Synergistic Effect Of Corrosion Research Articles

Safety Analysis and Condition Assessment of Corroded Energy Pipelines under Landslide Disasters

Corrosion poses a significant risk to the safety of energy pipelines, while landslide disasters emerge as the primary threat responsible for triggering pipeline failures across mountainous areas. To date, there is limited research focused on the safety of energy pipelines considering the synergistic effect of corrosion and landslides. The present study proposes a finite element (FE)-based model to assess the condition of corroded pipelines under landslides. The effects of corrosion dimensions (length and depth) and location are determined. A novel equation is finally developed to predict the maximum stress and determine the most disadvantageous position for corroded pipelines under various landslide displacements. The results demonstrate that (1) as the landslide progresses, the pipeline’s stress significantly increases; (2) corrosion depth has a more significant impact on the pipeline condition than the corrosion length, and it is positively correlated with the pipe’s stress; (3) the maximum stress exhibits a nonlinear relationship with the landslide-facing position and the corrosion circumferential location; and (4) when the axial position of the corrosion is more than 6.5 m away from the center of the landslide, the location of maximum stress shifts from the corrosion region to the central section of the pipeline within the landslide. This work contributes to helping pipeline owners to understand the applicability of energy pipelines subjected to the combined effects of corrosion and landslides and provides support for future risk assessment efforts in pipeline integrity management.

Corrosion wear behavior of 30CrNi2MoVA steel in simulated seawater

This study investigates the corrosion wear behavior of 30CrNi2MoVA steel in a simulated seawater environment using an electrochemical workstation and a friction-wear testing machine. The results indicate that under dry friction conditions, an increase in load leads to an increase in friction coefficient and wear depth. In seawater, an increase in speed results in a decrease in friction coefficient and an increase in wear depth, while the effect of load on material loss is minimal, highlighting the crucial role of speed in corrosion-wear behavior. The synergistic effect of corrosion and wear causes more severe damage than dry friction. The corrosion wear behavior of 30CrNi2MoVA steel is a dynamic process of “mechanical deoxidation-chemical reoxidation,” as evidenced by the change in corrosion potential from −0.6502 V to −0.8646 V and increased material loss.

Effect of shot peening on surface characterization and cavitation resistance of nickel aluminum bronze

Nickel aluminum bronze is subjected to cavitation corrosion as propellers working in the seawater. The cavitation corrosion is dominated by the synergistic effect of corrosion and mechanical attack. Previous studies have demonstrated that shot peening (SP) could enhance surface mechanical strength through residual stress and refined grains. In this work, shot peening with Almen intensities from 30 A to 40 A is performed on the nickel aluminum bronze to investigate the effect on the corrosion and cavitation performance. After shot peening with the rough surface, the samples exhibit higher corrosion current densities due to the increased corrosion area and galvanic cells compared to the as-treated samples. Meanwhile, the samples treated by 40 A show the lowest mass loss during the cavitation test and the highest surface micro-hardness. The enhancement of the cavitation resistance is dominated by the coupling mechanism of the surface corrosion aggravation and strain strengthening. Meanwhile, the higher current intensity, the more pronounced surface strengthening enhancement due to the grain refinement's synergistic mechanism and dislocation density.

Synergistic effect of corrosion and residual stress on fatigue cracks of finger-type bridge expansion joints

Finger-type expansion joints (FJs) have been extensively used in highway bridges and are exposed to the repeated impacts of traffic loading and corrosive environments. In this study, the corrosion and cracking behaviors of FJs serving in bridges for more than 25 years were investigated. The microstructure, electrochemical properties, and dynamic response of the FJs were investigated to analyze the fracture mechanism. The results showed that the crack-induced mechanisms of the two main failure modes were different because the synergistic effect of corrosion with residual stress changed depending on the degree of corrosion. First, considerable residual tensile stress, which enhanced the effective stress range, was the critical cause of fatigue crack initiation in the less corroded heat-affected zone (HAZ). Second, the dominant mechanism for cracking was the applied stress to the severely eroded FJ bottom, which was accelerated by galvanic corrosion. Crack-inducing factors included a combination of stress concentration and dynamic springback behavior.

