Corrosion Resistance Of Stainless Steel Research Articles

Corrosion resistance of austenitic stainless steel using cathodic plasma electrolytic oxidation

Substantial improvement of corrosion resistance of austenitic stainless steel (SS) has been demonstrated with a protective oxide layer formed by the cathodic plasma electrolytic oxidation (CPEO) process. Two distinct layers, a porous-structured outer layer comprising Fe oxides and a compact inner layer comprising Cr oxides, were created on the SS surface after the CPEO process. The thicknesses of the outer and inner layers were approximately 7 μm and 12 μm, respectively, and the oxide layers were fabricated in an exceptionally short time of <30 s. A potentiodynamic polarization analysis exhibited a 65 % decrease in the corrosion current after the formation of the protective oxide layer, verifying the effectiveness of the CPEO treatment on the corrosion resistance of SS. An electrochemical impedance spectroscopy study revealed that the outer layer captured corrosive species due to its porous structure, while the inner layer had high resistance to reactions with corrosive species due to the compact structure of Cr oxides. Additionally, a Rockwell C indentation test demonstrated the robust mechanical property of the protective oxide layer with a strong bonding strength to the substrate.

Effect of heat treatment atmospheres on microstructure evolution and corrosion resistance of 2205 duplex stainless steel weldments

The effects of post heat treatment atmosphere on microstructure and corrosion resistance of duplex stainless steel welded joints were investigated. Post weld heat treatment (PWHT) was carried out with and without protective atmospheres. Nitrogen and argon are used as protective gases individually. Detailed microstructure examination (optical and SEM) demonstrates that nitrides precipitates are highly observed in the welded zones for nitrogen protected samples. An observed drop of ferrite volume fraction in post weld heat treated samples compared with welded samples without heat treatment leading to corrosion resistance enhancement of heat treated welded joints. An exception for using nitrogen as heat treatment atmosphere a decreased corrosion resistance of weldments is investigated due to nitride precipitates. An increase in the weld zone hardness for post weld heat treated samples compared with base alloy. The initial hardness of duplex stainless steel was 286 Hv while average hardness of weld zone was 340, 411, 343, and 391 Hv for as welded, PWHT using air, argon, and nitrogen atmospheres, respectively. Weld zone hardness increased to 33, 44, 20, and 37%. A significant decrease in the ultimate tensile strength and elongation after PWHT. The initial Ultimate tensile strength duplex stainless steel base material was 734.9 MPa while Ultimate tensile strength of the welded joints was 769.3, 628.4, 737.8, and 681.4 MPa for the following conditions: as welded, PWHT using air, argon, and nitrogen atmospheres, respectively.

Improvement in Corrosion Resistance and Interfacial Contact Resistance Properties of 316L Stainless Steel by Coating with Cr, Ti Co-Doped Amorphous Carbon Films in the Environment of the PEMFCs.

In order to obtain films with high corrosion resistance and excellent interfacial contact resistance (ICR) on 316L stainless steel used for bipolar plates in proton-exchange membrane fuel cells (PEMFCs), Cr, Ti co-doped amorphous carbon films were prepared on 316L stainless steel. The preparation method for the coating was magnetron sputtering. The doping amount of the Ti element was controlled by a Cr target and a Ti target current. The change in the structure and properties of the coating after the change from Cr single-element doping to Cr and Ti co-doping was studied. The change rule of the structure and properties of the coating from Cr single-element doping to Cr and Ti co-doping was studied. An increase in the Ti content led to a decreased grain boundary, a flatter surface, and a higher sp2-hybridized carbon content. TiC and CrC nanocrystals were formed in the amorphous carbon structure together. The amorphous carbon films doped with Cr and Ti simultaneously achieved a low ICR and high corrosion resistance compared with single-Cr-doped amorphous carbon. The enhanced corrosion resistance was attributed to the decreasing grain boundary, the formation of the TiC crystal structure, and the smaller grain size. The best performance was obtained at a Ti target current of 2A. Compared with bare 316L stainless steel, the corrosion resistance of Cr, Ti co-doped amorphous carbon (Icorr = 5.7 × 10-8 A/cm2, Ti-2 sample) was greatly improved. Because Ti doping increased the content of sp2-hybridized carbon in the coating, the contact resistance of the coating decreased. Moreover, the interfacial contact resistance was 3.1 mΩ·cm2 in the Ti-2 sample, much lower than that of bare 316L stainless steel. After the potentiostatic polarization test, the coating still had excellent conductivity.

