Naturally high fatigue performance of a 3D printing titanium alloy across all stress ratios

Three-dimensional printing of structural materials, namely, additive manufacturing (AM), has notable advantages in fabricating structurally complex engineering components. These complex components usually endure comprehensive fatigue examination due to their complex stress distribution with varying stress ratios during service. Therefore, it is important to ensure the fatigue reliability of additive manufactured materials across all stress ratios. We found that the AM microstructure itself in a Ti-6Al-4V alloy successfully synthesizes the tripartite advantages of fine prior β grain boundaries, void-free, and fine α grains, which are respectively sensitive to the low, medium, and high stress ratio regions. Under this synergistic effect, the fatigue performance of the natural AM microstructure across all stress ratios not only outperforms all additive manufactured and forged Ti-6Al-4V alloys, but also surpasses other metallic materials. Our finding highlights the potential advantage of additive manufacturing technology in producing complex components with high fatigue resistance, substantially expanding its application scope.