New stared compounds including norfloxacin fragments were prepared via a multi-step route,which were employed as the target corrosion inhibitors(TCIs)for mild steel in 1 mol/L HCl solution.For comparisons,the linear c...New stared compounds including norfloxacin fragments were prepared via a multi-step route,which were employed as the target corrosion inhibitors(TCIs)for mild steel in 1 mol/L HCl solution.For comparisons,the linear compounds including a single norfloxacin part employed as the reference corrosion inhibitors(RCIs)were synthesized.The molecular structures of the stared compounds were confirmed.The material simulation calculations suggest the presence of large binding energies of the stared compounds on mild steel surface.The enhanced chemisorption of the stared compounds on mild steel surface was demonstrated,which could be resulted by the chemical complexion of the target stared molecules with iron atoms.The reinforced adsorption of the target compounds on mild steel surface was investigated by atomic force microscopy(AFM)and scanning electron microscopy(SEM).The electrochemical analyses reveal the super protection of the TCIs for mild steel in HCl solution,and the anticorrosion efficiency reaches 96.45%(TCI1,0.050 mM)and 96.61%(TCI2,0.010 mM)at 298 K.展开更多
Cerium tartrate(CeTar),produced in this study by precipitating cerium nitrate with potassium sodium tartrate(KNaTar),was examined as a corrosion inhibitor.Weight loss tests show inhibition efficiency of 71.7% with Ce(...Cerium tartrate(CeTar),produced in this study by precipitating cerium nitrate with potassium sodium tartrate(KNaTar),was examined as a corrosion inhibitor.Weight loss tests show inhibition efficiency of 71.7% with Ce(NO_(3))_(3) and 88.7% with CeTar inhibitor for one-month exposure to mild steel in 7 g/L NaCl solution.The inhibition efficiency drops to 28.6% with the fo rmer and remains around 8 7% with the latter inhibitor after six months of exposure.Similar results from electrochemical testing indicate that the inhibition efficiency decreases by adding cerium nitrate.Still,the cerium tartrate inhibitor demonstrates a nearly constant inhibition efficiency for up to 30 d,i.e.,≈90%.Electrochemical impedance spectroscopy(EIS) performed in these cases shows the following results:(ⅰ) with cerium nitrate,a film of iron and cerium oxide,which on prolonged exposure diminishes,and(ⅱ) with cerium tartrate,the formation of a bimetallic film(Fe-tartrate-Ce) and a mixture of cerium hydroxide and iro n oxide that protects steel for a longer duration.These inferences are based on the analyses of scanning electron microscopy/energydispersive X-ray analysis(SEM/EDAX),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron(XPS),and Raman spectroscopy results.展开更多
The metallurgical quality control of magnesium(Mg)and Mg alloys in melting process is required to ensure a satisfied mechanical and corrosion performance,while the typical used steel crucible introduces impurities and...The metallurgical quality control of magnesium(Mg)and Mg alloys in melting process is required to ensure a satisfied mechanical and corrosion performance,while the typical used steel crucible introduces impurities and interfacial interaction during melting process.Therefore,a systematic study about impurities diffusion and interfacial interaction between molten Mg and steel is necessary.In the present study,the interfacial reaction between molten AZ91D Mg alloy and mild steel during melting process was investigated with the melting temperatures of 700℃,750℃ and 800℃.The results show that Al(Fe,Mn)intermetallic layer is the intermetallic primarily formed at the interfaces of AZ91D melt and mild steel.Meanwhile,Al_(8)(Mn,Fe)5is indexed between Al(Fe,Mn)and AZ91D.AlFe_(3)C appears between the mild steel and Al(Fe,Mn)at 700℃ and 750℃,but absent at 800℃ due to the increased solubility of carbon in Mg matrix.It is found that the growth of the intermetallic layer is controlled by diffusion mechanism,and Al and Mn are the dominant diffusing species in the whole interfacial reaction process.By measuring the thickness of different layers,the growth constant was calculated.It increases from 1.89(±0.03)×10^(-12)m^(2)·s^(-1)at 700℃ to 3.05(±0.05)×10^(-12)m^(2)·s^(-1)at 750℃,and 5.18(±0.05)×10^(-12)m^(2)·s^(-1)at 800℃.Meanwhile,the content of Fe is linearly increased in AZ91D with the increase of holding time at 700℃ and 750℃,while it shows a significantly increment after holding for 8 h at 800℃,indicating holding temperature is more crucial to determine the Fe content of AZ91D than holding time.展开更多
The corrosion behaviors of the isolated short and vertical long scale Q235B steel in a simulated tidal zone were studied by electrochemical impedance spectroscopy （EIS） monitoring and corrosion weight loss calculati...The corrosion behaviors of the isolated short and vertical long scale Q235B steel in a simulated tidal zone were studied by electrochemical impedance spectroscopy （EIS） monitoring and corrosion weight loss calculation in an experimental indoor simulating trough. The results show that the corrosion rate of the isolated short scale Q235B steel in the tidal zone acquired by the EIS agrees with the corrosion weight loss result. The corrosion rates of the short scale steel are in the order of middle tidal zone 〉 the central zone between the middle tidal zone and low tidal zone 〉 high tidal zone 〉 low tidal zone. The fastest corrosion rate in the middle tidal zone is attributed to the longest wet time in a tidal cycle. According to the comparison of corrosion weight loss between the vertical long scale and isolated short scale specimens, the corrosion rate of vertical long scale specimens of Q235B steel is lower than that of the isolated short scale specimens in the tidal zone, but the result is contrary in the immersion zone.展开更多
