Corrosion Damage Mechanisms Research Articles

The impact fretting corrosion behavior and damage mechanism of Inconel 690TT under different impact forces in high temperature pressurized water

The impact fretting corrosion of Inconel 690TT under different impact forces was investigated. The results indicated that there was a competitive relationship between formation of third body layer (TBL) and fragmentation of TBL caused by impact force. With the increase of impact forces, damage mechanism changed from adhesive wear to delamination wear, and crack initiation sites gradually shifted from TBL to internal oxidation zone in tribologically transformed structure (TTS) layer. Nanocrystalline boundaries and defects induced by impact force provided channels for internal oxidation. The formation mechanism of TTS was the combined effect of continuous dynamic recrystallization (cDRX) and twin-assisted cDRX.

Study on mechanical properties and corrosion damage mechanism of mixed sand concrete

In order to address the excessive utilization of river sand resources in Inner Mongolia, an investigation is being conducted on the utilization of wind-blown sand and machine-made sand for the production of mixed sand concrete. A study is conducted to examine the influence of including mixed sand in concrete on its mechanical qualities, working performance, and erosion resistant durability. The findings suggest that when the proportion of wind-blown sand in the mixed sand mixture increases, the compressive strength of the mixed sand concrete exhibits a general pattern of initially increasing and subsequently dropping. At a ratio of 1:1 between wind-blown sand and machine-made sand, there is a maximum point. Nevertheless, the capacity for stretching under tension, resilience, and the strength of the connection all demonstrate a consistent decline. The wind-blown sand content of 50 % in the mixed sand is the critical value. When the wind-blown sand content exceeds 50 %, the tensile deformation capacity, toughness, and bond strength experience a steep decline. Utilizing a combination of different types of sand diminishes the efficiency of concrete. Nevertheless, the efficacy of concrete can be enhanced by modifying the water-cement ratio and the quantity of water-reducing admixtures. It is worth mentioning that although the work performance can be improved, there might be a little reduction in the mechanical qualities of the concrete. The erosion depth in mixed sand concrete has a growth rate that is 0.027 mm/d lower compared to ordinary river sand concrete under erosion conditions. The compressive erosion resistance coefficient and saturated surface dry water absorption rate show significantly reduced damage in mixed sand concrete compared to standard river sand concrete. Moreover, when erosion-freeze-thaw coupling circumstances are present, the structural deterioration of mixed sand concrete is less significant in comparison to ordinary river sand concrete. By using a mixture of sand, the concrete's ability to withstand erosion is improved, resulting in a longer lifespan. This discovery establishes a theoretical foundation for the secure utilization of concrete in aquatic environments in Inner Mongolia.

Corrosion damages of nickel-based alloy G3 in 600 °C H2O[sbnd]CO2[sbnd]H2S[sbnd]H2 steam

Corrosion damage mechanisms of nickel-based alloy G3 at 600 °C with a mixture of H2O, CO2, H2S and H2 were explored using ultra-high-temperature and high-pressure corrosion experiments, slow strain rate tensile tests and a series of microscopic characterization methods. Results unveil that G3 alloy exhibited a low corrosion rate on average. The corrosion product film consists of two layers – an inner layer of Cr2O3 and an outer layer of a mixture of Ni3S2 and Cr2O3. The material experienced plasticity losses of 49.5 % and 24.3 % after corrosion and aging, respectively. Precipitation of M23C6 at grain boundary occurred after corrosion and aging, resulting in chromium depletion and intergranular corrosion within weak grain boundary regions, which reduced plasticity of G3 alloy.

