Controllable Microstructural Variations in Additively Manufactured Ti-6Al-4V via Laser Powder Bed Fusion

Laser powder bed fusion (LPBF), a premier additive manufacturing (AM) technology offers the ability to produce complex metallic components. However, its widespread use is often limited by challenges in controlling the local microstructure, largely due to the intricate thermal cycles inherent in its layer-by-layer build process. In this work, we demonstrate a method for achieving controllable microstructure in Ti-6Al-4V by employing distinct LPBF “processing strategies” and leveraging the design flexibility of the process. By locally tailoring the thermal conditions spatially and temporally, we successfully generated two targeted microstructures: α′ martensite (hard domains that enhance strength) and lamellar α+β or globular α (soft and tough domains that improve ductility and toughness). These microstructures were engineered to form in situ as alternating layered bands, arranged either longitudinally or radially. The mechanical performance of the fabricated parts was found to depend strongly on the spatial orientation and thickness of these microstructural bands. This approach provides a promising pathway to simultaneously improve strength and ductility in multi-phase materials like Ti-6Al-4V fabricated by LPBF.