This study explored the coupling effects of microstructure,strain rate,and 3.5%NaCl solution on stress corrosion cracking(SCC)behaviors of low-cost Ti6411 and Ti52 titanium alloys,compared to those of marine TC4ELI an...This study explored the coupling effects of microstructure,strain rate,and 3.5%NaCl solution on stress corrosion cracking(SCC)behaviors of low-cost Ti6411 and Ti52 titanium alloys,compared to those of marine TC4ELI and Ti80 titanium alloys.Slow strain rate tensile(SSRT)tests were performed to evaluate SCC susceptibility.The SCC susceptibility index(I_(SSRT))was calculated,and the fracture morphologies were investigated to clarify the stress corrosion mechanisms.The experimental results show that the ISSRT of Ti6411 titanium alloy with a lamellar micro structure(LM)is the highest under a strain rate of 1×10^(-6)s^(-1),and the corresponding fracture mode shows a quasi-cleavage fracture with low ductility.TC4ELI alloy with an equiaxed microstructure exhibits excellent SCC resistance.However,the SCC behavior of the Ti80 alloy with a bimodal microstructure is relatively sensitive to high strain rates,and the Ti52 tube with a typical Widmanst?tten microstructure is sensitive to low strain rates.The stress corrosion mechanism can be attributed to the cyclic process of passive film rupture,anodic dissolution,and hydrogen-induced cracking due to a multifactor comprehensive interaction corresponding to specific microstructures,strain rates,and corrosive media.The LM of the Ti6411 plate allowed easy chloride penetration into the bare metal,thereby reducing the protection of the film and resulting in continuous anodic dissolution and hydrogen accumulation at the crack tip.The coupled effect of the internal hydrogen pressure and external tensile stress can easily cause crack propagation and failure under service conditions.展开更多
The transient current behaviour for Iron in 3.5%NaCl and 3.5%NaCl +1%NaNO2 solutions during corrosion fatigue (CF) process has been investigated at different given strain amplitudes and strain rates. The results show ...The transient current behaviour for Iron in 3.5%NaCl and 3.5%NaCl +1%NaNO2 solutions during corrosion fatigue (CF) process has been investigated at different given strain amplitudes and strain rates. The results show that elastic strain has little contribution to material dissolution. The elastic tension strain results in the decrease in the transient current, while the elastic compression strain increases the transient current. Compared to the elastic deformation, plastic deformation affects material dissolution evidently For iron in 3.5%NaCl solution, the strain amplitude plays a dominant role in the dissolution process accelerated by the plastic strain, while in 3.5%NaCl+1%NaNO2 solution, both the strain amplitude and strain rate play an important role in this process. In this paper, the effect of the elastic deformation on the material dissolution and the relation between the tension and compression current peak values under the plastic cycle deformation are discussed展开更多
The corrosion behavior of Cu-Cr alloy in 3.5%NaCl+NH3 solution had been studied, and the influences of the concentration of NH3 on corrosion resistance discussed by means of Metallograph, XRD, SEM and electrochemical ...The corrosion behavior of Cu-Cr alloy in 3.5%NaCl+NH3 solution had been studied, and the influences of the concentration of NH3 on corrosion resistance discussed by means of Metallograph, XRD, SEM and electrochemical method. The results show that the Cu is easier to corrosion than Cr, and the corrosion rate increases with the increasing of the concentration of NH3, and deformation worsen the corrosion resistance of the alloy in such corrosive environment.展开更多
Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3.5% sodium ch...Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3.5% sodium chloride （NaCl） solutions by cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS）, rotating disk electrode （RDE） and rotating ring-disk electrode （RRDE）. The cyclic voltammetric results demonstrated the cathodic process on Q235 carbon steel in O2-saturated 3.5% NaCl solution contains three reactions： dissolved oxygen reduction, iron oxides reduction and hydrogen evolution. The peak potential of oxygen reduction reaction （ORR） is - 0.85 V vs Ag/AgCl, 3 molL^-1 KCI. The EIS results indicated that the ORR occurring on Q235 carbon steel is a 4-electron process and that no finite diffusion is caused by the intermediate of H2O2 produced by ORR. The RDE and RRDE voltammograms confirmed the EIS results and it was found that the number of transferred electrons for ORR was nearly 4, i.e., dissolved oxygen reduced to water.展开更多
The enthalpies of dissolution of oxymatrine in 0.9%NaCl solution were measured using a RD496-2000 Calvet Microcalorimeter at 309.65 K under atmospheric pressure. The differen tial enthalpy and molar enthalpy of oxymat...The enthalpies of dissolution of oxymatrine in 0.9%NaCl solution were measured using a RD496-2000 Calvet Microcalorimeter at 309.65 K under atmospheric pressure. The differen tial enthalpy and molar enthalpy of oxymatrine dissolution in the 0.9%NaCl solution of were determined. The corresponding kinetic equation that described the dissolution process was elucidated. Moreover, the half-life, molar entropy, molar enthaply, and Gibbs free energy of the dissolution process were also obtained.展开更多
