scholarly journals Influence of Preaging Treatment on Bake-Hardening Response and Electrochemical Corrosion Behavior of High Strength Al-Zn-Mg-Cu-Zr Alloy

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 895 ◽  
Author(s):  
Hui Li ◽  
Xiao-Teng Liu ◽  
Jia-Yi Wang
Keyword(s):  
Corrosion Behavior ◽  
Potentiodynamic Polarization ◽  
Electrochemical Impedance ◽  
Solution Treatment ◽  
Natural Aging ◽  
Electrochemical Corrosion ◽  
High Strength ◽  
Optical Microscope ◽  
Bake Hardening ◽  
Na Effect

The influence of preaging (PA) treatments on the bake hardening (BH) response of a AlZnMgCuZr aluminum alloy which served as automotive body structures were studied in this paper. A novel two-step PA treatment was particularly designed and further employed. The mechanical properties of the alloy were tested in detail. The microstructure was characterized by optical microscope (OM), transmission electron microscopy (TEM) and 3D measuring laser microscope (3D–MLM). Meanwhile, the corrosion behavior was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results indicated that the PA treatment was beneficial for the improvement of BH response after baking at 180 °C immediately after the solution treatment and the micro-hardness reached the peak value (194 HV) after 10 h holding, which had a percentage improvement of 110.87% compared to the hardness under the solution condition. The PA treatments decreased natural aging (NA) adverse effects, while it had the lowest NA effect and optimal BH response under 120 °C/20 min. Such a novel two-step PA treatment was revealed further to decrease the NA effect and increase the BH response compared to the optimal PA treatment, in particular, the BH value could reach 168 MPa and was 21.7% higher than that of optimal PA + NA treatment. The optimal corrosion resistance has been shown up by the combined characterizations of potentiodynamic polarization curves, EIS Nyquist plots, and 3D–MLM images.

scholarly journals Corrosion Characteristics of Copper-Added Austempered Gray Cast Iron (AGCI)

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 503 ◽  
Author(s):  
Asiful H. Seikh ◽  
Amit Sarkar ◽  
Jitendra Kumar Singh ◽  
Sohail M. A. Khan Mohammed ◽  
Nabeel Alharthi ◽  
...  
Keyword(s):  
Cast Iron ◽  
Corrosion Behavior ◽  
Potentiodynamic Polarization ◽  
Gray Cast Iron ◽  
Electrochemical Impedance ◽  
Optical Microscope ◽  
Gray Cast ◽  
X Ray Diffraction ◽  
Different Temperatures ◽  
Austempering Temperature

The aim of this investigation was to assess the corrosion behavior of gray cast iron (GCI) alloyed with copper. Alloyed GCI specimens were austempered isothermally at varying temperatures. After austenitizing at 927 °C, the samples were austempered at different temperatures ranging from 260 to 385 °C with an interval of 25 °C for 60 minutes. As a result, these samples developed an ausferrite matrix with different percentages of austenite. The resulting microstructures were evaluated and characterized by optical microscope (OM), scanning electron microscope (SEM), and X-ray diffraction (XRD). The corrosion characteristics were determined using potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) of these samples. These tests were carried out in a medium of 0.5 M H2SO4 and 3.5% NaCl solution. It was observed from the potentiodynamic polarization results that with increasing austempering temperature, the corrosion rate decreased. All results of the EIS were in accordance with a constant phase element (CPE) model. It was found that with an increase in austempering temperature, the polarization resistance (Rp) increased. The austenite content was also found to influence the corrosion behavior of the austempered gray cast iron (AGCI).

scholarly journals Corrosion investigations of Al-Si casting alloys in 0.6 M NaCl solution

2021 ◽  
Vol 41 (3) ◽  
Author(s):  
Sunčana Smokvina Hanza ◽  
Ladislav Vrsalović ◽  
Lovro Štic ◽  
Lovro Liverić
Keyword(s):  
Potentiodynamic Polarization ◽  
Electrochemical Behavior ◽  
Die Casting ◽  
Electrochemical Corrosion ◽  
Microstructural Characterization ◽  
Casting Process ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Open Circuit ◽  
Polarization Measurements

