The influence of heat index (ω/v) on friction stir welded properties of high strength 7075-T6 aluminum alloy

In present work different friction stir welding condition were used to investigate the effect of heat input rate (ω/v) on microstructure and mechanical properties of 6 mm thick plates of 7075-T6 aluminum alloy at low welding speeds of 32 and 60 mm/min. The results obtained showed that the ω/v was not valid forpredicting the mechanical properties of the welded joints under the investigated welding condition. It was observed that the recrystallized grain size of the employed alloys was more sensitive to recrystallization temperature rather than the strain rate, since the grains became larger with increasingthe rotary speed. Besides, the increase in the tool traverse speed results in reduced thermal exposure; thereby increasing the hardness and strength of the welds. For the higher tool traverse speed of 60 mm/min, joint efficiency of the joints welded was higher than lower traverse speed of 32 mm/min. Finally, the different hardness profiles obtained suggest that the heat input during the friction stir welding cannot be rationalized by the parameter of ω/v, where traverse speed was an influential parameter in the welding process

Keywords:

Friction Stir Welding , heat rate , mechanical properties , microstructure , aluminum alloy