Some effects of tool geometric features on friction stir weld response parameters

ABSTRACT

Pin geometries (shape, dimensions, and surface features) have significant effects on friction stir welding, dictating, to some extent, the material flow which in turn affects process variables and joint quality. In this paper, volumetric defect content and process response variables (in-plane forces, torque, power, and temperature) as a function of pin thread forms and features (thread/flat/flute) on mildly tapered conical pins were examined in AA6061-T6 for a range of welding parameters. The coarser thread pitch with different pin features performed better for producing good quality welds compared to finer threaded pins. Forge force requirements can be minimised using counter-flow flutes in threaded pin. Variations of nugget geometry, torque, power, and temperature were reported to correlate their dependence on pin features.

KEYWORDS:

• Friction stir welding
• pin features
• normal thread
• coarse thread
• flats
• co-flow flutes
• counter-flow flutes
• process response variables

Acknowledgements

The authors thank Dr. Wei Tang and Mr. Daniel Wilhelm, Department of Mechanical Engineering, University of South Carolina, Columbia, SC, USA for their help in performing the welds.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors acknowledge the financial support of the Center for Friction Stir Processing which is a National Science Foundation I/UCRC (NSF I/UCRC) supported by grant no. 0934319 (https://www.nsf.gov/awardsearch/showAward?AWD_id=0934319&HistoricalAwards=false).