Effect of Friction Stir Processing Parameters on Microstructure and Mechanical Properties of Aluminum Alloy AA6061-T6: Experimental and Statistical Study

Abstract

The current study investigates the effects of friction stir processing (FSP) parameters on the mechanical and microstructural characteristics of the alloy AA6061-T6. The FSP's big-area stir zone is where the fine-equiaxed grains are created, and it was found that the size of the grain of every pass is homogenous there. The design of experiment (DOE) method has been used to identify the key variables affecting the final tensile strength. FSP was accomplished using threaded cylindrical pin profiles with three varying rotational speeds (930, 1100, and 1460 rpm) and various transverse speeds (23, 50, and 79), and the tilt angle of the tool was also set at 2°. The optimum FSP parameters were two passes at 1460 rpm and 79 mm/min with these values. It was found that the stir zone's center has a greater microhardness value of 235 kg/mm2 at three passes and that this value decreased toward the thermomechanically affected zone (TMAZ), HAZ, and base metal (107 kg/mm2). The result showed that the FSPed sample has a higher tensile strength at two passes than at one or three passes. Also, it was obtained from the ANOVA analysis results that travel speed is the most effective factor, giving 51.46% of the contribution feature pursued by No. of Pass (22.56%), followed by rotational speed (19.49%).