基金the financial support from the National Key R&D Program of China(No.2022YFB3705605)。
文摘This study explored the coupling effects of microstructure,strain rate,and 3.5%NaCl solution on stress corrosion cracking(SCC)behaviors of low-cost Ti6411 and Ti52 titanium alloys,compared to those of marine TC4ELI and Ti80 titanium alloys.Slow strain rate tensile(SSRT)tests were performed to evaluate SCC susceptibility.The SCC susceptibility index(I_(SSRT))was calculated,and the fracture morphologies were investigated to clarify the stress corrosion mechanisms.The experimental results show that the ISSRT of Ti6411 titanium alloy with a lamellar micro structure(LM)is the highest under a strain rate of 1×10^(-6)s^(-1),and the corresponding fracture mode shows a quasi-cleavage fracture with low ductility.TC4ELI alloy with an equiaxed microstructure exhibits excellent SCC resistance.However,the SCC behavior of the Ti80 alloy with a bimodal microstructure is relatively sensitive to high strain rates,and the Ti52 tube with a typical Widmanst?tten microstructure is sensitive to low strain rates.The stress corrosion mechanism can be attributed to the cyclic process of passive film rupture,anodic dissolution,and hydrogen-induced cracking due to a multifactor comprehensive interaction corresponding to specific microstructures,strain rates,and corrosive media.The LM of the Ti6411 plate allowed easy chloride penetration into the bare metal,thereby reducing the protection of the film and resulting in continuous anodic dissolution and hydrogen accumulation at the crack tip.The coupled effect of the internal hydrogen pressure and external tensile stress can easily cause crack propagation and failure under service conditions.
文摘The transient current behaviour for Iron in 3.5%NaCl and 3.5%NaCl +1%NaNO2 solutions during corrosion fatigue (CF) process has been investigated at different given strain amplitudes and strain rates. The results show that elastic strain has little contribution to material dissolution. The elastic tension strain results in the decrease in the transient current, while the elastic compression strain increases the transient current. Compared to the elastic deformation, plastic deformation affects material dissolution evidently For iron in 3.5%NaCl solution, the strain amplitude plays a dominant role in the dissolution process accelerated by the plastic strain, while in 3.5%NaCl+1%NaNO2 solution, both the strain amplitude and strain rate play an important role in this process. In this paper, the effect of the elastic deformation on the material dissolution and the relation between the tension and compression current peak values under the plastic cycle deformation are discussed
文摘The corrosion behavior of Cu-Cr alloy in 3.5%NaCl+NH3 solution had been studied, and the influences of the concentration of NH3 on corrosion resistance discussed by means of Metallograph, XRD, SEM and electrochemical method. The results show that the Cu is easier to corrosion than Cr, and the corrosion rate increases with the increasing of the concentration of NH3, and deformation worsen the corrosion resistance of the alloy in such corrosive environment.
基金supported by the National Natural Science Foundation of China ( Grant No 40876041)Science and Technology Basic Research Program of Qingdao (Grant No 09-1-3-16-jch)the National Key Technology Research and Development Program of China (Grant No 2007 BAB27B01)
文摘Electrochemical reduction of dissolved oxygen in seawater on metals is of great importance for corrosion studies. The present paper studied cathodic reduction of dissolved oxygen on Q235 carbon steel in 3.5% sodium chloride （NaCl） solutions by cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS）, rotating disk electrode （RDE） and rotating ring-disk electrode （RRDE）. The cyclic voltammetric results demonstrated the cathodic process on Q235 carbon steel in O2-saturated 3.5% NaCl solution contains three reactions： dissolved oxygen reduction, iron oxides reduction and hydrogen evolution. The peak potential of oxygen reduction reaction （ORR） is - 0.85 V vs Ag/AgCl, 3 molL^-1 KCI. The EIS results indicated that the ORR occurring on Q235 carbon steel is a 4-electron process and that no finite diffusion is caused by the intermediate of H2O2 produced by ORR. The RDE and RRDE voltammograms confirmed the EIS results and it was found that the number of transferred electrons for ORR was nearly 4, i.e., dissolved oxygen reduced to water.
文摘The enthalpies of dissolution of oxymatrine in 0.9%NaCl solution were measured using a RD496-2000 Calvet Microcalorimeter at 309.65 K under atmospheric pressure. The differen tial enthalpy and molar enthalpy of oxymatrine dissolution in the 0.9%NaCl solution of were determined. The corresponding kinetic equation that described the dissolution process was elucidated. Moreover, the half-life, molar entropy, molar enthaply, and Gibbs free energy of the dissolution process were also obtained.
