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Production process of high fatigue resistance 3D printing titanium alloy

The production of high fatigue-resistant 3D-printed titanium alloys involves a process that carefully manages defects and microstructure. Researchers at the Institute of Metal Research of the Chinese Academy of Sciences have made strides in this area1.The key steps include:

1. Understanding the Material: Recognizing that 3D-printed titanium alloys possess inherent high fatigue performance if produced in an ideal state. The intrinsic fatigue resistance of the as-printed microstructure (Net-AM) is often masked by defects like porosity introduced during the printing process.

2. Defect Management: The process aims to eliminate or minimize the formation of pores and other defects during 3D printing, as these flaws significantly reduce the material's fatigue performance.

3. Microstructure Control: Developing methods to retain the original printed microstructure while eliminating pores is crucial. Conventional methods to remove pores often lead to undesirable grain coarsening, while grain refinement techniques can cause pores to reappear.

4. New Process Development: A novel approach called NAMP (Net-Additive Manufacturing Process) was invented. This process involves carefully controlling defects and microstructure in separate steps.

5. Heat Treatment Optimization: The researchers discovered a specific heat treatment window for Ti-6Al-4V alloy that allows for the refinement of the microstructure without causing pore recurrence or the formation of undesirable α phase enrichment at grain boundaries.

6. Two-Step Defect and Structure Control: The new process uses a two-step approach to control defects and the microstructure, which results in a nearly pore-free titanium alloy.

7. Performance Improvement: The resulting titanium alloy exhibits significantly enhanced fatigue strength, with an increase of up to 106% compared to conventionally manufactured 3D-printed titanium alloys. The alloy also demonstrates the highest fatigue strength-to-density ratio among reported materials.