Grain refinement of Inconel 625 during wire-based directed energy deposition additive manufacturing by in-situ added TiB2 particles: Process development, microstructure evolution and mechanical characterization

• Published in: Intermetallics 2024-12, Vol.175, p.108540, Article 108540
• Main Authors: Rodrigues, Tiago A., Malfeito, A., Farias, Francisco Werley Cipriano, Duarte, V., Lopes, João, Cruz Payão Filho, João da, Avila, Julian A., Schell, N., Santos, Telmo G., Oliveira, J.P.
• Format: Article
• Language: English
• Subjects: Directed energy deposition; Grain refinement; Inconel; Inoculants; Synchrotron X-ray diffraction; Titanium diboride; Wire and arc additive manufacturing
• ISSN: 0966-9795
• DOI: 10.1016/j.intermet.2024.108540

In this study, a novel method for enhancing the quality of components fabricated by wire and arc additive manufacturing (WAAM) was developed. This approach employs an innovative mechanism featuring an actuator that dispenses a solution containing refinement particles (TiB2 inoculants), in conjunction with a soldering flux that vaporizes prior to reaching the electric arc. This leaves the particles to adhere to the welding wire or be carried by the shielding gas. By implementing this device, TiB2 particles were successfully incorporated into the molten pool during the WAAM process of Inconel 625 at levels of 0.31 and 0.56 wt%. Microstructural analysis reveals a significant reduction in the size of interdendritic segregation regions when TiB2 particles are introduced. Electron backscatter diffraction analysis further reveals the transformation of columnar grains into equiaxed grains. The average grain area decreased from 1823 μm2 in the as-built sample to 583 μm2 in the sample with a TiB2 content of 0.56 wt%. In addition, an improvement in the Inconel 625 fabricated by WAAM mechanical strength was observed due to the use of TiB2 inoculants, which was primarily attributed to the effect of the grain size refinement. [Display omitted] •Inconel 625 was fabricated by WAAM with addiction of TiB2 particles.•A new methodology to add inoculants particles in WAAM was developed.•Introduction of TiB2 in the melting pool induces the columnar to equiaxed transition.•The peak temperature in the melting pool did not exceed the TiB2 particles melting point.•The addition of TiB2 particles enhances the yield strength and hardness.