Mechanical Properties of Friction Stir Welded Mg/Mg- and Mg/Al-Joints (original) (raw)
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Microstructure and Corrosion Behavior of Friction Stir Welded Mg/Al- and Mg/Mg-Joints
2011
Joints made from ultrafine grained aluminium alloy 1050 are investigated in order to examine the corrosion behavior and microstructural changes between base materials and stir zones. Samples in the initial state, after four and eight passes of Incremental ECAP (I-ECAP) process were joined with similar plates using Friction Stir Welding. Initially refined microstructure after I-ECAP transformed to homogenous few micron sized grains structure in stir zones. AlFeSi particles present in the microstructure became fragmented during plastic deformation and welding process. The observed minor differences in corrosion resistance include slightly higher values of corrosion potentials but more complex pits' morphology for I-ECAP processed samples comparing to the stir zones.
Journal of Materials Engineering and Performance, 2017
Microstructure, mechanical properties and corrosion resistance of dissimilar friction stir-welded aluminum and magnesium alloys were investigated by applying three different rotational speeds at two different travel speeds. Sound joints were obtained in all the conditions. The microstructure was examined by an optical and scanning electron microscope, whereas localized chemical information was studied by energy-dispersive spectroscopy. Stir zone microstructure showed mixed bands of Al and Mg with coarse and fine equiaxed grains. Grain size of stir zone reduced compared to base metals, indicated by dynamic recrystallization. More Al patches were observed in the stir zone as rotational speed increased. X-ray diffraction showed the presence of intermetallics in the stir zone. Higher tensile strength and hardness were obtained at a high rotational speed corresponding to low travel speed. Tensile fractured surface indicated brittle nature of joints. Dissimilar friction stir weld joints showed different behaviors in different corrosive environments, and better corrosion resistance was observed at a high rotational speed corresponding to low travel speed (FW3) in a sulfuric and chloride environments. Increasing travel speed did not significantly affect on microstructure, mechanical properties and corrosion resistance as much as the rotational speed.
Friction Stir Welding is used already in routine, as well as critical applications, for the joining of structural components made of aluminium and its alloys. Indeed, it has been convincingly demonstrated that the process results in strong and ductile joints, sometimes in systems which have proved difficult using conventional welding techniques. The aim of this study was to evaluate microstructures, tensile strength and Hardness of welded specimen of Magnesium-Magnesium (Mg/Mg) similar joints and Magnesium-Aluminium (Mg/Al) dissimilar joints.
Evolution of Mechanical Properties and Microstructure of Friction Stir Welding of Aluminum and Magnesium Alloys, 2021
In this work, the quite possibly the main welding process explicitly the class of the solid-state welding process that is friction state welding process was discussed. Based on a base of experimental research results, the typical mechanical properties of butt-welded joints of thermally unhardened magnesium AZ31B and aluminum 7075 alloys are determined. The efficiency of the application of the friction stir welding to make fine microstructures from the given alloys operating under variable loads is substantiated.
Engineering review, 2015
This paper presents the influence of friction stir welding (FSW) on the microstructure, mechanical and corrosion behavior of precipitation hardening Al-Zn-Mg alloy AA7039. The microstructure of weld joints was investigated using an optical microscope. The grains in weld nugget zone (WNZ) and thermo-mechanically affected zone (TMAZ) of weld joints were finer than in the base metal and a reverse trend was observed for heat affected zone (HAZ). Mechanical properties of friction stir weld joints were determined by tensile and micro hardness test. The ultimate tensile strength of weld joints was found approximately equal to the base metal while yield strength and ductility of weld joints were found lower than in the base metal. HAZ of weld joints was more susceptible to corrosion than WNZ, TMAZ and base metal. The HAZ exibits the highest current density followed by the base metal.
Corrosion behaviour of friction stir welded lap joints of 6061-t6 aluminum alloy
2014
Friction stir welding (FSW) process is an emerging ―green‖ solid-state method in which is accepted as a favourable joining method for aluminium alloys and other engineering materials. The joining of metal plates is done at below their melting point temperature and based on a thermo-mechanical action used by a non-consumable welding tool onto metal plates. However, the microstructure of aluminium alloy and chemistry as well as dimension and distribution of the intermetallic particles in the matrix of aluminium alloy may be modified owing to heat generated and severe plastic deformation during the welding process. Accordingly, mechanical and corrosion properties of weldments can be changed after welding as opposed to the parent alloy. In this work, lap-welded joints of 6061-T6 aluminium alloy were produced by FSW, and the influence of process parameters on their welds quality of weldments in terms of welding defects, microstructure, hardness distribution, and tensile properties as wel...
2016
Original Research Paper Received 01 December 2015 Accepted 24 January 2016 Available Online 14 February 2016 Increasing usage of magnesium and aluminum light metals in the transportation industry has made joining of these two metals one of the challenges for researchers and engineers. The aim of this study was to investigate the relationship between mechanical properties of lap friction stir welded Al-Mg plates and characteristics of the interface. Therefore, joining of aluminum and magnesium in various conditions was conducted. Optical and scanning electron microscopy analysis, micro-hardness test and tensile tests were performed on samples. The results showed that in the joints where Mg was on top, an approximately 10 micron thick layer of intermetallic compounds is created, while in the Al-top joints, approximately 1 mm thick intermetallic compounds with solidified microstructure were visible. Mechanical test showed Mg-top joint has higher strength in comparison with Al-top joint...
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.
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.