Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in...Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in NaC1 and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g （0.012 7 tool）, 8 g （0.025 4 mol） and 6 g （0.019 l tool） NaaCr207 exhibited, in that order, high inhibition effectiveness, with respective efficiency, r/, of （90.46±1.30）%, （88.41＋2.24）% and （84.87±4.74）%, in the NaC1 medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g （0.025 4 mol） Na2Cr207 concentration having r/=（78.44±1.10）%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.展开更多
The self-healing effect of electrochemically deposited CeO2-Ce2O3 films on stainless steel OC404（SS） in 0.5 mol/L NaCl solution was studied. It was established that the corrosion potential of the steel, after coveri...The self-healing effect of electrochemically deposited CeO2-Ce2O3 films on stainless steel OC404（SS） in 0.5 mol/L NaCl solution was studied. It was established that the corrosion potential of the steel, after covering it with CeO2-Ce2O3 layer and thermal treatment（i.e. potential of the system CeO2-Ce2O3/SSt.t.）, was shifted sharply to a considerably more positive value, while the corrosion current was reduced noticeably. The X-ray photoelectron spectroscopy（XPS）, energy dispersive spectroscopy（EDS） and scanning electron microscopy（SEM） analyses on the observed scratched surface area of the system CeO2-Ce2O3/SSt.t., after exposure of investigated specimens to 0.5 mol/L NaCl corrosion media, showed partial accumulation of ceria, as well as remarkable increase in the concentrations of oxides of Al, Cr and Fe, on the mechanically revealed steel surface. On the basis of the obtained results one could conclude that the secondary passive oxide/hydroxide films, formed after a definite time interval of exposure to corrosion media, acted as barriers, hindering the corrosion processes in active zones. A hypothesis was put forward about the mechanism of self-repairing oxide layers on the steel surface and their corrosion protection effect respectively.展开更多
The effects of temperature on corrosion and the electrochemical behavior of Ni82.3Cr7Fe3Si4.5B3.2 glassy alloy in HC1,H2SO4,and H3PO4 acids were studied using AC and DC techniques.Impedance data reveal that the suscep...The effects of temperature on corrosion and the electrochemical behavior of Ni82.3Cr7Fe3Si4.5B3.2 glassy alloy in HC1,H2SO4,and H3PO4 acids were studied using AC and DC techniques.Impedance data reveal that the susceptibility to localized corrosion increases with increasing temperature.Potentiodynamic polarization curves reveal that the bulk glassy alloy is spontaneously passivated at all the investigated temperature in H2SO4 and H3PO4 solutions.A localized corrosion effect in HCl solution is clearly observed.The apparent activation energies in the regions of Tafel,active,and passive,as well as the enthalpies and entropies of the dissolution process were determined and discussed.The high apparent activation energy（Ea） value for H3PO4 solution in Tafel region is explained by the low aggressivity of PO4^3- ions.展开更多
The effect of sputtered Ti-50Al-10Cr and Ti-50A1-20Cr coatings on both isothermal and cyclic oxidation resistance at 800-900℃ and hot corrosion resistance at 850℃ of Ti-24Al-14Nb-3V was investigated. Results indicat...The effect of sputtered Ti-50Al-10Cr and Ti-50A1-20Cr coatings on both isothermal and cyclic oxidation resistance at 800-900℃ and hot corrosion resistance at 850℃ of Ti-24Al-14Nb-3V was investigated. Results indicated that Ti-24Al-14Nb-3V alloys exhibited poor oxidation resistance due to the formation of Al2O3+TiO2+AlNbO4 mixed scales in air at 800-900℃ and poor hot corrosion resistance due to the spoliation of scales formed in Na2SO4+K2SO4 melts at 850℃. Both Ti-50Al-10Cr and Ti-50Al-20Cr coatings remarkably improved the oxidation and hot corrosion resistance of Ti-24Al-14Nb-3V alloy.展开更多
Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosi...Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosion attack. The article utilized the principle of mass and energy conservation in the development of weight and temperature models to study the effect of corrosion on mild steel coupon inside the exchanger containing water and Mono ethanol amine (MEA). The models developed were resolved analytically using Laplace Transform and simulated using Excel as simulation tool and data obtained from experiment in the laboratory to obtain profiles of weight loss and temperature as a function of time. The weight loss and performance of mild steel under various corrosive conditions were examined which indicates the effect of corrosion on the mild steel heat exchanger in water and MEA media. The result shows that water is more corrosive than MEA at higher temperatures and at lower temperatures of 35°C and 1 atm, MEA has inhibitive properties than water as indicated by the weight loss result with time. The comparative analysis between the results obtained from the model simulation and experimental results shows that the result obtained from the model is more reliable and demonstrated better performance characteristics as it clearly shows mild steel heat exchanger experiences more corrosive effect in water medium than MEA at higher temperatures. And at lower temperatures, MEA becomes more inhibitive and less corrosive than water. The model simulation results correlate with various literatures and hence, it is valid for future referencing.展开更多
