Tailoring mechanical reliability and microstructural synergy of selective laser melted Ti-6Al-4V ELI via deep cryogenic treatment for enhanced performance in dental applications

Selective laser melting (SLM) holds significant prospects for customized dental applications of Ti-6Al-4V extra-low interstitial (ELI). However, conventional heat treatments often face the intrinsic strength-ductility trade-off, which constrains their clinical efficacy. This study innovatively introduced deep cryogenic treatment (DCT) as a post-processing strategy to promote strength-ductility synergy in SLM-fabricated Ti-6Al-4V ELI for dental applications, establishing an optimal mechanical reliability window of 6 hours. Under this optimized condition, the yield strength, elongation, impact toughness, and microhardness increased by 8.2%, 38%, 13.7%, and 6.4%, respectively. Microstructural characterization revealed that DCT triggered grain refinement, dislocation proliferation, and the formation of dense substructures, while simultaneously inducing crystallographic reorientation and the transformation of metastable α' martensite into an equilibrium α+β microstructure. The observed mechanical enhancements are attributed to the synergistic interplay of these microstructural changes. In conclusion, appropriate DCT serves as an effective mechanism to enhance the mechanical reliability of SLM-fabricated Ti-6Al-4V ELI, offering a novel technical pathway for the post-processing optimization of additively manufactured dental metallic components.