Corrosion Resistance Of Stainless Steel Research Articles

Influence of inclusions on the pitting behavior of cast duplex stainless steels and patch weld layers

Abstract The relationship between the corrosion resistance of cast duplex stainless steel welded joints and inclusions was investigated by metallographic characterization, electrochemical tests, in-situ tests, scanning electron microscopy (SEM) combined with energy dispersive X-ray spectrometry (EDS) and other methods. The results showed that inclusions were the main sites for pitting corrosion initiation in cast 2205 welded joints, and the MnS portion of the composite inclusions preferentially dissolved to form micro-pits, which triggered pitting corrosion. In addition, the density of inclusions in the heat-affected zone (HAZ) was high and the average size of inclusions was larger, resulting in poorer pitting resistance in the HAZ. And pitting was more likely to occur and subsequently a large pit was developed which ultimately leads to failure.

Microscopic analysis of the destruction of passive film on stainless steel caused by sulfide in simulated cooling water

Abstract Sulfide often appears in circulating cooling water due to the presence of sulfate reducing bacteria and could affect corrosion behavior of cooling pipe metals such as stainless steel. Scanning Kelvin probe and scanning electrochemical microscope measurements, combined with electrochemical testing, were used to investigate the micro-electrochemical information of passive film and analyzed the influence of sulfide in simulated cooling water on corrosion resistance of stainless steel. Results showed that the presence of sulfide in water caused a negative shift in surface potential of stainless steel, an increase in surface potential difference, and an increase in local response current on the surface, resulting in a current peak that gradually increased over time. The analysis results of passive film composition showed that the presence of sulfide caused increase in the ratio of Fe/Cr and OH−/O2−, as well as the content of Cr(OH)3 and Fe(OH)3 in passive film, whereas caused a decrease of Cr2O3 content, and led to the formation of FeS2 in the passive film. These changes in the composition of the passive film made it easier for active sites to appear on the surface of stainless steel and enhanced the conductivity of the passive film and significantly reducing its protective performance.

Effect of Ce Content on Modification Behavior of Inclusions and Corrosion Resistance of 316L Stainless Steel.

The changes in the inclusions in 316L stainless steel before and after Ce addition were studied by adding different contents of Ce. The effects of rare earth Ce treatment on the modification of MnS inclusions in steel and the pitting corrosion resistance of 316L stainless steel are studied by field-emission scanning electron microscopy, laser confocal microscopy, the 6% FeCl3 corrosion weight loss test, and Tafel polarization curve test. The results show that the addition of Ce reduces the corrosion rate of stainless steel in 6% FeCl3 solution, and reduces the number and size of corrosion pits. The corrosion resistance is the best at a 0.0082% Ce content. In addition, the addition of Ce reduced the corrosion current density of stainless steel in 3.5% NaCl solution and increased the corrosion potential. The corrosion potential increased from -329 mV to -31.4 mV. Through Ce treatment, the grain is refined and the inclusions in the experimental steel are modified. With the increase in rare earth content, Mn S gradually transforms into Ce2O2 S inclusions. The morphology of the inclusions gradually change from the original long strips to a spherical shape, and the average size is significantly reduced, which improves the corrosion resistance of the stainless steel. The addition of rare earth Ce plays modifies the inclusions and purifies molten steel.

Improved Mechanical Performances of Hastelloy C276 Composite Coatings Reinforced with SiC by Laser Cladding.

