Microstructural evolution and corrosion behaviour of thermally aged dissimilar metal welds of low-alloy steel and nickel-based alloy

Choi, Kyoung Joon; Yoo, Seung Chang; Kim, Seung Hyun; Kim, Sang Woo; Ham, Junhyuk; Lee, Jeonghyeon; Kim, Ji Hyun

doi:10.1016/j.corsci.2019.03.032

Cited by 24 publications

(8 citation statements)

References 40 publications

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“…Bode plots in Figure b show that the | Z | 0.01 Hz value of the superhydrophobic coating increased by approximately two orders of magnitude than that of bare Mg and CM. Furthermore, the high-frequency (1 to 10 5 Hz) loop corresponds to the charge resistance of the surface coating upon the Mg substrate, while the response from the electrochemical double layer can be reflected by the semicircle located in the low frequency range (0.01–1 Hz). − Nyquist plots in Figure c show that the high-frequency loop of the superhydrophobic coating is larger than other coatings and sharply increases in the order of pure Mg ≈ CM < PDMS < PO ≈ POZT. Meanwhile, we proposed several equivalent circuits (Figure d,e) to fit the impedance results: R s (CPE 1 ( R c1 (CPE 2 ( R c2 ( C dl R ct ))))) was used for fitting the EIS data of pure Mg and CM, and R s (CPE 1 ( R c (CPE 2 R ct ))) was used for fitting the EIS data of PDMS, PO, and POZT coatings.…”

Section: Resultsmentioning

confidence: 94%

Synergistic Coating Strategy Combining Photodynamic Therapy and Fluoride-Free Superhydrophobicity for Eradicating Bacterial Adhesion and Reinforcing Corrosion Protection

Wang

Song

Yang

et al. 2020

ACS Appl. Mater. Interfaces

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Device-associated infection is one of the significant challenges in the biomedical industry and clinical management. Controlling the initial attachment of microbes upon the solid surface of biomedical devices is a sound strategy to minimize the formation of biofilms and infection. A synergistic coating strategy combining superhydrophobicity and bactericidal photodynamic therapy is proposed herein to tackle infection issues for biomedical materials. A multifunctional coating is produced upon pure Mg substrate through a simple blending procedure without involvement of any fluoride-containing agents, differing from the common superhydrophobic surface preparations. Superhydrophobic features of the coating are confirmed through water contact angle measurements (152.5 ± 1.9°). In vitro experiments reveal that bacterial-adhesion repellency regarding both Gram-negative (Escherichia coli) and Gram-positive ( Staphylococcus aureus) strains approaches over 96%, which is evidently ascribed to the proposed synergistic strategy, that is, superhydrophobic nature and microbicidal ability of photodynamic therapy. Electrochemical analysis indicates that the superhydrophobic coating provides pronounced protection against corrosion to underlying Mg with 80% reduction in the corrosion rate in minimum essential medium and retains the original surface features after 168 h exposure to neutral salt spray. The proof-of-concept research holds a great promise for tackling the notorious bacterial infection and poor corrosion resistance of Mg-based biodegradable materials in a simple, efficient, and environmentally benign manner.

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Section: Resultsmentioning

confidence: 94%

Synergistic Coating Strategy Combining Photodynamic Therapy and Fluoride-Free Superhydrophobicity for Eradicating Bacterial Adhesion and Reinforcing Corrosion Protection

Wang

Song

Yang

et al. 2020

ACS Appl. Mater. Interfaces

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“…The potential difference between IMCs and Al matrix is a motive force for galvanic corrosion, accelerating the cathodic and anodic reactions by transferring electrons from anode to cathode. 57 The higher the potential difference, the more corrosion can occur. The coarser Mg 2 Si precipitates formed in NCFSW joint without interlayer have more negative corrosion potential.…”

Section: Resultsmentioning

confidence: 99%

Influence of brass interlayer and water cooling on microstructure, mechanical and corrosion behaviour of friction stir welded AA6061-T6 alloy

Nagu

Kumar

2022

Proceedings of the Institution of Mechanical Engineers, Part L:

