جوشكاري اصطكاكي-اغتشاشي نقطه اي ﴿FSSW﴾ كامپوزيت Al-Cu توليد شده به روش نورد تجمعي ﴿ARB﴾ و ارزيابي خواص اتصال

چكيده انگليسي :

Friction Stir Spot Welding FSSW of Al Cu Composite Produced by Accumulative Roll Bonding ARB and Joint Properties Evaluation Milad Shiraly m shiraly@ma iut ac ir March 17 2012 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiDr M Shamanian Supervisor shamanian@cc iut ac irDr M R Toroghinejad Supervisor toroghi@cc iut ac irAbstractIn curent study Properties of friction stir spot welding FSSW of Al Cu composite produced byaccumulative roll bonding ARB have been investigated Four aluminum sheets with thickness of 500 mwere used to produce Al Cu composite Also Three copper sheets with the thickness of 100 m were insertedbetween aluminum sheets This produced sandwich then rolled for six cycles Finally Al Cu composite withthe thickness of 1 mm was produced In welding process effect of tool rotational speed plunge depth of tool and it s geometry on the properties of welds were investigated After welding process first the appearance ofworkpieces was examined In very low tool rotational speeds for example 560 rpm because of low heatinput small fragments were chipped away from the workpiece on the other hand with increasing toolrotational speed for example to 1400 rpm Surfaces of sheets were squeezed because heat input increases inthese speeds welding with 710 and 900 rpm resulted in creation of soundness appearance of welds due to themoderated heat input produced by these rotational speeds during friction stir spot welding different regionsof joints such as stir zone transitional zone and base metal were charactrized by using optical microscopyand scanning electron microscopy EDS equiped with chemical microanalyzer EDS Results showed thatwith increasing tool rotational speed plunge depth of tool and using cylindrical pin the volume of stir zoneand it s essential length d were increased The increment of these processing parameters resulted insufficient heat input during friction stir spot welding process Furthermore due to the smaller frontal surfaceof the triangular pin less pressure was applied by the pin face when plunging into the workpiece This factled to creation of smaller stir zone by using triangular pin rather than cylindrical pin Increasing in thevolume of stir zone and it s essential length led to increase the tensile shear force of the fractured jointswelded with friction stir spot welding by applying these processing parameters The material flow duringfriction stir spot welding of Al Cu composite was investigated This issue investigated by plunging the toolinto different plunging depthes before the shoulder contacted the surface of the upper sheet results werecompared joints that were welded by full plunging depth Furthermore existance of sufficient contrastbetween aluminum and copper layers asisted the analysis of material flow and finding movement direction ofmaterials Examination of material flow showed that several regions exist in the stir zone of welds due todifferent applied forces and heat input in this region Weakness in creation of some part of the stir zone thathave lower heat input or and have weaker movement force resulted in decrement of the stir zone s volume orisolation of the base metal in the stir zone This phenomenon occured during friction stir spot welding whenusing triangular pin X ray diffraction patterns showed that intermetallic compounds exist in the stir zone ofwelds These phases were Al2Cu and AlCu3 Existance of these intermetallic compounds resulted inincreasing hardness of the stir zone rather than base metal in the joints Keywords Friction stir spot welding Al Cu composite Accumulative roll bonding Intermetallic compounds

شيرالي، ميلاد

جوشكاري اصطكاكي-اغتشاشي نقطه اي ﴿FSSW﴾ كامپوزيت Al-Cu توليد شده به روش نورد تجمعي ﴿ARB﴾ و ارزيابي خواص اتصال

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