The recognition and monitoring of localized corrosion at the early stage on the inner wall surface of pipes are extremely difficult and simultaneously the reliable approach for recognition and monitoring is missing.He...The recognition and monitoring of localized corrosion at the early stage on the inner wall surface of pipes are extremely difficult and simultaneously the reliable approach for recognition and monitoring is missing.Here we report a spatially resolved method to recognize and monitor the localized corrosion in a non-destructive way based on the permeating hydrogen signal generated from localized corrosion itself.A simulative localized corrosion was created on one side surface of the carbon steel specimen where a dot of wet elemental sulfur was introduced to accelerate the corrosion on the local region.While,the potential on the other side surface(the reverse side of the corrosion site)of the specimen was measured using a scanning Kelvin probe.The results show that the permeating hydrogen generated from localized corrosion easily arrives on the reverse side surface of the corrosion site and then causes a huge change in surface potential.The location resolution of potential distribution can be revealed with micron level.Therefore,it is thought that the location of localized corrosion can be recognized by the permeating hydrogen signal distribution on the reverse side surface of the corrosion site since the region of potential decreasing is highly corresponding to the corrosion site.Moreover,the strength of the permeating hydrogen signal is highly related to the corrosion depth and transient corrosion rate of localized corrosion.This means that the localized corrosion development can also be monitored using the permeating hydrogen signal.Therefore,it can be expected that the localized corrosion occurring on the inner wall surface of pipes or equipment can be recognized and monitored successfully on the outer wall surface in a non-destructive way once the permeating hydrogen is present during the localized corrosion proceeding.展开更多
Corrosion poses a major threat to the safety of transportation pipelines.Therefore,it is crucial to have an in-depth understanding of corrosion mechanisms in pipeline steels for the effective management of pipeline in...Corrosion poses a major threat to the safety of transportation pipelines.Therefore,it is crucial to have an in-depth understanding of corrosion mechanisms in pipeline steels for the effective management of pipeline integrity.Conducting research on corrosion mechanisms relies on the use of efficient and reliable corrosion monitoring and analysis techniques.The advancements in corrosion monitoring techniques specifically designed for the localized corrosion monitoring were aimed to be introduced,and a comprehensive overview of recent progress in understanding the localized corrosion mechanisms in pipeline steels was provided.Based on the different corrosive environments encountered,the localized corrosion issues inside pipelines are classified into two categories:localized corrosion primarily influenced by electrochemical processes and localized corrosion controlled by both electrochemical and mechanical factors.Additionally,a thorough analysis of the synergistic effects between micro-cell and macro-cell currents,as well as the interplay of mechanics and electrochemistry is presented.Finally,recommendations for future research on the mechanisms of internal localized corrosion in pipelines are provided.展开更多
The surface properties of weathering steel(WS)is very important for its service performance and safety,and the localized corrosion induced by inclusions is closely related to the surface properties of WS and its appli...The surface properties of weathering steel(WS)is very important for its service performance and safety,and the localized corrosion induced by inclusions is closely related to the surface properties of WS and its application.In the current work,a common spherical(Al,Mg,Ca,Mn)-oxy-sulfide inclusion was selected to investigate the corrosion evolution of complex inclusion and its effect on localized corrosion on WS surface.The results indicate the inclusion in WS consists of(Ca,Mn)sulfides part and(Ca,Al,Mg)oxides part with complex core-shell structure.Locally preferential dissolution occurs in(Ca,Mn)sulfides part as well as metal matrix around the inclusions.Furthermore,both parts of the inclusions with poor conductivity and high-density dislocation at metal matrix around the inclusions was found,which suggests that traditional micro-galvanic corrosion cell may not be the cause of inclusion-induced localized corrosion on WS surface at initial stage of corrosion.The variation in maximum and average depth around the inclusion or selected region with immersion time indicates that localized corrosion induced by inclusions is overwhelmed by uniform corrosion of WS in the latter stage of immersion,then the rust formed on WS surface consists of two layers.展开更多
Certain inclusions in high-strength 60Si2Mn-Cr spring steel result in poor resistance to localized corrosion.In this work,to study the effect of inclusions on the localized corrosion behavior of spring steel,accelerat...Certain inclusions in high-strength 60Si2Mn-Cr spring steel result in poor resistance to localized corrosion.In this work,to study the effect of inclusions on the localized corrosion behavior of spring steel,accelerated corrosion tests were performed by immersing spring steel in 3wt%FeCl_(3)solution for different times.The results show that severe corrosion occurred in areas of clustered CaS inclusions.Sulfide inclusions containing Ca and Mg induced the strongest localized corrosion susceptibility.For the case of(Ca,Mn,Mg)S inclusions,the ability to induce localized corrosion susceptibility is ranked as follows:MgS>CaS>MnS.Moreover,CaS,(Ca,Mn)S,and(Ca,Mn,Mg)S inclusions were mainly responsible for inducing environmental embrittlement.展开更多
There are a great variety of commercial nickel alloys mainly because nickel is able to dissolve a large amount of alloying elements while maintaining a single ductile austenitic phase. Nickel alloys are generally desi...There are a great variety of commercial nickel alloys mainly because nickel is able to dissolve a large amount of alloying elements while maintaining a single ductile austenitic phase. Nickel alloys are generally designed for and used in highly aggressive environments, for example, those where stainless steels may experience pitting corrosion or environmentally assisted cracking. While nickel alloys are generally resistant to pitting corrosion in chloride-containing environments, they may be prone to crevice corrosion attack. Addition of chromium, molybdenum and tungsten increases the localized corrosion resistance of nickel alloys. This review on the resistance to localized corrosion of nickel alloys includes specific environments such as those present in oil and gas upstream operations, in the chemical process industry and in seawater service.展开更多
