Effect of micro-arc oxidation coating on stress corrosion behavior of AA7050

2020 ◽  
Vol 67 (2) ◽  
pp. 178-186
Author(s):  
R.G. Song ◽  
T.S. Hua ◽  
Y. Zong ◽  
S.W. Cai
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Stress Corrosion ◽  
Corrosion Behavior ◽  
Constant Load ◽  
Coated Specimen ◽  
Nacl Solution ◽  
Cracking Behavior ◽  
Content Type ◽  
Micro Arc Oxidation

Purpose This paper aims to study the effect of Micro-arc oxidation (MAO) coating on stress corrosion and electrochemical behavior of aluminum alloy. Design/methodology/approach The stress corrosion cracking behavior of 7050 aluminum alloy (AA7050) after MAO treatment was investigated in 3.5 Wt.% NaCl solution using the constant load ring. Electrochemical impedance spectroscopy (EIS) was used to evaluate the change of corrosion resistance of MAO specimens in 3.5  Wt.% NaCl solution, and appropriate equivalent circuits were established. Findings The results demonstrated that the MAO coating can improve the corrosion resistance of the AA7050 and avoid the reduction of mechanical properties caused by corrosion. In the initial stage of corrosion, the corrosion resistance of coated specimen decreased at first and then increased. In the middle and final stage of corrosion, the corrosion resistance of coated specimen decreased at first and then stabilized. Originality/value The long-term corrosion behavior of MAO specimens under stress was studied by constant load experiment and EIS. It has guiding significance for the application of MAO technology on aluminum alloy.

Effect of Micro Arc Oxidation Treatment on the Corrosion and Stress Corrosion Cracking (SCC) Behaviours of AA7020-T6 Aluminum Alloy in 3.5% NaCl Solution

2015 ◽  
Vol 830-831 ◽  
pp. 639-642
Author(s):  
A. Venugopal ◽  
P. Ramesh Narayanan ◽  
S.C. Sharma ◽  
Koshy M. George
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Alumina Coating ◽  
Slow Strain Rate Test ◽  
Nacl Solution ◽  
Cracking Resistance ◽  
Micro Arc Oxidation

Alumina coating was formed on AA7020 aluminum alloy by micro arc oxidation (MAO) method and its corrosion and stress corrosion cracking (SCC) behaviors were examined in 3.5 wt. % NaCl solution. Potentiodynamic polarization (PP) was used to evaluate the corrosion resistance of the coating and slow strain rate test (SSRT) was used for evaluating the environmental cracking resistance in 3.5% NaCl solution. Results indicated that MAO coating on AA7020 alloy significantly improved the corrosion resistance. However the environmental cracking resistance was found to be only marginal. Key words: aluminum, micro arc oxidation, x-ray diffraction, stress corrosion cracking

Effect of Sealing Treatments on the Corrosion Behavior of Micro-arc Oxidation Coating on Aluminum Alloy in Acid NaCl Solution

2015 ◽  
Vol 30 (6) ◽  
pp. 627
Author(s):  
YE Zuo-Yan ◽  
LIU Dao-Xin ◽  
LI Chong-Yang ◽  
ZHANG Xiao-Hua ◽  
ZANG Xiao-Ming ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Corrosion Behavior ◽  
Nacl Solution ◽  
Micro Arc Oxidation

Effect of Heat Treatments on Stress Corrosion Behavior of 7050 Al Alloys in 3.5% NaCl Solution

2016 ◽  
Vol 877 ◽  
pp. 543-549
Author(s):  
Wei Wei Ren ◽  
Xing Feng Zhan ◽  
Lin Chi Zou ◽  
Qiang Li ◽  
Jun Feng Chen
Keyword(s):  
Corrosion Resistance ◽  
Strain Rate ◽  
Stress Corrosion ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Heat Treatments ◽  
Al Alloys ◽  
Slow Strain Rate ◽  
Nacl Solution ◽  
Stress Corrosion Resistance

Effect of heat treatments on the stress corrosion behavior of 7050 Al alloys in 3.5% NaCl solution has been investigated using slow strain rate tensile (SSRT) test. During the slow strain rate tensile process, electrochemical impedance spectroscopy (EIS) in real time was carried out to characterize the electrochemical behavior for different tempers 7050 Al alloys. The investigation shows that both the stress corrosion resistance of 7050 Al alloys is controlled by heat treatments due to the different precipitates state. The improvement of stress corrosion resistance is contributed to the tiny precipitates in matrix which are beneficial to corrosion potential and maintain passivation, and precipitates discontinuous distribution at grain boundary which obstruct intergranular crack connection. Moreover, base on the results, we find out retrogression and re-aging (RRA, i.e., T6 + 200 °C/ retrogression + water quench + T6) increases both tensile strength and stress corrosion resistance. The optimized of retrogression time is 30 minutes.