Notch corrosion fatigue behaviour and simplified strain energy density-based notch fatigue life assessment of Grade-A shipbuilding steel

Corrosion fatigue is a key challenge in lifecycle management of ship hull structures. Although sea wave fatigue stresses are linear-elastic, highly-damaging elastic–plastic conditions occur at geometrical discontinuities or notches. Estimation of notch stress-strains to characterize notch fatigue behaviour conventionally requires large computational efforts. Also, constant strain energy density (SED), as a driving force, is far more effective in realistic applications versus constant stress and strain fatigue life approaches. Identified research gaps were the development of a simplified SED approach for fatigue life assessment of hole-notched structures. Fatigue studies were conducted on hole-notched specimens of Grade-A shipbuilding steel in air and corrosion mediums. Strong synergistic interactions of corrosion and fatigue damage mechanisms were studied by scanning electron microscope (SEM) fractography. Notch corrosion fatigue life was reduced by 70% from notch air fatigue life due to environmental effect. Two new parameters are proposed to improve the efficiency of notch fatigue life assessment, namely “fatigue notch strain energy density concentration factor (K_SED) and “fatigue notch toughness”. This improved fatigue life assessment method was demonstrated as equally reliable but much simpler to implement, eliminating the complex computational analysis. This improved method has promising applications in real-time structural health monitoring (SHM) of ship hull structures.

Fretting corrosion running regime and damage mechanism evolution of zirconium alloy mated with Inconel 718 alloy in high temperature high pressure water environment

Fretting corrosion behavior and damage mechanism of Zr-4 alloy mated with Inconel 718 alloy under different fretting regimes in high temperature high pressure water were studied. The corresponding running condition fretting corrosion map (RCFM) and material response fretting corrosion map (MRFM) were established. The results showed that the change of fretting regime led to the differences of fretting corrosion behavior and damage mechanism. Based on the damage mechanism, the MRFM could be divided into partial slip regime with only slight surface damage; mixed fretting regime-I dominated by cracks; mixed fretting regime-II dominated by cracks and abrasive wear; and gross slip regime dominated by severe adhesive wear and oxidation. The transformation of fretting regime also resulted in different oxides.

Service Characteristic Evolution of 3D Four‐Directional Braided C/SiC Ceramic Matrix Composites Under Space Electron Radiation Erosion Environment

The specific effects on the evolution of microstructure, components, and mechanical properties of the 3D braided C/SiC composites under different‐time electron irradiation environment tests are analyzed and discussed to elaborate the corresponding corrosion damage mechanism. The damage to the C/SiC composites is intensified by the continuous electron irradiation, the areas of surface bulges and cracks are significantly enlarged, and the surface roughness increases. The density of white dots on the surface of the specimen increased as the electron irradiation time is prolonged, while the size does not change significantly, and the oxygen content on the surface of the specimen increases to some extent. With the prolongation of electron irradiation time, the decrease of bending strength of C/SiC composites increases, but does not level off after a certain degree, probably because of the existence of certain pores on the surface layer of the C/SiC composite. With the increase of electron radiation time, the crack defects on the surface layer of the C/SiC composite increase, and the electron radiation further damages the internal matrix and reinforcing fibers in the C/SiC composite; thus, the mechanical properties decline continuously and seriously after the radiation exceeds 1 h.

