CAJ | 학술논문

　　利用拉压疲劳实验研究 AZ31板材搅拌摩擦点焊连接件的疲劳行为。结果表明：AZ31镁合金板材搅拌摩擦点焊连接件的疲劳失效均发生在搅拌区，疲劳裂纹均起源于搅拌区外侧边缘，位于上下板之间。当循环加载等于1 kN 时，疲劳裂纹沿着热影响区和热机械区界面且垂直载荷的方向扩展；而当循环载荷等于3 kN时，疲劳裂纹则沿着搅拌区直径方向扩展，并最终发生剪切断裂。另外，断口横截面显微分析显示，在AZ31板间搅拌区外侧存在一个“舌状区”，“舌状区”的方向是沿搅拌区向外，疲劳裂纹均起源于“舌状区”。
　　이용랍압피로실험연구 AZ31판재교반마찰점한련접건적피로행위。결과표명：AZ31미합금판재교반마찰점한련접건적피로실효균발생재교반구，피로렬문균기원우교반구외측변연，위우상하판지간。당순배가재등우1 kN 시，피로렬문연착열영향구화열궤계구계면차수직재하적방향확전；이당순배재하등우3 kN시，피로렬문칙연착교반구직경방향확전，병최종발생전절단렬。령외，단구횡절면현미분석현시，재AZ31판간교반구외측존재일개“설상구”，“설상구”적방향시연교반구향외，피로렬문균기원우“설상구”。
The fatigue behavior of friction stir spot welded (FSSW) AZ31 magnesium alloy sheet joints was investigated by tension?compression of fatigue test. The results suggest that all the fatigue failures occur at the stir zone of the FSSW AZ31 sheet joints, and all cracks initiate at the stir zone outer edge between the upper and lower sheet. When the cycle force equals 1 kN, the crack propagates along the interface of heat-affected zone and thermo-mechanical zone, simultaneously across the direction of force;while the cycle force equals 3 kN, the crack propagates along the diameter of stir zone and shear failure occurs finally. Moreover, the transverse microsections indicate that there is a tongue-like region at the outer edge of stir zone between the two AZ31 sheets, and the direction of tongue-like region is toward outside of the stirred zone and all fatigue cracks initiate at the tongue-like region.