三角函数恒等变换
Trans.Nonferrous Met.Soc.China29(2019)1824−1835diannao
Effect of tool tilt angle on strength and microstructural characteristics of friction stir welded lap joints of AA2014-T6aluminum alloy
C.RAJENDRAN1,K.SRINIVASAN2,V.BALASUBRAMANIAN2,H.BALAJI3,P.SELV ARAJ3
1.Department of Mechanical Engineering,Sri Krishna College of Engineering and Technology,
Coimbatore Tamil Nadu641008,India;
素蟹粉
2.Center for Materials Joining and Rearch(CEMAJOR),Annamalai University,Tamil Nadu608002,India;
蜂的作者是谁3.Aeronautical Development Agency,Bangalore,Karnataka560017,India
Received16November2018;accepted15July2019
Abstract:Friction stir welding(FSW)has been extensively adopted to fabricate aluminium alloy joints by incorporating various welding parameters that include welding speed,rotational speed,diameters of shoulder and pin and tool tilt angle.FSW parameters significantly affect the weld strength.Tool tilt angle is one of the significant process parameters among the weld parameters.The prent study focud on the effect of tool tilt angle on strength of friction stir lap welding of AA2014-T6aluminium alloy.The tool tilt angle was varied between0°and4°with an equal increment of1°.Other process parameters were kept constant.Macrostructure and microstructure analysis,microhardness measurement,scanning electron micrograph,transmission electron micrograph and energy dispersive spectroscopy analysis were performed to evaluate the lap shear strength of friction stir lap welded joint.Results proved that,defect-free weld joint was obtained while using a tool tilt angle of1°to3°.However,sound joints were welded using a tool tilt angle of2°,which had the maximum lap s
hear strength of14.42kN and microhardness of HV132.The joints welded using tool tilt angles of1°and3°yielded inferior lap shear strength due to unbalanced material flow in the weld region during FSW.
Key words:AA2014aluminium alloy;friction stir lap welding;tool tilt angle;lap shear strength;microstructure吉他怎么换琴弦
1Introduction
关于生日的句子Copper-containing aluminium alloys such as2xxx and7xxx ries are most preferred while manufacturing aircraft fulage and wing skins[1]for achieving the required strength ratio.Often,the structures are conventionally joined by rivets,bolts,nuts and screws[2]as they are prone to the formation of an oxide layer(Al2O3)which results in welding difficulties such as solidification cracking and porosity while using fusion welding process.To alleviate such weld difficulties, solid-state welding process was developed[3,4].Friction stir welding(FSW)is now successfully applied to welding the alloys for aircraft application of lap joint configuration.The substitution of fastening joints with FSW decread the weight reduction of aircraft structures by providing fuel efficiency[5].Apart from FSW process and tool parameters,the lap shear strength (LSS)of friction stir
lap welded joints is predominantly influenced by certain factors.Such factors include hook height,hook width,stir zone area and effective sheet thickness(combined thickness of both top and bottom sheet).Lap welding between two sheets results in the formation of oxide layer.This oxide layer may enter into the stir zone no matter the chon proper process and tool parameters.ABHIJIT et al[6]studied the impact of tool tilt angle(TA)with two pin geometries on mechanical and metallurgical properties of friction stir welded(FSWed)AA6061-T6aluminium alloy.They obrved that an increa in TA showed a significant increa in thrust and forging forces at the interface (tool‒work piece).Using taper thread tool,the mean grain size decread while TA incread.LONG et al[7] established a thermo-mechanical finite element model to analyze the thermal gradient,material flow and levelness of stress during FSW.They found a wormhole defect in the weld at0°TA and no-defect when the tool axis was titled to2°TA.A CFD model was propod to investigate the effect of TA in a heating and cooling cycle and the following obrvations were made:(i)the maximum temperature was obrved by tilted tool on the
表扬信模板Corresponding author:C.RAJENDRAN;Tel:+91-9865432576;E-mail: DOI:10.1016/S1003-6326(19)65090-9
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