Composite coatings reinforced with varying mass fractions of SiC particles were successfully fabricated on 316 stainless steel substrates via laser cladding. The phase compositions, elemental distribution, microstructural characteristics, hardness, wear resistance and corrosion resistance of the composite coatings were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Vickers hardness testing, friction-wear testing and electrochemical methods. The coatings have no obvious pores, cracks or other defects. The phase compositions of the Hastelloy C276 coating includes γ-(Ni, Fe), Ni2C, M6C, M2(C, N) and M23C6. SiC addition resulted in the formation of high-hardness phases, such as Cr3Si and S5C3, with their peak intensity increasing with SiC content. The dendrites extend from the bonding zone towards the top of the coatings, and the crystal direction diffuses from the bottom to each area. Compared with the dendritic crystals formed at the bottom, the microstructure at the top is mostly equiaxed crystals and cellular crystals with smaller volume. When SiC powder particles are present around the crystals, the microstructure of the cladding layer grows acicular crystals containing Si and C. These acicular crystals tend to extend away from the residual SiC powder particles, and the grain size in this region is smaller and more densely distributed. This indicates that both melted and unmelted SiC powder particles can contribute to refining the grain structure of the cladding layer. The optimal SiC addition was determined to be 9 wt%, yielding an average microhardness of 670.1 HV0.5, which is 3.05 times that of the substrate and 1.19 times that of the 0 wt% SiC coating. The wear resistance was significantly enhanced, reflected by a friction coefficient of 0.17 (43.59% of the substrate, 68% of 0 wt%) and a wear rate of 14.32 × 10-6 mm3N-1·m-1 (27.35% of the substrate, 40.74% of 0 wt%). The self-corrosion potential measured at 315 mV, with a self-corrosion current density of 6.884 × 10⁻6 A/cm2, and the electrochemical charge-transfer resistance was approximately 25 times that of the substrate and 1.26 times that of the 0 wt%. In this work, SiC-reinforced Hastelloy-SiC composite coating was studied, which provides a new solution to improve the hardness, wear resistance and corrosion resistance of 316L stainless steel.

Comparison of etchants for corrosion-resistant stainless steels in medical engineering

Abstract Corrosion-resistant stainless steels are widely used in medical engineering. Today, additive manufacturing techniques are also used for this purpose, in particular for implant steels. Additively processed materials sometimes react differently to etching than conventionally processed ones. The use of etchants for contrasting the microstructure must therefore be adapted. Chemical etching using V2A etchant, Murakami, and anhydrous Kalling solutions, as well as electrochemical etching using nitric acid, sodium hydroxide, and oxalic acid were performed. Etched samples made of conventionally processed X2CrNi-Mo17-12-2 were compared to samples manufactured using selective laser melting and sintering, and the optimal contrast was developed in each case. It can be shown that the different etchants reveal different microstructural constituents and that etchants must therefore be selected as a function of the application.

Effect of Mn Content on the Microstructure and Corrosion Resistance of Duplex Stainless Steels Fabricated by Wire Arc Additive Manufacturing

Effect of Mn Content on the Microstructure and Corrosion Resistance of Duplex Stainless Steels Fabricated by Wire Arc Additive Manufacturing

Effect of inclusion and microstructure transformation on corrosion resistance of 316L stainless steel after isothermal heat treatment

Effect of inclusion and microstructure transformation on corrosion resistance of 316L stainless steel after isothermal heat treatment

Improvement of the Corrosion Resistance for Martensitic Stainless Steel By Laser Thermal Processing