The corrosion behavior of mild steel in a simulated coastal atmosphere environment has been investigated by the indoor accelerated wet/dry cyclic corrosion acceleration test(CCT),scanning electron microscopy(SEM),Rama...The corrosion behavior of mild steel in a simulated coastal atmosphere environment has been investigated by the indoor accelerated wet/dry cyclic corrosion acceleration test(CCT),scanning electron microscopy(SEM),Raman spectroscopy and electrochemical measurements.During the CCT test of 60 cycles,the evolution of logarithmic(corrosion rate)vs.logarithmic(CCT cycles)presents a turning point at the 5th cycle,presenting a tendency to increase first and then decrease to gradually stabilize as the CCT cycle prolonged.Before the 5th cycle,γ-FeOOH andβ-FeOOH and Fe_(3)O_(4)were detected,respectively.And then,α-FeOOH as a new chemical composition was detected in the subsequent corrosion cycles.It is found that,after long term corrosion,the rust separated into a relatively dense inner layer rich withα-FeOOH and a loose outer layer rich withγ-FeOOH,both of which have poor electrical conductivity.The rapid increase of corrosion rate in the early stage since reducible corrosion products are involved in the reduction process of the cathode which promotes the dissolution of the anodic metal substrate.Afterward,as the rust layer thickens,the resistance of the rust increases,and the aggressive ions diffusion is blocked,gradually suppressing the electrochemical corrosion process.At last,when the composition and distribution of the rust layer remain stable,the corrosion presents a fluctuating speed around a certain value during the cracking and self-repairing process of the rust layer.展开更多
The kinetics of mild steel corrosion in aqueous acetic acid solution has been investigated by weight loss and polarization techniques at 25,35 and 45℃.The weight loss of mild steel at room temperature （25℃） has be...The kinetics of mild steel corrosion in aqueous acetic acid solution has been investigated by weight loss and polarization techniques at 25,35 and 45℃.The weight loss of mild steel at room temperature （25℃） has been found to be quite significant,indicating poor corrosion resistance in acetic acid.The maximum corrosion rate has been observed in 25% acetic acid solution at all three experimental temperatures.The decrease in corrosion rate after attaining a maximum value has been attributed to the deposition of corrosion product on the surface.Anodic polarization curves exhibit active behaviour at each concentration and temperature with a shift towards higher current density region and increased corrosion rates at higher temperatures.The cathodic polarization curves are almost identical irrespective either of the concentration of acetic acid or temperature.The results obtained by both the techniques are in good agreement,while the surface studies support the conclusions drawn from the weight loss method.展开更多
The Morinda tinctoria (MT) plant leaves extract was prepared in aqueous and hydrochloric acid media and was used as corrosion inhibitor for mild steel in hydrochloric acid medium. MT is found to be an efficient inhibi...The Morinda tinctoria (MT) plant leaves extract was prepared in aqueous and hydrochloric acid media and was used as corrosion inhibitor for mild steel in hydrochloric acid medium. MT is found to be an efficient inhibitor at room temperature and the efficiency decreases with increase in temperature. Results from colorimetric studies predict the amount of iron present in the test solution and the percentage inhibition efficiency values calculated from this data fit well with the weight loss experiments. The AC impedance studies reveal that the mild steel surface is positively charged and the process of inhibition is through charge transfer. Polarisation studies indicate the mixed nature of the inhibitor. Thermodynamic parameters obtained predict that the process of inhibition is a spontaneous one.展开更多
The corrosion of mild steels by liquid aluminum is an intractable issue in aluminum industry.This review aims to provide an overview of the corrosion behavior of mild steels in the static liquid aluminum with an empha...The corrosion of mild steels by liquid aluminum is an intractable issue in aluminum industry.This review aims to provide an overview of the corrosion behavior of mild steels in the static liquid aluminum with an emphasis on the thermodynamic and kinetic aspects.The corrosion mechanisms of mild steels in liquid aluminum are discussed systematically,based on which four corrosion control approaches including alloying,introducing secondary phase,matrix microstructure control and surface treatment are introduced.Currently,a combination of improvement approaches may have a great potential for further enhancement in corrosion resistance.展开更多
In continuation of the extensive studies carried out to update the corrosion map of India, in this study, the degradation of mild steel by air pollutants was studied at 16 different locations from Nagore to Ammanichat...In continuation of the extensive studies carried out to update the corrosion map of India, in this study, the degradation of mild steel by air pollutants was studied at 16 different locations from Nagore to Ammanichatram along the east coast of Tamilnadu, India over a period of two years. The weight loss study showed that the mild steel corrosion was more at Nagapattinam site, when compared to Ammanichatram and Maravakadu sites. A linear regression analysis of the experimental data was attempted to predict the mechanism of the corrosion. The composition of the corrosion products formed on the mild steel surfaces was identified by XRD technique. The corrosion rate values obtained are discussed in the light of the weathering parameters, atmospheric pollutants such as salt content ＆ SO2 levels in the atmosphere, corrosion products formed on the mild steel surfaces.展开更多
