The effect of nitrogen additions on fatigue behavior has been examined in near-equiaxed, rolled Ti-6Al-4V bar. This is the first-time nitrogen content that has been systematically explored with respect to monotonic and cyclic properties in a Ti-6Al-4V alloy base composition. Nitrogen additions were found to increase the \(\beta \)-transus temperature and strength, but they decreased ductility, even in microstructures where some \(\beta \) phase remained. This carried across into both the low- and high cycle fatigue behavior; even small contents of 240 and 560 ppmwN caused reductions in both low cycle fatigue life and high cycle fatigue strength. In samples containing 240 and 560 ppmwN, a conventional striated fractographic appearance was observed, but a dramatic change to a macroscopically brittle fracture surface was observed at 1800 and 3600 ppmwN, but still with substantial evidence of plasticity at the microscale. Therefore, neither microstructure or fractographic examination, nor EDX-based compositional analysis in the electron microscope are necessarily a reliable indicator of an absence of deleterious nitrogen contamination. This is significant for the investigation of potentially nitrogen-contaminated surface-initiated cracks, either due to service or processing exposures.

已经在接近等压的轧制Ti-6Al-4V棒中检查了氮添加对疲劳行为的影响。这是首次就Ti-6Al-4V合金基础成分中的单调性和循环性探讨的氮含量。发现添加氮会增加\（\ beta \）的温度和强度，但即使在某些\（\ beta \）的微观结构中，它们也会降低延展性。阶段仍然存在。这会影响低周疲劳行为和高周疲劳行为。即使240和560 ppmwN的含量很少，也会降低低周疲劳寿命和高周疲劳强度。在含有240和560 ppmwN的样品中，观察到了常规的条纹形貌，但是在1800和3600 ppmwN处观察到了宏观脆性断裂表面的显着变化，但仍具有大量可塑性的明显证据。因此，电子显微镜中的微观结构或分形检查或基于EDX的成分分析都不一定是不存在有害氮污染的可靠指标。这对于研究由于维修或加工暴露而可能被氮污染的表面引发的裂纹具有重要意义。