This paper presents results of the corrosion investigations of specimens made from finished parts for the automotive industry, produced by high-pressure die casting and gravity die casting process of six Al-Si alloys (40000 series). Open circuit potential and potentiodynamic polarization measurements have been performed using a potentiostat with three-electrode set-up in 0.6 M NaCl naturally aerated solution. Microstructural characterization before and after electrochemical investigations has been carried out with optical microscope to establish the connection between microstructure and corrosion parameters of investigated alloys and to analyze and record surface changes of each sample due to electrochemical corrosion. All alloys show good corrosion resistance, which manifests with low values of corrosion rates, calculated from the corrosion current densities obtained from potentiodynamic polarization measurements. Differences in electrochemical behavior appear due to the distinctions in their chemical composition and microstructure. The type of casting process does not affect electrochemical behavior of Al-Si alloys.

scholarly journals Effect of Dissolution of η′ Precipitates on Mechanical Properties of A7075-T6 Alloy

2022 ◽  
Vol 60 (1) ◽  
pp. 83-93
Author(s):  
Young-We Kim ◽  
Yong-Hee Jo ◽  
Yun-Soo Lee ◽  
Hyoung-Wook Kim ◽  
Je-In Lee
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Solution Treatment ◽  
Aluminum Matrix ◽  
Natural Aging ◽  
Aging Treatment ◽  
Nucleation Site ◽  
Treatment Temperature ◽  
Solution Treatment Temperature ◽  
Bake Hardening

The effects of dissolution of the η′ phase by solution treatment on the mechanical properties of A7075-T6 alloy were investigated. Immediately after solution treatment of the T6 sheet at 450 oC or higher, elongation significantly increased and dissolution of the η′ phase occurred. η′ is the main hardening phase. After natural-aging, GPI, which is coherent with the aluminum matrix, was formed and strength increased. When bake hardening after natural-aging was performed, the yield strength slightly increased due to partial dissolution of the GPI and re-precipitation of the η′ phase. In contrast, after solution treatment at 400 oC, there was less elongation increase due to the precipitation of the coarse η phase at grain boundaries and low dissolution of the η′ phase. In addition, when bake hardening after natural-aging was performed, the yield strength decreased due to insufficient GPI, which is the nucleation site of the η′ phase. To promote reprecipitation of the η′ phase, the solution treatment temperature was set to a level that would increase solubility. As a result, the yield strength was significantly increased through re-precipitation of a large number of fine and uniform η′ phase. In addition, to increase the effect of dissolution, a pre-aging treatment was introduced and the bake hardenability can be improved after dissolution.

Corrosion Protection of Nano-Silica Powder Coatingon Artificial Seawater

2021 ◽  
Vol 904 ◽  
pp. 519-524
Author(s):  
Gui Yun Zhang ◽  
Yong Wang ◽  
Tian Wei Zhang ◽  
Chen Yu Zhao
Keyword(s):  
Corrosion Protection ◽  
Corrosion Behavior ◽  
Sea Water ◽  
Electrochemical Impedance ◽  
Water Solution ◽  
Electrochemical Corrosion ◽  
Artificial Seawater ◽  
Protection Effect ◽  
Aluminum Sheets ◽  
Electrochemical Corrosion Behavior

Sea water resources are extensive and can be used to extinguish fires, but their corrosiveness is a major problem. Using the method of electrochemical workstation, the electrochemical corrosion behavior of aluminum sheet in artificial sea water solution and silica-coated artificial seawater was studied; by analyzing the surface morphology, polarization curve and electrochemical impedance spectroscopy, the electrochemical corrosion behavior of aluminum sheets under different immersion times and different immersion media is obtained. The conclusion is that the coating of nanosilica powder has a certain corrosion protection effect on artificial seawater.

scholarly journals Erosion-Corrosion Protection Due to Cr3C2-NiCr Cermet Coating on Stainless Steel

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1042
Author(s):  
Panneer Selvam Kevin ◽  
Abhishek Tiwari ◽  
Saravanan Seman ◽  
Syed Ali Beer Mohamed ◽  
Rengaswamy Jayaganthan
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Potentiodynamic Polarization ◽  
Electrochemical Impedance ◽  
Turbine Blades ◽  
Continuous Exposure ◽  
Hydro Power ◽  
Cermet Coating ◽  
Erosion Corrosion