IntroductionStainless steels are widely used as medical devices. Martensitic stainless steels can be hardened by quenching. Therefore, in the medical field, martensitic stainless steels are mainly used for knives and surgical instruments with cutting edges. However, carbon, a necessary additive for the hardenability of martensitic stainless steels, reduces their corrosion resistance. Therefore, it is theoretically difficult to achieve both high hardness and high corrosion resistance in stainless steels. To ensure the safety and longevity of devices made of martensitic stainless steels, improved corrosion resistance is required. In this study, an improved corrosion resistance of martensitic stainless steels was tried by laser thermal processing. Rapid heating and rapid cooling process by laser irradiation is expected to suppress the formation of corrosion-inducing (MnS) inclusions. The effects of the laser thermal processing on the corrosion resistance, microstructure, and hardness of the specimen surface and substrate layers were investigated.Materials and methodsThe specimens were commercially available type 420J2 stainless steel plates. Each plate was irradiated with a laser of 10 mm diameter at a rate of 100 cm min-1. The irradiation powers were 950 W, 1100 W, 1650 W, 2000 W, 2500 W, 3000 W, 3500 W, and 4000 W. The surface and cross-sectional metallography and inclusions of the laser-irradiated specimens were observed and analyzed using OM, SEM/EDS, and EBSD. Corrosion resistance was also evaluated by anodic polarization tests. A mixed aqueous solution of 0.1 M Na2SO4 and 0.585 M NaCl at 297 ± 3 K was used as the test solution. A Pt plate and a Ag/AgCl (saturated KCl aqueous solution) electrode were used as the counter and reference electrodes, respectively. The potential sweep rate was 20 mV min-1.Results and discussionThe specimens surface after the laser thermal process were observed. The surfaces of the specimens processed at 950 W or 1100 W were smooth, while those processed at 1650 W or higher had a wavy shape. The specimens with exposed cross sections were chemically etched. A light-colored area on the surface layer, and a dark-colored area around and inside the surface layer were formed. The light-colored area is the layer whose microstructure has been changed by laser irradiation. In addition, the light-colored area of the specimens processed at 1650W or higher were divided into two parts. Defined as phase A (upper part of light-colored area), phase B (lower part of light- colored area), and phase C (dark-colored area), in order from the surface. The main phase of the unprocessed specimen is ferrite with a small amount of residual austenite. EBSD and XRD results indicated that the main phase of phase A is martensite with some austenite phase. Additionally, Vickers hardness of phase A significantly increased compared to the unprocessed specimen. This result confirms that phase A is a martensitic phase, indicating that rapid heating and rapid cooling by laser irradiation caused the martensitic phase to form. Corrosion resistance of phase A layer was better than unprocessed specimen. The pitting potential of the phase A layer increased with irradiation power, with the highest value at 3500 W. Some cracks appeared on the surface of the specimen processed at 4000W. These cracks are the reason for the lower corrosion resistance. Inclusions consisting of spherical Si oxides smaller than 1 µm were observed in the microstructure of the phase A layer; no MnS inclusions were observed. The presence of fine spherical Si inclusions and the wavy surface suggest that phase A was formed by melting and then rapidly solidifying due to laser irradiation. MnS was solidly soluble in the matrix phase by melting, and its formation was inhibited by rapid solidification. As a result, MnS inclusions in phase A were reduced and the corrosion resistance of phase A was improved. On the other hand, phase C showed similar hardness and corrosion resistance to the unprocessed specimen, and there was no difference in corrosion resistance depending on irradiation power. Thus, although phase C was heated by the laser, no melting or microstructural transformation occurred. In other words, laser thermal processing does not degrade the properties of the inner layer. The corrosion resistance, hardness, and microstructure of phase B were intermediate between those of phases A and C.Conclusion420J2 stainless steel was subjected to laser thermal process at various power to evaluate microstructure and corrosion resistance. Laser thermal process suppressed the formation of corrosion-induced inclusions in the surface layer, and the surface layer transformed to martensitic structure. Laser thermal processing succeeded in modifying the surface to have both high corrosion resistance and hardness. Figure 1

