Optimizing the Interaction Between Rotational Speed, Tool Geometry, and Cooling Conditions in Friction Stir Welding of AA6061

Authors

• Karwan B. Mohammed, Mechanical and Manufacturing Engineering Dept., Technical College of Engineering, Sulaimani Polytechnic University, Sulaymaniyah 46001, Kurdistan Regional Government, IraqFollow
• Ayad F. Shahab, Mechanical and Manufacturing Engineering Dept., Technical College of Engineering, Sulaimani Polytechnic University, Sulaymaniyah 46001, Kurdistan Regional Government, IraqFollow

Keywords

Friction stir welding (FSW), AA6061-T6 aluminum alloy, Taguchi method, Optimization, Tensile strength

Document Type

Article

Abstract

Friction stir welding (FSW) is a solid-state joining process. It is widely suitable for welding high-strength aluminum alloys. This study presents a systematic optimization of friction stir welding parameters for AA6061-T6 aluminum alloy by investigating the interaction effects of tool rotational speed, tool pin geometry, and cooling conditions. A Taguchi L27 orthogonal array was employed to examine three rotational speeds (820, 1120, and 1420 rpm), three pin profiles (square, triangular, and tapered), and three cooling conditions (compressed air, water, and crushed ice) while maintain a constant traverse speed of 35 mm/min. Mechanical performance was evaluated through tensile testing and stir-zone micro-Vickers hardness measurements, while fracture surface morphology was characterized using field-emission scanning electron microscopy (FESEM) to identify fracture mechanisms. In the results, signal-to-noise ratio analysis and ANOVA revealed that tool rotational speed was the most influential parameter, contributing 80.73% to the variation in tensile strength and 65.95% to stir-zone hardness. While tool pin geometry showed a significant secondary influence on tensile strength, cooling conditions influenced hardness evolution. The optimal condition for tensile strength was (1120 rpm, square pin geometry, and crushed ice cooling) yielded a maximum strength of 264.7 MPa, corresponding to approximately 85% of the base material strength. The highest stir-zone hardness of 91.2 HV, was achieved at 1120 rpm using a square pin geometry with water cooling. FESEM fractography confirmed ductile fracture behavior, characterized by fine and uniformly distributed dimples in high-strength joints and coarse dimples with tearing features in low-strength joints. Confirmation experiments validated the Taguchi predictions, with errors of approximately 2.58% for tensile strength and 1.43% for hardness.

Recommended Citation

Mohammed, Karwan B. and Shahab, Ayad F. (2026) "Optimizing the Interaction Between Rotational Speed, Tool Geometry, and Cooling Conditions in Friction Stir Welding of AA6061," Engineering and Technology Journal: Vol. 44: Iss. 7, Article 4.
DOI: https://doi.org/10.30684/2412-0758.1559

DOI

10.30684/2412-0758.1559

First Page

78

Last Page

110