Welding speed effect on joint properties in air and immersed friction stir welding of AA2014

Abstract

In immersed friction stir welding, the workpiece is fully immersed in the water during welding. This work illustrates the effect of welding speed on mechanical properties and microstructure. Friction stir welding joints were produced using AA2014-T6 at different welding speeds ranging from 80 to 125 mm/min with constant rotational speed of 1000 r/min in air and immersed water conditions. Results revealed that with an increase in welding speed, the tensile strength of joint increased, this is due to a reduction in heat input while using both air and immersed friction stir welding, which in turn reduces the dissolution of strengthening precipitates. Microstructure result showed that grain size decreased with an increase in welding speed due to less heat input at increased welding speed. The dissolution of strengthening precipitates weakened with an increase in welding speed in both air and immersed friction stir welding, leading to an increase in hardness value at the nugget zone. Maximum tensile strength was obtained at a welding speed of 100 mm/min in immersed friction stir welding and was around 17% higher compared with a maximum tensile strength obtained using air friction stir welding.