Effect of N on Pit Initiation at MnS in Type 304 Stainless Steel

N is known as an element that improves the pitting corrosion resistance of stainless steels, but its mechanism of action is unknown. Since N is not a resource constraint and the addition of N does not reduce toughness in FCC, it is important to clarify the effect of N on pitting corrosion resistance of austenitic steels and to find a means to utilize N more effectively from the viewpoint of resource conservation in the production of corrosion-resistant steels. In this study, the effect of N on the occurrence of pitting corrosion was analyzed by electrochemical measurements on Type 304 stainless steel containing MnS.Type 304 stainless steel containing 0.120 mass% N was used as a sample, and Type 304 stainless steel containing 0.005 mass% N was used as a comparison material. Each sample was heat treated at 1100°C for 30 minutes and then water cooled.After heat treatment, the specimens were polished with 1 µm diamond paste, and inclusions were observed using optical microscopy and SEM-EDS.Polarization curves were measured under 0.1 M NaCl solution at pH 6.0 and water temperature of 25°C, to compare pitting potentials. After the measurements were made, the areas where pitting corrosion was occurring were observed under an optical microscope.For each steels, it was confirmed that pitting corrosion occurred starting from MnS inclusions.The N-doped steels showed a higher pitting corrosion potential than the steels containing little or no N.

Enhancing Corrosion Resistance of Type 316L Stainless Steel in Marine Environments: Role of Surface Roughness and Organic Acid Passivation

Stainless steel is widely used in marine environments due to its excellent corrosion resistance properties. However, recent occurrences of corrosion issues related to Type 316L stainless steel in marine atmospheric environments have led to concerns regarding the suitability of Type 316L stainless steel material selection according to international standards. Factors such as surface roughness and passivation treatments can significantly affect the corrosion behavior of stainless steel in marine atmospheres. In particular, the surface roughness of conventional stainless steel piping can lead to corrosion in marine atmospheric environments when exposed for extended periods. Either option requires improving the surface roughness or applying passivation treatments to enhance corrosion resistance.This study examines the effect of surface roughness on the corrosion resistance of Type 316L stainless steel in a marine environment using potentiodynamic polarization and accelerated corrosion tests. In addition, the impact of organic acid passivation on the corrosion behavior of stainless steel in a marine atmosphere is investigated. Surface roughness was controlled by mechanical polishing, while organic acid passivation was achieved using a solution containing citric acid, phosphoric acid, and hydrogen peroxide. Electrochemical measurements and surface characterization techniques were employed to assess the corrosion resistance of the specimens. The results demonstrate that surface roughness and organic acid passivation significantly impact the corrosion resistance of stainless steel in a marine atmosphere. Understanding the synergistic effects of these factors is crucial for enhancing the durability and performance of stainless steel components in marine applications.

Localized Corrosion Behavior of Type 304 Stainless Steel Electrolytically Charged with Hydrogen

The authors have been studying the relationship between hydrogen-induced crack initiation and propagation mechanisms in type 304 stainless steels in chloride solution environments. As part of this study, plastic strain was applied to hydrogen-charged austenitic stainless steels to investigate crack initiation and propagation behavior. Interestingly, the induction time of localized corrosion and crack initiation almost disappeared in the case of hydrogen charging. Furthermore, it was observed that localized corrosion initiation also occurred quickly in the case of hydrogen-charged, however not plastically strained, specimens. Such localized corrosion behavior was attributed to the decrease in corrosion resistance of the passive film due to hydrogen charging. However, a detailed evaluation of the corrosion resistance of hydrogen-charged stainless steel has not been conducted. In this study, the effect of hydrogen charging on localized corrosion behavior was investigated by measuring anodic polarization curves of type 304 stainless steel electrochemically charged with hydrogen. The specimen used in the experiments was type 304 stainless steel. Hydrogen charging was performed by cathodic polarization at constant current in 1 M NaCl solution. The anodic polarization curves of hydrogen-charged 304 stainless steel were measured by a three-electrode method, using a Pt wire as the counter electrode and an Ag/AgCl electrode (saturated KCl) as the working electrode. Anodic polarization behavior of type 304 stainless steel after electrolytic hydrogen charging was the same as that of the specimens without hydrogen charging, and current changes in passivity and localized corrosion were observed, however pitting potential became lower due to cathodic polarization. The localized corrosion behavior due to hydrogen charging is discussed in this study.

