Local electrochemical behaviour of friction stir welded Mg-Al-Mn alloy joints

CORROSION ◽  
10.5006/3604 ◽  
2020 ◽  
Author(s):  
SITI HAWA MOHAMED SALLEH ◽  
Geraint Williams ◽  
Sebastian Thomas ◽  
Zhuoran Zeng ◽  
Beth McNally ◽  
...  
Keyword(s):  
Welded Joint ◽  
Electrochemical Behaviour ◽  
Scanning Electrochemical Microscopy ◽  
Electrochemical Characteristics ◽  
Electrochemical Tests ◽  
Friction Stir ◽  
Base Materials ◽  
Galvanic Interaction ◽  
Electrode Technique ◽  
Electrochemical Microscopy

Local scanning electrochemical microscopy (SECM), along with a scanning vibrating electrode technique (SVET), were employed to spatially map anodic and cathodic regions in a complex assembly including a friction stir lap welded joint between two Mg-Al-Mn alloys, namely AM60 and AM30. The assembly investigated herein was comprised of the two base materials (AM60 and AM30) and a stir zone (SZ). The transitory electrochemical characteristics of the three regions were perceived from different electrochemical tests and have been correlated to their respective microstructures. Potentiometric and voltametric SECM performed on the assembly in 0.01 M NaCl revealed that during the first few minutes of exposure, AM60 and SZ regions act as dominant anodic regions in the assembly whilst after 2 hours of exposure these regions transition to become cathodic relative to the AM30 region. Galvanic interaction between the different weld regions immersed in a significantly more conductive NaCl electrolyte was investigated by SVET. Under such conditions, filiform-like corrosion initiated, and propagated exclusively within the AM30 region, resulting in cathodic activation of the corroded surface. However, after approximately 5 hours of exposure, the AM60 region preferentially dissolves following sufficient cathodic activation of the AM30 region.

An investigation on microstructure and mechanical properties of post-weld heat-treated friction stir welds in aluminum alloy 2024-W

2012 ◽  
Vol 227 (4) ◽  
pp. 649-662 ◽  
Author(s):  
Hakan Aydın ◽  
Ali Bayram ◽  
İsmail Durgun
Keyword(s):  
Room Temperature ◽  
Welded Joint ◽  
Solution Treatment ◽  
Heat Treatments ◽  
Maximum Hardness ◽  
Friction Stir ◽  
Base Materials ◽  
Heat Treated ◽  
Aluminum Alloy 2024 ◽  
Weld Heat

The present work describes the results obtained from microstructural and mechanical evaluation of post-weld heat treated friction stir welds of 2024 aluminum alloys in the W temper state. Post-weld heat treatments have been carried out at 510 °C for 2.5 h followed by ageing at room temperature for 6 months, at 100 °C and 190 °C for 10 h, and by cooling in static air (O-temper). The solution treatment caused abnormal coarsening of the grains in the stir zone, which resulted in a drop in microhardness. The strength of the as-welded joint was significantly incrased by post weld heat treatments. The maximum hardness and strength values were obtained in T6 (190 °C, 10 h) treated joint. However, the T6 (190 °C, 10 h) treated joint had the lowest ductility. On the other hand, the tensile properties of the post-weld heat treated joints were far lower than those of the unwelded base materials in the same temper states. In addition, the post-weld heat treatments did not significantly change the fracture locations of the friction stir welds.

scholarly journals The Corrosion Properties of S355J2 Steel Welded Joint in Chlorides Environment

2018 ◽  
Vol 47 (4) ◽  
pp. 342-347
Author(s):  
Kamil Borko ◽  
Branislav Hadzima ◽  
Filip Pastorek
Keyword(s):  
Corrosion Resistance ◽  
Weld Metal ◽  
Welded Joint ◽  
Electrochemical Impedance ◽  
Base Material ◽  
Electrochemical Characteristics ◽  
Corrosion Properties ◽  
Electrochemical Tests ◽  
Different Types ◽  
Submerged Arc

Nowadays are steels the most used structural material for creation of constructions in different types of industry for lot of applications but suffer from unsatisfactory corrosion resistance in the presence of aggressive chlorides. Steel S355J2 represents common type steel for constructions. Very important property of S355J2 steel is weldability. S355J2 steel was welded by submerged arc welding (SAW) method. Corrosion resistance of welded joint was evaluated by electrochemical methods - linear polarization (LP) and electrochemical impedance spectroscopy (EIS). Results from electrochemical tests are general electrochemical characteristics - ECorr, iCorr, vCorr and RP. Environments for testing were solutions with different concentration of chlorides (0.01M, 0.1M and 1M NaCl solution). Difference of corrosion resistance between base material and weld metal is app. 14.5 %. This difference is preserved in all concentrations of tested environments. The highest corrosion resistance was reached by base material in 0.01M NaCl and the lowest corrosion resistance was reached by weld metal in 1M NaCl.

