Interface structural analysis of similar and dissimilar magnetic - PowerPoint PPT Presentation

Interface structural analysis of similar and dissimilar magnetic pulse welded joints R. Raoelison, M. Rachik, N. Buiron R. Raoelison, M. Rachik, N. Buiron R. Raoelison, M. Rachik, N. Buiron R. Raoelison, M. Rachik, N. Buiron Laboratoire Roberval, Université de Technologie de Compiègne UTC, France Project MSIM (2010-2012): Funded by Région Picardie Workshop Impulse forming & joining Workshop Impulse forming & joining Workshop Impulse forming & joining Workshop Impulse forming & joining IBS Belgium, 7 IBS Belgium, 7 IBS Belgium, 7- IBS Belgium, 7 - - -8 may 2013 8 may 2013 8 may 2013 8 may 2013

MOTIVATION MOTIVATION MOTIVATION MOTIVATION -1 - - - 1- 1 1 - - - Current challenge : Current challenge Current challenge Current challenge Development of multi-material assembly for lightweight structures → MPW : joining solution Optimization of the MPW → improvement of durability and reliability of dissimilar-material assemblies Project MSIM : Project MSIM Project MSIM Project MSIM Driving the MPW toward its optimal ability for an efficient welding of dissimilar-material assemblies • Analysis of the interaction process parameters/joint quality • Analysis of the effect of metal dissymetry on the joint quality • Modeling and computational simulation of the MPW • Modeling and computational simulation of the MPW • Feasibility study and development of tooling present results : weld quality depending on the present results : weld quality depending on the present results : weld quality depending on the present results : weld quality depending on the process parameters process parameters process parameters process parameters Experimental approach : Experimental approach : Experimental approach : Experimental approach : • characterization and classification of the different joints encountered • relation between weld quality and process parameters • weldability study of Al/Al and Al/Cu assemblies Interface structural analysis of similar and dissimilar magnetic pulse welded joints

- -2 - - 2 2 2- - - - Material and method Material and method Material and method Material and method Comparison between two cases of assembly : Comparison between two cases of assembly Comparison between two cases of assembly Comparison between two cases of assembly Similar materials : Al6060T6/Al6060T6 Welding test investigated with identical parameter sets Dissimilar materials : Al6060T6/Cu Material chemical composition (% weight) Mg Si Fe Mn Cr Zn Ti Cu Al Al6060T6 0,8-1,2 0,4-0,8 0,7 0,15 0,04-0,35 0,25 0,15 0,15-0,4 Balance Cu - - - - - - - 99,9 - Material properties σ él (Ωm) -1 σ (Ωm) -1 Tf( ° C) Tf( ° C) ρ(kg/m 3 ) ρ(kg/m 3 ) E(GPa) E(GPa) G(GPa) G(GPa) Rm(MPa) Rp Rm(MPa) Rp 0,2 (MPa) (MPa) Ar(%) Ar(%) Hv Hv Al6060T6 2,5.10 7 650 2,7.10 3 70 26,6 290 240 10 80 Cu 5,8.10 7 1065 8,9.10 3 124 46,6 250 200 14 80 Geometrical characteristic of the samples Target : Flyer : d D d 1 d 2 d 1 l 1 l 2 L D=25mm l 1 = 21mm d=22mm d 2 L= 50mm l 2 = 23mm

Characterization of the joint Characterization of the joint Characterization of the joint Characterization of the joint -3 - - - 3 3 3- - - - weld weld weld weld Stress Stress Stress Stress Peel test → deviation of the failure Weld Weld Weld Weld Stress Stress Stress Stress → failure at the interface Torsion-shear test weld → dimensional characterization dimensional characterization dimensional characterization dimensional characterization Push-out test Compression Inner tube 16mm Weld Flyer Microstructure examination → mechanical characterization mechanical characterization mechanical characterization mechanical characterization → structural characterization structural characterization structural characterization structural characterization Interface structural analysis of similar and dissimilar magnetic pulse welded joints

Joint characteristics Joint characteristics Joint characteristics Joint characteristics -4 - - - 4- 4 4 - - - Dimensional characterization Dimensional characterization Dimensional characterization Dimensional characterization Unwelded interface Beginning of bonding Beginning of good welding (trace of residue) (thin weld) Large weld Striation : circular path due to interfacial deformation → ductile and potentially permanent weld Structural characterization Structural characterization Structural characterization Structural characterization Structural characterization Structural characterization Structural characterization Structural characterization Beginning of bonding Potentially permanent weld Beginning of good welding EBSD analysis Emergence of slip band SubGB Interface Interface structural analysis of similar and dissimilar magnetic pulse welded joints