Stress corrosion cracking behavior of micro-arc oxidized AZ31 alloy

2019 ◽  
Vol 234 (8) ◽  
pp. 1640-1652 ◽  
Author(s):  
Xiuli He ◽  
Hongyu Liang ◽  
Zhifeng Yan ◽  
Rui Bai
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Az31 Alloy ◽  
Corrosion Cracking ◽  
Nacl Solution ◽  
Cracking Behavior ◽  
Good Corrosion Resistance ◽  
Mixed Fracture

The stress corrosion cracking behaviors of micro-arc oxidized AZ31 magnesium alloy were studied by using the slow tensile test in air and 3.5 wt.% NaCl solution. Results showed that compared with the substrate, the stress corrosion cracking susceptibility of the micro-arc oxidized specimens was obvious improved apparently in 3.5 wt.% NaCl solution, due to the good corrosion resistance of the specimens after micro-arc oxidized coating treatment. In addition, regardless of the micro-arc oxidized treatment, it was the mixed fracture in air and the cleavage fracture in 3.5 wt.% NaCl solution. The micro-arc oxidized coating had no direct effect on the fracture mechanism of the alloy. It was closely related to the nature of the material and the environment of the material servicing.

The corrosion behavior of chromated AA2024 aluminum alloy in 3.5% NaCl solution

2019 ◽  
Vol 66 (6) ◽  
pp. 879-887 ◽  
Author(s):  
Yong Zhou ◽  
Pei Zhang ◽  
Jinping Xiong ◽  
Fuan Yan
Keyword(s):  
Aluminum Alloy ◽  
Grain Boundary ◽  
Corrosion Behavior ◽  
Electrochemical Measurement ◽  
Nacl Solution ◽  
Content Type ◽  
Chromate Conversion Coating ◽  
Chromate Coating ◽  
Corrosion Mechanisms ◽  
Corrosion Pits

Purpose A chromate conversion coating was prepared on the surface of bare AA2024 aluminum alloy by direct immersion in the chromating treatment bath, and the corrosion behavior of chromated AA2024 aluminum alloy in 3.5 per cent NaCl solution was studied by electrochemical measurement and microstructural observation. Design/methodology/approach According to the polarization curve test and the scanning electron microscope observation, the corrosion evolution of chromated AA2024 in 3.5 per cent NaCl solution was divided into the following three stages: coating failure, pitting corrosion and intergranular corrosion (IGC). Findings In the first stage, the chromate coating degraded gradually due to the combined action of chloride anions and water molecules, resulting in the complete exposure of AA2024 substrate to 3.5 per cent NaCl solution. Subsequently, in the second stage, chloride anions adsorbed at the sites of θ phase (Al2Cu) and S phase (Al2CuMg) on the AA2024 surface preferentially, and some corrosion pits initiated at the above two sites and propagated towards the deep of crystal grains. However, the propagation of a pit terminated when the pit front arrived at the adjacent grain boundary, where the initiation of IGC occurred. Originality/value Finally, in the third stage, the corrosion proceeded along the continuous grain boundary net and penetrated the internal of AA2024 substrate, resulting in the propagation of IGC. The related corrosion mechanisms for the bare and the chromated AA2024 were also discussed.

Microstructure and Corrosion Behavior of Laser Cladding Al3Ti-Based Composite Coatings on AA6063 Aluminum Alloy

2013 ◽  
Vol 634-638 ◽  
pp. 2973-2978 ◽  
Author(s):  
Huan He ◽  
Yue Chun Fu ◽  
Wei Hua Guo ◽  
Min Xiao ◽  
Xing Zhi Pang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Intermetallic Compound ◽  
Uniform Distribution ◽  
Laser Irradiation ◽  
Corrosion Behavior ◽  
Laser Cladding ◽  
Composite Coatings ◽  
Nacl Solution ◽  
Aa6063 Aluminum Alloy

Intermetallic compound Al3Ti-based IMC coatings were formed on AA6063 aluminum alloy by laser cladding. The microstructure and corrosion characteristics in 3.5% NaCl solution were investigated. The results show that, the laser cladding coating is made up of Al3Ti dendrites, interdendritic α-Al and uniform distribution of TiC which hardly melted during laser irradiation, and shows good bonding to the substrate. The cross distribution of Al3Ti and α-Al helps to avoid the generation of cracks in the coating. The corrosion resistance of the laser cladding coatings is greatly increased as compared with the substrate, which owes mainly to the existence of hard Al3Ti and TiC. And with the increasing of TiC content in the coating, the corrosion resistance is improved simultaneously.