Corrosion caused by fertigation with urea and potassium chloride solutions resembles that generated by irrigation

AbstractCorrosion is a common problem in irrigation systems consisting of metal parts. Fertigation can aggravate this phenomenon because fertilizers, once dissolved in water, usually tend to be corrosive. In this study, the effects of corrosion resulting from fertigation with solutions of white potassium chloride (10 g L−1) and urea (10 g L−1) on galvanized steel and AISI 304 stainless steel specimens, materials similar to the centre pivots and injection pumps, were evaluated by simulation tests. During the experiment, the mass loss, corrosion penetration rate, thickness loss and estimated useful life of the specimens were calculated. The results showed that the variation in the fertilizer source as well as the type of metal influenced the corrosion effects. Furthermore, the useful life expectancy of steels intended for irrigation in systems that practice fertigation practically does not differ from the systems where only irrigation is practiced. The corrosion resistance of stainless steel is significantly higher than that of galvanized steel, so its use should be considered in irrigation systems. In addition, it is interesting that the Zn coating on the galvanized steel pipes used for irrigation presents at least twice the thickness to ensure greater protection of the steel substrate.

Enhancement of microbiologically influenced corrosion resistance of copper-containing nickel-free high nitrogen stainless steel against marine corrosive Pseudomonas aeruginosa

The antibacterial performance and marine microbiologically influenced corrosion (MIC) resistance of a novel copper-containing nickel-free high‑nitrogen stainless steel (HNS) against marine Pseudomonas aeruginosa were studied. The electrochemical tests indicated that the copper content (0, 2 and 4 wt%) would hardly affect the corrosion resistance of HNS in abiotic simulated seawater. In the presence of bacteria, HNS-4Cu showed the best MIC resistance, while MIC rates of HNS-0Cu and HNS-2Cu were comparatively faster. Addition of 4 wt% copper significantly improved the antibacterial effect and the quality of the passive film of HNS, achieving a better MIC resistance.

Effects of Ar-N2-He shielding gas on microstructure, mechanical properties and corrosion resistance of the Laser-MIG additive manufacturing 316L stainless steel

Effects of Ar-N2-He shielding gas on microstructure, mechanical properties and corrosion resistance of the Laser-MIG additive manufacturing 316L stainless steel

Corrosion Resistance of AISI 310s Stainless Steel in Lead Melt at a Temperature of 450°C

Corrosion Resistance of AISI 310s Stainless Steel in Lead Melt at a Temperature of 450°C

Effect of Mn on Microstructure and Corrosion Resistance of Duplex Stainless Steel Surfacing Layer

Effect of Mn on Microstructure and Corrosion Resistance of Duplex Stainless Steel Surfacing Layer

Influence on Pitting Corrosion Resistance of AISI 301LN and 316L Stainless Steels Subjected to Cold-Induced Deformation

Austenitic stainless steels that exhibit good corrosion resistance have recently found increasing applications in industry and transportation. This article addresses the influence of cold rolling and deformation on the pitting corrosion resistance of AISI 301LN and 316L stainless steels. The results indicate that the content of martensite increases as the cold rolling reduction also increases. The current work combined different techniques such as optical microscopy and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) analyses. Corrosion tests were carried out, in accordance with the ASTM standards. The results confirm that the 316L steel performed better than the 301LN, regarding pitting corrosion, even when deformed. This is due to the high molybdenum (Mo) content, which guarantees greater corrosion resistance. The conducted corrosion tests showed that the increase of cold deformation reduces the resistance to pitting and overall corrosion in both steels. It was found that the 301LN stainless steel has higher susceptibility to deformation-induced martensite and, despite the addition of nitrogen, it still has a lower performance relative to the 316L steel. The current work focused on evaluating the formation of pits and the dynamics of the microstructures of the AISI 301LN and 316L steels with their mechanical properties and corrosion resistance in a saline environment including chlorides.