Titanium alloys are extensively used in power, chemical and petroleum industries as constructional materials for vessels and heat transfer tubes. Moreover they are candidate materials for nuclear waste disposal. These...Titanium alloys are extensively used in power, chemical and petroleum industries as constructional materials for vessels and heat transfer tubes. Moreover they are candidate materials for nuclear waste disposal. These alloys have superior resistance to localized forms of corrosion compared to stainless steels and Ni-base alloys. However, this resistance is not as remarkable in crevice corrosion conditions in some aggressive media. Electrochemical corrosion tests were conducted on two ASTM Ti grades namely, Ti-2 and Ti-12 in extremely low pH acidic environment. Results indicated that Ti-2 has less resistance to both general and crevice corrosion attack than Ti-12. Both alloys possess better resistance to general corrosion than to crevice corrosion. Also, results showed that the molybdate addition improves remarkably the resistance of Ti-2 to both types of attack. The increase of molybdate ions concentration from 0.03 mol/L to 0.15 mol/L made Ti-2 to be as resistant as, or somewhat higher than, Ti-12. The elecrochemical findings were further supplemented by optical examination of the corroded surface.展开更多
Experiments were conducted to study the general room temperature corrosion characteristics of heat-treated and non-heat-treated Al-Li alloys with different Li compositions. Corrosion rate was measured using both the p...Experiments were conducted to study the general room temperature corrosion characteristics of heat-treated and non-heat-treated Al-Li alloys with different Li compositions. Corrosion rate was measured using both the polarisation method and the weight-loss method. It was observed that the samples with higher Li content had lower corrosion resistance than those with lower Li content. Moreover, for all the specimens tested, it was fOund that heat treatment at 180℃ for 2 h (for the purpose of precipitation hardening) severely reduced the corrosion resistance,whereas heat treatment at 180℃ for 6 h significantly increased the corrosion resistance.展开更多
The microstructure and the corrosion product films have been investigated on Cu-Ni alloys by TEM, SEM, AES and electrochemical technique as well as natural seawater exposure tests. Experimental results showed that the...The microstructure and the corrosion product films have been investigated on Cu-Ni alloys by TEM, SEM, AES and electrochemical technique as well as natural seawater exposure tests. Experimental results showed that the alloys had two kinds of microstructure, i.e. recrystallizatjon and incomplete recrystallization. In synthetic seawater containing 2x10^-6 S^2-, the stability of the alloy increased with the increase of deformation and annealing temperature, i.e., the degree of recrystallization. After exposure to natural seawater for different periods of time, the corrosion product films of the recrystallized alloy were rich in Ni and compact, and there were cracks in the outer layer which contained a small amount of S; the films of the alloy of incomplete recrystallization became thick, loose and porous, and obviously of layered structure, and the intergranular corrosion took place in the underlying substrate Besides, a great amount of seawater substance existed in the outer layer and some sulfur was found within the grain boundaries that prefer to corrode. The accelerating effect of sulfides in corrosion of Cu-Ni alloys in seawater is attributed to the coexistence and absorption of sulfides and carbides promoting the preference of corrosion where they absorb, and the formation of dissolvable Cu2S results in keeping the surface of the alloys in the active state.展开更多
Corrosion behavior of two nanocrystalline bulk Ag–50Cu alloys and one coarse-grained counterpart prepared by liquid-phase reduction(LPR), mechanical alloying(MA) and powder metallurgy(PM) methods,respectively, were i...Corrosion behavior of two nanocrystalline bulk Ag–50Cu alloys and one coarse-grained counterpart prepared by liquid-phase reduction(LPR), mechanical alloying(MA) and powder metallurgy(PM) methods,respectively, were investigated in Na Cl solutions. They were finished by means of PARM273 A and M5210 electrochemical apparatus through potentiodynamic polarization method and electrochemical impedance spectroscopy(EIS) technique. The results show that corrosion rates of three Ag–50Cu alloys increase with the increment of Na Cl solution concentrations. Corrosion rates of LPRAg–50Cu alloy are a little higher than those of PMAg–50Cu alloy,but evidently lower than those of MAAg–50Cu alloy. The difference in corrosion rates is attributed to the large reduction in the grain size and homogeneous microstructure of nanocrystalline alloys. Passive current densities decrease and afterward increase for PMAg–50Cu alloy,decrease for MAAg–50Cu alloy, and increase for LPRAg–50Cu alloy with the increment of Na Cl solution concentrations. After the grain sizes are refined, passive current densities become lower.展开更多
Improvement of the fatigue life of welded tubular T-joints in offshore platforms due to weld toe grinding and TIG dressing is studied physically and experimentally. It is shown that the two methods of treatment can im...Improvement of the fatigue life of welded tubular T-joints in offshore platforms due to weld toe grinding and TIG dressing is studied physically and experimentally. It is shown that the two methods of treatment can improve the fatigue strength of welded tubular joints not only in the environment of air but even in the envirnment of seawater accordingly.展开更多
