Spot Friction Welds

Investigator: Van-Xuan Tran

A new spot friction welding technology for joining aluminum sheets has been recently developed by Mazda Motor Corporation and Kawasaki Heavy Industry. The most significant advantage of the spot friction welding process comparing to the conventional welding processes is that the joint can be made without melting the base metals. This advantage leads to saving in energy (up to 90%), low initial investment cost and a simple, clean and economical working environment. The purposes of this research are therefore to investigate the fundamental aspects of the static and dynamic strengths and fatigue failure of spot friction welds between similar and dissimilar sheet materials, and to model the spot friction welding process for selection of the optimal processing parameters for the strength and durability of the welds. The fundamental aspects of the static and dynamic strengths and fatigue failure of spot friction welds between similar and dissimilar sheet materials were investigated based on a combined theoretical, numerical and experimental approach. Experiments to determine the static and dynamic strengths and fatigue failure of the welds were conducted. Different fatigue life estimation models were developed to predict the fatigue lives of the welds with different fatigue crack growth patterns. Finally, micromechanics models are developed to link the processing parameters to the strength and fatigue failure of the welds with different cracking mechanisms.



A schematic plot of the spot friction weld process

 


Optical micrographs of the cross sections along the symmetry planes of a failed dissimilar 7075/5754 spot friction welds in lap-shear specimens under cyclic loading conditions.

 


Optical micrographs of the cross sections along the symmetry planes of a failed Al/Fe spot friction welds in lap-shear specimens under cyclic loading conditions.