The presented paper deals with the mechanical properties of Friction Stir Welded (FSW) AA2024-T351-joints. The material’s response to the static and fatigue strength (S–N curve) is summarised from previous work and referenced, while the testing methods and results for the fatigue and fracture mechanics’ parameters regarding to the fatigue crack growth and occurrence of final fracture are discussed in the greater details and represent the main contribution of this work. The evaluation of the obtained experimental results was performed for three different welding speeds (v = 73, 116 and 150 mm/min), which enabled the determination of the most appropriate welding speed in regard to the fatigue and fracture behaviour of the analysed FSW-joint. The highest value of the threshold stress intensity factor range, ΔK_th, and, consequently, the highest resistance against crack extension, was obtained for the welding speed v = 116 mm/min. A similar conclusion was observed when determining the fracture toughness K_JIc, where the highest value was obtained for the same welding speed. On the other hand, not significant differences in the slope m were obtained between the considered welding speeds when analysing the fatigue behaviour in the modified Paris diagram. In that respect, it can be concluded that the welding speed v = 116 mm/min is favourable in regard to the fatigue and fracture behaviour of the analysed FSW-joint.

所提交的论文涉及摩擦搅拌焊接 (FSW) AA2024-T351 接头的机械性能。总结了材料对静态和疲劳强度（S - N曲线）的响应并参考了以前的工作，同时讨论了疲劳裂纹扩展和最终断裂发生的疲劳和断裂力学参数的测试方法和结果在更详细的情况下，代表了这项工作的主要贡献。针对三种不同的焊接速度 ( v = 73、116 和 150 毫米/分钟），从而能够确定最适合分析 FSW 接头疲劳和断裂行为的焊接速度。当焊接速度v  = 116 mm/min时，阈值应力强度因子范围的最高值 Δ K _th，因此，获得了最高的裂纹扩展阻力。在确定断裂韧性K _JIc时观察到类似的结论，在相同焊接速度下获得最高值。另一方面，斜率m没有显着差异在分析修改后的巴黎图中的疲劳行为时，在考虑的焊接速度之间获得。在这方面，可以得出结论，焊接速度v  = 116 mm/min 对所分析的 FSW 接头的疲劳和断裂行为是有利的。