Abstract
Process force and tensile properties in friction stir welding of AA2024 sheets were studied. Results show that the forces present a periodic variation with the same periodicity which is nearly equal to the time of one tool rotation, and thus it only depends on rotation speed. With increasing welding speed the forces increase gradually, while with increasing rotation speed the forces first decrease and then increase. Joints with superior strength-ductility synergy are produced at 900 rev min−1–300 mm min−1 and 1000 rev min−1–350 mm min−1. These joints experience nearly the same peak temperature and axial force. As heat input increases the failure initiates from the interface between nugget zone (NZ) and thermo-mechanically affected zone to heat-affected zone continuing to NZ.
Acknowledgements
This work has been supported by National Natural Science Foundation of China (51175255), Funding of Jiangsu Innovation Program for Graduate Education (KYLX_0230) and the Fundamental Research Funds for the Central Universities.