The advantages of 3D printing – namely additive manufacturing (AM) of structural materials – have been severely undermined by its disappointing fatigue properties. In general, poor fatigue properties appear to be due to the presence of microvoids caused by current printing process procedures. Therefore, our question is whether this elimination of micropores can provide a viable solution to significantly improve the fatigue resistance of non-porous AM (net AM) alloys. Here, we successfully reconstruct an approximate development of Net-AM processing techniques for Ti-6Al-4V titanium alloys in void-free AM microstructures, by understanding the nonlinearities of phase transitions and grain growth. We determined the fatigue resistance of such AM microstructures and showed that they result in a high fatigue limit of about 1 GPa, exceeding the fatigue resistance of all AM and wrought titanium alloys, as well as other metallic materials. We confirmed the high fatigue resistance of the Net-AM microstructure and the potential advantages of AM processing in the production of structural components with maximum fatigue strength, which is conducive to the further application of AM technology in the field of engineering.
Illustration:Micropore distribution and microstructure in the printed state and three other states. Printed AM (a), HIP AM (b), Near Net AM (c) and Net AM (d)