Evolution in microstructure, wear, corrosion, and tribocorrosion behavior of Mo-containing high-entropy alloy coatings fabricated by laser cladding

The exploration of non-equimolar high-entropy alloy coating provides a broader space for the development of high-performance coatings. In this work, the microstructure, hardness, wear, corrosion, and tribocorrosion of CoCr2FeNiMox (x = 0, 0.1, 0.2, 0.3, 0.4) coatings fabricated by laser cladding were investigated. The results showed that Mo addition significantly increased the hardness and wear resistance. CoCr2FeNiMo0.3 coating exhibited excellent performance during the synergistic effect of corrosion and wear in acidic 3.5 wt.% NaCl solution. The tribocorrosion mechanism of the Mo-containing coating was a combination of abrasion, adhesion wear, and corrosion.

Experimental and numerical simulation of erosion-corrosion of 90° steel elbow in shale gas pipeline

Coexistence of the solid particle erosion and acid liquid corrosion is common in shale gas gathering and transportation pipelines. It is conceivable that the synergistic effect of erosion and corrosion accelerates the pipeline damage process. In this research, a novel experimental device is designed to study the erosion-corrosion characteristics of 90° steel elbow in the gas-liquid-solid three-phase flow. A total of 28 group experiments are designed including 4 gas velocities, 3 liquid pH values, and 150 μm average sand particles. Moreover, a numerical simulation model is built based on the FLUENT code to predict the erosion-corrosion behavior. Experimental and simulation results show that the most severe erosion-corrosion region of the pipe bend occurs at the axial angle of the elbow between 20° and 50° and at the radial angle of the elbow between −45° and 45°. At the bottom of the elbow and the outer wall surface close to the outlet, the synergistic effect of erosion and corrosion accelerates the wear of the pipeline, but the opposite phenomenon exists at the position of the elbow with an axial angle of 50–70°.

Structure and tribocorrosion behavior of CrMoSiCN nanocomposite coating with low C content in artificial seawater

CrMoSiCN nanocomposite coatings with a low C content were prepared on Ti-6Al-4V using an unbalanced magnetron sputtering system, and their corresponding microstructures, mechanical properties, and tribocorrosion performance were evaluated in detail. The results revealed that the CrMoSiCN coating had a compact nanocomposite microstructure consisting of CrN and Mo2N nanocrystallites, (Cr, Mo)N solid solution, and Si-C-N amorphous phases. Moreover, the coating exhibited superior mechanical properties with a hardness of 28.6 GPa and an elastic modulus of 273 GPa, owing to the solid solution strengthening effect. The tribocorrosion test results showed that the dominant failure of the Ti-6Al-4V alloy was caused by the corrosion contribution to wear behaviors (synergistic effect). The CrMoSiCN nanocomposite coating could effectively alleviate the material loss caused by the synergistic effect of corrosion and wear behaviors, leading to pure wear behaviors during the entire tribocorrosion process. The corresponding tribocorrosion mechanisms under the open circuit potential and dynamic polarization conditions were discussed in terms of their tribocorrosion behaviors.

Slurry Erosion-Corrosion Characteristics of As-Built Ti-6Al-4V Manufactured by Selective Laser Melting.

Erosion and erosion–corrosion tests of as-built Ti-6Al-4V manufactured by Selective Laser Melting were investigated using slurries composed of SiO2 sand particles and either tap water (pure water) or 3.5% NaCl solution (artificial seawater). The microhardness value of selective laser melting (SLM)ed Ti-6Al-4V alloy increased as the impact angle increased. The synergistic effect of corrosion and erosion in seawater is always higher than erosion in pure water at all impact angles. The seawater environment caused the dissolution of vanadium oxide V2O5 on the surface of SLMed Ti-6Al-4V alloy due to the presence of Cl− ions in the seawater. These findings show lower microhardness values and high mass losses under the erosion–corrosion test compared to those under the erosion test at all impact angles.