Electrochemical and localized corrosion behavior of a 4045/7072/3003 M/4045 Al alloy composite in 3.5 wt.%NaCl solution was investigated from cross-sectional and plane directions by electrochemical impedance spectrosc...Electrochemical and localized corrosion behavior of a 4045/7072/3003 M/4045 Al alloy composite in 3.5 wt.%NaCl solution was investigated from cross-sectional and plane directions by electrochemical impedance spectroscopy,polarization curves,and high-resolution microscopic examination.Plane directions showed higher corrosion resistance than the cross-sectional surface,with almost all localized corrosion initiated from Si-containing inclusions.The cross-section showed a complex galvanic effect among the four layers,the galvanic coupling between 4045/7072 accelerated the dissolution of 7072 because 7072 served as the anode,however,the galvanic coupling between 3003 M/4045 protected 4045 from corrosion,indicating that 3003 M served as the anode.展开更多
The microstructure,localized corrosion (LC) and stress corrosion cracking (SCC) behavior of 7003 aluminum alloy (AA7003) under various aging treatments (peak aging (PA),double peak aging (DPA),regression and re-aging ...The microstructure,localized corrosion (LC) and stress corrosion cracking (SCC) behavior of 7003 aluminum alloy (AA7003) under various aging treatments (peak aging (PA),double peak aging (DPA),regression and re-aging (RRA)) were investigated by means of transmission electron microscope (TEM),scanning electron microscopy (SEM),electrochemical impendence spectroscopy (EIS) and slow strain rate tensile test.The results of TEM showed a discontinuous distribution of grain boundary precipitates of AA7003 under DPA and RRA treatments,which is beneficial for increasing the resistance of LC and SCC.Meanwhile,LC was found initiating firstly on intermetallics which caused the dissolution of surrounding matrix,then pitting holes were formed and developed into matrix.In addition,the SCC process of AA7003 could be divided into two stages,i e,initial pre-cracking and breeding cracking.The EIS analysis,cross-section morphologies and fracture surfaces of specimens indicated that DPA and RRA treatments significantly decreased the crack growth rate during breeding cracking stage,especially for RRA treatment.展开更多
The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,inte...The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,intergranular corrosion test,exfoliation corrosion test,slow strain rate tensile test and electrochemical test,and the mechanism has been discussed based on microstructure examination by optical microscopy,electron back scattered diffraction,scanning electron microscopy and scanning transmission electron microscopy.The NIA treatment includes a heating stage from 40℃to 180℃with a rate of 20℃/h and a cooling stage from 180℃to 40℃with a rate of 10℃/h.The results show that the hardness and strength increase rapidly during the heating stage of NIA since the increasing temperature favors the nucleation and the growth of strengthening precipitates and promotes the transformation of Guinier-Preston(GPI)zones toη'phase.During the cooling stage,the sizes ofη'phase increase with a little change in the number density,leading to a further slight increase of the hardness and strength.As NIA proceeds,the corroded morphology in the alloy changes from a layering feature to a wavy feature,the maximum corrosion depth decreases,and the reason has been analyzed based on the microstructural and microchemical feature of precipitates at grain boundaries and subgrain boundaries.展开更多
The effects of inclusions on localized corrosion of Zr–Ti deoxidized low-alloy steels in marine environment were investigated by various analytical techniques including scanning electron microscopy with X-ray microan...The effects of inclusions on localized corrosion of Zr–Ti deoxidized low-alloy steels in marine environment were investigated by various analytical techniques including scanning electron microscopy with X-ray microanalysis(SEM/EDS),confocal Raman microscopy(CRM),and in situ scanning vibrating electrode technique(SVET).It was found that complex(Zr,Ti,Al)-O_(x)inclusions were responsible for the initiation of localized corrosion.Localized corrosion pref-erentially occurred at Fe matrix adjacent to these inclusions and formed micro-gaps.In the early stage of corrosion,catalytic-occluded cells and the diffusion of chloride ions played a major role in the propagation of corrosion,further accelerating the dissolution of Fe matrix and(Zr,Ti,Al)-O_(x)inclusions.Combining SVET and CRM results,it revealed that the maximum anodic current density in local area gradually decreased with prolonged exposure time,indicating that corrosion products covered the steel surface and lowered the propagation rate of corrosion.In the later stage of corrosion,the barrier effect of corrosion products played an important role in inhibiting localized corrosion.展开更多
Revealing the localized corrosion process of Mg alloy is considered as one of the most significant ways for improving its corrosion resistance.The reliable monitor should be high distinguishability and real-time in li...Revealing the localized corrosion process of Mg alloy is considered as one of the most significant ways for improving its corrosion resistance.The reliable monitor should be high distinguishability and real-time in liquid environment.Herein,Mg-9Al-1Fe and Mg-9Al-1Fe-1Gd alloys were designed to highlight the impact of intermetallic on the corrosion behaviour.In-situ AFM with a special electrolyte circulation system and quasi-in-situ SEM observation were used to monitor the corrosion process of the designed alloys.SEM-EDS and TEM-SAED were applied to identify the intermetallic in the designed alloys,and their volta potentials were measured by SKPFM.According to the real-time and real-space in-situ AFM monitor,the corrosion process consisted of dissolution of anodicα-Mg phase,accumulation of corrosion products around cathodic phase and shedding of some fine cathodic phase.Then,the localized corrosion process of Mg alloy was revealed combined with the results of the monitor of corrosion process and Volta potential difference.展开更多
