本研究是以第二代鐵鋁合金摩擦攪拌扣件製程為基礎，針對扣件鋁料會穿透下試片鋼板的外觀缺陷進行參數改善。首先，採用6061-T6鋁合金及熱浸鍍鋅低碳鋼製作扣件試片，參數改善完成後，製作剪力及十字試片進行疲勞測試，並以光學及掃描式電子顯微鏡分析扣件在周次負載下的疲勞行為，觀察結果為有三種剪力試片破壞模式，而十字試片僅有一種。參考試片破壞模式，本研究使用兩種方法進行壽命預測。首先是結構應力法，此法採用剪力及十字試片的結構應力理論解，配合材料之應力-壽命曲線圖，進行壽命預測。其次是應力強度因子法，此法依據主導疲勞裂縫的路徑，取得裂縫的異材不等厚度的局部應力強度因子解，結合Paris Law，完成壽命預測。最後，本研究以韋伯分析這種統計手法取得各信心水準下的疲勞壽命曲線，將可對複雜受力狀態的扣件，進行精確的疲勞壽命預測。 This research is based on the second generation friction stir clinching (FSC) process. A flaw is occured that aluminum pierces through lower sheet, low carbon steel. The appearace is improved via parameter optimization. 6061-T6 Al sheets and hot dip galvamized low carbon steel sheets were used for the FSC process. After acomplishin the optimization, we made FSC LP and CT specimens. Conducting fatigue tests and investigated their failure behavior under quasi-static and cyclic loading conditions through optical and scanning electron microscope. Experimental results indicated that LP specimens have three failure modes, while CT specimens have only one failure mode.According to the failure modes of FSC joints, two life prediction methods were used. First was the structural stress (SS) method, which predicted lives by using the SS solutions of LP and CT specimens, associated with S-N curves of sheet materials. Second was the stress intensity factor (SIF) method, which predicted lives by using the different-material-and-unequal-thickness local SIFs for the paths of dominant fatigue cracks, associated with the Paris Law. Finally, Via a statistical technique, Weibull analysis, to obtain load range- life curve for LP and CT specimens .These methods make predicting fatigue lives of FSC joints under complex loading conditions more accurately.