Welding3.7
A Comparison Between the Deformation Behaviour of Dissimilar AA2024-T3/AA7050-T7651 Welds Produced By Stationary Shoulder Friction Stir Welding and Standard Friction Stir Welding
FSW and SSFSW have a high potential to fulfill the demand of the aircraft industry regarding to build environmentally friendly aircrafts with a simple production. The processes join Aluminums with no filler metal and can be seen as one work step compared to riveting.
The present study is about the comparison between FSW and SSFSW made on basis of mechanical and metallographic results of produced welds and of process parameter.
For both processes the used probes had the same geometry and dimension. As consequence of the process for the SSFSW a non-rotating shoulder was used.
The materials welded were the alloys AA2024 and AA7050. For the investigation dissimilar butt joints of sheets with two millimeter thickness were produced. Different process parameters were set in order to create different energy input. Regarding to a formula made by Khandkar et al. the performed welds achieved the same energy input for the same feedrate but with the double rpm at SSFSW.
Metallographic images showed that the stationary shoulder produces a homogenous and narrow weld. The TMAZ which at FSW is spread below the whole shoulder diameter is here reduced significantly. Furthermore first observations had shown that the TMAZ is growing with a lower energy input respectively a higher feedrate.
Tensile tests reached higher values for the SSFSW in yield strength and ultimate strength and were rising with a lower energy input respectively a higher feedrate.
SSFSW is showing new possibilities in joint properties, geometries and work piece material and is promising to achieve at least equal results as FSW.