Enhancement of Corrosion Resistance and Hardness for Type 420J2 Martensitic Stainless Steel Via Laser Powder Bed Fusion Process

In the field of materials engineering, physical properties such as mechanical properties are considered as the most important properties, however, chemical properties such as corrosion resistance are also critical properties that cannot be ignored. In particular, Japan is island country where metallic materials are frequently used in coastal areas. Therefore, the problems of failures and accidents caused by corrosion reaction of structural materials are more serious than in other countries.Recently, laser powder bed fusion (LPBF) process which is a type of additive manufacturing (AM), has been attracting attention as an advanced processing tool for fabrication of metallic materials in various industrial fields. The direct-forming process by AM with the applicability of intricate-structured materials is strong advantage for manufacturing value-added and relatively small products such as medical implants or aerospace assemblies.Our previous study demonstrated the excellent corrosion resistance of LPBF-processed type 316L austenitic stainless steel, focusing on its crystallographic planes and grain boundaries [1]. Therefore, in this study, we investigated the corrosion resistance of LPBF-processed type 420J2 martensitic stainless steel. Martensitic stainless steels have the lowest corrosion resistance among all kinds of stainless-steel types such as precipitation hardening, ferritic, austenitic, and duplex, because of minimum chromium content without other corrosion-resistant elements, and high content of carbon. The primary advantage of martensitic stainless steel is superior hardness, which can be achieved quenching heat treatment. In other words, corrosion resistance and hardness are conflicting properties for stainless steels, and it is difficult to realize coexistence.In this study, the electrochemical and the non-electrochemical corrosion tests were performed to evaluate the corrosion behavior of LPBF-processed and commercial 420J2 stainless steels. The microstructural characterization and hardness tests were also performed.Commercial 420J2 stainless steel powder was used as the primary material for specimen fabrication by LPBF in this study. The nominal composition of 420J2 stainless steel was Fe-12Cr-0.3C. The LPBF process was performed in an argon atmosphere using a 3D printer. To examine the evolved texture and planes of interest of the specimens, the z-axis was defined as the build direction, and the x- and y-axes were defined as the laser scanning directions. In this study, we fabricated cubic specimens with dimensions of 11 mm × 11 mm × 11 mm. The specimens were cut mechanically to expose their yz-, xz-, and xy-planes. No post-processing was performed on the LPBF specimens.Anodic polarization measurement (linear sweep voltammetry) was performed using a potentiostat (HABF-501G, Hokuto Denko, Japan) connected to a function generator (HB-111, Hokuto Denko, Japan) with an analog cable. A saturated calomel electrode (SCE) and platinum electrode were used as the reference and counter electrodes, respectively. The specimens were fixed in a polytetrafluoroethylene holder with an O-ring. The exposed area contacting the electrolyte was 0.35 cm2 (6.7 mm in diameter). After immersing the specimens in a simulated body fluid (physiological saline: 0.9 mass% NaCl aqueous solution, aerated) at 310K, their open circuit potentials (OCPs) were recorded for 10 min. Then, a gradient anodic potential was applied at a constant sweep rate of 1 mVs-1 from the initial potential of −50 mV from the OCP. The measurement was stopped when the current density limit of 1 mAcm-2 was recorded.Figure shows the polarization curves of LPBF-processed and commercial 420J2 stainless steel specimens in physiological saline. The pitting potentials of LPBF specimens were significantly higher than those of commercial specimens. These experimental results indicate that localized corrosion resistance was effectively improved as like 316L austenitic stainless steel in the previous study [1]. The results of the hardness test showed that LPBF specimens was 53.50 ± 0.25 HRC, regardless of the measuring position. The hardness of the commercial specimens varied from 54 to 27 HRC depending on the tempering treatment conditions after the primal quenching.Thus, LPBF is found to be an ideal process that can simultaneously enhance corrosion resistance and hardness of martensitic stainless steels. The experimental results of another corrosion resistance evaluation and inclusion extraction will be presented in the session.Reference:[1] Tsutsumi Y et al. Additive Manufacturing 45 (2021) 102066. Figure 1

