Corrosion behaviour of friction stir welded lap joints of 6061-t6 aluminum alloy (original) (raw)
Related papers
2013
Friction-stir welding (FSW), a solid-state innovative joining technique, is being widely used for joining aluminium alloys for the aerospace, marine, automotive industries and many other applications of commercial importance. FSW trials were carried out using a vertical machining centre (VMC) on an AA6061 alloy. The main objective of the present work was to evaluate the weld-processing parameters of FSW for the AA6061-T6 alloy and to determine the properties of the obtained joints with respect to the welding speed. The experiments were conducted by varying the welding speed between 55–70 mm/min and the rotating speed was fixed at 1700 r/min. The tensile properties, microstructure, microhardness, fractography and corrosion resistance of the FSW joints were investigated in this study. The result showed that there was a variation in the grain size in each weld zone depending upon the material and the process parameters of FSW in a joint. The coarsest grain size was observed in the heat...
Corrosion behavior of Al6061 alloy weldment produced by friction stir welding process
Journal of Materials Research and Technology, 2015
Intermetallic particles a b s t r a c t In this work, the corrosion behavior of welded lap joints of AA6061-T6 aluminum alloy produced by friction stir welding process has been investigated. Corrosion properties of welded lap joints were studied by cyclic polarization and electrochemical impedance spectroscopy tests. All tests were performed in an aerated 0.6 mol L −1 NaCl aqueous solution with pH = 6.5 at a temperature of 30 • C to characterize corrosion morphology and realize corrosion features of weld regions as opposed to the parent alloy. The microstructure of weld nugget (WN), heated affected zone (HAZ), and parent alloy were analyzed using scanning electron microscopy and energy dispersive spectroscopy. The experimental results indicated that the welding process has a major effect on the corrosion resistance, which possibly associated to the break-down and dissolution of intermetallic particles. It is supposed that an increasing in intermetallic distributed throughout the matrix of weld regions increases the galvanic corrosion couples. Furthermore, by decreasing the grain size in the weld regions, the susceptibility to corrosion is enhanced. The pitting corrosion and intergranular attack are the dominant corrosion types in the weld regions and the parent alloy.
Corrosion behavior of friction stir welded lap joints of AA6061-T6 aluminum alloy
Materials Research, 2014
In this work, the corrosion behaviors of friction-stir lap welding of 6061-T6 Al-alloy are studied. The friction-stir lap welding was performed under different welding conditions (rotation speed and welding speed). The corrosion behavior of the parent alloy, the weld nugget zone (WNZ), and the heat affected zone (HAZ) of each welded sample working as an electrode, were investigated by the Tafel polarization test in 3.5 wt. (%) NaCl at ambient temperature. The morphology of the corroded surface of each region was analyzed by scanning electron microscopy together with energy dispersive spectroscopy (SEM-EDS). The results showed that the corrosion resistance of the parent alloy was better than the WNZ and the HAZ in both welding conditions. Localized pit dissolution and intergranular corrosion were the dominant corrosion types observed in the parent alloy, WNZ, and HAZ. The parent alloy, WNZ, and HAZ exhibited similar corrosion potentials (E corr ) after T6 heat treatment. This treatment had a better effect on the corrosion resistance of the welded regions than the parent alloy.
international journal of advanced design and manufacturing technology, 2013
Abstract: Friction stir welding, a solid state innovative joining technique, is widely being used for joining aluminium alloys for aerospace, marine automotive and many other applications of commercial importance. FSW trials were carried out using a vertical machining centre (VMC) on AA6061 alloy. The main objective of the present work was to evaluate the weld processing parameter of friction stir weld (FSW) process for AA6061-T6 alloy and to determine the properties of the obtained joints with respect of welding speed. Experiments have been conducted by varying the welding speed of 55-70 mm/min and the rotating speed was fixed at 1700rpm. Tensile properties, microstructure, microhardness, fractography, and corrosion resistance of FSW joints were investigated in this study. The result showed that there was a variation of grain size in each weld zone which depends upon the material and process parameters of FSW in the joint itself. The coarsest grain size was observed in heat affec...
STUDIES ON FRICTION STIR WELDING OF ALUMINIUM ALLOYS 6061-TO-6061 SIMILAR METALS
The joining of similar 6061 –to-6061 aluminium plates of 4mm thickness was carried out by friction stir welding (FSW) technique. FSW process, a so-called welding-head pin rotating at speeds usually in excess of a few hundred rpm, travels down the length of contacting metal plates, creating a highly plastically deformed zone through the associated force and frictional heating. FSW of Aluminium to Aluminium has captured important attention from manufacturing industries, such as Shipbuilding, Automotive, Railway and Aircraft production. Variable Process Parameters have been employed to analyse the influence of Microstructural and Tensile Properties. Effect of welding speed on microstructures, hardness distribution and tensile properties of the welded joints were investigated. By varying the process parameters, defect free and high efficiency welded joints were produced.