Effect of hydrogen on pitting corrosion of 2205 duplex stainless steel under alternating dry/wet marine environment

Stainless steels play an extremely vital role in the field of marine engineering equipment. However, stainless steel products in service are still subject to corrosion from severe environments such as alternating dry/wet condition and damage caused by hydrogen introduced during heat treatment or cathodic protection. Under alternating dry/wet marine environment, the synergistic effect of hydrogen and corrosion can influence the corrosion resistance of stainless steels dramatically. In this work, the corrosion behavior and mechanism of 2205 duplex stainless steel under alternating dry/wet marine environment are investigated before and after hydrogen charging using electrochemical testing, component characterization and morphological observation. The results show that the open circuit potential, film resistance and breakdown potential all reduce and the passive current density increases after 12 h hydrogen charging. The ratio of Fe3+ and O2−/OH− decreases. The components of the hydrogen charged passive film alter and the performance deteriorates. The number of surface pits increases after 12 h hydrogen charging and additional 10 d alternating dry/wet corrosion. The pitting potential drops much lower. Consequently, The synergistic effect of high concentrations of Cl− in the thin liquid film and hydrogen accelerates the destruction of the passive film, further reducing the corrosion resistance of stainless steels.

The effects of Cr and Ni equivalents on the microstructure and corrosion resistance of austenitic stainless steels fabricated by laser powder bed fusion

In this study, two gas-atomized austenitic stainless steel (ASS) powders with a predominant difference in Cr contents, Mod.-A (18Cr-14Ni-2.6Mo) and Mod.-B (22Cr-14Ni-2.5Mo), were applied in the laser powder bed fusion (LPBF) process. The two kinds of powders and the Mod.-B LPBF sample contained a certain amount of ferrite, whereas, the Mod.-A LPBF sample was found to contain no ferrite. Furthermore, the ferrite content of the Mod.-B LPBF sample determined by ferrite scope (about 5.5 %) was lower than that estimated by Schaeffler diagram (over 10 %). The rapid solidification of the LPBF process tended to reduce the ferrite contents of the fabricated sample as compared with the amount of ferrite present in the feedstock powder or estimated by Schaeffler diagram. It was noted that the chemical compositions of the austenite and ferrite in the Mod.-B LPBF sample had no noticeable differences. Moreover, few ferrites in the LPBF sample caused a significant grain refinement, which resulted in obvious increases in yield and ultimate tensile strength but a decrease in ductility. The corrosion behavior of the 316L plate and two LPBF samples was investigated in 3.5 wt% NaCl, 1 M HCl and 0.5 M H2SO4 solution in this work. The corrosion resistance of the LPBF samples were higher than that of 316L plate in 3.5 wt% NaCl and 1 M HCl solution. In 0.5 M H2SO4 solution, all three tested samples exhibited nearly the same potentiodynamic polarization curves. Overall, the Mod.-B LPBF sample exhibited corrosion resistance equivalent or superior to that of the 316L plate and Mod.-A LPBF sample.