The resistances against localized corrosion of 1Cr18Ni9Ti microcrystals with normal grain size and bcc structure obtained hy magnetron sputtering have been compared.The two kinds of microcrystals with (110) and (211) ...The resistances against localized corrosion of 1Cr18Ni9Ti microcrystals with normal grain size and bcc structure obtained hy magnetron sputtering have been compared.The two kinds of microcrystals with (110) and (211) textures respectively were obtained under different sputtering conditions.Both microcrystals were found to have better resistance against local- ized corrosion than the crystal with normal grain.The microcrystal with (110) preferred orientation has larger resistance to localized corrosion than that with (211) preferred orientation.展开更多
An unusual form of localized corrsion in copper tubes was detected early in service and in leakage tests after manufacturing.The morphology of this corrosion is similar to that of an ant's nest when viewed in cros...An unusual form of localized corrsion in copper tubes was detected early in service and in leakage tests after manufacturing.The morphology of this corrosion is similar to that of an ant's nest when viewed in cross section. The corrosion mechanisms, cases ofant's nest corrosion, and preventive measures are presented.展开更多
An artificial localized corrosion system is assembled and some parameters related to the localized corrosion in active dissolution state (i.e., non-passive state) have been studied. The results showed that the develop...An artificial localized corrosion system is assembled and some parameters related to the localized corrosion in active dissolution state (i.e., non-passive state) have been studied. The results showed that the developed electrochemical system can satisfactorily imitate a naturally formed localized corrosion and the coupling current can indicate the maximum localized propagating rate. In this artificial system, the anodic dissolution reaction followed the auto-catalytic mechanism. The localized corrosion current density was dependent on the area ratio R of the cathode to the occluded anode. While R was equal to or more than 6, the coupling current reached at a maximum value and did not alter with the increase in R-value. Therefore, R=7 is chosen as one of these optimum parameters used in constructing the system, with which the biggest galvanic current might be obtained. In contrast, the thickness of the polymer filler separating the occluded anode area from the bulk electrolyte solution and the volume of the occluded anode area did not affect the corrosion current obviously. They might affect the response time to approach a steady state.展开更多
The effect of grain orientation and grain boundary angle on the microscopic corrosion behavior of pure zinc was employed by the systematic integrated SECM, EBSD and AFM analysis. With confirmed different orientation g...The effect of grain orientation and grain boundary angle on the microscopic corrosion behavior of pure zinc was employed by the systematic integrated SECM, EBSD and AFM analysis. With confirmed different orientation grains, we proved the zinc grain near <0001>//ND orientation shows the lowest corrosion rate compared to that near <01■0>//ND and <■0>//ND orientation. Even though the grain orientation distribution is random and the grain corrosion rates of <01■0>//ND and <■0>//ND orientations are similar, the <0001>//ND have the lowest reactivity. The corrosion morphology of <0001>//ND orientation grain appears hexagonal corrosion pit,and the morphology of <01■0>//ND and <■0>//ND orientation grain shows striated structures. This behavior could be explained by the corrosion morphology and rate of zinc grain depending on the orientation.展开更多
The localized and uniform corrosion resistances of bulk nanocrystalline 304 stainless steel（NC-304 SS）produced by severe rolling technique, and its conventional polycrystalline 304 stainless steel（CC-304 SS）counte...The localized and uniform corrosion resistances of bulk nanocrystalline 304 stainless steel（NC-304 SS）produced by severe rolling technique, and its conventional polycrystalline 304 stainless steel（CC-304 SS）counterpart, were investigated in high-concentration hydrochloric acid solutions at room temperature.NC-304 SS can scarcely suffer from localized corrosion in 4 mol/L and 5 mol/L HCl solutions during 5-day immersion tests, and in 1-3 mol/L HCl solutions during thirty-five-day immersion tests. The corrosion rate of NC-304 SS was also less than that of CC-304 SS during these immersion tests. The improved localized and uniform corrosion resistances of NC-304 SS were explained in terms of the adsorption and chemical activity of Cl;on NC-304 SS and CC-304 SS characterized by X-ray photoelectron spectroscopy,and the valence electron configurations of NC-304 SS and CC-304 SS were characterized by ultra-violet photoelectron spectroscopy rather than conventional electrochemical results.展开更多
Macrophages play a central role in immunological responses to metallic species associated with the localized corrosion of metallic implants,and mediating in peri-implant inflammations.Herein,the pathways of localized ...Macrophages play a central role in immunological responses to metallic species associated with the localized corrosion of metallic implants,and mediating in peri-implant inflammations.Herein,the pathways of localized corrosion-macrophage interactions were systematically investigated on 316L stainless steel(SS)implant metals.Electrochemical monitoring under macrophage-mediated inflammatory conditions showed a decreased pitting corrosion resistance of 316L SSs in the presence of RAW264.7 cells as the cells would disrupt biomolecule adsorbed layer on the metal surface.The pitting potentials were furtherly decreased when the RAW264.7 cells were induced to the M1 pro-inflammatory phenotype by the addition of lipopolysaccharide(LPS),and pitting corrosion preferentially initiated at the peripheries of macrophages.The overproduction of aggressive ROS under inflammatory conditions would accelerate the localized corrosion of 316L SS around macrophages.Under pitting corrosion condition,the viability and pro-inflammatory polarization of RAW264.7 cells were region-dependent,lower viability and more remarkable morphology transformation of macrophages in the pitting corrosion region than the pitting-free region.The pitting corrosion of 316L SS induced high expression of CD86,TNF-α,IL-6 and high level of intracellular ROS in macrophages.Uneven release of metallic species(Fe^(2+),Cr^(3+),Ni^(2+),etc)and uneven distribution of surface overpotential stimulated macrophage inflammatory responses near the corrosion pits.A synergetic effect of localized corrosion and macrophages was revealed,which could furtherly promote localized corrosion of 316L SS and macrophage inflammatory reactions.Our results provided direct evidence of corrosion-macrophage interaction in metallic implants and disclosed the pathways of this mutual stimulation effect.展开更多