Multiscale characterization of the Al/Al joint Multiscale characterization of the Al/Al joint Multiscale characterization of the Al/Al joint Multiscale characterization of the Al/Al joint - -5 - - 5- 5 5 - - - EBSD analysis EBSD analysis EBSD analysis EBSD analysis TEM analysis TEM analysis TEM analysis TEM analysis Interface features Interface features Interface features Interface features Slip band Sub grain → grain deformation (strong) Interface TEM analysis TEM analysis TEM analysis TEM analysis TEM analysis of the interface : ● high density of dislocation ● grain size (< 500nm) → modification of the mecanichal properties Nanoidentation → gradient of hardness (Hv interface ≈1.5*Hv base metal) Interface structural analysis of similar and dissimilar magnetic pulse welded joints

Fractal analysis of the Al/Al joint Fractal analysis of the Al/Al joint - -6 - - 6 6 6- - - - Fractal analysis of the Al/Al joint Fractal analysis of the Al/Al joint Further SEM analysis Further SEM analysis Further SEM analysis Further SEM analysis Formation of the dimple : - creation of cavities (heterogeneous material structure ) : decohesion at the phases interface - création of cavities from inclusion : matrice/inclusion decohesion (e.g. due to precipitates) Al6060T6 material : with Al x Al6060T6 material : with Al Al6060T6 material : with Al Al6060T6 material : with Al x - -Mg - - Mg Mg Mg y y - -Si - - Si Si z Si z precipitates precipitates precipitates precipitates x x y y z z - observation of spheroïdal inclusion inside ome dimples - EDX analysis of the inclusion : diffraction of Al and Mg → development of dimple: potentialydue to precipitates Interface structural analysis of similar and dissimilar magnetic pulse welded joints

MET analysis of the Al/Al joint MET analysis of the Al/Al joint MET analysis of the Al/Al joint MET analysis of the Al/Al joint - -7 - - 7- 7 7 - - - Structural analysis of the precipitates Structural analysis of the precipitates Structural analysis of the precipitates Structural analysis of the precipitates Base metal : → matrix of Al → needle shape precipitate Interface : → needle shape p/tes dissapear → spheric p/tes appear → spheric p/tes appear

Analysis of defective Al/Al joint Analysis of defective Al/Al joint Analysis of defective Al/Al joint Analysis of defective Al/Al joint - -8 - - 8 8 8- - - - → creation of macro-cavities (crack initiation sites) Fractal analysis Fractal analysis Fractal analysis Fractal analysis → regular distribution of humps → porous zone within the hump Interface structural analysis of similar and dissimilar magnetic pulse welded joints

SEM examination of the porous pockets and mechanichal effect SEM examination of the porous pockets and mechanichal effect SEM examination of the porous pockets and mechanichal effect SEM examination of the porous pockets and mechanichal effect - - - -9 9 9 9- - - - Effect on the mechanical behaviour Effect on the mechanical behaviour Effect on the mechanical behaviour Effect on the mechanical behaviour F(kN) 20 Large weld Thin weld 15 Weld with voids 10 5 U column (mm) 0 0 0,5 1 1,5 2 2,5 Local analysis of the porous zones → porosity with high density (attributable to cavitation) Local analysis of the porous zones Local analysis of the porous zones Local analysis of the porous zones porosity with high density (attributable to cavitation) porosity with high density (attributable to cavitation) porosity with high density (attributable to cavitation)

Effect of material dissymetry : effect on the weld features Effect of material dissymetry Effect of material dissymetry Effect of material dissymetry effect on the weld features effect on the weld features effect on the weld features -10 - - - 10 10- 10 - - - Al/Al Al/Al Al/Al Al/Al U=6.5kV,g=1.5mm U=6.5kV,g=1.5mm U=6.5kV,g=1.5mm U=6.5kV,g=1.5mm Al/Cu Al/Cu Al/Cu Al/Cu U=6.5kV,g=1.5mm U=6.5kV,g=1.5mm U=6.5kV,g=1.5mm U=6.5kV,g=1.5mm → Formation of intermetallic phase → continuous layer or discontinous pockets Interface structural analysis of similar and dissimilar magnetic pulse welded joints