K. S. Arora, M. Schaper, Technical University of Dresden, Dresden, Germany; S. Pandey, Indian Institute of Technology Delhi, New Delhi, India; R. Kumar, National Metallurgical Laboratory, Jamshedpur, India
The increased use of aluminum is fuelled by the need for materials with high specific modulus of elasticity. Aluminum alloys with their characteristic light weight and high strength to weight ratio are being used in both structural and non structural applications in aerospace industries with excellent success. This investigation attempts to understand the effect of tool rotational speed and welding speed on process forces, microstructural transformations and mechanical characteristics of the welded joint. Process forces were measured using a designed and fabricated dynamometer. The process forces showed a direct relationship with the welding speed and inverse relationship with the rotational speed. Maximum joint efficiency and percentage elongation was observed for weld made with a rotational speed of 325 rpm and welding speed of 2.0 mm/s. Fracture surfaces showed dimple-like characteristics. The effect of heat input was also correlated with the weld responses.
The material of this study was 5.0 mm thick high strength aluminium alloy, AA2219 in temper condition T87 (solution heat-treated, cold worked and artificially aged). The welding parameters are given in Table-1.
Table-1: Weld Parameters
Weld Designation
| Rotational speed (RPM)
| Welding speed (mm/min)
|
A
| 250
| 120
|
B
| 325
| 60
|
C
| 325
| 120
|
D
| 325
| 180
|
E
| 400
| 120
|
Summary: Effect of welding speed and rotational speed was investigated during friction stir welding of aluminium alloy 2219-T87. Pin and shoulder diameter were kept constant. Results show the effects on process forces, microstructural transformations and mechanical characteristics of the welded joint.