Synergistic effect of erosion and hydrogen on properties of passive film on 2205 duplex stainless steel

Stainless steels have shown great potential in the application of offshore oil and gas industry. However, the internal surface of stainless steel pipeline may simultaneously suffer erosion from the fluid media inside the pipeline and the damage of hydrogen that is generated from the external activities such as cathodic protection. The synergistic effect of erosion and hydrogen on the properties of passive film on 2205 duplex stainless steel was studied for the first time in a loop system coupled with a hydrogen-charging cell. The components, protective performance and semiconductive structure as well as properties of the passive film under different conditions were investigated using in-situ electrochemical techniques, surface characterization and computational fluid dynamics simulation. The results show that the combination of erosion and hydrogen could greatly thin the passive film, furthermore, the Fe3+/Fe2+ ratio and O2−/OH- ratio in the passive film also decrease dramatically under such a condition. Therefore, the hydration degree of the passive film greatly increases, resulting in an increase in active sites and a decrease in the stability of the passive film. Erosion could destroy the passive film through the impact of sand particles and accelerate the mass transfer process of electrochemical reaction. While hydrogen can not only enhance the charge transfer process, but also make the passive film highly defective. Under the combination of erosion and hydrogen condition, erosion could enhance the hydrogen damage and simultaneously hydrogen could also enhance erosion. Therefore, the synergistic effect of erosion and hydrogen could dramatically change the passive film component, decrease the protective performance, and increase the susceptibility of pitting corrosion of 2205 stainless steel in Cl--containing environment.

Enhanced Cavitation Erosion–Corrosion Resistance of High-Velocity Oxy-Fuel-Sprayed Ni-Cr-Al2O3 Coatings Through Stationary Friction Processing

Cavitation erosion is a huge problem in engineering structures working under hydrodynamic conditions. The synergistic effect of erosion and corrosion can aggravate the material removal by several orders of magnitude. Surface coatings are widely used to address material degradation by erosion–corrosion. However, non-homogenous microstructure and presence of defects leads to premature coating failure under erosion–corrosion conditions. Thus, it is imperative to identify plausible solutions to address cavitation-related material degradation. In this study, Ni-Cr-5Al2O3 coatings were deposited on stainless steel substrate using high-velocity-oxy-fuel technique. The as-sprayed coating showed highly non-homogeneous microstructure comprising splats, pores, intermetallic compounds and elemental segregation. A new thermo-mechanical processing technique, stationary friction processing (SFP), was utilized for achieving through-thickness microstructural refinement in as-sprayed coating. As-sprayed and SFP-treated coatings were tested in pure cavitation erosion, corrosion in 3.5% NaCl solution and erosion–corrosion. SFP treatment resulted in 5-times enhancement in the erosion and corrosion resistance compared to as-sprayed coating. The remarkable performance of Ni-Cr-5Al2O3 coatings after SFP treatment is attributed to significant enhancement in the mechanical properties including hardness and fracture toughness which is the consequence of complete removal of splat boundaries, pores, intermetallic compounds and uniform element distribution up to the coating–substrate interface.

Corrosive wear behaviors and mechanisms of a biocompatible Fe-based bulk metallic glass

Wear behaviors of the FeCoCrMoCBY bulk metallic glass (BMG), 316 L stainless steel (SS), and CoCrMo alloy under wet sliding in the phosphate buffered saline (PBS) solution were studied and compared with those under dry sliding. The Fe-based BMG exhibited an excellent corrosive wear resistance with a low wear rate of 1.84 × 10−8 mm3 mm−1•N − 1. On the contrary, the CoCrMo alloy and 316 L SS suffered from the synergistic effect of corrosion and wear in the PBS solution. The electrochemical results revealed that the Fe-based BMG possessed the greatest corrosion performance in the PBS solution among three alloys. The excellent corrosion behavior of the Fe-based BMG was attributed to the highly-protective surface passivation film enriched in Cr and Mo elements. The triobocorrosion results manifested that the great anti-corrosive-wear capacity of the Fe-based BMG can be ascribed to the high stable passivation process during wet sliding.