Development of Evaluation Method of Corrosion Resistance and Long-Term Durability of Stainless Steel for PEMFC

In recent years, Proton Exchange Membrane Fuel Cell (PEMFC) have attracted attention as an important technology for achieving carbon neutral society due to high energy efficiency without carbon dioxide emission during power generation. In order to cost reduction of PEMFC, the use of cheaper structural materials, such as stainless steels, that possess excellent processability, has been studied in substitution for titanium for bipolar plate (separator). The practical environment in PEMFC is severely corrosive: high temperature, acidic, and fluoride-containing solution. Many study has been conducted on the development of materials that have sufficient corrosion resistance and low contact resistance enabling long-term durability even in such severe environment. However, present evaluation method is insufficient for diagnosis the lifetime of bipolar plate. The new evaluation technique, that accurately simulates the environment inside PEMFC and appropriately accelerates the corrosion degradation reaction, make it easier to predict the lifetime of products and precisely evaluate the performance of newly developed materials. Therefore, the purpose of this study is development of novel corrosion evaluation method with high reproducibility, high and rapid diagnosis performance via applying various electrochemical measurements simulating PEMFC environment and for elucidation the corrosion behavior in practical environment.Firstly, several common corrosion resistance tests were performed in a specific solution (80 ℃, pH3, 10ppm Cl-, 3ppm F-) that simulated the internal environment of PEMFC. As a result, potentiostatic polarization (0.724 V vs. Ag/AgCl, 24 h) showed poor reproducibility because the corrosion behavior in later stage depends largely on the occurrence of localized corrosion initial stage of the test. In the case of potentiodynamic polarization(+1 mV/s sweep from open-circuit potential), risk of localized corrosion could be investigated, however, it was not suitable to predict long-term corrosion behavior. In the case of potentiodynamic cyclic polarization (cyclic voltammetry), it was found that the cathodic sweep, which never occur at in-sever PEMFC condition, inhibited the stable growth of the passivation film on the steel surface by reduction reaction, resulting in improperly accelerated excessive corrosion.Then, new testing method of the intermittent polarization, which was a combination of potentiostatic polarization and open-circuit condition, was performed. It has the advantage in flexibility of testing conditions such as polarization potential and duty cycle in accordance with to the degree the corrosion acceleration. In fact, it was found that the localized corrosion caused by initial stage of potentiostatic polarization step was repassivated during the following open circuit step. Therefore, the reproducibility was improved and the passive film growth was properly evaluated by intermittent polarization test, therefore. It was expected to be promising technique to diagnose the long-term durability of PEMFC bipolar plate.In order to demonstrate the effectiveness of the intermittent potentiostatic polarization method, a variety of type 304 stainless steel specimens with different corrosion resistance were used. The detailed results will be presented on the relevant session.

Prediction of Hydrogen Diffusion Behavior under the Influence of Defect Structures in Stainless Steel Passivation Film Based on Molecular Dynamics.

The excellent corrosion resistance of stainless steel primarily relies on the formation of a dense passivation film on its surface. Stress corrosion and hydrogen embrittlement are the primary forms of damage to the stainless steel passivation film, leading to film rupture and subsequent corrosion of the stainless steel substrate. The passivation film exhibits semiconducting properties and typically consists of a bilayer structure with a chromium-rich inner layer and an iron-rich outer layer. This study employs molecular dynamics simulations to investigate the interaction energy between hydrogen atoms and pristine stainless steel passivation films (Fe2O3/Cr2O3) as well as those containing three different types of defects and predicts the diffusion processes of hydrogen atoms in passivation films. The results indicate that the strongest interaction energy of -1.4402 eV is observed between hydrogen atoms and the pristine passivation film. However, as defects emerge within the passivation film, the interaction energy decreases, with a minimum energy of -0.1931 eV observed for the film containing chromium vacancies (VCr), representing a nearly one-order-of-magnitude reduction compared to the defect-free case. Furthermore, the diffusion coefficients of hydrogen atoms in the three defective passivation films are calculated as 6.437 × 10-10, 8.249 × 10-10, and 50.892 × 10-10 m2/s, respectively. Notably, the presence of a VCr defect enhances the hydrogen diffusion coefficient by an order of magnitude compared to the pristine film. Anisotropic diffusion paths and properties are elucidated through an analysis of the self-diffusion behavior of hydrogen in different detective passivation films, providing a theoretical basis for the prediction of hydrogen-induced cracking and the development of early warning technologies for passivation film surface failure.

