In addition to oxidizing chloride solutions, some data are presented on cast duplex stainless steels in reducing brines containing H2S, where the main corrosion problem is sulfide stress corrosion cracking. Finally, the importance of using a suitable technical specification, over and above ASTM, combined with selecting a suitably skilled foundry in order to obtain satisfactory castings is discussed.

The effect of ceramic friction pairs on the tribocorrosion behavior of AISI 304 stainless steel in seawater

PurposeThis paper aims to study the tribocorrosion behavior of 304 stainless steel (SS) sliding against SiC and Si3N4 counterparts in artificial seawater.Design/methodology/approachThe tribocorrosion behavior of 304SS sliding against SiC and Si3N4 balls in artificial seawater has been investigated. The tests were conducted using a ball-on-disk rig equipped with an electrochemical workstation. The friction coefficient, surface morphology, wear volume and current density were determined.FindingsWhen 304SS sliding against SiC ball, a smooth surface with a silica layer was formed on the top, which led to the low friction coefficient, current density and small wear volume. For 304SS-Si3N4 tribo-pair, a lot of metal debris was scattered on contact surfaces leading to high friction coefficient, current density and big wear volume.Research limitations/implicationsThis research suggests that the lubrication effect of silicon-based ceramics is related to counterpart specimen in artificial seawater.Practical implicationsThe results may help us to choose the appropriate ceramic ball under seawater environment.Originality/valueThe main originality of the work is to reveal the tribocorrosion behavior of 304SS sliding against SiC and Si3N4 balls, which help us to realize that the Si3N4 ball as water-lubricated ceramics could not exhibit lubrication effect when coupled with 304SS in artificial seawater.

Corrosion Inhibition on Austenitic Stainless Steel in Sea Water Using Onion (Allium Cepa) as Corrosion Inhibitor

Corrosion Inhibition on Austenitic Stainless Steel in Sea Water Using Onion (Allium Cepa) as Corrosion Inhibitor

Corrosion and Cavitation Resistance of High-Strength Austenitic Nitrogen Stainless Steels in Seawater

Abstract—The corrosion and cavitation resistance of high-strength economically alloyed nitrogen-bearing chromium–nickel–manganese austenitic C10Cr19Mn10Ni6Mo2N and C09Cr19Mn10Ni6Mo2Cu2N stainless steels in seawater is compared experimentally with the properties of chromium–nickel C04Cr18Ni9 and C04Cr18Ni9N steels. The resistance to pitting corrosion is tested by a chemical method in a 100-g/L FeCl3 · 6H2O solution. The overall corrosion resistance is assessed by tests in synthetic seawater (3% NaCl). The cavitation resistance in seawater is tested by means of a high-intensity cavitation system based on a Hielscher Ultrasonic UIP 1000hd ultrasound unit in 3% aqueous NaCl solution (vibration frequency 20 kHz, power 1000 W, amplitude 25 μm) for 8–36 h. After cavitation treatment, the damage and change in microhardness at the sample surface is estimated, as well as the change in phase composition and mass of the samples in the tests. According to the tests, C10Cr19Mn10Ni6Mo2N and C09Cr19Mn10Ni6Mo2Cu2N steels are free of pits after exposure to seawater and iron-chloride solution. The overall corrosion rate is lower than for chromonickel Cr18Ni9 steel. Ultrasonic cavitation may lead not only to surface damage by erosion and intensification of local corrosion but also to change in the physical and mechanical properties on account of cold working and phase transformations. The resistance to ultrasonic cavitation in seawater is greater for C10Cr19Mn10Ni6Mo2N and C09Cr19Mn10Ni6Mo2Cu2N steels, containing thermally and mechanically stable austenite, than for chromonickel steels, especially C04Cr18Ni9, which is weaker and less stable. For example, after 36-h cavitational treatment in seawater, significant changes in state are seen in C04Cr18Ni9 and C04Cr18Ni9N steels: considerable damage (etching) and hardening of the surface and also the formation of a small quantity of martensite in C04Cr18Ni9 steel. For C10Cr19Mn10Ni6Mo2N and C09Cr19Mn10Ni6Mo2Cu2N steels, the tests indicate only slight change in state of the surface and hardening.

Effect of displacement amplitude on fretting wear of 304 stainless steel in air and sea water

AbstractThe fretting wear behaviours of 304 stainless steel at different displacement amplitudes were investigated by using a SRV‐IV fretting tester in air and sea water, respectively. In air, the friction coefficient as well as the fretting damage of 304 stainless steel increased with the increase of displacement amplitude, and the fretting regime changed from partial slip regime to gross slip regime. Correspondingly, the wear mechanisms transformed from local fatigue and slight oxidation to the combination damages of adhesion wear, abrasive wear, and oxidation. Compared with the dry friction conditions, sea water had a strong effect on fretting behaviour of 304 stainless steel. Adhesion wear was effectively suppressed due to the cooling and lubrication effect of sea water. Therefore, friction coefficient and wear depth decreased significantly. And the damages of 304 stainless steel in sea water were mainly caused by abrasive wear, slight adhesion wear, and corrosion wear.

Significance of an in-situ generated boundary film on tribocorrosion behavior of polymer-metal sliding pair

Polymer composites have a high potential for applications as tribo-materials exposed to sea water owing to their self-lubrication characteristic and high chemical stability. In the present work, tribological behaviors of polyetheretherketone (PEEK) composites rubbing with stainless steel in sea water were explored using a pin-on-disc tribometer integrated with a potentiostat for electrochemical control. It was demonstrated that further adding 5 vol% hexagonal boron nitride (h-BN) nanoparticles into PEEK reinforced with short carbon fibers (SCF) significantly enhanced the wear resistance. Moreover, the stainless steel exhibited significantly enhanced tribocorrosion resistance when rubbing with the hybrid nanocomposite, in comparison to the sliding against PEEK filled only with SCF. Nanostructures of the boundary films formed on the steel surface were comprehensively investigated. It was manifested that tribo-chemistry products of h-BN, i.e. H3BO3 and B2O3, were arrayed in a closely packed boundary film. It seems that inclusion of layer-structured H3BO3 and B2O3 improved the resilience of the boundary film. The continuous boundary film covering the steel surface provided a lubrication effect and strengthened the passivation layer. A new route for enhancing simultaneously tribological and corrosion resistance of polymer-metal pairs by controlling in-situ tribo-chemistry was thus proposed.

Tribocorrosion behaviors of multilayer PVD DLC coated 304L stainless steel in seawater

The multilayer DLC coating was successfully fabricated on the surface of 304L stainless steel and silicon wafers by unbalanced magnetron sputtering technology. The tribocorrosion tests were carried out in a triboelectrochemical cell using a ball-on-plate tribometer integrated with a potentiostat for electrochemical control. Results showed that the open circuit potential (OCP) and corrosion potential (Ecorr) of 304L substrate presented great fluctuation. However, the OCP and Ecorr values of the multilayer DLC coating remained relatively stable during these tests. Meanwhile, the friction coefficient decreased and the wear-loss increased with the polarization potential increased from −1 to 0.5V. In addition, with an increase in polarization potential, the mechanical wear decreased obviously and the corrosion-induced wear gradually occupied a dominant position for 304L substrate, nevertheless, the mainly volume loss of the multilayer DLC coating was mainly attributed to pure mechanical wear. Thus, the tribocorrosion resistance of the multilayer DLC coating was superior to 304L substrate in seawater, manifesting its good potential as a protective material for marine industry.