Deposition and cavitation erosion behavior of multimodal WC-10Co4Cr coatings sprayed by HVOF

Cavitation erosion is one of the major failure modes for engineering components operating in the marine environment. In this study, WC-10Co4Cr coatings with multi-scale WC particles were prepared on 304 stainless steel substrates by two high velocity oxygen fuel (HVOF) systems differentiated by the types of fuel. The splat formation process of the multimodal cermet particles was investigated, as well as coatings' porosity, microhardness, fracture toughness and electrochemical performance. In addition, the cavitation erosion resistance of the coatings was evaluated by ultrasonic vibratory apparatus in 3.5 wt% NaCl solution. The results show that the splats sprayed by high velocity oxygen liquid fuel (HVOLF) had a more disk-like shape, leading to much lower porosity and superior mechanical properties in the corresponding coating. The low porosity also significantly hindered the formation of cavitation sources and reduced the cavitation rate. More importantly, the synergistic effect of corrosion on cavitation erosion made the coating much more vulnerable in NaCl solution than in fresh water.

Synergistic effect of corrosion and wear of the 316 stainless steel in molten zinc alloy at 460 °C

The failure of 316 stainless steel under tribo-corrosion in molten zinc alloy (Zn-0.2Al, wt%) at 460 °C was investigated and compared with corrosion or the sole wear. In the absence of wear, intact Fe2Al5Znx layer forms and protects the steel from dramatic corrosion. Without liquid-metal corrosion, the steel suffers from plastic deformation on friction and slight adhesive wear. While for tribo-corrosion, the synergy of corrosion and wear accounts for 90 % of material loss. Firstly, corrosion generates a brittle scale and leads to embrittlement at subsurface, which accelerate wear. Secondly, wear promotes the formation of less-protective FeZn10 scale, accelerating corrosion.

Influences of Load and Microstructure on Tribocorrosion Behaviour of High Strength Hull Steel in Saline Solution

The tribocorrosion behaviour of two different hull steels (namely, EH36 and EH47) was investigated using a ball-on-disk tribometer under varying normal loads from 10 to 100 N in a 3.5 wt% NaCl saline solution. Sliding in pure water was also performed for a comparison purpose. The results indicate that the corrosion products mainly consist of lath lepidocrocite (γ-FeOOH) with residual NaCl crystals when sliding against both steels EH36 and EH47 in the saline solution. Tribocorrosion on EH36 (pearlitic steel) shows lower coefficient of friction (COF) values than those obtained in water, while tribocorrosion on EH47 (bainitic steel) leads to higher COF values instead. The former is due to the formation of considerable hydroxide particulates and films with small sizes. In contrast, the latter is ascribed to the ploughing of hydroxides with smaller amounts and bigger sizes. In particular, the synergistic effects of corrosion and wear in tribocorrosion result in much higher total materials degradation, compared to that obtained through pure mechanical wear in water.

Direct and indirect corrosion wear performance of AISI 630 steel for the slipper/swashplate pair in a water hydraulic pump

To explore feasibility of AISI 630 steel applied to slipper/swashplate pair of a water hydraulic pump. Frictional corrosion experiment simulating slipper/swashplate pair operation was systematically conducted under three different lubricating conditions, and the influence of lubricating medium and solution aging on corrosion wear of AISI 630 steel and indirect corrosion wear of its dual PEEK surface were evaluated by means of scanning electron microscopy, X-ray photoelectron spectroscopy, and electrochemical corrosion test analysis. It was shown that synergistic effect of corrosion and wear played an important role on wear of AISI 630 steel and occupied up to 25% of its total wear loss. Solution aging of AISI 630 steel could help to decrease wear rate of its dual PEEK surface in freshwater, but would significantly increase friction coefficient and wear rate of AISI 630 in seawater and aggravate the wear and indirect corrosion wear of its dual PEEK surface. Therefore, for the water hydraulic slipper/swashplate pair, it is suggested that when taking service in freshwater, solution aging of AISI 630 steel can be considered to alleviate wear of its dual PEEK surface, but when taking service in seawater, solution aging is not recommended, and the original AISI 630 steel is more conducive to obtain preferable friction and wear performance.

Synergistic effects of corrosion and slow strain rate loading on the mechanical and electrochemical response of an aluminium alloy

Tensile specimens of an aluminium alloy, AA7075, with grains aligned parallel to the tensile axis are subjected to a range of slow strain rate tensile loading in a very low pH corrosive environment. The degradation in mechanical response together with the emerging electrochemical characteristics of the material using electrochemical impedance spectroscopy (EIS) are characterized. The EIS measurements coupled with the post-mortem microscopic characterization of the specimens provide an unprecedented view of all the interfacial phenomena affecting the mechanical response of the material. A failure mechanism of the material under consideration is proposed and rationalized by a qualitative fracture mechanics analysis.