The corrosion behavior of Q420 steel under constant temperature and freezing-thawing conditions is investigated.The steel exhibits the highest corrosion rate at 25℃ and the lowest corrosion rate at−30℃,while the ste...The corrosion behavior of Q420 steel under constant temperature and freezing-thawing conditions is investigated.The steel exhibits the highest corrosion rate at 25℃ and the lowest corrosion rate at−30℃,while the steel that undergoes freezing-thawing cycling shows lower corrosion rate than that at 0℃.The localized corrosion is significantly affected by the temperature variations,with the samples corroded under freezing-thawing conditions showing the highest pit number density and the highest possibility of the pit initiation.The samples immersed at 0 and 25℃ show comparable pit size with higher pit depth,diameter,and volume,attributed to the higher rate of pit propagation along the vertical and horizontal directions.Galvanic corrosion results demonstrate that there are areas of activated metal under the ice,which form microcells with surrounding unaffected areas,attributed to the local ion concentration and the water crystallization.展开更多
The poor mechanical properties of pure zinc(Zn)restrain its applications in orthopedics,which requires high loading capacity.Alloying with lithium(Li)element can enhance strength,however,the work-hardening rate is imp...The poor mechanical properties of pure zinc(Zn)restrain its applications in orthopedics,which requires high loading capacity.Alloying with lithium(Li)element can enhance strength,however,the work-hardening rate is impaired with increased Li content.Here,introducing scandium(Sc)into a low Li-containing Zn-0.1Li alloy could effectively refine its microstructure,reducing the average grain size from 10 to 4μm.The refinement in microstructure led to a significant improvement in tensile strength,im-proving from 257 MPa of Zn-0.1Li to 341 MPa of Zn-0.1Li-0.1Sc,meanwhile,the work-hardening rate remained positive during the whole plastic deformation stage.The addition of Sc-impaired elongation is due to numerous microcracks formed at the Zn/ScZn_(12)interfaces,as well as in the large-sized ScZn_(12)particles.Corrosion tests revealed an accelerated corrosion rate due to the galvanic effect between the Zn matrix and ScZn_(12)phase.Even so,the Zn-0.1Li-1.0Sc alloy still exhibited superior biocompatibility with rat/mouse mesenchymal stem cells and close osteogenesis capacity to the original Zn-0.1Li alloy.These findings demonstrated that the addition of Sc in low Li-containing alloys could improve mechanical strength without sacrificing the work-hardening rate and biocompatibility.展开更多
The present work investigates the corrosion behaviour of an AA2024 alloy thin wall structure produced by wire arc additive manufacturing(WAAM)with interpass rolling,focussing on the influence of interpass rolling.It i...The present work investigates the corrosion behaviour of an AA2024 alloy thin wall structure produced by wire arc additive manufacturing(WAAM)with interpass rolling,focussing on the influence of interpass rolling.It is found that although interpass rolling does not change the typical configuration of thin wall structure,i.e.melt pool zone(MPZ),melt pool border(MPB)and heat-affected zone(HAZ),the plastic deformation introduced by interpass rolling leads to the variation of grain-stored energy across the structure,which consequently results in the highest corrosion susceptibility of MPB due to its relatively high stored energy.展开更多
The Mg-9Li-1Zn(LZ91)alloy was subjected to an ultrasonic surface rolling process(USRP)with varying passes for the purpose of modifying its surface state.The USRP transformed surface residual stress from initial tensil...The Mg-9Li-1Zn(LZ91)alloy was subjected to an ultrasonic surface rolling process(USRP)with varying passes for the purpose of modifying its surface state.The USRP transformed surface residual stress from initial tensile stress to compressive stress,decreasing the surface roughness and increasing the ratio of the β-Li phase.The USRPed LZ91 sample(3 passes)showed superior corrosion resistance,with the corrosion current density changing from 57.11 to 24.70μA cm^(-2),and the polarization resistance increasing from 576.3 to 1146.1Ωcm^(2).According to the corrosion procedure evaluations,in situ observation revealed that the LZ91 alloy initially experiences pitting,which subsequently develops into cracking.The substantial area coverage of the β-Li phase facilitates the formation of a protective film on the surface,effectively delaying localized corrosion.展开更多
基金support from the National Natural Science Foundation of China(No.52171080)。
文摘The recognition and monitoring of localized corrosion at the early stage on the inner wall surface of pipes are extremely difficult and simultaneously the reliable approach for recognition and monitoring is missing.Here we report a spatially resolved method to recognize and monitor the localized corrosion in a non-destructive way based on the permeating hydrogen signal generated from localized corrosion itself.A simulative localized corrosion was created on one side surface of the carbon steel specimen where a dot of wet elemental sulfur was introduced to accelerate the corrosion on the local region.While,the potential on the other side surface(the reverse side of the corrosion site)of the specimen was measured using a scanning Kelvin probe.The results show that the permeating hydrogen generated from localized corrosion easily arrives on the reverse side surface of the corrosion site and then causes a huge change in surface potential.The location resolution of potential distribution can be revealed with micron level.Therefore,it is thought that the location of localized corrosion can be recognized by the permeating hydrogen signal distribution on the reverse side surface of the corrosion site since the region of potential decreasing is highly corresponding to the corrosion site.Moreover,the strength of the permeating hydrogen signal is highly related to the corrosion depth and transient corrosion rate of localized corrosion.This means that the localized corrosion development can also be monitored using the permeating hydrogen signal.Therefore,it can be expected that the localized corrosion occurring on the inner wall surface of pipes or equipment can be recognized and monitored successfully on the outer wall surface in a non-destructive way once the permeating hydrogen is present during the localized corrosion proceeding.