Bending fatigue tests were carried out on cruciform welded joints of China-made platform steel E36-Z35 with plate thickness of 16mm, 32mm and 40mm. The tests consisted of testing in air and in sea water with and witho...Bending fatigue tests were carried out on cruciform welded joints of China-made platform steel E36-Z35 with plate thickness of 16mm, 32mm and 40mm. The tests consisted of testing in air and in sea water with and without cathodic protection (-850mV. SCE). The sea water corrosion fatigue tests were conducted at loading frequency of 0.2 Hz and sea water temperature of 20°C. The test results show an obvious reduction in fatigue strength of welded joints with increasing plate thickness in all the three test conditions. The present paper proposes different thickness corrections for fatigue strength and fatigue life of welded joints in air and in sea water with and without cathodic protection respectively. In addition, an explanation for thickness effect on fatigue life of welded joints is given by using the theory of fracture mechanics.展开更多
Based on the elastic-plastic, large-deformation finite element method, burst capacity of steel pipeline with longitudinal corrosion defect subjected to internal pressure is studied. The appropriate stress-based criter...Based on the elastic-plastic, large-deformation finite element method, burst capacity of steel pipeline with longitudinal corrosion defect subjected to internal pressure is studied. The appropriate stress-based criterion is used to predict the failure pressure of finite element model of corroded pipeline under internal pressure. By considering the pipe steel grades and geometries of corrosion defects, a series of finite element analyses is conducted. The effects of corrosion depth, length and width on burst capacity are also discussed. A specific failure pressure solution for the assessment of corrosion defects in moderate-to-high strength pipeline is proposed on the base of numerical results. The failure pressures predicted by the proposed method are in better agreement with the experimental results than the results by the other methods.展开更多
Numerical simulation is an effective research approach to assess the condition and predict the remaining service life of process pipelines suffering corrosion hazards.This work comprises a critical review of 182 acade...Numerical simulation is an effective research approach to assess the condition and predict the remaining service life of process pipelines suffering corrosion hazards.This work comprises a critical review of 182 academic articles to analyze environmental factors affecting the pipeline corrosion process,basic numerical methods for corrosion simulation,and single-and coupled-factor numerical investigations.Nu-merical simulation of corroded pipelines could combine the electrochemical corrosion processes and structural characteristics of pipelines to obtain more accurate results.Multiphysics-based techniques have been successfully applied to simulate the evolution process of corroded pipelines affected by two or more coupled factors under stray current interference.Through integration with learning-based algorithms,pre-dictive studies are conducted to assess the development of corrosion.The challenge for current research is that the remaining types of corrosion are difficult to describe by numerical methods.Opportunities are proposed to improve the pipeline corrosion simulation model to describe more corrosion types and realistic corrosion morphologies,including time-varying corrosion simulation,randomfield in the simulation,and microelectrochemical corrosion simulation.展开更多
Ozone is the principal active substances and usually employed in ballast water management systems. In the present study, the corrosion protective effect of ozone was conducted by immersion test and electrochemical tec...Ozone is the principal active substances and usually employed in ballast water management systems. In the present study, the corrosion protective effect of ozone was conducted by immersion test and electrochemical techniques. It was found that corrosion protective effect was revealed in the range of 2.0 to 2.7 ppm of ozone concentration in seawater. The ratio of the rust area of specimen became 20% in that concentration region. The rusted area is strongly influenced by the ozone concentration and the flow rate determined by FEM （finite element method）. Ozone has a good influence for ballast tanks, i.e., ozone can delay the rust of ballast tanks, provided that the suitable concentration of ozone is selected. In this case, ozone may stop the corrosion at the defects, if a part of the paint in ballast tank is peeled off. However, ozone may also promote the corrosion of steel when the ozone concentration is very high, e.g., 10 ppm. Attention should be paid to the ozone concentration, if we use ozone as an active substance for ballast water management systems.展开更多
文摘Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in NaC1 and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g （0.012 7 tool）, 8 g （0.025 4 mol） and 6 g （0.019 l tool） NaaCr207 exhibited, in that order, high inhibition effectiveness, with respective efficiency, r/, of （90.46±1.30）%, （88.41＋2.24）% and （84.87±4.74）%, in the NaC1 medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g （0.025 4 mol） Na2Cr207 concentration having r/=（78.44±1.10）%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.
