Landgrebe, Dirk

Linnemann, Maik

Psyk, Verena

Scheffler, Christian

English

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1Process analysis for magnetic pulse welding of aluminium-copper jointsVerena Psyk, Christian Scheffler, Maik Linnemann, Dirk LandgrebeI2FG workshop on impulse metalworking 2016December 1st-2nd, 2016Nantes, FranceAgenda• Introduction to the JOIN’EM project• Process analysis for magnetic pulse welding of aluminium-copper joints• Setup and process parameters• Welding experiments• Characterisation of the joint• Correlation of adjustable process parameters and weld quality• Quantification of collision parameters via numerical simulation• Correlation of collision parameters and weld quality• Summary2**Word clouddesignedusingTagxedoJOIN’EM – facts and figures• Titel JOINing of copper to aluminium by ElectroMagnetic fields• Acronym JOIN’EM• Duration 01.09.2015 - 31.08.2018• Budget 4.7 Mio. €• Grant 4.1 Mio. €• Coordinator Fraunhofer IWU (Dr.-Ing. Verena Psyk)• Project partners 3• Supplementing the heavy use of full copper components in applications related to electrical and thermal conductivity  by hybrid copper – aluminium solutions Reduce material costs  Reduce product weight• Development of a flexible, highly productive, and cost effective joining process for high quality dissimilar material joints  magnetic pulse welding (MPW)• Enabling the industrial implementation of MPW and facilitating the exploitation of known process advantages in series productionJan2000Jul2002Jan2005Jul2007Feb2010Nov201300.51.01.52.02.53.03.54.0AluminiumPrice in €/lb(Source: www.infomine.com)CopperJOIN’EM – overall aimsCopper AluminiumElectricalconductivity58 MS/m 36 MS/mThermal conductivity401 W/mK 236 W/mKDensity 8.9 g/cm³ 2.7 g/cm³Price 4.478 €/ton* 1.550 €/ton*(Source: http://www.boerse-online.de/rohstoffe; 2016-11-04)4• Experimental and numerical process analysis and design• Development of validated process and joint design concepts• Development of multiscale simulation strategies• Development of optimized tools for industrial implementation• Development and automation of non-destructive testing and quality control• Design, realization, and evaluation of industrial demonstrators• Economic process and product evaluation via life cycle cost analysisHigh power electronicspassive coolingSource: CalyosSource: WhirlpoolWhite goodsHVAC Source: RefcoBattery systemsSource: CegasaTransport/automotive componentsSource: AlkeFields of application and suggesteddemonstratorsJOIN’EM – objectives5Setup and process parametersCapacitor charging energy E (10 up to 40 kJ)Flyer thickness  tflyer (0.3 up to 1.5 mm)Initial gap between flyer and target ginitial  (1.0 up to 3.0 mm)x-position of the flyer edge  xflyer (-2 up to +2 mm)Fixed parametersCapacitance   C (300 µF)Target thickness   ttarget (2 mm)x-position of target edge   xtarget (14 mm)Free length   l (16 mm) Width of flyer and target wflyer = wtarget (100 mm)Parameters considered for detailed investigation Experimental setupTool coilLactive= 100mmFlyer(Cu-DHP)CoilconductorSpacerTarget(EN AW-1050)Support6Welding experimentsTool coil(housing)Fixture (adjustablein height)FlyerCu-DHPExemplary welded partEN AW-10500 5 10 15 20 25 30-400-200200400600800Time t in µs 0Current Iin kA Capacitor charging energy10 kJ 15 kJ 20 kJ30 kJ 40 kJ7Characterization of the joint• Electrical resistance measurement• Lap shear test• Metallographic analysisweldPosition of specimens in the hybrid sheetTarget: EN AW-1050Flyer: Cu-DHP100micrograph2Specimen no.3751901108Characterization of the joint• Electrical resistance measurement•Measurement points• Lap shear testMetallographic analysisImposed current: I=4 AMeasurement of voltage drop UResistance of the joining partners is negligible if measurement points are close to the joining zone. Calculated resistance corresponds to resistance of the joint.Resistance  9• Electrical resistance measurement• Lap shear test• Metallographic analysisCharacterization of the jointFailure casesForce in kN01230 10 20 30Base materialaluminiumcopperHybrid Al-Cu partElongation in mmFailure in the joint(occurs for all flyer thicknesses)Cu-DHP EN AW-10500120 10 20 30Base materialaluminiumcopperHybrid Al-Cu