Unveiling the effect of bovine serum albumin on the corrosion resistance of high nitrogen stainless steel for cardiac stents

Herein, the effect of bovine serum albumin (BSA) on the corrosion resistance of high nitrogen stainless steel (HNS) is systematically investigated based on experimental characterizations and first-principle calculations. Electrochemical measurements firstly prove that the anodic dissolution rate of HNS has significantly increased due to BSA adsorption and the potential deterioration of the passive film. By subsequent morphology and composition characterizations, it is demonstrated that BSA forms a 1.9 μm porous adsorption layer on HNS surface via the peptide bond mostly in α-helix and β-turn structure. Furthermore, Mott-Schottky tests confirm that the carrier (cation vacancy) density in the passive film has dramatically risen from 6.29 × 1021 cm−3 to 1.97 × 1022 cm−3 after BSA adsorption, which could be ascribed to the detachment of Cr atom from its original lattice due to the preference interaction between BSA molecule and Cr atom. Most importantly, such an increased defects will further promote the dissolution process of both the passive film and HNS matrix according to point defect model (PDM), which will definitely undermine the protective ability of the passive film and eventually result in the declined corrosion resistance of HNS in BSA-contained solution.

Enhancing wear and corrosion resistance of AISI410 stainless steel in simulated seawater environments through PVD sputtering of TiCrN and CrSiN coatings

Enhancing wear and corrosion resistance of AISI410 stainless steel in simulated seawater environments through PVD sputtering of TiCrN and CrSiN coatings

A 10-year study of the corrosion resistance of stainless steels used as reinforcement in chloride-contaminated concrete exposed to severe conditions

A 10-year study of the corrosion resistance of stainless steels used as reinforcement in chloride-contaminated concrete exposed to severe conditions

Effects of Thermal Aging on Corrosion Resistance of Duplex Stainless Steel Fabricated by Different Methods

Effects of Thermal Aging on Corrosion Resistance of Duplex Stainless Steel Fabricated by Different Methods

Effect of Boronizing on the Corrosion Resistance of Martensitic Stainless Steels

Effect of Boronizing on the Corrosion Resistance of Martensitic Stainless Steels

Facile fabrication of TiN coatings to enhance the corrosion resistance of stainless steel

Stainless steel, widely used for its excellent mechanical properties, suffers from low surface hardness that reduces its corrosion resistance. Herein, a straightforward ultrasonic shot peening technique was employed to fabricate a TiN coating (USG) that is well-bonded to the substrate. Corrosion tests demonstrated a significant decrease in corrosion current density (icorr) from 6.09 × 10−7 A·cm−2 to 7.40 × 10−9 A·cm−2, and the corrosion rate decreased from 299.49 mm/year to 121.67 mm/year. The high-energy processing chamber facilitated rapid formation of a chemically-bonded TiN layer. The chemical inertness of TiN in environments containing water and chloride ions helps to avoid corrosive reactions, thereby enhancing the corrosion resistance of the USG samples. Further AIMD calculations reveal the corrosion-resistant mechanism of TiN at the atomic scale, showing strong chemical bonding between TiN and the substrate, forming a dense protective layer. Additionally, the chemical inertness of TiN in saline environments effectively prevents substrate corrosion. This work demonstrates a novel and effective approach for fabricating corrosion-resistant coatings on stainless steel surfaces.