基金sponsored by the National Key R&D Program of China(No.2022YFC2806200)the National Natural Science Foundation of China(No.52001055)the Open Foundation of State Key Laboratory of Structural Analysis for Industrial Equipment(GZ22118).
文摘Corrosion poses a major threat to the safety of transportation pipelines.Therefore,it is crucial to have an in-depth understanding of corrosion mechanisms in pipeline steels for the effective management of pipeline integrity.Conducting research on corrosion mechanisms relies on the use of efficient and reliable corrosion monitoring and analysis techniques.The advancements in corrosion monitoring techniques specifically designed for the localized corrosion monitoring were aimed to be introduced,and a comprehensive overview of recent progress in understanding the localized corrosion mechanisms in pipeline steels was provided.Based on the different corrosive environments encountered,the localized corrosion issues inside pipelines are classified into two categories:localized corrosion primarily influenced by electrochemical processes and localized corrosion controlled by both electrochemical and mechanical factors.Additionally,a thorough analysis of the synergistic effects between micro-cell and macro-cell currents,as well as the interplay of mechanics and electrochemistry is presented.Finally,recommendations for future research on the mechanisms of internal localized corrosion in pipelines are provided.
基金financially supported by the National Key Research and Development Program of China(No.2017YFB0702302)the National Natural Science Foundation of China(No.51771174)the National Materials Corrosion and Protection Data Center。
文摘The surface properties of weathering steel(WS)is very important for its service performance and safety,and the localized corrosion induced by inclusions is closely related to the surface properties of WS and its application.In the current work,a common spherical(Al,Mg,Ca,Mn)-oxy-sulfide inclusion was selected to investigate the corrosion evolution of complex inclusion and its effect on localized corrosion on WS surface.The results indicate the inclusion in WS consists of(Ca,Mn)sulfides part and(Ca,Al,Mg)oxides part with complex core-shell structure.Locally preferential dissolution occurs in(Ca,Mn)sulfides part as well as metal matrix around the inclusions.Furthermore,both parts of the inclusions with poor conductivity and high-density dislocation at metal matrix around the inclusions was found,which suggests that traditional micro-galvanic corrosion cell may not be the cause of inclusion-induced localized corrosion on WS surface at initial stage of corrosion.The variation in maximum and average depth around the inclusion or selected region with immersion time indicates that localized corrosion induced by inclusions is overwhelmed by uniform corrosion of WS in the latter stage of immersion,then the rust formed on WS surface consists of two layers.
基金the National Natural Science Foundation of China(Nos.51574190,51734003,51874116)Fundamental Research Funds for the Central Universities(No.FRF-TP-18-009C1).
文摘Certain inclusions in high-strength 60Si2Mn-Cr spring steel result in poor resistance to localized corrosion.In this work,to study the effect of inclusions on the localized corrosion behavior of spring steel,accelerated corrosion tests were performed by immersing spring steel in 3wt%FeCl_(3)solution for different times.The results show that severe corrosion occurred in areas of clustered CaS inclusions.Sulfide inclusions containing Ca and Mg induced the strongest localized corrosion susceptibility.For the case of(Ca,Mn,Mg)S inclusions,the ability to induce localized corrosion susceptibility is ranked as follows:MgS>CaS>MnS.Moreover,CaS,(Ca,Mn)S,and(Ca,Mn,Mg)S inclusions were mainly responsible for inducing environmental embrittlement.
文摘There are a great variety of commercial nickel alloys mainly because nickel is able to dissolve a large amount of alloying elements while maintaining a single ductile austenitic phase. Nickel alloys are generally designed for and used in highly aggressive environments, for example, those where stainless steels may experience pitting corrosion or environmentally assisted cracking. While nickel alloys are generally resistant to pitting corrosion in chloride-containing environments, they may be prone to crevice corrosion attack. Addition of chromium, molybdenum and tungsten increases the localized corrosion resistance of nickel alloys. This review on the resistance to localized corrosion of nickel alloys includes specific environments such as those present in oil and gas upstream operations, in the chemical process industry and in seawater service.