part3Elongation in mmFailure in the alumi-nium base material(occurs for flyer thick-nesses ≥ 1 mm)Cu-DHP EN AW-1050Elongation in mm0120 10 20 30Base materialaluminiumcopperHybrid Al-Cu part3Failure in the copperbase material(occurs for flyer thick-nesses of 0.5 mm only)Cu-DHP EN AW-105010All cases: Welding of copper flyers to aluminium targets• Electrical resistance measurement• Lap shear test• Metallographic analysisCharacterization of the jointWidth of the weldStart of the weldEnd of the weldEN AW-1050Cu-DHP11Correlation of adjustable process parameters and weld qualityMaximum transferable force in a lap shear test is considered for mechanical joint characterisation5 15 25 35 450123210Pre-selected value:=30 kJEPre-selected value:=1 mmtFlyerPre-selected value:=3 mmginitialPre-selected value:=-2 mmxflyer0 0.5 1.0 1.5 2.0 0.5 1.5 2.5 3.5 -3 -1 1 3Capacitor chargingenergy in kJEFlyer thicknessin mmtFlyerInitial gap widthbetween flyer and target in mmginitialx-position of the flyer edge in mmxflyer01.53.04.5Weld widthwweldin mmJoint resistanceRin µΩTransferableforceFin kNReference value of a non-welded (clamped) connection12Numerical modellingExperimentCorrespondingmacroscopic simulationsV109: 30kJ, 544kA, 22.2kHz, tflyer=2, gap=3, x=-2Flyer: AW1050A H14/24Target: Cu-DHP R240V109: 30kJ, 544kA, 22.2kHz, tflyer=2, gap=3, x=-212 2015120.5Target(EN AW-1050)Coil conductor(CuCrZr)Flyer (Cu-DHP)Flyer: AW1050A H14/24SupportFlyer (Cu-DHP)Target(EN AW-1050)Coil conductor(CuCrZr)Support13Numerical calculation of collision parameters12 2015120.5Target(EN AW-1050)Coil conductor(CuCrZr)Flyer (Cu-DHP)SupportFlyer (Cu-DHP)Target(EN AW-1050)Coil conductor(CuCrZr)Support0 2 4 6 8 10 12 140100200300400500Distance to flyer edge d in mm TargetFlyervimpactCoordinate dd=0αimpactImpacting velocity vimpactin m/s 0 2 4 6 801020304050Impacting angle αimpactin ° Process parametersCapacitor charging energy: 30 kJInitial gap flyer / target: 3mmFlyer Material: Cu-DHPThickness: 1 mmEdge position: -2 mmTarget Material: EN AW-1050Thickness: 2 mmEdge position: 14 mmDistance to flyer edge d in mm 14Correlation of adjustable process parameters and collision parametersCollision parameters at a distance of 2 mm from the flyer edge are considered because typically this area is welded if welding occurs at all.0204060Impacting angleαimpacttflyer in mm xflyer in mmginitial in mmE in kJ5 25 35 45 0 21 1.50.515 0.5 3.52.51.5 -3 -2 -1 0 1 2 3800200400600800Impacting velocityvimpactPre-selected value: E=20 kJPre-selected value: tflyer =1 mmPre-selected value: ginitial =2 mmPre-selected value: xflyer =0 mmTargetαvimpact2 mm15Correlation of collision parameters and joint quality16200 300 400 50002461.51.00Pre-selected value: vimpact =400 m/sPre-selected value: αimpact=15°0 10 20 30Impacting velocity v impact in m/s Impacting angle in mmαimpact4003210.5TransferableForce Fin kNResistance Rin µΩWeld widthwweldin mmMaximum transferable force in a lap shear test is considered for mechanical joint characterisationSummary• JOIN’EM aims at reducing the heavy use of copper to reduce cost and weight. • Hybrid aluminium copper parts shall replace current full copper solutions.• MPW is a promising technology for manufacturing copper aluminium joints.• An experimental and numerical process analysis considering MPW of aluminium copper joints has shown that high quality joints require by trend• high impacting velocity (i.e. >250 m/s for welding of Cu-DHP and EN AW-1050) and • low impacting angle (i.e. 5°-20° for welding of Cu-DHP and EN AW-1050).• The impacting velocity is higher if  • high capacitor charging energy (and consequently higher force) is applied and• the flyer thickness (and consequently the flyer mass to be accelerated) is low.• The impacting angle is lower if• the initial gap width between flyer and target is small and• the overlap of flyer and tool is relatively long.17AcknowledgementThe JOIN’EM project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 677660.18

Process analysis for magnetic pulse welding of aluminium-copper joints

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Process analysis for magnetic pulse welding of aluminium-copper joints

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