Influence of FSW Tool Pin Profile and Mechanical Properties of Friction Stir Welded of Dissimilar Aluminium Alloy

Abstract

Friction stir welding (FSW), a solid-state joining technique, is being extensively used in similar as well as similar joining of Al, Cu, Ti, and their alloys. In the present study, friction stir welding of two aluminium alloys— AA 6082 and AA5052 were carried out at various combinations of tool rotation speeds and various shapes of tool profile pin and axial force. In this experimental proper selection of input friction welding parameters necessary in order to control weld distortion and subsequently increase the productivity of the process. In order to obtain a good quality weld and control weld distortion, it is therefore, necessary to control the input welding parameters. During the FSW process, the materials were transported from the advancing side to retreating side behind the pin where the weld were formed. Based on the above results FSW process with cylindrical pin profile execute highest tensile and medium hardness strength value fifth sample 57.7 N/mm2, 59 HRB and depth of penetration value obtained fourth sample good compared than others. Medium speed and higher axial force were very important parameter for the FSW process of bimetallic aluminum alloy with cylindrical tool profile pin.

Introduction

Friction Stir Welding (FSW) is an energy-efficient solid-state joining technique widely used for high-strength and hard-to-weld metals like aerospace aluminum alloys. FSW employs a non-consumable rotating tool with a pin and shoulder that generates frictional heat, plasticizing material at the joint to form a high-quality weld. Tool design, dimensions, and process parameters significantly influence the mechanical properties, microstructure, and material flow of welded joints.

Key Research Findings:

• Studies on dissimilar aluminum alloys (AA5052, AA5086, AA5754, AA6082, AA7075) show that tool pin profiles, rotation speeds, and feed rates affect hardness, tensile strength, and ductility.

• Optimized welding parameters using Taguchi and statistical approaches yield superior mechanical properties.

• Proper selection of tool pin profiles (square, cylindrical, taper) and process parameters increases tensile strength and hardness due to fine grain formation and reduced weak zones in the stir zone.

• FSW can join aluminum alloys to steel, forming intermetallic compounds like Al–Fe, while avoiding cracks and porosity.

Experimental Setup in Current Study:

• Bimetallic joints of AA6082 and AA5052 sheets were welded using H-13 steel tools with three pin profiles (square, taper cylindrical, cylindrical).

• Parameters varied: tool rotational speed (800–1000 RPM), axial force (8–10 kN), tool profile shape, shoulder diameter (22 mm), pin length (5.6 mm), and 1° tool inclination.

• Taguchi L9 orthogonal array was used to analyze and optimize welding parameters.

Results:

• Hardness and tensile strength were measured and analyzed using Taguchi methodology and ANOVA.

• Optimal conditions were identified for both hardness and tensile strength.

• Angle distortion of welded plates was minimal (0–1°), indicating precise weld alignment.

• Weld bead geometry (width and depth) was analyzed with ImageJ software, showing variation across samples but optimal penetration achieved in some cases.

• Weld appearance and mechanical behavior were thoroughly assessed.

Conclusion

Welds were obtained according to the experimental design with using without filler materials. All welds were found without major defect. The intermixing of metals was also found in the welded samples. During the FSW process, the materials were transported from the advancing side to retreating side behind the pin where the weld were formed. Based on the above results FSW process with cylindrical pin profile execute highest tensile and medium hardness strength value fifth sample 57.7 N/mm2, 59 HRB and depth of penetration value obtained fifth sample good compared than others. Medium speed and higher axial force were very important parameter for the FSW process of bimetallic aluminium alloy with cylindrical tool profile pin.

References

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Copyright

Copyright © 2025 Mr. S. Rajkumar, Mr. E. Deepak, Mr. S. Sunil Kumar, Mr. S. S. Nanthakumar, Mr. R. Palanisamy. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.