The inhibition effect of synthesized diethyl 3,4-bis（4-methoxybenzylideneamino） thieno[2,3-b] thiophene-2,5- dicarboxylate （Inh I） and diethyl 3,4-bis（benzylideneamino） thieno[2,3-b] thiophene-2,5-dicarboxylate ...The inhibition effect of synthesized diethyl 3,4-bis（4-methoxybenzylideneamino） thieno[2,3-b] thiophene-2,5- dicarboxylate （Inh I） and diethyl 3,4-bis（benzylideneamino） thieno[2,3-b] thiophene-2,5-dicarboxylate （Inh II）, on cor- rosion of mild steel in 15% HC1 solution was investigated using weight loss measurements, electrochemical polarization, and electrochemical impedance spectroscopy techniques. The experimental results show that the inhibition efficiency of studied inhibitors increased with the increase of inhibitors concentration but decreased with the increase of temperature. Corrosion inhibition efficiencies of 94.5% and 92.1% were obtained with 250 ppm of Inh I and Inh II at 303 K, respectively. The potentiodynamic polarization measurements indicate that the studied inhibitors act as mixed inhibitor. The thermodynamic parameters of the corrosion and adsorption processes were calculated and evaluated. The adsorption of these inhibitors was found to obey Langmuir adsorption isotherm. Scanning electron microscopy was used to characterize the surface morphology of the mild steel specimens in presence and absence of inhibitors. The mechanism of the inhibition process was discussed in the light of the chemical structure and quantum-chemical calculations of the investigated inhibitors.展开更多
The inhibition ability of 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol （APTT）, ethylenediaminetetra-acetic acid （EDTA） and thiourea （TU） for mild steel corrosion in 1.0 moFL HC1 solution at 30 ℃ was investigated...The inhibition ability of 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol （APTT）, ethylenediaminetetra-acetic acid （EDTA） and thiourea （TU） for mild steel corrosion in 1.0 moFL HC1 solution at 30 ℃ was investigated. Tafel polarization and electrochemical impedance spectroscopy （EIS） were used to investigate the influence of these organic compounds as corrosion inhibitors of mild steel in 1.0 mol/L HC1 solution at 30 ℃. The inhibition mechanism was discussed in terms of Langrnuir isotherm model. Results obtained from Tafel polarization and impedance measurements are in a good agreement. The inhibition efficiency increases with the increase of the inhibitor concentration. The adsorption of the inhibitors on the mild steel surface follows Langmuir adsorption isotherm and the free energy of adsorption AGads indicates that the adsorption of APTT, EDTA, and TU molecules is a spontaneous process and a typical chemisorption.展开更多
This study proposes a novel mild steel damper with non-uniform vertical slits. The influence of different shapes of vertical slits of the core energy plate on the energy dissipation and buckling resistance capacities ...This study proposes a novel mild steel damper with non-uniform vertical slits. The influence of different shapes of vertical slits of the core energy plate on the energy dissipation and buckling resistance capacities is analyzed. Based on the theoretical analysis, formulas of key parameters of the dampers, including the elastic lateral stiffness, shear bearing capacity and yield displacement, are derived. The effectiveness of the proposed damper is demonstrated through pseudo static tests on four 0.25-scale specimens. Performance of these dampers, i.e. cyclic deformation, stress distribution, energy dissipation capacity, etc., are presented and discussed. Using the numerical models of dampers calibrated through test data, earthquake time-history analyses were conducted, and it is observed that the dampers significantly reduce the seismic responses of the prototype frame and have a desirable energy dissipation capacity.展开更多
This work is devoted to the study of the inhibition of corrosion of mild steel(MS)in molar hydrochloric acid(1 mol·L-1 HCl)by two named quinoxaline derivatives namely,2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline...This work is devoted to the study of the inhibition of corrosion of mild steel(MS)in molar hydrochloric acid(1 mol·L-1 HCl)by two named quinoxaline derivatives namely,2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline(HQ)and 2-(2,4-dichlorophenyl)-6-methyl-1,4-dihydroquinoxaline(CQ).The inhibitory efficacy of HQ and CQ compounds is first evaluated using the gravimetric method and using electrochemical techniques(stationary and transient techniques).The results showed that our compounds are efficient corrosion inhibitors and the inhibition rates(ηEIS%)reached up to 91%and 94.2%at 10-3 mol·L-1 for HQ and CQ,respectively.The mentioned molecules are classified as mixed-type inhibitors.The adsorption of these inhibitors on the surface of steel in hydrochloric HCl 1 mol·L-1 medium obeys the Langmuir adsorption isotherm.The results of the scanning electron microscope(SEM)showed the formation of a protective film on the surface of the steel in the presence of the inhibitors studied.Elementary analysis is obtained by energy dispersive X-ray spectroscopy(EDS).The inhibition property was further elucidated by theoretical approaches such as:Density Functional Theory(DFT),quantum chemical descriptors(QCD),local reactive indices,solvent effect,theoretical complexation,Molecular Dynamic(MD)simulation,effect of temperature on adsorption energy(Eads),Radial Distribution Function(RDF),and Mean Square Displacement(MSD).The results of these approaches support the experimental results.展开更多