Developing ultrafine-grained structure with balanced α/γ fraction via underwater friction stir processing enables enhanced wear and corrosion resistance of duplex stainless steel

Further improving the wear and corrosion resistance of duplex stainless steel (DSS) without disrupting the balanced ferrite (α)/austenite (γ) ratio is worth exploring, but very challenging. Here, we explored the feasibility of utilizing solid-state friction stir processing in air (AFSP) and underwater (UFSP) to realize surface modification of DSS. Notably, we successfully developed an ultrafine-grained (UFG) structure with balanced α/γ ratio on the DSS by UFSP, which imparts both enhanced wear and corrosion resistance to the sample surface. Further, the associated microstructure evolution mechanism during FSP of DSS in both environments is systematically elucidated. The simultaneous improvement in both wear and corrosion resistance is well correlated with the resulting microstructure characteristics. This work provides a simple and cost effective pathway to achieve a synergistic increase in the wear and corrosion resistance of DSS. We anticipate that the UFSP should be applicable to many dual-phase metallic systems.

Copper content effects on passive film of modified 00Cr20Ni18Mo6CuN super austenitic stainless steels in acidic environment

To provide a theoretical basis for the design of super austenitic stainless steel used in flue gas desulfurization environment, by changing the Cu content in 00Cr20Ni18Mo6CuN super austenitic stainless steel to explore the influence of Cu on its corrosion resistance, by electrochemical methods, XPS and first-principle computational simulations. The results show that Cu promotes the selective dissolution of Fe, Cr and Mo in stainless steel, and the copper content changes the proportion of compounds in the passive film, as well as its surface quality, resistance and defect density. The addition of one Cu atom increases the adsorption energy and work function of NH3 on Cr2O3 surface, reduces the charge transfer and hybridization. However, when the Cu content exceeds 1 wt%, the surface of the passive film is loose and has many defects. The appearance of oxygen vacancy and two Cu atoms leads to the decrease of adsorption energy and work function, and enhances the charge transfer and hybrid effect. The optimal Cu content is obtained through research, which not only improves the corrosion resistance of 00Cr20Ni18Mo6CuN super austenitic stainless steel in flue gas desulfurization environment, prolonging the service life of 00Cr20Ni18Mo6CuN super austenitic stainless steel, but also has practical application value.

Influence of low temperature heat treatment on microstructure, corrosion resistance and biological performance of 316L stainless steel manufactured by selective laser melting

Influence of low temperature heat treatment on microstructure, corrosion resistance and biological performance of 316L stainless steel manufactured by selective laser melting

Revealing the Corrosion Resistance of 316 L Stainless Steel by an In Situ Grown Nano Oxide Film.

It is widely accepted that the corrosion resistance of stainless steel originates from a compact Cr2O3 layer in the native passive film that serves as a barrier to aggressive ions. However, this suggestion has been questioned by some researchers. They believe that protectiveness might be related to the film recovery. Herein, the pitting development of bare 316 L stainless steel was compared with a corrosion-resistance enhanced steel obtained by tuning the native passive film of the alloy. Statistical software was employed for tracing the size and number of pits on the alloy surface. The statistical results for 12 weeks in 1 M sodium chloride solution (80 °C) revealed that there was a crossover in the growing rates of stable pits (diameter > 9 µm) between the bare alloy and the film-enhanced one. Stable pits on bare 316 L occurred early but showed a comparatively slow increase in the following weeks, demonstrating that self-repairability of metastable pits rather than impermeability of the native passive film plays the key role in the early stage of pitting corrosion.

Nanostructure, Mechanical Properties, and Corrosion Resistance of Super Duplex Stainless Steel 2507 Aged at 500 °C

In order to investigate the effect of phase separation (PS) on the super duplex stainless steel SAF 2507, the evolution of the nanostructure, mechanical properties, and corrosion resistance of the alloy was studied after aging at 500 °C for 1, 10, 100, and 1000 h. The nanostructure of PS was quantitatively characterized by small-angle neutron scattering. The hardness, impact toughness, and pitting corrosion resistance were measured for different conditions. The results show that the early stage of PS had a more significant impact on the nanostructure and properties of SAF 2507. The fracture behavior of the alloy was likely determined by the mechanical properties of ferrite for aged conditions. The pitting corrosion resistance of SAF 2507 aged at 500 °C was closely related to the Cr depletion caused by PS, and the resistance became weaker with the progression of PS. The evolution of the passivation region with aging time correlated well with that of mechanical properties and characteristic parameters of PS, indicating that it is possible to develop a new nondestructive electrochemical method to quantify the evolution of PS in SAF 2507.