基金supported by the National Science Fund,Bulgaria(Т02-22/12.12.2014)
文摘The self-healing effect of electrochemically deposited CeO2-Ce2O3 films on stainless steel OC404（SS） in 0.5 mol/L NaCl solution was studied. It was established that the corrosion potential of the steel, after covering it with CeO2-Ce2O3 layer and thermal treatment（i.e. potential of the system CeO2-Ce2O3/SSt.t.）, was shifted sharply to a considerably more positive value, while the corrosion current was reduced noticeably. The X-ray photoelectron spectroscopy（XPS）, energy dispersive spectroscopy（EDS） and scanning electron microscopy（SEM） analyses on the observed scratched surface area of the system CeO2-Ce2O3/SSt.t., after exposure of investigated specimens to 0.5 mol/L NaCl corrosion media, showed partial accumulation of ceria, as well as remarkable increase in the concentrations of oxides of Al, Cr and Fe, on the mechanically revealed steel surface. On the basis of the obtained results one could conclude that the secondary passive oxide/hydroxide films, formed after a definite time interval of exposure to corrosion media, acted as barriers, hindering the corrosion processes in active zones. A hypothesis was put forward about the mechanism of self-repairing oxide layers on the steel surface and their corrosion protection effect respectively.
基金supported by the Kink Abdulaziz City of Science and Technology (KACST) (No.GSP–14–105)
文摘The effects of temperature on corrosion and the electrochemical behavior of Ni82.3Cr7Fe3Si4.5B3.2 glassy alloy in HC1,H2SO4,and H3PO4 acids were studied using AC and DC techniques.Impedance data reveal that the susceptibility to localized corrosion increases with increasing temperature.Potentiodynamic polarization curves reveal that the bulk glassy alloy is spontaneously passivated at all the investigated temperature in H2SO4 and H3PO4 solutions.A localized corrosion effect in HCl solution is clearly observed.The apparent activation energies in the regions of Tafel,active,and passive,as well as the enthalpies and entropies of the dissolution process were determined and discussed.The high apparent activation energy（Ea） value for H3PO4 solution in Tafel region is explained by the low aggressivity of PO4^3- ions.
文摘The effect of sputtered Ti-50Al-10Cr and Ti-50A1-20Cr coatings on both isothermal and cyclic oxidation resistance at 800-900℃ and hot corrosion resistance at 850℃ of Ti-24Al-14Nb-3V was investigated. Results indicated that Ti-24Al-14Nb-3V alloys exhibited poor oxidation resistance due to the formation of Al2O3+TiO2+AlNbO4 mixed scales in air at 800-900℃ and poor hot corrosion resistance due to the spoliation of scales formed in Na2SO4+K2SO4 melts at 850℃. Both Ti-50Al-10Cr and Ti-50Al-20Cr coatings remarkably improved the oxidation and hot corrosion resistance of Ti-24Al-14Nb-3V alloy.