基金financed by the National Key Research and Development Program(No.2022YFB3705801)the National Natural Science Foundation of China(Nos.52031007 and 52171077).
文摘Electrochemical and localized corrosion behavior of a 4045/7072/3003 M/4045 Al alloy composite in 3.5 wt.%NaCl solution was investigated from cross-sectional and plane directions by electrochemical impedance spectroscopy,polarization curves,and high-resolution microscopic examination.Plane directions showed higher corrosion resistance than the cross-sectional surface,with almost all localized corrosion initiated from Si-containing inclusions.The cross-section showed a complex galvanic effect among the four layers,the galvanic coupling between 4045/7072 accelerated the dissolution of 7072 because 7072 served as the anode,however,the galvanic coupling between 3003 M/4045 protected 4045 from corrosion,indicating that 3003 M served as the anode.
基金Funded by National Natural Science Foundation of China(Nos.51371039 and 51871031)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘The microstructure,localized corrosion (LC) and stress corrosion cracking (SCC) behavior of 7003 aluminum alloy (AA7003) under various aging treatments (peak aging (PA),double peak aging (DPA),regression and re-aging (RRA)) were investigated by means of transmission electron microscope (TEM),scanning electron microscopy (SEM),electrochemical impendence spectroscopy (EIS) and slow strain rate tensile test.The results of TEM showed a discontinuous distribution of grain boundary precipitates of AA7003 under DPA and RRA treatments,which is beneficial for increasing the resistance of LC and SCC.Meanwhile,LC was found initiating firstly on intermetallics which caused the dissolution of surrounding matrix,then pitting holes were formed and developed into matrix.In addition,the SCC process of AA7003 could be divided into two stages,i e,initial pre-cracking and breeding cracking.The EIS analysis,cross-section morphologies and fracture surfaces of specimens indicated that DPA and RRA treatments significantly decreased the crack growth rate during breeding cracking stage,especially for RRA treatment.
基金Project(202302AB080024)supported by the Department of Science and Technology of Yunnan Province,China。
文摘The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,intergranular corrosion test,exfoliation corrosion test,slow strain rate tensile test and electrochemical test,and the mechanism has been discussed based on microstructure examination by optical microscopy,electron back scattered diffraction,scanning electron microscopy and scanning transmission electron microscopy.The NIA treatment includes a heating stage from 40℃to 180℃with a rate of 20℃/h and a cooling stage from 180℃to 40℃with a rate of 10℃/h.The results show that the hardness and strength increase rapidly during the heating stage of NIA since the increasing temperature favors the nucleation and the growth of strengthening precipitates and promotes the transformation of Guinier-Preston(GPI)zones toη'phase.During the cooling stage,the sizes ofη'phase increase with a little change in the number density,leading to a further slight increase of the hardness and strength.As NIA proceeds,the corroded morphology in the alloy changes from a layering feature to a wavy feature,the maximum corrosion depth decreases,and the reason has been analyzed based on the microstructural and microchemical feature of precipitates at grain boundaries and subgrain boundaries.
基金The financial support from the National Natural Science Foundation of China(Nos.51601138 and 51601137)and the State Key Laboratory of Refractories and Metallurgy(No.2018QN18)is highly acknowledged.The authors are also grateful to the support from the 973 Program(No.2014CB643300)+1 种基金the 111 Project(No.D18018)Excellent Young and Middle-aged Science and Technology Innovation Team in Colleges and Universities of Hubei Province(No.T201903).
文摘The effects of inclusions on localized corrosion of Zr–Ti deoxidized low-alloy steels in marine environment were investigated by various analytical techniques including scanning electron microscopy with X-ray microanalysis(SEM/EDS),confocal Raman microscopy(CRM),and in situ scanning vibrating electrode technique(SVET).It was found that complex(Zr,Ti,Al)-O_(x)inclusions were responsible for the initiation of localized corrosion.Localized corrosion pref-erentially occurred at Fe matrix adjacent to these inclusions and formed micro-gaps.In the early stage of corrosion,catalytic-occluded cells and the diffusion of chloride ions played a major role in the propagation of corrosion,further accelerating the dissolution of Fe matrix and(Zr,Ti,Al)-O_(x)inclusions.Combining SVET and CRM results,it revealed that the maximum anodic current density in local area gradually decreased with prolonged exposure time,indicating that corrosion products covered the steel surface and lowered the propagation rate of corrosion.In the later stage of corrosion,the barrier effect of corrosion products played an important role in inhibiting localized corrosion.
基金support by the National Natural Science Foundation of China(51961026)the Interdisciplinary Innovation Fund of Nanchang University(Project No.2019-9166-27060003).
文摘Revealing the localized corrosion process of Mg alloy is considered as one of the most significant ways for improving its corrosion resistance.The reliable monitor should be high distinguishability and real-time in liquid environment.Herein,Mg-9Al-1Fe and Mg-9Al-1Fe-1Gd alloys were designed to highlight the impact of intermetallic on the corrosion behaviour.In-situ AFM with a special electrolyte circulation system and quasi-in-situ SEM observation were used to monitor the corrosion process of the designed alloys.SEM-EDS and TEM-SAED were applied to identify the intermetallic in the designed alloys,and their volta potentials were measured by SKPFM.According to the real-time and real-space in-situ AFM monitor,the corrosion process consisted of dissolution of anodicα-Mg phase,accumulation of corrosion products around cathodic phase and shedding of some fine cathodic phase.Then,the localized corrosion process of Mg alloy was revealed combined with the results of the monitor of corrosion process and Volta potential difference.
