Influence of Welding Parameters on Weld Quality and Spindle Load During Friction Stir Welding

Friction stir welding brings advantage in utilisation of green joining technology even to companies dealing only with machining.In contrary to machining, FSW uses tools with not sharp geometry therefore welding parameters and tool geometry play main role in application of this process to standard machines.Different welding speed was applied during experiment to see the influence on spindle load.Results confirmed almost linear dependence between welding speed and spindle load.Highest spindle load of 2.55 kW was observed while welding 5mm thick AW7075 aluminium alloy at 800 mm/min welding speed.Experiment showed a good performance of the tool while producing good quality weld joints in welding speeds lower than 600 mm/min.Macroscopic and microscopic analysis did not show any abnormalities, however welding speeds exceeding 600 mm/min exhibited discontinuities in root section that may indicate the formation of tunnel defect.Microscopic analysis showed significant deformation of original grains in thermomechanically affected zone and very fine grain structure in stir zone.