by A research team at the Institute of Metal Research of the Chinese Academy of Sciences, led by Profs. Zhang Zhefeng and Zhang Zhenjun, have introduced an innovative approach to developing an anti-fatigue 3D-printed titanium alloy. Termed as net-additive manufacturing preparation (NAMP), this strategy focuses on regulating the microstructure and defects separately.
Additive manufacturing (AM), commonly known as 3D printing, has revolutionized the manufacturing sector. However, the subpar fatigue performance of 3D-printed materials under cyclic loading as compared to traditionally manufactured components has constrained their application in critical fields like aerospace and space exploration.
The researchers, drawing from their prior fatigue prediction theories, put forth a novel idea that 3D-printed microstructures (Net-AM microstructures) possess inherently superior fatigue resistance. Nevertheless, the current printing process-induced microvoids diminish the fatigue performance of 3D materials.
To validate their concept, the team devised the Net-Additive Manufacturing Process (NAMP), incorporating a hot-isostatic pressing (HIP) to eliminate microvoids and a subsequent high-temperature-short-time (HTSt) heat treatment to reinstate the AM microstructure with fine martensite lath. This procedure facilitates the restoration of a nearly void-free Net-AM microstructure in the titanium alloy.
Remarkably, the Net-AM microstructure exhibits exceptional fatigue resistance surpassing that of all other additively manufactured and forged titanium alloys. It also boasts the highest specific fatigue strength (fatigue strength/density) among all materials reported globally. The fatigue cracks in the microstructures produced using the NAMP process typically initiate at clean primary β grain boundaries and fine martensite lath, circumventing conventional fatigue vulnerabilities and averting localized damage accumulation, thereby demonstrating outstanding fatigue resistance.
This study unveils the innate high fatigue resistance of 3D-printed microstructures and underscores the potential benefits of 3D printing technology in manufacturing structural components. It also indicates clear pathways for 3D printing anti-fatigue manufacturing.
