Effect of Welding Speed on 6061 Aluminum Alloy Tube Weldments in Preheated Friction Stir Welding

6061 aluminum alloy is widely used in industry; the welds of this alloy require high quality and good strength. This work studies the effect of tool travel speed on the quality of preheated friction stir welds. Experiments were conducted on aluminum alloy 6061 tubes (outer diameter 80 mm, thickness 5mm) through 9 different welding speeds (from 25mm/min to 12mm/min, in an arithmetic progression of 12.5mm/min) while keeping the rotation speed of the welding tool at 1500 rpm, preheat temperature 100° C and tool diameter 15 mm. It points out that the weld quality is best when the welding speed is between 75mm/min and 100mm/min. The study results show that choosing the appropriate welding speed is very important for preheated friction stir welds to reduce residual stress, improve the weld's mechanical properties, ensure durability, and minimize weld defects.