Friction stir spot welding of rare-earth containing ZEK100 magnesium alloy sheets

• Friction stir spot welding was used to join rare-earth containing ZEK100 Mg alloy.
• Variation in tool rotation speed and plunge depth affect peak joint strength.
• The highest joint strength was associated with large upper effective sheet thickness.

In this study, rare-earth containing ZEK100 magnesium alloy sheets were joined using friction stir spot welding. In order to determine the influence of welding parameters on lap-shear strength, overlap joints were created under various tool rotational rate and shoulder plunge depths. Relationships between the maximum lap-joint strength and key features of the weld including effective sheet thickness, interfacial hook width, and shoulder plunge depth were established. Based on the results of this study, welds with larger effective upper sheet thickness and small interfacial hook height generally exhibited the highest lap-shear strength. In addition, experiments indicated that overlap joints welded at 1500 rpm and 0.2 mm tool shoulder plunge depth exhibited the highest lap-shear strength.