A team of international scientists led by the Chinese experts has broken through the technological bottleneck caused by the poor fatigue properties of 3D-printed materials, and proposed an innovative strategy to fabricate an anti-fatigue titanium alloy via near void-free 3D printing.

According to the study published in the latest issue of academic journal Nature, the advantage of 3D printing, or additive manufacturing (AM) technology, had previously been severely compromised by the poor fatigue performance of 3D-printed materials under cyclic loading, which resulted from the presence of microvoids induced by prevailing printing process.

To solve the problem, the research team under the leadership of Professor Zhang Zhefeng and Professor Zhang Zhenjun from the Institute of Metal Research of the Chinese Academy of Sciences, managed to successfully produce an approximate void-free Ti-6Al-4V titanium alloy by developing a new 3D-printing processing technique to regulate microstructure and defects separately.

This new technique, known as Net-Additive Manufacturing Process, includes hot-isostatic pressing to eliminate the microvoids and subsequent high-temperature-short-time heat treatment to restore the AM microstructure with fine martensite lath, which can successfully restore a nearly void-free Net-AM microstructure to the titanium alloy.

The team confirmed the fatigue resistance of such a void-free 3D-printed titanium alloy, and found that it exceeded the level of resistance of all other 3D-printed and forged titanium alloys as well as that of other metallic materials.

"This research has revised people's previous understanding of the low fatigue performance of 3D printing materials and is expected to advance such materials' application in aerospace and other fields," said Zhang Zhefeng.