An appraisal of characteristic mechanical properties and microstructure of friction stir welding for Aluminium 6061 alloy – Silicon Carbide (SiCp) metal matrix composite

2019 ◽  
Vol 13 (4) ◽  
pp. 5804-5817
Author(s):  
Ibrahim Sabry
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Metal Matrix Composite ◽  
Matrix Composite ◽  
Metal Matrix ◽  
Welded Joint ◽  
Rotation Speed ◽  
Fusion Welding ◽  
Friction Stir ◽  
Al 6061

It is expected that the demand for Metal Matrix Composite (MMCs) will increase in these applications in the aerospace and automotive industries sectors, strengthened AMC has different advantages over monolithic aluminium alloy as it has characteristics between matrix metal and reinforcement particles.  However, adequate joining technique, which is important for structural materials, has not been established for (MMCs) yet. Conventional fusion welding is difficult because of the irregular redistribution or reinforcement particles.  Also, the reaction between reinforcement particles and aluminium matrix as weld defects such as porosity in the fusion zone make fusion welding more difficult. The aim of this work was to show friction stir welding (FSW) feasibility for entering Al 6061/5 to Al 6061/18 wt. % SiCp composites has been produced by using stir casting technique. SiCp is added as reinforcement in to Aluminium alloy (Al 6061) for preparing metal matrix composite. This method is less expensive and very effective. Different rotational speeds,1000 and 1800 rpm and traverse speed 10 mm \ min was examined. Specimen composite plates having thick 10 mm were FS welded successfully. A high-speed steel (HSS) cylindrical instrument with conical pin form was used for FSW. The outcome revealed that the ultimate tensile strength of the welded joint (Al 6061/18 wt. %) was 195 MPa at rotation speed 1800 rpm, the outcome revealed that the ultimate tensile strength of the welded joint (Al 6061/18 wt.%) was 165 MPa at rotation speed 1000 rpm, that was very near to the composite matrix as-cast strength. The research of microstructure showed the reason for increased joint strength and microhardness. The microstructural study showed the reason (4 %) for higher joint strength and microhardness.  due to Significant   of SiCp close to the boundary of the dynamically recrystallized and thermo mechanically affected zone (TMAZ) was observed through rotation speed 1800 rpm. The friction stir welded ultimate tensile strength Decreases as the volume fraction increases of SiCp (18 wt.%).

scholarly journals Use of Amperometric and Potentiometric Probes in Scanning Electrochemical Microscopy for the Spatially-Resolved Monitoring of Severe Localized Corrosion Sites on Aluminum Alloy 2098-T351

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1132 ◽  
Author(s):  
Rejane M. P. da Silva ◽  
Javier Izquierdo ◽  
Mariana X. Milagre ◽  
Abenchara M. Betancor-Abreu ◽  
Isolda Costa ◽  
...  
Keyword(s):  
Scanning Electrochemical Microscopy ◽  
Oxygen Depletion ◽  
Localized Corrosion ◽  
Alloy Surface ◽  
Al Alloy ◽  
Spatially Resolved ◽  
Lower Oxygen ◽  
Local Ph ◽  
Electrochemical Microscopy

Amperometric and potentiometric probes were employed for the detection and characterization of reactive sites on the 2098-T351 Al-alloy (AA2098-T351) using scanning electrochemical microscopy (SECM). Firstly, the probe of concept was performed on a model Mg-Al galvanic pair system using SECM in the amperometric and potentiometric operation modes, in order to address the responsiveness of the probes for the characterization of this galvanic pair system. Next, these sensing probes were employed to characterize the 2098-T351 alloy surface immersed in a saline aqueous solution at ambient temperature. The distribution of reactive sites and the local pH changes associated with severe localized corrosion (SLC) on the alloy surface were imaged and subsequently studied. Higher hydrogen evolution, lower oxygen depletion and acidification occurred at the SLC sites developed on the 2098-T351 Al-alloy.

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