A nonlocal peridynamics modeling approach for corrosion damage and crack propagation

Corrosion and its synergistic interactions with mechanical loading are a major cause of damage and failure of structural components. In this work, we present a recently developed peridynamics model for modeling corrosion damage and resulting crack propagation phenomena under synergistic effects of corrosion and mechanical loading. The approach is based on nonlocal peridynamics theory that replaces governing equations of classical continuum mechanics with integro-differential equations that are easy to solve across discontinuities like cracks. Here we introduce a micro-chemically sensitive peridynamic modeling approach developed for corrosion damage phenomena. First we introduce the theoretical approach and then simplify it to obtain a peridynamic model for mechanistic corrosion damage and crack propagation. Subsequently, numerical simulations are used demonstrate the capabilities of the peridynamic model for capturing mechanics of corroding solid. The framework is able to capture corrosion pitting, nucleation, crack path propagation under synergistic influence of corrosion and mechanical loading, without the need to re-mesh the domain or special numerical treatments. The developed peridynamic approach provides a physics-based alternative to conventional theories and enables crack propagation studies in corrosive environments.

Failure analysis on synergistic effect of erosion and corrosion on failed fittings in specialty chemical plant. Part I: Elbows

Elbow is widely considered as a vulnerable part in the whole steam pipelines due to the special geometry and complex flow property. In this study, unexpected leakages took place on two elbows utilized in the same steam system of a specialty chemical plant. However, these two failed elbows exhibited completely different morphologies, which indicated that they might have undergone different failure processes. A series of macroscopic and microscopic analysis methods were conducted to identify and differentiate the root causes of the failures. Totally four corrosion mechanisms were involved and the key factor that led to the different morphologies of these two elbows was discussed in detail. The results show that the failure of one elbow resulted from the synergistic effect of uniform corrosion and under‐deposit corrosion, while the failure of the other elbow was caused by the combined effect of pitting corrosion and erosion. Some effective countermeasures were proposed to avoid the similar failure occurring again.

Failure analysis on synergistic effect of erosion and corrosion on failed fittings in specialty chemical plant. Part II: Control valve

Failure analysis was carried out on a control valve in the steam system of a specialty chemical plant. Comprehensive analyses were conducted to investigate the operating conditions, base materials, macroscopic, and microscopic morphologies of the failed steam control valve and a computational fluid dynamic model was also adopted. The results showed that the synergistic effect of electrochemical corrosion favored by chlorides and two phase flow erosion accounted for the premature failure of the steam control valve. Considering the fact that the valve was designed by a German company, assembled by an American company and used in a Chinese company, our failure analysis seems to be crucial for the imputation of the responsibility. The failure mechanisms were discussed and the relevant countermeasures were proposed to prevent the occurrence of similar failure again.

A New Asperity-Scale Mechanistic Model of Tribocorrosive Wear: Synergistic Effects of Mechanical Wear and Corrosion

A corrosive wear model is considered at the asperity-scale of a tribocorrosive wear system as well as the traditional Archard-type mechanical wear model. The geometry of the surface asperities is modified in a contact mechanics model with respect to both corrosive and mechanical wear calculations. This model was presented and validated for prediction of the electrochemistry in the first part of this work. The material used in the experimental part of this work was CoCrMo plate working electrode (WE) and Si3N4 ball as the counter body in a reciprocating configuration. Experiments were conducted at loads of 5, 7.5, and 10 N and the contributions of total mechanical wear and corrosion were measured. The model is then tuned to predict the chemical and mechanical components of the total wear of the system. The synergistic effect of corrosion on mechanical wear and mechanical wear on corrosion are modeled numerically in this work. The values are then used to explain different components of mechanistic tribocorrosive wear models present in the literature. This deterministic model, for the first time, calculates the corrosion-enhanced wear in a tribocorrosive wear environment and proposes that changes in the topography are responsible for this synergistic effect. The results show a linear dependence of the corrosion enhanced wear, wear-enhanced corrosion, and the pure mechanical wear on the applied load. Results also suggest that the wear enhanced corrosion has a significant contribution in the overall degradation of the material.