Abstract
The aim of this paper is to determine the feasibility of submerged friction stir welding of 6061-T6 aluminium alloy on different water heads through macrostructuralanalysis.In this work, aluminium 6061-T6 alloy was friction stir welded under normal and submerged conditions at different rotational speeds of 400 rpm, 800 rpm, 1200 rpm, 1600 rpm. The water head was varied from 10 to 30 mm in the case of thesubmerged friction stir welding process. In both normal and submerged friction stir welding processes, a welding speed of 45 mm/min, a normal load of 30 kN, tool tilt angle of 2˚, depth of tool penetration and tool geometry were kept constant. Torque is measured during the welding process, and power (kW) is calculated after the welding process. The macrostructural analysis was carried out for locating defect formation and identifying the feasible working range of process parameters of the welded aluminium 6061-T6 alloy. The mechanical properties such as ultimate tensile strength and microhardness of submerged friction stir welded of 6061 aluminium alloys were investigated.Scanning Electron Microscope (SEM) metallography was used for comparing the microstructure of the parent material, friction stir welded and submerged stir welded samples.
Highlights
Friction Stir Welding (FSW) was invented by The Welding Institute (TWI), the UK during the 1990s
The results showed that the submerged friction stir welding produced good weld strength and considerable diminution in the void fraction.Zhang et al.[17] exhibited submerged friction stir welded on 2219-T6 aluminum alloy at a fixed welding speed of 100 mm/min and different rotational speeds of 600, 800, 1000, 1200 and 1400 rpm respectively
The maximum tensile strength (MPa) of 207, 218 and 211MPa were found during submerged friction stir welding condition at the rotational speed of 1200 rpm in the water head of 10, 20 and 30 mm.In this work, the maximum tensile strength was found at the rotational speed of 1200 rpm in the water head of 20 mm which was supported by the formation of onion ring pattern strongly.during submerged friction stir welding process, the tensile strength of the welded plate first increased from 400 to 1200 rpm, but it is decreased in 1600 rpm.Zhang et al.[17] have found identical results
Summary
High-density dislocations and refined grain structures were formed in submerged friction stir joint due to the precipitates dissolved in the matrix This leads to the enhancement of the weld properties such as hardness and tensile strength.Basil Darras et al.[14] hasdiscussedthe friction stir processing of AZ31 Magnesium alloy in normal and submerged conditions and their inherence on tensile properties, grain structure, power consumption, and thermal fields. The void defect was identified in the stir zone due to the excess heat generation of the welded plates at the higher rotational speed of 1400 rpm.The minimum hardness value was obtained in the SFSW at a rotation speed of too low and too high conditions. Thewater head (water depth) parameter is important, and it is taken as one of the submerged friction stir welding process parameters in this work.The objective of this work is to study the feasibilityof weld, with submergence of the 6061-T6 aluminiumalloy under varied water heads through macrostructural analysis
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