文摘Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosion attack. The article utilized the principle of mass and energy conservation in the development of weight and temperature models to study the effect of corrosion on mild steel coupon inside the exchanger containing water and Mono ethanol amine (MEA). The models developed were resolved analytically using Laplace Transform and simulated using Excel as simulation tool and data obtained from experiment in the laboratory to obtain profiles of weight loss and temperature as a function of time. The weight loss and performance of mild steel under various corrosive conditions were examined which indicates the effect of corrosion on the mild steel heat exchanger in water and MEA media. The result shows that water is more corrosive than MEA at higher temperatures and at lower temperatures of 35°C and 1 atm, MEA has inhibitive properties than water as indicated by the weight loss result with time. The comparative analysis between the results obtained from the model simulation and experimental results shows that the result obtained from the model is more reliable and demonstrated better performance characteristics as it clearly shows mild steel heat exchanger experiences more corrosive effect in water medium than MEA at higher temperatures. And at lower temperatures, MEA becomes more inhibitive and less corrosive than water. The model simulation results correlate with various literatures and hence, it is valid for future referencing.
文摘Titanium alloys are extensively used in power, chemical and petroleum industries as constructional materials for vessels and heat transfer tubes. Moreover they are candidate materials for nuclear waste disposal. These alloys have superior resistance to localized forms of corrosion compared to stainless steels and Ni-base alloys. However, this resistance is not as remarkable in crevice corrosion conditions in some aggressive media. Electrochemical corrosion tests were conducted on two ASTM Ti grades namely, Ti-2 and Ti-12 in extremely low pH acidic environment. Results indicated that Ti-2 has less resistance to both general and crevice corrosion attack than Ti-12. Both alloys possess better resistance to general corrosion than to crevice corrosion. Also, results showed that the molybdate addition improves remarkably the resistance of Ti-2 to both types of attack. The increase of molybdate ions concentration from 0.03 mol/L to 0.15 mol/L made Ti-2 to be as resistant as, or somewhat higher than, Ti-12. The elecrochemical findings were further supplemented by optical examination of the corroded surface.
文摘Experiments were conducted to study the general room temperature corrosion characteristics of heat-treated and non-heat-treated Al-Li alloys with different Li compositions. Corrosion rate was measured using both the polarisation method and the weight-loss method. It was observed that the samples with higher Li content had lower corrosion resistance than those with lower Li content. Moreover, for all the specimens tested, it was fOund that heat treatment at 180℃ for 2 h (for the purpose of precipitation hardening) severely reduced the corrosion resistance,whereas heat treatment at 180℃ for 6 h significantly increased the corrosion resistance.
文摘The microstructure and the corrosion product films have been investigated on Cu-Ni alloys by TEM, SEM, AES and electrochemical technique as well as natural seawater exposure tests. Experimental results showed that the alloys had two kinds of microstructure, i.e. recrystallizatjon and incomplete recrystallization. In synthetic seawater containing 2x10^-6 S^2-, the stability of the alloy increased with the increase of deformation and annealing temperature, i.e., the degree of recrystallization. After exposure to natural seawater for different periods of time, the corrosion product films of the recrystallized alloy were rich in Ni and compact, and there were cracks in the outer layer which contained a small amount of S; the films of the alloy of incomplete recrystallization became thick, loose and porous, and obviously of layered structure, and the intergranular corrosion took place in the underlying substrate Besides, a great amount of seawater substance existed in the outer layer and some sulfur was found within the grain boundaries that prefer to corrode. The accelerating effect of sulfides in corrosion of Cu-Ni alloys in seawater is attributed to the coexistence and absorption of sulfides and carbides promoting the preference of corrosion where they absorb, and the formation of dissolvable Cu2S results in keeping the surface of the alloys in the active state.
基金financially supported by the National Natural Science Foundation of China (Nos. 51271127 and 51501118)
文摘Corrosion behavior of two nanocrystalline bulk Ag–50Cu alloys and one coarse-grained counterpart prepared by liquid-phase reduction(LPR), mechanical alloying(MA) and powder metallurgy(PM) methods,respectively, were investigated in Na Cl solutions. They were finished by means of PARM273 A and M5210 electrochemical apparatus through potentiodynamic polarization method and electrochemical impedance spectroscopy(EIS) technique. The results show that corrosion rates of three Ag–50Cu alloys increase with the increment of Na Cl solution concentrations. Corrosion rates of LPRAg–50Cu alloy are a little higher than those of PMAg–50Cu alloy,but evidently lower than those of MAAg–50Cu alloy. The difference in corrosion rates is attributed to the large reduction in the grain size and homogeneous microstructure of nanocrystalline alloys. Passive current densities decrease and afterward increase for PMAg–50Cu alloy,decrease for MAAg–50Cu alloy, and increase for LPRAg–50Cu alloy with the increment of Na Cl solution concentrations. After the grain sizes are refined, passive current densities become lower.