文摘The resistances against localized corrosion of 1Cr18Ni9Ti microcrystals with normal grain size and bcc structure obtained hy magnetron sputtering have been compared.The two kinds of microcrystals with (110) and (211) textures respectively were obtained under different sputtering conditions.Both microcrystals were found to have better resistance against local- ized corrosion than the crystal with normal grain.The microcrystal with (110) preferred orientation has larger resistance to localized corrosion than that with (211) preferred orientation.
文摘An unusual form of localized corrsion in copper tubes was detected early in service and in leakage tests after manufacturing.The morphology of this corrosion is similar to that of an ant's nest when viewed in cross section. The corrosion mechanisms, cases ofant's nest corrosion, and preventive measures are presented.
文摘An artificial localized corrosion system is assembled and some parameters related to the localized corrosion in active dissolution state (i.e., non-passive state) have been studied. The results showed that the developed electrochemical system can satisfactorily imitate a naturally formed localized corrosion and the coupling current can indicate the maximum localized propagating rate. In this artificial system, the anodic dissolution reaction followed the auto-catalytic mechanism. The localized corrosion current density was dependent on the area ratio R of the cathode to the occluded anode. While R was equal to or more than 6, the coupling current reached at a maximum value and did not alter with the increase in R-value. Therefore, R=7 is chosen as one of these optimum parameters used in constructing the system, with which the biggest galvanic current might be obtained. In contrast, the thickness of the polymer filler separating the occluded anode area from the bulk electrolyte solution and the volume of the occluded anode area did not affect the corrosion current obviously. They might affect the response time to approach a steady state.
基金supported by the China Postdoctoral Science Foundation (2023MD744187)Guangxi Science and Technology Major Project (AA 23062036)+1 种基金Open Foundation of State Key Laboratory of Featured Metal Materials and Life–cycle Safety for Composite Structures(2022GXYSOF 12)Key Laboratory of High Performance Structural Materials and Thermo-surface Processing,Education Department of Guangxi Zhuang Autonomous Region
文摘The effect of grain orientation and grain boundary angle on the microscopic corrosion behavior of pure zinc was employed by the systematic integrated SECM, EBSD and AFM analysis. With confirmed different orientation grains, we proved the zinc grain near <0001>//ND orientation shows the lowest corrosion rate compared to that near <01■0>//ND and <■0>//ND orientation. Even though the grain orientation distribution is random and the grain corrosion rates of <01■0>//ND and <■0>//ND orientations are similar, the <0001>//ND have the lowest reactivity. The corrosion morphology of <0001>//ND orientation grain appears hexagonal corrosion pit,and the morphology of <01■0>//ND and <■0>//ND orientation grain shows striated structures. This behavior could be explained by the corrosion morphology and rate of zinc grain depending on the orientation.
基金financially supported by the National Natural Sciences Foundation of China(No.51171199)the State key Project of Research and Development of China(No.2017YFA0206302)
文摘The localized and uniform corrosion resistances of bulk nanocrystalline 304 stainless steel（NC-304 SS）produced by severe rolling technique, and its conventional polycrystalline 304 stainless steel（CC-304 SS）counterpart, were investigated in high-concentration hydrochloric acid solutions at room temperature.NC-304 SS can scarcely suffer from localized corrosion in 4 mol/L and 5 mol/L HCl solutions during 5-day immersion tests, and in 1-3 mol/L HCl solutions during thirty-five-day immersion tests. The corrosion rate of NC-304 SS was also less than that of CC-304 SS during these immersion tests. The improved localized and uniform corrosion resistances of NC-304 SS were explained in terms of the adsorption and chemical activity of Cl;on NC-304 SS and CC-304 SS characterized by X-ray photoelectron spectroscopy,and the valence electron configurations of NC-304 SS and CC-304 SS were characterized by ultra-violet photoelectron spectroscopy rather than conventional electrochemical results.
基金financially supported by National Natural Science Foundation of China(52201295,51825302,&52021004)State Key Project of Research and Development(2022YFB3804400)+1 种基金Natural Science Foundation of Chongqing(cstc2021jcyj-cxttX0002)China Postdoctoral Science Foundation(2021M693707).
文摘Macrophages play a central role in immunological responses to metallic species associated with the localized corrosion of metallic implants,and mediating in peri-implant inflammations.Herein,the pathways of localized corrosion-macrophage interactions were systematically investigated on 316L stainless steel(SS)implant metals.Electrochemical monitoring under macrophage-mediated inflammatory conditions showed a decreased pitting corrosion resistance of 316L SSs in the presence of RAW264.7 cells as the cells would disrupt biomolecule adsorbed layer on the metal surface.The pitting potentials were furtherly decreased when the RAW264.7 cells were induced to the M1 pro-inflammatory phenotype by the addition of lipopolysaccharide(LPS),and pitting corrosion preferentially initiated at the peripheries of macrophages.The overproduction of aggressive ROS under inflammatory conditions would accelerate the localized corrosion of 316L SS around macrophages.Under pitting corrosion condition,the viability and pro-inflammatory polarization of RAW264.7 cells were region-dependent,lower viability and more remarkable morphology transformation of macrophages in the pitting corrosion region than the pitting-free region.The pitting corrosion of 316L SS induced high expression of CD86,TNF-α,IL-6 and high level of intracellular ROS in macrophages.Uneven release of metallic species(Fe^(2+),Cr^(3+),Ni^(2+),etc)and uneven distribution of surface overpotential stimulated macrophage inflammatory responses near the corrosion pits.A synergetic effect of localized corrosion and macrophages was revealed,which could furtherly promote localized corrosion of 316L SS and macrophage inflammatory reactions.Our results provided direct evidence of corrosion-macrophage interaction in metallic implants and disclosed the pathways of this mutual stimulation effect.