Modeling fatigue-assisted pitting in pipeline steel with PCA-XFEM

We present a localized corrosion and cracking damage mechanism (initiation of the pit, propagation of the pit, pit-to-crack transition, and stable cracking) in a pipeline steel under the application of fatigue loading by using sequential coupling of Probabilistic Cellular Automata (PCA) and eXtended Finite Element Method (XFEM). PCA is utilized for describing the localized corrosion damage mechanism. XFEM is used to simulate arbitrary inhomogeneities (cracks, voids, and soft/hard material interfaces (inclusions)) with the help of Level Set Methods (LSM). In the XFEM, the standard finite element is enriched by additional degrees of freedom by invoking the notion of the partition of unity, which alleviates the burden of mesh conformity to the internal boundaries and avoids re-meshing. LSM is used to locate the voids and material interfaces and track the crack propagation location. A localized strain criterion initiates cracks from the pit surface when the pit reaches a critical strain value.The coupling of PCA and XFEM demonstrates good agreement with experimental data regarding stress-assisted pitting corrosion and pit-induced fatigue cracking in the pipeline steel. The study also investigates the effects of boundaries, and initial pit size on fatigue crack initiation and growth. Boundary effects significantly influence crack initiation life and growth behavior, highlighting the importance of considering both defect characteristics and boundary conditions in assessing fatigue performance and structural integrity. Various initial pit sizes and geometric features further affect crack initiation location and transition time. Furthermore, the PCA-XFEM model effectively captures crack behavior in both short and long crack regimes, demonstrating good agreement with experimental data for a selected pit width of 140μm. By incorporating crack driving parameters derived from experiments, the model accurately predicts crack propagation, further enhancing its reliability and predictive capabilities in assessing fatigue crack behavior. Overall, this approach provides valuable insights for predicting the service life and integrity of pipelines subjected to similar loading conditions, thus aiding in designing and maintaining these critical infrastructure components.

Impermeability performance and corrosion resistance mechanism of basalt fiber recycled concrete under the coastal tidal environment

The application of Recycled Aggregate Concrete (RAC) can effectively reduce resource consumption and mitigate environmental pollution. Under the coastal tidal environments, the performance of concrete is significantly impacted by environmental degradation. Incorporating fibers into RAC can enhance its performance in such special conditions. This study investigates the variations in properties of RAC with different Basalt Fiber (BF) volume ratios (0%, 0.5%, 1.0%, 1.5%) under composite salt dry-wet cyclic erosion cycles (0 d, 30 d, 60 d, 90 d). The results from apparent corrosion morphology analysis, internal microstructure examination, and impermeability testing demonstrate that BF can effectively inhibit the expansion of micro cracks and micropores within the test block while improving the overall compactness of the internal structure of RAC. When the BF content reaches 1.0%, it exhibits an optimal toughening effect on RAC with significantly improved impermeability and corrosion resistance properties. Furthermore, this paper comprehensively summarizes and verifies the corrosion damage mechanism of Basalt Fiber Recycled Aggregate Concrete (BFRAC) under composite salt dry-wet cycles through chemical reaction principles. A salt solution erosion model for BFRAC is proposed to elucidate fiber crack resistance mechanisms and explain accelerated corrosion caused by ion crack channels within salt solutions. This proposed model provides theoretical support for understanding salt erosion damage in fiber-reinforced concrete.

Electrochemical study on the fretting corrosion synergistic damage mechanism of Inconel 690 alloy in different dissolved oxygen solution

In-situ electrochemical measurement was used to investigate the fretting corrosion synergistic damage mechanism of Inconel 690 alloy in the solution with different dissolved oxygen (DO) concentrations. The synergistic mechanism of fretting corrosion was quantified. Results show that the minimum fretting corrosion damage of Inconel 690 was obtained at DO concentration of 2 ppm and the corrosion-accelerated wear, which can be represented by the influence of third body layer (TBL) on the fretting corrosion damage mechanism, is the key contributor. The formation and rupture of TBL have been observed under different DO concentrations. In transitional stages of TBL formation and the stage where uniform morphology formed, the TBL with excellent ductility can improve the contact behavior and reduce fretting corrosion damage. In stages during which TBL breaks into hard spinel oxides, severe abrasive wear and fretting corrosion damage will be caused.

Effect of coating degradation on the hot corrosion behavior of yttria-stabilized zirconia (YSZ) and blast furnace slag (BFS) coatings