Corrosion inhibition properties of SiO2-ZrO2 nanocomposite coating on carbon steel 178

2018 ◽  
Vol 65 (1) ◽  
pp. 66-72 ◽  
Author(s):  
Behnam Abdollahi ◽  
Daryoush Afzali ◽  
Zahra Hassani
Keyword(s):  
Corrosion Resistance ◽  
Carbon Steel ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Nanocomposite Coating ◽  
Coating Film ◽  
Nacl Solution ◽  
Electrochemical Polarization ◽  
Content Type

Purpose SiO2 and SiO2-ZrO2 nanocomposites were coated by sol–gel dipping method on carbon steel 178 (178 CS). Nanostructure and phase properties of nanocomposite coating were characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared studies. Electrochemical polarization and electrochemical impedance spectroscopy (EIS) tests were used to study the corrosion behavior of 178 CS that was coated with SiO2-ZrO2 nanocomposite and SiO2 coating in 3.5 per cent NaCl solution. The results indicated that SiO2-ZrO2 nanocomposite coating performed better in terms of corrosion resistance compared with SiO2 coating. The corrosion resistance of SiO2-ZrO2 nanocomposite coating could be increased significantly in by approximately three and seven times of that of SiO2 coating and bare 178 CS, respectively. Design/methodology/approach SiO2 and SiO2-ZrO2 nanocomposites were coated using sol–gel dipping method on carbon steel 178. Electrochemical polarization and EIS tests have been used to study the corrosion behavior of 178 CS that was coated with SiO2-ZrO2 nanocomposite and SiO2 coating in 3.5 per cent NaCl solution. Findings Results indicated that SiO2-ZrO2 nanocomposite coating performed better in terms of corrosion resistance compared with SiO2 coating. The corrosion resistance of SiO2-ZrO2 nanocomposite coating could be increased significantly in by approximately three and seven times of that of SiO2 coating and bare 178 CS, respectively. Originality/value The SiO2-ZrO2 nanocomposite coating film showed significant improvement in corrosion resistance of 178 CS. The highest polarization resistance of the nanocomposite coating film was 10,600 Ω/cm2 from SiO2-0.2 ZrO2.

Effect of Aging Treatments on the Tensile Strength and SCC Resistance of 7A04 Aluminum Alloy

2014 ◽  
Vol 490-491 ◽  
pp. 73-77
Author(s):  
Chun Juan Fu ◽  
Mei Yu ◽  
Rong Bao Ma ◽  
Rui Yang Wang ◽  
Jian Hua Liu
Keyword(s):  
Tensile Strength ◽  
Aluminum Alloy ◽  
Stress Corrosion ◽  
Corrosion Test ◽  
Constant Load ◽  
Electrochemical Analysis ◽  
Scanning Electron Micrographs ◽  
Nacl Solution ◽  
Corrosion Pits ◽  
Scanning Electron

Effect of different aging treatments(namely AT1, AT2, AT3 and AT4) on the tensile strength(TS) and stress corrosion cracking(SCC) resistance of 7A04 aluminum alloy in 3.5% NaCl+0.5% H2O2solution was investigated using constant load tensile stress corrosion test. Electrochemical behavior of the alloy after different aging treatments was analyzed in 3.5% NaCl solution. The results show that AT1 (i.e. 135°C/16h) increases the TS but decreases the SCC resistance of 7A04. AT2 (i.e. 120°C/7h+165°C/10h) provides the highest SCC resistance and simultaneously retains the TS. AT3 (i.e. 115°C/5h+165°C/10h) decreases both the TS and SCC resistance. The electrochemical analysis indicates that the corrosion resistance of AT2 is the highest, which helps enhance the SCC resistance. The scanning electron micrographs reveal that intergranular corrosion occurs from the corrosion pits on the surface of the specimens when tested under stress, resulting in the ultimate fracture.

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