A Novel Approach to Enhancing Mechanical Properties of Additively Manufactured Ti-6Al-4V Alloy via Post-Process Heat Treatment
Authors: John A. Smith, Emily R. Johnson, Michael T. Brown
Additive manufacturing (AM) of Ti-6Al-4V alloy has gained significant attention due to its potential for producing complex geometries with reduced material waste. However, the as-built microstructure often exhibits acicular martensite and high residual stresses, leading to inferior mechanical properties compared to wrought counterparts. This study investigates the effect of post-process heat treatment (HT) on the microstructure and mechanical properties of Ti-6Al-4V fabricated by laser powder bed fusion (LPBF). Samples were subjected to sub-transus (800°C) and super-transus (1050°C) heat treatments followed by furnace cooling. Microstructural characterization was performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Tensile tests were conducted to evaluate mechanical properties. Results indicate that sub-transus HT transforms the martensitic structure into a fine lamellar α+β microstructure, significantly improving ductility while maintaining high strength. Super-transus HT leads to a coarser lamellar structure, further enhancing ductility but with a slight reduction in strength. The optimal balance of strength and ductility was achieved with sub-transus HT, yielding an ultimate tensile strength of 1100 MPa and elongation of 14%. This study provides valuable insights into tailoring the microstructure of LPBF Ti-6Al-4V for enhanced mechanical performance, making it suitable for aerospace and biomedical applications.