Cr3C2–NiCr coatings have been used extensively to combat the erosion corrosion of hydro power turbine blades made of stainless steel. Cr3C2–NiCr coatings are also used in aqueous corrosive environments due to the high corrosion resistance rendered by the NiCr binder. In this investigation, both erosion and corrosion environments are introduced to cermet coating to study corrosion behavior using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The cermet coatings are useful for reducing the risk of deterioration of mechanical properties of hydro power turbines due to the continuous exposure to the erosive and corrosive action of the corrosive environment containing silt. It was observed that Cr3C2–NiCr coating offered a reasonable improvement in corrosion resistance when compared to bare substrate. The corrosion behavior of the coating was studied in a 150 mL solution of 0.1 M NaCl with 2 gms of quartz particles (0.2–0.8 mm) at various rotation speeds (3000, 4500, 6000 rpm) of the solution over a 1 h immersion using potentiodynamic polarization and EIS studies in a specifically designed experimental set-up for erosion corrosion. When compared to the bare stainless steel samples at 3000 rpm and 6000 rpm, the coating showed the highest improvement at 6.57 times and the least improvement at 3.79 times, respectively.

Studies on Corrosion Behavior of S-165 and HP Supermartensitic Stainless Steels in Cl- Environment

2011 ◽  
Vol 695 ◽  
pp. 425-428
Author(s):  
Duo Wang ◽  
De Ning Zou ◽  
Chang Bin Tang ◽  
Kun Wu ◽  
Huan Liu
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Corrosion Behavior ◽  
Stainless Steels ◽  
Potentiodynamic Polarization ◽  
Electrochemical Impedance ◽  
Polarization Curves ◽  
Chemical Compositions ◽  
Pitting Potential ◽  
Potentiodynamic Polarization Curves

Supermartensitic stainless steel grades are widely used in oil and gas industries to substitute duplex and super duplex stainless steels these years. In this paper the corrosion behavior of supermartensitic stainless steels with different chemical compositions, S-165 and HP, was investigated in Cl-environment. All the samples were treated by quenching at 1000 °C followed by tempering at 630 °C for 2h. After heat treatment, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) were determined on both kinds of samples. Polarization curves shows that the metastable pitting nucleuses were formed in passive area and the Cr content is the most important factor leading to the differences of pitting potential. The potentiodynamic polarization curves were conducted at various NaCl contents (5000, 15000 and 35000 ppm) and emphasized the need to account for the Cl-sensitivity of samples under corrosion environment. The results show that, the pitting potential decrease with the increase of chloride contents. The behavior of passive film was analyzed by electrochemical impedance spectroscopy.

Corrosion Behavior of High-Strength Low-Alloy Steel in High-Temperature Water with Zinc and Aluminum Simultaneous Injection

CORROSION ◽  
10.5006/3545 ◽  
2020 ◽  
Vol 76 (10) ◽  
pp. 918-929
Author(s):  
Shenghan Zhang ◽  
Chenhao Sun ◽  
Yu Tan
Keyword(s):  
Oxide Film ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Oxide Films ◽  
High Strength ◽  
Corrosion Current ◽  
Pressurized Water ◽  
Simultaneous Injection ◽  
Primary Water ◽  
Photocurrent Measurement

Oxide films were formed on A508-3 steel in simulated pressurized water reactor (PWR) primary water at the temperature of 561 ± 1 K for 168 h with zinc and/or aluminum injection. Corrosion behaviors of oxide films were analyzed by electrochemical polarization, electrochemical impedance spectroscopy, Mott-Schottky plots, photocurrent measurement, scanning electronic microscopy, and x-ray diffraction. The results showed that zinc and aluminum simultaneous injection technology decreased the corrosion current density, increased the impedance value, made the oxide film more compact, and affected the semiconductor properties of the oxide film. The increase in zinc concentration improved the corrosion resistance to some extent. ZnAl2O4 phase, with extremely low solubility and high stability, had been detected in the oxide film; this substance changed the composition of the oxide film and affected the corrosion behavior of A508-3 steel.