基金National Key Research and Development Program of China(No.2023YFB3710300)the Key R&D Program of Shandong Province(No.2023CXGC010406)+2 种基金the National Natural Science Foundation of China(No.52371080)the Natural Science Foundation of Shandong Province(ZR2024JQ028)the Project of Taishan Scholars(tsqn202312107).
文摘The corrosion behavior of Q420 steel under constant temperature and freezing-thawing conditions is investigated.The steel exhibits the highest corrosion rate at 25℃ and the lowest corrosion rate at−30℃,while the steel that undergoes freezing-thawing cycling shows lower corrosion rate than that at 0℃.The localized corrosion is significantly affected by the temperature variations,with the samples corroded under freezing-thawing conditions showing the highest pit number density and the highest possibility of the pit initiation.The samples immersed at 0 and 25℃ show comparable pit size with higher pit depth,diameter,and volume,attributed to the higher rate of pit propagation along the vertical and horizontal directions.Galvanic corrosion results demonstrate that there are areas of activated metal under the ice,which form microcells with surrounding unaffected areas,attributed to the local ion concentration and the water crystallization.
基金supported by the National Natural Science Foundation of China(Grant Nos.U22A20121 and 52101283)the Suzhou Science and Technology Project(Grant No SJC2023005)+3 种基金the Science and Technology Planning Project of Guangzhou(Grant No 202102010008)the High-Level Hospital Construction Project(Grant No KJ012019520)the Beijing Mu-nicipal Health Commission(BMHC-2021-6,BJRITO-RDP-2024)the Beijing Municipal Public Welfare Development and Reform Pilot Project for Medical Research Institutes(Nos.JYY2023-11 and JYY2023-8).
文摘The poor mechanical properties of pure zinc(Zn)restrain its applications in orthopedics,which requires high loading capacity.Alloying with lithium(Li)element can enhance strength,however,the work-hardening rate is impaired with increased Li content.Here,introducing scandium(Sc)into a low Li-containing Zn-0.1Li alloy could effectively refine its microstructure,reducing the average grain size from 10 to 4μm.The refinement in microstructure led to a significant improvement in tensile strength,im-proving from 257 MPa of Zn-0.1Li to 341 MPa of Zn-0.1Li-0.1Sc,meanwhile,the work-hardening rate remained positive during the whole plastic deformation stage.The addition of Sc-impaired elongation is due to numerous microcracks formed at the Zn/ScZn_(12)interfaces,as well as in the large-sized ScZn_(12)particles.Corrosion tests revealed an accelerated corrosion rate due to the galvanic effect between the Zn matrix and ScZn_(12)phase.Even so,the Zn-0.1Li-1.0Sc alloy still exhibited superior biocompatibility with rat/mouse mesenchymal stem cells and close osteogenesis capacity to the original Zn-0.1Li alloy.These findings demonstrated that the addition of Sc in low Li-containing alloys could improve mechanical strength without sacrificing the work-hardening rate and biocompatibility.
基金supported by the National Natural Science Foundation of China(No.52371065).
文摘The present work investigates the corrosion behaviour of an AA2024 alloy thin wall structure produced by wire arc additive manufacturing(WAAM)with interpass rolling,focussing on the influence of interpass rolling.It is found that although interpass rolling does not change the typical configuration of thin wall structure,i.e.melt pool zone(MPZ),melt pool border(MPB)and heat-affected zone(HAZ),the plastic deformation introduced by interpass rolling leads to the variation of grain-stored energy across the structure,which consequently results in the highest corrosion susceptibility of MPB due to its relatively high stored energy.
基金financially supported by the National Natural Science Foundation of China(No.52271091)the National Key Research and Development Program of China(No.2021YFB3701100)the Natural Science Foundation Project of Ningxia Province(No.2023AAC03324).
文摘The Mg-9Li-1Zn(LZ91)alloy was subjected to an ultrasonic surface rolling process(USRP)with varying passes for the purpose of modifying its surface state.The USRP transformed surface residual stress from initial tensile stress to compressive stress,decreasing the surface roughness and increasing the ratio of the β-Li phase.The USRPed LZ91 sample(3 passes)showed superior corrosion resistance,with the corrosion current density changing from 57.11 to 24.70μA cm^(-2),and the polarization resistance increasing from 576.3 to 1146.1Ωcm^(2).According to the corrosion procedure evaluations,in situ observation revealed that the LZ91 alloy initially experiences pitting,which subsequently develops into cracking.The substantial area coverage of the β-Li phase facilitates the formation of a protective film on the surface,effectively delaying localized corrosion.
