The effects of friction stir processing (FSP) on the fatigue crack growth (FCG) behavior of super duplex stainless steel (SDSS) SAF 2507 was investigated. Both base metal (BM) and friction stir processed (FSPed) compact tension (CT) samples were fatigue tested under constant amplitude load; at a stress ratio (R) of 0.1 and frequency of 10 Hz. Crack length was monitored using a video camera. The crack growth behavior for both BM and FSPed CT specimens was characterized using stress intensity factor and the J-integral computed using elastic-plastic finite element analysis (FEA). Optical and scanning electron microscopes (SEM) were used to analyze the fracture surfaces. The results of this study show that FSPed specimens have higher fatigue crack growth (FCG) resistance and fatigue life as compared to base material. In addition, the crack propagation under the above-mentioned conditions has revealed changes in fracture mechanisms, due to FSP. The microscopic analyses of the fracture surface of FSPed specimens revealed numerous crack initiations sites and complicated crack propagation paths which contributed to the retardation of the crack propagation.

研究了搅拌摩擦处理（FSP）对超级双相不锈钢（SDSS）SAF 2507疲劳裂纹扩展（FCG）行为的影响。在恒定振幅载荷下对贱金属（BM）和摩擦搅拌处理（FSPed）紧密拉伸（CT）样品进行了疲劳测试；应力比（R）为0.1且频率为10 Hz。使用摄像机监控裂纹长度。使用应力强度因子和采用弹塑性有限元分析（FEA）计算的J积分来表征BM和FSPed CT试样的裂纹扩展行为。使用光学和扫描电子显微镜（SEM）分析断裂表面。这项研究的结果表明，与基础材料相比，FSPed试样具有更高的抗疲劳裂纹扩展（FCG）能力和疲劳寿命。此外，在上述条件下的裂纹扩展显示出由于FSP引起的断裂机理的变化。对FSPed试样的断裂表面进行的显微分析表明，存在大量的裂纹萌生部位和复杂的裂纹扩展路径，这导致了裂纹扩展的延迟。