Corrosion Behavior of Copper in Halide Solutions

2012 ◽  
Vol 189 ◽  
pp. 36-39
Author(s):  
Hai Jiao Yang ◽  
Sheng Tao Zhang ◽  
Lei Zhang
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Corrosion Behavior ◽  
Theoretical Basis ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Halide Ions ◽  
Corrosive Effect ◽  
Electrochemical Corrosion Behavior

The corrosion behavior of copper in halide solutions was investigated by cyclic voltammetry, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). On this basis, the mechanism of electrochemical corrosion behavior of Cu in halide solutions has been analyzed. The study explores the corrosive effect of the halide ions on copper materials and provides a theoretical basis for the inhibition of halide ions on the corrosion of copper materials.

scholarly journals Effect of combined surface treatment on quality and electrochemical corrosion properties of manganese phosphate on hsla steel domex 700

2018 ◽  
Vol 62 (2) ◽  
pp. 45-53 ◽  
Author(s):  
Kamil Borko ◽  
F. Pastorek ◽  
Jacková M. Neslušan ◽  
S. Fintová ◽  
B. Hadzima
Keyword(s):  
Corrosion Resistance ◽  
Surface Treatment ◽  
Electrochemical Impedance ◽  
Hsla Steel ◽  
Electrochemical Corrosion ◽  
High Strength Steels ◽  
High Strength ◽  
Corrosion Properties ◽  
Manganese Phosphate ◽  
Pre Treatment

Abstract The actual industrial trend is focused on weight reduction of constructions while preserving strength properties. For this purpose, conventional steel are replaced by high strength steels.. The aim of this study was to evaluate the effects of mechanical surface pre-treatment on corrosion resistance of high strength low alloy steel Domex 700 before and after surface treatment by manganese phosphating. Tested environment was 0,1M NaCl solution. Evaluation of mechanical pre-treatment and phosphating effects on corrosion resistance was realized by electrochemical measurements: potentiodynamic polarization measurements (Tafel analysis) and electrochemical impedance spectroscopy (equivalent circuits). From resulsts it is possible to conclude, that creation of manganese phosphate layer on ground and shot peened steel surface significantly increases the corrosion resistance of Domex 700 steel.

Electrochemical corrosion behavior and surface passivation of bulk nanocrystalline copper in alkaline solution

2020 ◽  
Vol 67 (5) ◽  
pp. 465-472
Author(s):  
Wei Luo ◽  
Lei Hu ◽  
Yimin Xv ◽  
Jian Zhou ◽  
Wentao Xv ◽  
...  
Keyword(s):  
Grain Size ◽  
Corrosion Resistance ◽  
Passive Film ◽  
Corrosion Behavior ◽  
Potentiodynamic Polarization ◽  
Electrochemical Corrosion ◽  
Content Type ◽  
Naoh Solution ◽  
Electrochemical Corrosion Behavior ◽  
Bulk Nanocrystalline

Purpose This paper aims to focus on an assessment of the electrochemical corrosion performance of bulk NC copper in a variety of corrosion environments. Design/methodology/approach The electrochemical corrosion behavior of bulk nanocrystalline (NC) copper prepared by inert gas condensation and in situ warm compress technique was studied by using potentiodynamic polarization and electrochemical impedance spectroscopy tests in de-aerated 0.1 M NaOH solution. Findings NC copper exhibited a typical active-passive-transpassive behavior with the formation of duplex passive films, which was qualitatively similar to coarse-grain (CG) copper. Although a compact passive film formed on NC copper surface, the corrosion resistance of NC copper was lower in comparison with CG copper. The increase in corrosion rate for NC copper was mainly attributed to the high activity of surface atoms and intergranular atoms. These atoms led to an enhancement of passive ability and an increase of dissolution rate of passive film in oxygen-deficiency solution. For NC copper, the corrosion resistance decreased as grain size increased in NC range. Originality/value The difference in corrosion resistance between bulk NC copper and its CG counterpart is dependent upon the corrosion solution. In a previous work, the potentiodynamic polarization tests revealed that NC copper bulks (grain size 48, 68, 92 nm) had identical corrosion resistance to CG copper bulk in naturally aerated 0.1 M NaOH solution. The results might be related to the dissolved oxygen in the medium.

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