Microbiologically influenced corrosion （MIC） is very severe corrosion for constructions buried under sea mud environment. Therefore it is of great importance to carry out the investigation of the corrosion behavior ...Microbiologically influenced corrosion （MIC） is very severe corrosion for constructions buried under sea mud environment. Therefore it is of great importance to carry out the investigation of the corrosion behavior of marine steel in sea mud. In this paper, the effect of sulfate-reducing bacteria （SRB） on corrosion behavior of mild steel in sea mud was studied by weight loss, dual-compartment cell, electronic probe microanalysis （EPMA）, transmission electron microscopy （TEM） combined with energy dispersive X-ray analysis （EDX） and electrochemical impedance spectroscopy （EIS）. The results showed that corrosion rate and galvanic current were influenced by the metabolic activity of SRB. In the environment of sea mud containing SRB, the original corrosion products, ferric （oxyhydr） oxide, transformed to iron sulfide. With the excess of the dissolved H2S, the composition of the protective layer formed of FeS transformed to FeS2 or other non-stoichiometric polysulphide, which changed the state of the former layer and accelerated the corrosion process.展开更多
The variation in arc characteristics and behavior of metal transfer with the change in pulse parameters has been studied by high speed video camera during pulse current flux-cored arc weld deposition.A comparative stu...The variation in arc characteristics and behavior of metal transfer with the change in pulse parameters has been studied by high speed video camera during pulse current flux-cored arc weld deposition.A comparative study of similar nature has also been carried out during flux-cored arc weld deposition in globular and spray transfer modes.The effect of pulse parameters has been studied by considering their mean current and arc voltage.The arc characteristics studied by its root diameter,projected diameter and length,and the behavior of metal transfer noted by the metal transfer model and the droplet diameter have been found to vary significantly with the pulse parameters.The observation may help in understanding the arc characteristics with respect to the variation in pulse parameters which may be beneficial in using pulse current FCAW to produce desired weld quality.展开更多
In order to get more precise bursting pressure formula of mild steel, hundreds of bursting experiments of mild steel pressure vessels such as Q235（Gr.D） and 20R（1020） are done. Based on statistical data of burstin...In order to get more precise bursting pressure formula of mild steel, hundreds of bursting experiments of mild steel pressure vessels such as Q235（Gr.D） and 20R（1020） are done. Based on statistical data of bursting pressure and modification of Faupel formula, a more precise modified formula is given out according to the experimental data. It is proved to be more accurate after examining other bursting pressure value presented in many references. This bursting formula is very accurate in these experiments using pressure vessels with different diameter and shell thickness. Obviously, this modified bursting formula can be used in mild steel pressure vessels with different diameter and thickness of shell.展开更多
Macro-deformation characteristics of continuous drive friction welded mild steel joints were examined by using one deformable workpiece （objective） and the other undeformable one （rigid）. The microstructure evolut...Macro-deformation characteristics of continuous drive friction welded mild steel joints were examined by using one deformable workpiece （objective） and the other undeformable one （rigid）. The microstructure evolution and hardness change across the joint were studied. The results show that the axial shortening and radial increment of joints increase with increasing the frictiou time at l 200 rpm. The cementite particles of pearlites in the weld center are uniformly distributed on the ferrite matrix, while the cementites of the pearlite in the thermal-mechanically affected zone are broken and discontinuously dispersed in the pearlite. The hardness decreases rapidly from the weld center to the parent metal under the coupled effects of heat and deformation during the rapid heating and cooling processes.展开更多
A three dimensional finite difference electrical thermal model for resistance spot welding nugget process of mild steel and stainless steel is introduced. A simulation method of the interaction of electrical and the...A three dimensional finite difference electrical thermal model for resistance spot welding nugget process of mild steel and stainless steel is introduced. A simulation method of the interaction of electrical and thermal factors is presented. Meanwhile, calculation method of contact resistance and treatment method of heater structure is provided. The influence of the temperature dependent material properties and various cooling boundary conditions on welding process was also taken into account in the model. A method for improving the mild steel and stainless steel joint was analyzed in numerical simulation process. Experimental verification shows that the model prediction agrees well with the practice. The model provides a useful theoretic tool for the analysis of the process of resistance spot welding of mild steel and stainless steel.展开更多
The ethanolic extract of Kleinia grandiflora leaves was characterized and tested for its potential anticorrosion properties on mild steel in 1 M H2SO4 medium using mass-loss analysis, potentiodynamic polarization meas...The ethanolic extract of Kleinia grandiflora leaves was characterized and tested for its potential anticorrosion properties on mild steel in 1 M H2SO4 medium using mass-loss analysis, potentiodynamic polarization measurements, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, UV–visible spectroscopy, and X-ray diffraction analysis. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 308 to 328 K. The inhibition efficiency was observed to increase with increasing concentration of the extract. Polarization curves revealed that the Kleinia grandiflora leaf extract is a mixed inhibitor. Impedance diagrams revealed that an increase of Kleinia grandiflora leaf extract concentration increased the charge transfer resistance and decreased the double-layer capacitance. The adsorption process obeys Langmuir＇s model, with a standard free energy of adsorption（ΔGads） of-18.62 k J/mol. The obtained results indicate that the Kleinia grandiflora leaf extract can serve as an effective inhibitor for the corrosion of mild steel in a sulfuric acid medium.展开更多
