The building of Inconel 625 material was carried out using the selective laser melting method, and its fatigue crack growth property at ambient temperature was experimentally investigated. Compact‐tension specimens with different building orientations were utilized to determine the stress intensity factor threshold and fatigue crack growth rate curves at different stress ratios (R). The results indicated that the fatigue crack growth properties in the near threshold stress intensity factor and Paris regions were greatly affected by the loading factor, as well as the orientation of the alloy. The mechanism of fatigue crack growth at different stages was observed and discussed using scanning electron microscopy. Finally, based on the framework of the linear elastic fracture, a new and applicable effective driving force factor range was introduced to replace the traditional stress intensity factor range (ΔK) with good accuracy for all of the fatigue crack growth test data, considering both the stress ratio and orientation.

中文翻译：

---

关于选择性激光熔炼Inconel 625的疲劳裂纹扩展行为：构造方向和应力比的影响

使用选择性激光熔融法进行Inconel 625材料的构建，并实验研究其在环境温度下的疲劳裂纹扩展性能。利用具有不同建筑物方向的紧凑型拉伸试样来确定在不同应力比下的应力强度因子阈值和疲劳裂纹扩展速率曲线（R）。结果表明，在接近阈值应力强度因子和巴黎区域的疲劳裂纹扩展特性受载荷因子以及合金取向的影响很大。使用扫描电子显微镜观察并讨论了不同阶段疲劳裂纹扩展的机理。最后，基于线性弹性断裂的框架，针对所有疲劳裂纹扩展测试数据，引入了一种新的且适用的有效驱动力因子范围，以高精度替代了传统的应力强度因子范围（ΔK）。应力比和方向。