In order to provide thermal insulation thermal barrier coatings (TBCs) used in gas turbine engine components under conditions of impure fuels and high turbine inlet temperatures are expected to have hot corrosion resistance. Techniques and material combinations used in the production of TBCs are primarily effective in the progression of failure mechanisms as a result of hot corrosion. In this study, the hot corrosion damage mechanism, which is caused by the impurities of the fuels used in the industry and causes great damage to the TBC systems, was simulated and evaluated in the laboratory environment. For the creation of TBC systems, CoNiCrAlY metallic bond coating powders were deposited on Ni-based super alloy substrates by the detonation gun (D-gun) process. Commercial yttria-stabilized zirconia (YSZ) and blast furnace slag (BFS) powders were deposited on the bond coating by Atmospheric plasma spraying (APS) technique. Hot corrosion testing of TBCs was performed at 800 °C for 8, 24, 50, and 75 h in an environmental condition consisting of a 45 wt% Na2SO4 and 55 wt% V2O5 corrosive salt mixture. Blast furnace slag, which is completely cost-free and a waste product, provided excellent protection against hot corrosion damage without deteriorating its stability at high temperatures. In this way, it is open to be evaluated as a new type of coating material alternative to the traditional top coating material YSZ, which has a very high production and cost, and to be used in different areas.

Life prediction of corrosion-fatigue based on a new crack growth rate model with damage and the extended finite element method

A fatigue crack growth rate model introducing corrosion damage is proposed in this paper, where the fracture parameter is modified by the damage variable and the exponential influence factor. The corrosion damage mechanism is coupled to the crack growth rate model, which quantifies the influence of the environment and reflects the interaction between corrosion and fatigue. To accurately predict the corrosion-fatigue crack growth life by the extended finite element method (XFEM), a simple crack surface updating method is developed. This method does not depend on the complex level set marching algorithm which often brings serious computational convergence problem, so it has good robustness and high efficiency. Moreover, the stress intensity factors at arbitrary crack tip can be calculated by combining the interaction integral method and the piecewise interpolation method, so it is suitable for the double crack-tip problem. The corrosion-fatigue crack growth life is calculated based on the cycle-by-cycle method and the corresponding algorithm is developed. The corrosion-fatigue crack growth life can be accurately predicted by calculating the corrosion damage and crack propagation length under each load cycle. In this paper, sufficient examples are given to verify the accuracy of the proposed method in simulating crack propagation path and predicting corrosion-fatigue life. Finally, this method is well applied to a practical engineering structure.

Investigation of the corrosion-induced damage mechanism of steel fibers in ultra-high-performance steel fiber-reinforced concrete using X-ray computed tomography

To investigate the corrosion damage mechanism of ultra-high-performance steel fiber-reinforced concrete (UHPSFRC), the electrically accelerated corrosion process of specimens with different steel fiber contents was evaluated using micron-level X-ray computed tomography. The results showed that the grid structure formed by the interconnecting steel fibers was a key factor in inducing corrosion damage in the UHPSFRC. The 1% steel fiber content specimens were strongly corrosion-resistant. Steel fiber corrosion triggered the concrete cover of the UHPSFRC to crack or spall from the outside to the inside, and areas with a higher initial density of steel fibers showed a higher degree of damage.

A critical review of the recent advances in inclusion-triggered localized corrosion in steel

AbstractLocalized corrosion triggered by inclusions is prone to metallic material failure. Except for chemical dissolution of some special inclusions, the principle of galvanic coupling is the most acceptable theory to explain the above corrosion damage mechanism over the past decades. Still, controversies continue to present, in particular, mounting recent evidence obtained by advanced technologies emphasizes the limitations of previous entrenched idea and discloses unexpected results. Here, we review relevant recent studies and carefully summarize their similarities and differences to reduce the knowledge gap between inclusion-triggered localized corrosion and material design, whilst the source of typical inclusions is treated and discussed.