The variation in altitude density function （ADF） of the surface topography of mild steel during electrochemical polishing （ECP） was investigated, and the mechanism of the variation of surface roughness with polish...The variation in altitude density function （ADF） of the surface topography of mild steel during electrochemical polishing （ECP） was investigated, and the mechanism of the variation of surface roughness with polishing time was analyzed. The results show that the variation trend of ADF with polishing time is flat-steep-flat; the variation of surface roughness results in the different distri- butions of surface current density, and there is a fine surface smoothness in the special period of ECP from 4 to 8 s.展开更多
基金Funded by the National Natural Science Foundation of China(NSFC)of China(No.21878029)the Chongqing Science and Technology Commission(Nos.2022NSCQ-MSX1298 and CSTB2023NSCQ-MSX0345)。
文摘New stared compounds including norfloxacin fragments were prepared via a multi-step route,which were employed as the target corrosion inhibitors(TCIs)for mild steel in 1 mol/L HCl solution.For comparisons,the linear compounds including a single norfloxacin part employed as the reference corrosion inhibitors(RCIs)were synthesized.The molecular structures of the stared compounds were confirmed.The material simulation calculations suggest the presence of large binding energies of the stared compounds on mild steel surface.The enhanced chemisorption of the stared compounds on mild steel surface was demonstrated,which could be resulted by the chemical complexion of the target stared molecules with iron atoms.The reinforced adsorption of the target compounds on mild steel surface was investigated by atomic force microscopy(AFM)and scanning electron microscopy(SEM).The electrochemical analyses reveal the super protection of the TCIs for mild steel in HCl solution,and the anticorrosion efficiency reaches 96.45%(TCI1,0.050 mM)and 96.61%(TCI2,0.010 mM)at 298 K.
基金funding agency University Grants Commission (UGC),Government of India,for giving a fellowship and other financial assistance for her Ph.D.thesis study。
文摘Cerium tartrate(CeTar),produced in this study by precipitating cerium nitrate with potassium sodium tartrate(KNaTar),was examined as a corrosion inhibitor.Weight loss tests show inhibition efficiency of 71.7% with Ce(NO_(3))_(3) and 88.7% with CeTar inhibitor for one-month exposure to mild steel in 7 g/L NaCl solution.The inhibition efficiency drops to 28.6% with the fo rmer and remains around 8 7% with the latter inhibitor after six months of exposure.Similar results from electrochemical testing indicate that the inhibition efficiency decreases by adding cerium nitrate.Still,the cerium tartrate inhibitor demonstrates a nearly constant inhibition efficiency for up to 30 d,i.e.,≈90%.Electrochemical impedance spectroscopy(EIS) performed in these cases shows the following results:(ⅰ) with cerium nitrate,a film of iron and cerium oxide,which on prolonged exposure diminishes,and(ⅱ) with cerium tartrate,the formation of a bimetallic film(Fe-tartrate-Ce) and a mixture of cerium hydroxide and iro n oxide that protects steel for a longer duration.These inferences are based on the analyses of scanning electron microscopy/energydispersive X-ray analysis(SEM/EDAX),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron(XPS),and Raman spectroscopy results.
基金supported by the Natural Science Foundation of Chongqing,China(Grant Nos.cstc2020jcyj-msxm X0544,CSTB2022NSCQ-MSX0352,CSTB2022NSCQ-MSX0891,cstc2020jcyj-msxm X0184)Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202001416)National Natural Science Foundation of China(Grant Nos.11847077,52001028)。
文摘The metallurgical quality control of magnesium(Mg)and Mg alloys in melting process is required to ensure a satisfied mechanical and corrosion performance,while the typical used steel crucible introduces impurities and interfacial interaction during melting process.Therefore,a systematic study about impurities diffusion and interfacial interaction between molten Mg and steel is necessary.In the present study,the interfacial reaction between molten AZ91D Mg alloy and mild steel during melting process was investigated with the melting temperatures of 700℃,750℃ and 800℃.The results show that Al(Fe,Mn)intermetallic layer is the intermetallic primarily formed at the interfaces of AZ91D melt and mild steel.Meanwhile,Al_(8)(Mn,Fe)5is indexed between Al(Fe,Mn)and AZ91D.AlFe_(3)C appears between the mild steel and Al(Fe,Mn)at 700℃ and 750℃,but absent at 800℃ due to the increased solubility of carbon in Mg matrix.It is found that the growth of the intermetallic layer is controlled by diffusion mechanism,and Al and Mn are the dominant diffusing species in the whole interfacial reaction process.By measuring the thickness of different layers,the growth constant was calculated.It increases from 1.89(±0.03)×10^(-12)m^(2)·s^(-1)at 700℃ to 3.05(±0.05)×10^(-12)m^(2)·s^(-1)at 750℃,and 5.18(±0.05)×10^(-12)m^(2)·s^(-1)at 800℃.Meanwhile,the content of Fe is linearly increased in AZ91D with the increase of holding time at 700℃ and 750℃,while it shows a significantly increment after holding for 8 h at 800℃,indicating holding temperature is more crucial to determine the Fe content of AZ91D than holding time.