Simultaneously Enhancing Strength, Ductility and Corrosion Resistance of a Martensitic Stainless Steel via Substituting Carbon by Nitrogen

Simultaneously Enhancing Strength, Ductility and Corrosion Resistance of a Martensitic Stainless Steel via Substituting Carbon by Nitrogen

The effect of microstructural and texture evolutions during thermomechanical treatment on corrosion resistance of 310s austenitic stainless steel

In this study, the evolution of the microstructure and texture during thermomechanical treatment and its effect on corrosion properties of 310s austenitic stainless steel were investigated. This stainless steel was cryo-rolled at 50 and 90% thickness reductions, and then the 90% cryo-rolled sample was annealed at 750 °C for 5 and 30 min. SEM and optical microscope images were used to examine the microstructure of the samples. Fritoscopy test was also used to calculate the volume fraction of the martensite phase. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and cyclic potentiodynamic polarization tests were performed in the 3.5 wt.% NaCl solution to investigate the corrosion behavior of the studied steel. The results showed that the cryo-rolling process caused the reduction of grain size, texture strengthening and transformation of austenite to strain-induced αʹ-martensite phase. Decreasing grain size and increasing texture components containing dense planes are beneficial factors and the formation of the αʹ-martensite phase is a harmful factor for corrosion resistance. It was observed that annealing at 750 °C for 30 min caused the grain growth and texture weakening, while a favorable condition is developed in the annealed sample for 5 min. After 90% cryo-rolling and subsequent annealing at 750 °C for 5 min, the corrosion resistance was significantly improved compared to the as-received sample and reached 37 kΩ.cm2. Formation of the sub-micron microstructure along with the high volume fraction of Brass and Goss texture components were the main reasons for improving corrosion resistance at 750 °C–5 min.

Clarify the effect of reversed austenite on the pitting corrosion resistance of super 13Cr martensitic stainless steel

The effect of reversed austenite on the pitting behavior of super 13Cr martensitic stainless steel (S13Cr MSS) was investigated. The results revealed that reversed austenite was a FCC structure with Ni enrichment after tempering process, and there were no Ni-depleted regions adjacent to it. The reversed austenite content increased with increasing tempering temperature, and the pit depth decreased, as well as the dispersion degree of the Kelvin potential distribution. The reversed austenite reduced the risk of pitting corrosion through increasing the passive film compactness, and inhibiting Cl- penetration. Accordingly, the pitting corrosion resistance was enhanced as the tempering temperature increased.

A Super Anticorrosive Ultrathin Film by Restarting the Native Passive Film on 316L Stainless Steel.

The corrosion resistance of stainless steel is attributed to the extraordinary protectiveness of the ultrathin native passive film (~3 nanometers) on alloy surface. This protectiveness, independent of alloying, can possibly be further increased by modifying the native film to resist corrosion in harsh conditions. However, the modification based on the film itself is extremely difficult due to its rapid, self-limiting growth. Here we present a strategy by using low-temperature plasma processing so as to follow the growth kinetics of the native film. The native oxide film is restarted and can uniformly grow up to ~15 nanometers in a self-limiting manner. High-resolution TEM found that the film exhibited a well-defined, chemical-ordering layered structure. The following corrosion tests revealed that the anodic current density of the alloy decreased by two orders of magnitude in 0.6 M NaCl solution with a remarkable increase of pitting potential. This enhancement is also observed in Fe-Cr alloys with Cr contents above ~10.5 wt.%. The superior protectiveness of the alloy is thus attributed to the continuous and thickened high-quality ultrathin Cr2O3 layer in the restarted film.