Oxidative Corrosion Mechanism of Ti2AlNb-Based Alloys during Alternate High Temperature-Salt Spray Exposure

This study investigates the corrosion damage mechanisms of Ti2AlNb-based alloys under high temperature, salt spray and coupled high temperature-salt spray conditions. This alloy was analysed in detail from macroscopic to microscopic by means of microscale detection (XRD, SEM and EDS). The results indicated that Ti2AlNb-based alloy surface oxide layer is dense and complete, and the thickness is only 3 µm after oxidation at 650 °C for 400 h. Compared to the original sample, the production of the passivation film resulted in almost no damage to Ti2AlNb-based alloy after 50 cycles of salt spray testing at room temperature. The tests showed that Ti2AlNb alloy shows good erosion resistance at 650 °C and in salt spray. However, this alloy had an oxide layer thickness of up to 30 µm and obvious corrosion pits on the surface after 50 cycles of corrosion under alternating high temperature-salt spray conditions. The Cl2 produced by the mixed salt eutectic reaction acted as a catalytic carrier to accelerate the volatilisation of the chloride inside the oxide layer and the re-oxidation of the substrate. In addition, the growth of unprotected corrosion products (Na2TiO3, NaNbO3 and AlNbO4) altered the internal structure of the oxide layer, destroying the surface densification and causing severe damage to the alloy surface.

Characterization of the Erosion Damage Mechanism of Coal Gangue Slopes through Rainwater Using a 3D Discrete Element Method: A Case Study of the Guizhou Coal Gangue Slope (Southwestern China)

Coal gangue is one of the largest solid wastes in the world. In previous studies, the influence and mechanisms of rainfall infiltration on coal gangue slope stability and possible rain erosion have been studied through theoretical analysis, numerical simulation, and modelling, and the results have indicated that discontinuous discrete element methods are the most suitable for determining the erosion mechanism of coal gangue slopes. In this study, we take a Guizhou coal gangue slope as a general case, use three-dimensional Particle Flow Code (PFC3D) as the key method, and combine discrete element fluid–structure coupling technology with optimized erosion shear failure theory to determine the erosion failure mechanism of coal gangue slopes. We investigate a coal gangue slope near the electric power plant in Panzhou City, Guizhou Province (China) as a case study, and conduct a comprehensive analysis of the erosion induced by the corrosion damage mechanism. We use the PFC3D method, combined with optimized rain erosion shear failure theory, for our investigation. The applied methods mainly consider dynamic inversion of the erosion process, as well as the changes in coordination number, porosity, unbalanced force, and energy dissipation. The scour damage type of the studied gully is intermittent fragmentary damage, with the following inferred damage sequence: Center–bottom–top of the slope. The entire erosion damage process can be divided into three stages: catchment–fracture, erosion–accumulation, and piping–penetration failure. In the first stage of erosion, the force chain fracture is the most severe. The maximum kinetic energy reaches 25 MJ and the coordination number decreases from 5.3 to 4.0, whereas the porosity increases from 0.42 to 0.45. Unexpected lateral erosion and expansion occur at 40–60 m (in the central slope) in the y-direction of the slope, the unbalanced force reaches 7500 N, and the peak porosity is increased by 10%. This paper provides a simulation method for extreme precipitation events in geotechnical slopes (contributing to spatio-temporal connections, forecasting, generation, impact analysis, and vulnerability and risk assessment). Our improved methods provide valuable tools for engineering disaster early warning, and contribute to a better understanding of hydrodynamic processes in general.

Internal Corrosion Damage Mechanisms of the Underground Ferrous Water Pipelines

Internal Corrosion Damage Mechanisms of the Underground Ferrous Water Pipelines

Investigation of oxidation and hot corrosion behavior of molybdenum coatings produced by high-velocity oxy-fuel coating method

Thermal spray coatings methods are frequently used in automotive, aerospace, and marine vehicles. The most obvious damage mechanisms of coating systems, which are exposed to many damages during use, are high-temperature oxidation and corrosion. While the oxygen element coming from the atmosphere creates the high-temperature oxidation damage in the coating systems, the molten salts such as Na2SO4 and V2O5 coming from low-quality fuels constitute the high-temperature hot corrosion damage mechanism. In this study, its behavior against high-temperature oxidation and hot corrosion damage mechanisms was investigated by coating Molybdenum (Mo) on a 316 L stainless steel substrate with the High-Velocity Oxy-Fuel technique, which is an innovative thermal spray coating method. Both damage mechanisms were carried out isothermally at 650 °C. Oxidation tests were carried out for 5, 25, and 50 h, while hot corrosion tests were carried out for 1, 3, and 5 h. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), Elemental mapping, and Energy Distribution Spectroscopy (EDS) analysis was performed on molybdenum-coated samples before and after both tests. The results obtained were evaluated and discussed in light of the literature.