基金supported finically by the National Natural Science Foundation of China(Nos.51201170,51131007 and 50971120)
文摘The corrosion behaviors of the isolated short and vertical long scale Q235B steel in a simulated tidal zone were studied by electrochemical impedance spectroscopy （EIS） monitoring and corrosion weight loss calculation in an experimental indoor simulating trough. The results show that the corrosion rate of the isolated short scale Q235B steel in the tidal zone acquired by the EIS agrees with the corrosion weight loss result. The corrosion rates of the short scale steel are in the order of middle tidal zone 〉 the central zone between the middle tidal zone and low tidal zone 〉 high tidal zone 〉 low tidal zone. The fastest corrosion rate in the middle tidal zone is attributed to the longest wet time in a tidal cycle. According to the comparison of corrosion weight loss between the vertical long scale and isolated short scale specimens, the corrosion rate of vertical long scale specimens of Q235B steel is lower than that of the isolated short scale specimens in the tidal zone, but the result is contrary in the immersion zone.
基金financially the Natural Science Foundation of Liaoning Province,China(No.2019JH3/30100037)the National Natural Science Foundation of China(No.51671200)the State Key Laboratory of Metal Material for Marine Equipment and Application(No.SKLMEA-K201907)。
文摘The corrosion behavior of mild steel in a simulated coastal atmosphere environment has been investigated by the indoor accelerated wet/dry cyclic corrosion acceleration test(CCT),scanning electron microscopy(SEM),Raman spectroscopy and electrochemical measurements.During the CCT test of 60 cycles,the evolution of logarithmic(corrosion rate)vs.logarithmic(CCT cycles)presents a turning point at the 5th cycle,presenting a tendency to increase first and then decrease to gradually stabilize as the CCT cycle prolonged.Before the 5th cycle,γ-FeOOH andβ-FeOOH and Fe_(3)O_(4)were detected,respectively.And then,α-FeOOH as a new chemical composition was detected in the subsequent corrosion cycles.It is found that,after long term corrosion,the rust separated into a relatively dense inner layer rich withα-FeOOH and a loose outer layer rich withγ-FeOOH,both of which have poor electrical conductivity.The rapid increase of corrosion rate in the early stage since reducible corrosion products are involved in the reduction process of the cathode which promotes the dissolution of the anodic metal substrate.Afterward,as the rust layer thickens,the resistance of the rust increases,and the aggressive ions diffusion is blocked,gradually suppressing the electrochemical corrosion process.At last,when the composition and distribution of the rust layer remain stable,the corrosion presents a fluctuating speed around a certain value during the cracking and self-repairing process of the rust layer.
文摘The kinetics of mild steel corrosion in aqueous acetic acid solution has been investigated by weight loss and polarization techniques at 25,35 and 45℃.The weight loss of mild steel at room temperature （25℃） has been found to be quite significant,indicating poor corrosion resistance in acetic acid.The maximum corrosion rate has been observed in 25% acetic acid solution at all three experimental temperatures.The decrease in corrosion rate after attaining a maximum value has been attributed to the deposition of corrosion product on the surface.Anodic polarization curves exhibit active behaviour at each concentration and temperature with a shift towards higher current density region and increased corrosion rates at higher temperatures.The cathodic polarization curves are almost identical irrespective either of the concentration of acetic acid or temperature.The results obtained by both the techniques are in good agreement,while the surface studies support the conclusions drawn from the weight loss method.
文摘The Morinda tinctoria (MT) plant leaves extract was prepared in aqueous and hydrochloric acid media and was used as corrosion inhibitor for mild steel in hydrochloric acid medium. MT is found to be an efficient inhibitor at room temperature and the efficiency decreases with increase in temperature. Results from colorimetric studies predict the amount of iron present in the test solution and the percentage inhibition efficiency values calculated from this data fit well with the weight loss experiments. The AC impedance studies reveal that the mild steel surface is positively charged and the process of inhibition is through charge transfer. Polarisation studies indicate the mixed nature of the inhibitor. Thermodynamic parameters obtained predict that the process of inhibition is a spontaneous one.
基金financially supported by the National Natural Science Foundation of China(Nos.51804197,51674166 and U1902220)the Startup Fund for Youngman Research at Shanghai Jiao Tong University。
文摘The corrosion of mild steels by liquid aluminum is an intractable issue in aluminum industry.This review aims to provide an overview of the corrosion behavior of mild steels in the static liquid aluminum with an emphasis on the thermodynamic and kinetic aspects.The corrosion mechanisms of mild steels in liquid aluminum are discussed systematically,based on which four corrosion control approaches including alloying,introducing secondary phase,matrix microstructure control and surface treatment are introduced.Currently,a combination of improvement approaches may have a great potential for further enhancement in corrosion resistance.
