Refill friction stir spot welding parameter development in transport industry aluminium alloys
TWI Core Research Project P31030
Refill friction stir spot welding (Refill FSSW) has several advantages over other mainstream single-point joining or fastening processes. As a solid-state process producing forged microstructures, refill FSSW joints generate minimal residual stresses/distortions, whilst completely avoiding the common defects associated with fusion welding, such as porosity and solidification cracking. Refill FSSW is also a zero-mass adding technology, as no material is added to the weld. The flush surface finish (Fig. 1D) is highly desirable for applications where aerodynamics and aesthetics are critical factors.
With early adopters appearing in the railcar and automotive production industries, current industrial research focuses on proving joint properties and further decreasing the cycle time to attract more large-scale, high rate producers, who may typically value marginal cycle time gains over quality and mass penalties.
This report provides the reader with an impartial gathering of core data on the performance and properties of refill FSSW welds in various transport-sector aluminium alloys.