文摘Improvement of the fatigue life of welded tubular T-joints in offshore platforms due to weld toe grinding and TIG dressing is studied physically and experimentally. It is shown that the two methods of treatment can improve the fatigue strength of welded tubular joints not only in the environment of air but even in the envirnment of seawater accordingly.
文摘Bending fatigue tests were carried out on cruciform welded joints of China-made platform steel E36-Z35 with plate thickness of 16mm, 32mm and 40mm. The tests consisted of testing in air and in sea water with and without cathodic protection (-850mV. SCE). The sea water corrosion fatigue tests were conducted at loading frequency of 0.2 Hz and sea water temperature of 20°C. The test results show an obvious reduction in fatigue strength of welded joints with increasing plate thickness in all the three test conditions. The present paper proposes different thickness corrections for fatigue strength and fatigue life of welded joints in air and in sea water with and without cathodic protection respectively. In addition, an explanation for thickness effect on fatigue life of welded joints is given by using the theory of fracture mechanics.
基金financially supported by Ministry of Science and Technology of China(Grant No.2011CB013702)the Program for New Century Excellent Talents in University(Grant No.NCET-11-0051)
文摘Based on the elastic-plastic, large-deformation finite element method, burst capacity of steel pipeline with longitudinal corrosion defect subjected to internal pressure is studied. The appropriate stress-based criterion is used to predict the failure pressure of finite element model of corroded pipeline under internal pressure. By considering the pipe steel grades and geometries of corrosion defects, a series of finite element analyses is conducted. The effects of corrosion depth, length and width on burst capacity are also discussed. A specific failure pressure solution for the assessment of corrosion defects in moderate-to-high strength pipeline is proposed on the base of numerical results. The failure pressures predicted by the proposed method are in better agreement with the experimental results than the results by the other methods.
基金the China Postdoctoral Science Foundation(2021M703509)Natural Science Foundation of Jiangsu Province(BK20221120)(BK20221545)+3 种基金the Opening Project of Material Corrosion and Protection Key Laboratory of Sichuan Province(2022CL29)Fundamental Research Funds for the Central Universities(2022QN1042)(2021YCPY0109)the Natural Science Foundation of China(52174153)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)for the financial support for this research.
文摘Numerical simulation is an effective research approach to assess the condition and predict the remaining service life of process pipelines suffering corrosion hazards.This work comprises a critical review of 182 academic articles to analyze environmental factors affecting the pipeline corrosion process,basic numerical methods for corrosion simulation,and single-and coupled-factor numerical investigations.Nu-merical simulation of corroded pipelines could combine the electrochemical corrosion processes and structural characteristics of pipelines to obtain more accurate results.Multiphysics-based techniques have been successfully applied to simulate the evolution process of corroded pipelines affected by two or more coupled factors under stray current interference.Through integration with learning-based algorithms,pre-dictive studies are conducted to assess the development of corrosion.The challenge for current research is that the remaining types of corrosion are difficult to describe by numerical methods.Opportunities are proposed to improve the pipeline corrosion simulation model to describe more corrosion types and realistic corrosion morphologies,including time-varying corrosion simulation,randomfield in the simulation,and microelectrochemical corrosion simulation.
文摘Ozone is the principal active substances and usually employed in ballast water management systems. In the present study, the corrosion protective effect of ozone was conducted by immersion test and electrochemical techniques. It was found that corrosion protective effect was revealed in the range of 2.0 to 2.7 ppm of ozone concentration in seawater. The ratio of the rust area of specimen became 20% in that concentration region. The rusted area is strongly influenced by the ozone concentration and the flow rate determined by FEM （finite element method）. Ozone has a good influence for ballast tanks, i.e., ozone can delay the rust of ballast tanks, provided that the suitable concentration of ozone is selected. In this case, ozone may stop the corrosion at the defects, if a part of the paint in ballast tank is peeled off. However, ozone may also promote the corrosion of steel when the ozone concentration is very high, e.g., 10 ppm. Attention should be paid to the ozone concentration, if we use ozone as an active substance for ballast water management systems.