Microstructural and corrosion behaviours of dissimilar friction stir welded aluminium alloys
Manufacturing review, 2024
In this study, the friction stir welding (FSW) process was employed to investigate the effect of tool geometry on the corrosion behaviour and microstructure of friction stir welded AA7075-7651 and AA1200-H19 using Central Composite Design. The workpieces were machined and welded, and the interfaces were milled. A 2-level full factorial experimental design was deployed using Response Surface Methodology (RSM). A rotational speed of 1500 rpm, welding speed of 30, 60, and 90 mm/min, and a 2°tilt angle of the tool with a plunge force of 7 kN were utilized. The results show that regardless of the tool geometry, multi-response optimum weldment can be achieved at 60 mm/min welding speed and a tilt angle. The microstructure of the optimal weldments presents an 'onion ring' pattern, indicating proper mixing of the alloys during FSW. Analysis of the corrosion behaviour revealed a decrease in the polarization resistance when the transverse speed increased from 30 to 90 mm/min, as polarization resistance has a direct relationship with corrosion rate. It can be concluded that FSW ensures excellent weldment, as evident in the microstructural evolution of the resulting weldments, and that tool geometry plays a significant role in the corrosion inhibition efficiency of the alloys.
Procedia Engineering, 2017
The present study was carried out to evaluate how the process parameters affect the mechanical properties and the corrosion behavior of joints obtained by friction stir welding (FSW). The experimental study was performed by means of a CNC machine tool for the friction stir welding of two aluminum alloys, namely AA7075 and AA2024, taking also into account the combination between the two materials. The joints were executed varying the process parameters, namely rotational speed and feed rate. Tensile tests and hardness tests were carried out to evaluate the mechanical properties of the joints. The corrosion behavior of welded specimens was analyzed by means of local free corrosion potential measurements to determine anodic and cathodic areas of welds. The results evidenced that the low hardness areas have the free corrosion potential more anodic than the nearest zones. The differences of potential between the different areas of the welding have the consequence of galvanic corrosion of the less noble area. The location and the extension of the anodic areas depend both on the alloy and on the welding parameters. The preferentially corrosion of these areas were confirmed by means of long time immersion tests. The attacks morphology depends on the alloy: in AA2024 a severe crevice and pitting attack takes place, whereas the AA7075 shows exfoliation corrosion along the rolling bands. Coupling the two different alloys, a severe galvanic attack takes place on the AA7075, in the correspondence of the lower hardness areas. The decreasing of hardness and the different electrochemical behavior in the correspondence of the welding were due to the microstructural alteration of the alloys during the FSW. The correlation between process parameters and joints properties allowed to identify the most suitable welding conditions.
Materials & Design, 2012
Wrought aluminum sheets with thickness of 13 mm were square butt-welded by friction stir welding (FSW) and gas tungsten arc welding (GTAW) methods. Corrosion behavior of the welding zone was probed by Tafel polarization curve. Optical metallography (OM) and scanning electron microscopy together with energy dispersive spectroscopy (SEM-EDS) were used to determine morphology and semi-quantitative analysis of the welded zone. FSW resulted in equiaxed grains of about 1–2 μm, while GTAW caused dendritic structure of the welded region. Resistance to corrosion was greater for the FSW grains than the GTAW structure. In both cases, susceptibility to corrosion attack was greater in the welded region than the base metal section. T6 heat treatment resulted in shifting of the corrosion potential towards bigger positive values. This effect was stronger in the welded regions than the base metal section.► FSW demonstrated higher corrosion resistance than GTAW of 6061 Al alloy. ► FSW and GTAW both demonstrated poorer corrosion behavior than the base metal. ► FSW produced ∼1–2 μm equiaxed grains in joint region and ∼150 μm in base metal. ► GTAW resulted in semi-cast dendritic structure. ► T6 heat treatment improved corrosion resistance of both FSW and GTAW joints.
Study of Corrosion Behavior of Friction Stir Welded Aluminum Alloy (2024-T3)
uotechnology.edu.iq
Friction stir welding (FSW) is a promising solid state joining process and is widely being considered for Al-alloys especially for joining aerospace and aircraft aluminum alloys. In this work, the microstructure and corrosion behavior of the FSW 2024-T3 Al-alloy are studied. The friction stir welding was carried out by using CNC milling machine at different tool rotational speeds and welding speeds. The microstructure of weld or stir nugget (SN), thermo-mechanically affected zone (TMAZ), heated affected zone (HAZ) and base metal were observed by optical microscopy. The corrosion tests of base alloy and welded joints were carried out in 3.5%NaCl solution at a temperature of 30°C. Corrosion current and potential were determined using potentiostatic polarization measurements. It was found that the corrosion rates of welded joints were higher than that of base alloy.