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This study investigated the effect of brass interlayer and water cooling on the mechanical properties and corrosion behaviour of friction stir welded AA6061 alloy. Although grain refinement was observed in the stir zone (SZ) of FSW without interlayer, strength loss occurred due to thermal softening. The insertion of a brass interlayer resulted in more grain refinement which could be attributed to brass particles acting as a nucleation site for further recrystallization. The weld strength with interlayer improved due to the formation of strengthening intermetallic compounds (IMCs) such as Al2Cu and Al4Cu9. However, the strength recovery is not attainable in a heat-affected zone (HAZ). Moreover, hard and brittle IMCs formed in SZ of weld with interlayer resulted in premature failure. Therefore, water cooling was used to enhance the hardness in HAZ. Very fine grains in SZ with a high fraction of high angle grain boundaries were obtained with water cooling FSW with interlayer, while HAZ softening was also reduced. Moreover, the water-cooling FSW with interlayer inhibited the formation of brittle intermetallics and decreased volume fraction of IMCs attributed to faster cooling rate. Thereby the strength of the overall weld joint was enhanced. The corrosion test was performed in 3.5% NaCl solution. The corrosion findings stated that the decrease in the number of intermetallics formed low galvanic coupling with aluminium matrix resulted in better corrosion resistance and minimum corrosion rate for water-cooled FSW than natural cooling.

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“…It can be attributed to the fact that when the temperature is increased, the pH of the electrolyte shifted towards more an acidic value and the mobility of the anion species, i.e., Cl − ions, increases. The Cl − ions are a strong oxidizing agent and cause pitting or localized corrosion in passive alloys like nickel alloys; they penetrate through the porous oxide film and can be absorbed on surface resulting in higher deterioration of the surface of those alloys [ 16 , 17 , 18 , 19 ]. After absorbing on the surface, these ions can promote the diffusion of metal ions from the surface to the corrosive medium leading to formation of metal hydrides [ 20 ].…”

Section: Resultsmentioning

confidence: 99%

Effect of Post Weld Heat Treatment on the Microstructure and Electrochemical Characteristics of Dissimilar Material Welded by Butter Method

et al. 2020

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In the present study, the effect of post weld heat treatment (PWHT) on the microstructure and corrosion kinetics of butter welded Nickel Alloy 617 and 12Cr steel was investigated. Buttering was carried out on the 12Cr side with the Thyssen 617 filler metal. Furthermore, post weld heat treatment (PWHT) was conducted at 730 °C with a holding time of 4 h followed by furnace cooling. Optical Microscopy (OM) was conducted to study the microstructural evolution in dissimilar material welding as a result of PWHT. Moreover, Scanning Electron Microscopy with energy dispersive spectroscopy (SEM-EDS) was employed to determine the elemental concentrations in all important regions of the butter weld before and after the PWHT. In addition, the effect of PWHT on the corrosion kinetics of the butter weld was also investigated by potentiodynamic polarization measurements in 5 wt.% NaCl + 0.5 wt.% CH3COOH electrolyte at room temperature, 30 °C, 50 °C and 70 °C. The corrosion activation parameters were also determined for both the samples by using Arrhenius plots. The results revealed the higher susceptibility of corrosion of the butter weld after PWHT, which was attributed to the reduced Cr content in the heat affected zone of the 12Cr region due to the sensitization effect of the heat treatment, resulting in higher corrosion rates.

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Microstructural evolution and corrosion behaviour of thermally aged dissimilar metal welds of low-alloy steel and nickel-based alloy

Cited by 24 publications

References 40 publications

Synergistic Coating Strategy Combining Photodynamic Therapy and Fluoride-Free Superhydrophobicity for Eradicating Bacterial Adhesion and Reinforcing Corrosion Protection

Synergistic Coating Strategy Combining Photodynamic Therapy and Fluoride-Free Superhydrophobicity for Eradicating Bacterial Adhesion and Reinforcing Corrosion Protection

Influence of brass interlayer and water cooling on microstructure, mechanical and corrosion behaviour of friction stir welded AA6061-T6 alloy

Effect of Post Weld Heat Treatment on the Microstructure and Electrochemical Characteristics of Dissimilar Material Welded by Butter Method

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