Damage analysis of rotation speed on corrosion film of 3Cr steel in the CO2 environment with silty sand

The 3Cr steel used as the tubing has serious corrosion damage in a flowing CO2 environment with silty sand. Hence, the investigation for the influence of flow velocity on the corrosion behavior of 3Cr steel has an important and practical significance. It could not only unveil the corrosion damage mechanism of the steel under dynamic conditions, but also provide a theoretical basis for the corrosion protection of the tubing. In this paper, the effect of flow velocity on the corrosion film of 3Cr steel in a CO2 environment with silty sand was investigated by adjusting rotation speed. The results revealed that the corrosion resistance of 3Cr steel was first reduced, followed by enhancing and then reduced as the rotation speed increased. There was a critical rotation speed for the transformation of corrosion mechanism of 3Cr steel, i.e., 600 r/min. When the rotation speed was lower than the critical speed, the mass transfer process of corrosive medium dominated the corrosion resistance of 3Cr steel, and silty sand participated in the formation of corrosion film. The increasing rotation speed accelerated the mass transfer process, which first reduced and then improved the corrosion resistance. When the rotation speed was higher than the critical speed, the shear stress of silty sand played a predominant role. At the same time, silty sand impinged on the corrosion film, and then destroyed the stability of the film, leading to a significant decrease of the corrosion resistance. Silty sand changed from participating in the corrosion film to destroying the corrosion film with increasing rotation speed.

Hot corrosion damage mechanism of Ti6Al4V alloy in marine environment

This study investigated the corrosion behaviors of Ti6Al4V alloy during the hot salt and hot salt - water vapor tests. Ti6Al4V suffered from slight oxygen erosion at the initial stage, while chlorine greatly accelerated the oxide growth. The initial and accelerated oxidation reactions resulted in a continuous mass gain of Ti6Al4V during the hot salt test. Ti6Al4V experienced severe corrosion degradation during the hot salt - water vapor test. The reaction between oxides, chloride salt and water induced the formation of hydrochloric acid (HCl), while chlorine reacted with water to form HCl. The HCl subsequently reacted with the alloy to form gaseous chlorides, that volatilized to the outside and consequently led to a significant mass loss of Ti6Al4V. These results confirmed that the oxidation - hot salt - water vapor synergism effect showed a strong damage on the hot end components of titanium alloy during the marine service.

Effects of Acid Environment on Mechanical Properties of Cemented Tailings Backfill

The characteristics of cemented tailings backfill (CTB) in the underground acidic environment under the corrosion of sulfuric acid solution were studied. The parameters were tested and analyzed, including uniaxial compressive strength (UCS), elastic modulus, cohesion, internal friction angle. In addition the XRD analysis and electron scanning of the surface material of CTB was carried out, and the sulfuric acid corrosion mechanism of CTB was discussed. The research results showed that the changes of UCS, elastic modulus and cohesion over time are approximately the same under the corrosion of sulfuric acid solution, all showing a trend of increasing first and then decreasing. The internal friction angle presents a volatility downward trend. Sulfuric acid solution corrosion has an effect on the mechanics of CTB, although it is beneficial to the strength of CTB in the early stage and unfavorable in the long term. Regardless of whether the initial solution is strong acid or weakly acidic, the pH of the solution tends to be neutral. The mechanism of corrosion damage of CTB is caused by the dissolution of hydrogen ion and sulfate ion reaction produces an expansive substance, resulting in deterioration of the strength of CTB.