Background
Friction stir welding (FSW) is an exotic solid-state joining process (meaning the metal is not melted during the process) and is used for applications where the original metal characteristics must remain unchanged as far as possible. To improve the quality of FSW welding, it is essential to understand and control the microstructure of the welds, in particular the evolution of the texture and residual stress across the welds.
Rigaku's SmartLab® diffractometer is capable of mapping stress and texture in samples of as large as 6-inch with sub-millimeter resolution.
Investigation
In the figure below, the residual stress distribution in an aluminum FSW weld is mapped by classic sin2ψ method. Tensile stress is observed at one end of the weld, but it quickly evolves into compressive towards the other end. Meanwhile, the texture of the weld changes accordingly, as shown by the pole figures recorded at five different positions across the weld.