基金M/s IRCON International Pvt,Ltd,Muthupettai,Tamilnadu,Sponsored project No:SSP09/06
文摘In continuation of the extensive studies carried out to update the corrosion map of India, in this study, the degradation of mild steel by air pollutants was studied at 16 different locations from Nagore to Ammanichatram along the east coast of Tamilnadu, India over a period of two years. The weight loss study showed that the mild steel corrosion was more at Nagapattinam site, when compared to Ammanichatram and Maravakadu sites. A linear regression analysis of the experimental data was attempted to predict the mechanism of the corrosion. The composition of the corrosion products formed on the mild steel surfaces was identified by XRD technique. The corrosion rate values obtained are discussed in the light of the weathering parameters, atmospheric pollutants such as salt content ＆ SO2 levels in the atmosphere, corrosion products formed on the mild steel surfaces.
文摘The inhibition effect of synthesized diethyl 3,4-bis（4-methoxybenzylideneamino） thieno[2,3-b] thiophene-2,5- dicarboxylate （Inh I） and diethyl 3,4-bis（benzylideneamino） thieno[2,3-b] thiophene-2,5-dicarboxylate （Inh II）, on cor- rosion of mild steel in 15% HC1 solution was investigated using weight loss measurements, electrochemical polarization, and electrochemical impedance spectroscopy techniques. The experimental results show that the inhibition efficiency of studied inhibitors increased with the increase of inhibitors concentration but decreased with the increase of temperature. Corrosion inhibition efficiencies of 94.5% and 92.1% were obtained with 250 ppm of Inh I and Inh II at 303 K, respectively. The potentiodynamic polarization measurements indicate that the studied inhibitors act as mixed inhibitor. The thermodynamic parameters of the corrosion and adsorption processes were calculated and evaluated. The adsorption of these inhibitors was found to obey Langmuir adsorption isotherm. Scanning electron microscopy was used to characterize the surface morphology of the mild steel specimens in presence and absence of inhibitors. The mechanism of the inhibition process was discussed in the light of the chemical structure and quantum-chemical calculations of the investigated inhibitors.
基金Project(UKM-GUP-BTT-07-25-170) supported by Universiti Kebangsaan Malaysia
文摘The inhibition ability of 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol （APTT）, ethylenediaminetetra-acetic acid （EDTA） and thiourea （TU） for mild steel corrosion in 1.0 moFL HC1 solution at 30 ℃ was investigated. Tafel polarization and electrochemical impedance spectroscopy （EIS） were used to investigate the influence of these organic compounds as corrosion inhibitors of mild steel in 1.0 mol/L HC1 solution at 30 ℃. The inhibition mechanism was discussed in terms of Langrnuir isotherm model. Results obtained from Tafel polarization and impedance measurements are in a good agreement. The inhibition efficiency increases with the increase of the inhibitor concentration. The adsorption of the inhibitors on the mild steel surface follows Langmuir adsorption isotherm and the free energy of adsorption AGads indicates that the adsorption of APTT, EDTA, and TU molecules is a spontaneous process and a typical chemisorption.
基金Natural Science Foundation of China under Grant No.51278104
文摘This study proposes a novel mild steel damper with non-uniform vertical slits. The influence of different shapes of vertical slits of the core energy plate on the energy dissipation and buckling resistance capacities is analyzed. Based on the theoretical analysis, formulas of key parameters of the dampers, including the elastic lateral stiffness, shear bearing capacity and yield displacement, are derived. The effectiveness of the proposed damper is demonstrated through pseudo static tests on four 0.25-scale specimens. Performance of these dampers, i.e. cyclic deformation, stress distribution, energy dissipation capacity, etc., are presented and discussed. Using the numerical models of dampers calibrated through test data, earthquake time-history analyses were conducted, and it is observed that the dampers significantly reduce the seismic responses of the prototype frame and have a desirable energy dissipation capacity.
文摘This work is devoted to the study of the inhibition of corrosion of mild steel(MS)in molar hydrochloric acid(1 mol·L-1 HCl)by two named quinoxaline derivatives namely,2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline(HQ)and 2-(2,4-dichlorophenyl)-6-methyl-1,4-dihydroquinoxaline(CQ).The inhibitory efficacy of HQ and CQ compounds is first evaluated using the gravimetric method and using electrochemical techniques(stationary and transient techniques).The results showed that our compounds are efficient corrosion inhibitors and the inhibition rates(ηEIS%)reached up to 91%and 94.2%at 10-3 mol·L-1 for HQ and CQ,respectively.The mentioned molecules are classified as mixed-type inhibitors.The adsorption of these inhibitors on the surface of steel in hydrochloric HCl 1 mol·L-1 medium obeys the Langmuir adsorption isotherm.The results of the scanning electron microscope(SEM)showed the formation of a protective film on the surface of the steel in the presence of the inhibitors studied.Elementary analysis is obtained by energy dispersive X-ray spectroscopy(EDS).The inhibition property was further elucidated by theoretical approaches such as:Density Functional Theory(DFT),quantum chemical descriptors(QCD),local reactive indices,solvent effect,theoretical complexation,Molecular Dynamic(MD)simulation,effect of temperature on adsorption energy(Eads),Radial Distribution Function(RDF),and Mean Square Displacement(MSD).The results of these approaches support the experimental results.
