The　mechanical　properties　and　failure　process　of　2　mm-thick　5052　Al　and　6　mm-thick　2A12　Al　fabricated　by　refill　friction　stir　spot-welding　were　investigated.　The　hooks　were　bent　respectively　downwards　and　upwards　at　plunge　depths　smaller　and　larger　than　the　upper　plate　thickness.　The　joint　area　of　the　lap　interface　and　bearing　thickness　of　the　upper　plate　were　related　to　the　hook　direction.　The　tensile　shear　failure　load　was　affected　by　structural　characteristics　and　hardness　of　the　joints.　Stress　concentration　occurred　in　the　hook　and　strain　expanded　with　the　hook　during　fracture.　There　were　two　fracture　modes:　shear　fracture　and　shear　plug　fracture,　where　both　cracks　passed　through　the　hook　and　fracture　morphology　of　the　hook　was　less　plastic.