基金the National Natural Science Foundation of China （No. 40376023 and 40406022）
文摘Microbiologically influenced corrosion （MIC） is very severe corrosion for constructions buried under sea mud environment. Therefore it is of great importance to carry out the investigation of the corrosion behavior of marine steel in sea mud. In this paper, the effect of sulfate-reducing bacteria （SRB） on corrosion behavior of mild steel in sea mud was studied by weight loss, dual-compartment cell, electronic probe microanalysis （EPMA）, transmission electron microscopy （TEM） combined with energy dispersive X-ray analysis （EDX） and electrochemical impedance spectroscopy （EIS）. The results showed that corrosion rate and galvanic current were influenced by the metabolic activity of SRB. In the environment of sea mud containing SRB, the original corrosion products, ferric （oxyhydr） oxide, transformed to iron sulfide. With the excess of the dissolved H2S, the composition of the protective layer formed of FeS transformed to FeS2 or other non-stoichiometric polysulphide, which changed the state of the former layer and accelerated the corrosion process.
文摘The variation in arc characteristics and behavior of metal transfer with the change in pulse parameters has been studied by high speed video camera during pulse current flux-cored arc weld deposition.A comparative study of similar nature has also been carried out during flux-cored arc weld deposition in globular and spray transfer modes.The effect of pulse parameters has been studied by considering their mean current and arc voltage.The arc characteristics studied by its root diameter,projected diameter and length,and the behavior of metal transfer noted by the metal transfer model and the droplet diameter have been found to vary significantly with the pulse parameters.The observation may help in understanding the arc characteristics with respect to the variation in pulse parameters which may be beneficial in using pulse current FCAW to produce desired weld quality.
文摘In order to get more precise bursting pressure formula of mild steel, hundreds of bursting experiments of mild steel pressure vessels such as Q235（Gr.D） and 20R（1020） are done. Based on statistical data of bursting pressure and modification of Faupel formula, a more precise modified formula is given out according to the experimental data. It is proved to be more accurate after examining other bursting pressure value presented in many references. This bursting formula is very accurate in these experiments using pressure vessels with different diameter and shell thickness. Obviously, this modified bursting formula can be used in mild steel pressure vessels with different diameter and thickness of shell.
文摘Macro-deformation characteristics of continuous drive friction welded mild steel joints were examined by using one deformable workpiece （objective） and the other undeformable one （rigid）. The microstructure evolution and hardness change across the joint were studied. The results show that the axial shortening and radial increment of joints increase with increasing the frictiou time at l 200 rpm. The cementite particles of pearlites in the weld center are uniformly distributed on the ferrite matrix, while the cementites of the pearlite in the thermal-mechanically affected zone are broken and discontinuously dispersed in the pearlite. The hardness decreases rapidly from the weld center to the parent metal under the coupled effects of heat and deformation during the rapid heating and cooling processes.
文摘A three dimensional finite difference electrical thermal model for resistance spot welding nugget process of mild steel and stainless steel is introduced. A simulation method of the interaction of electrical and thermal factors is presented. Meanwhile, calculation method of contact resistance and treatment method of heater structure is provided. The influence of the temperature dependent material properties and various cooling boundary conditions on welding process was also taken into account in the model. A method for improving the mild steel and stainless steel joint was analyzed in numerical simulation process. Experimental verification shows that the model prediction agrees well with the practice. The model provides a useful theoretic tool for the analysis of the process of resistance spot welding of mild steel and stainless steel.
文摘The ethanolic extract of Kleinia grandiflora leaves was characterized and tested for its potential anticorrosion properties on mild steel in 1 M H2SO4 medium using mass-loss analysis, potentiodynamic polarization measurements, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, UV–visible spectroscopy, and X-ray diffraction analysis. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 308 to 328 K. The inhibition efficiency was observed to increase with increasing concentration of the extract. Polarization curves revealed that the Kleinia grandiflora leaf extract is a mixed inhibitor. Impedance diagrams revealed that an increase of Kleinia grandiflora leaf extract concentration increased the charge transfer resistance and decreased the double-layer capacitance. The adsorption process obeys Langmuir＇s model, with a standard free energy of adsorption（ΔGads） of-18.62 k J/mol. The obtained results indicate that the Kleinia grandiflora leaf extract can serve as an effective inhibitor for the corrosion of mild steel in a sulfuric acid medium.
基金the National Natural Science Foundation of China (No.59831030).
文摘The variation in altitude density function （ADF） of the surface topography of mild steel during electrochemical polishing （ECP） was investigated, and the mechanism of the variation of surface roughness with polishing time was analyzed. The results show that the variation trend of ADF with polishing time is flat-steep-flat; the variation of surface roughness results in the different distri- butions of surface current density, and there is a fine surface smoothness in the special period of ECP from 4 to 8 s.
