Investigation of Microstructure and Mechanical Properties for Ti-6Al-4V Alloy Parts Produced Using Non-Spherical...

Area of Science:

• Materials Science
• Additive Manufacturing
• Metallurgy

Background:

• Titanium alloys, particularly Ti-6Al-4V, are critical in aerospace applications.
• Spherical, atomized powders are conventionally used in additive manufacturing, but non-spherical powders offer cost advantages.
• Laser beam powder-bed fusion (L-PBF) is a key additive manufacturing technique for titanium alloys.

Purpose of the Study:

• To evaluate the feasibility of using unmodified, non-spherical hydride-dehydride (HDH) Ti-6Al-4V powder for L-PBF.
• To characterize the mechanical properties and microstructures of as-built and heat-treated components.
• To compare the performance of HDH Ti-6Al-4V components with commercial wrought products.

Main Methods:

• Fabrication of test components using L-PBF with optimized parameters.
• Post-processing heat treatments including annealing and hot isostatic pressing (HIP).
• Mechanical testing (Rockwell-C hardness, tensile yield stress, UTS, elongation) and microstructural analysis.

Main Results:

• As-built components achieved a Rockwell-C hardness of 44.6.
• Heat treatments (annealing, HIP, HIP + anneal) resulted in hardness values of 43.9, 40.7, and 40.4 HRC, respectively.
• HIP treatment yielded tensile properties (1.03 GPa yield strength, 16.7% elongation) comparable to wrought Ti-6Al-4V, with a microstructure of elongated grains containing fine alpha/beta lamellae.

Conclusions:

• Unmodified, non-spherical HDH Ti-6Al-4V powder is suitable for L-PBF fabrication.
• Optimized processing and heat treatments, particularly HIP, can yield aerospace-grade mechanical properties.
• HDH Ti-6Al-4V presents a cost-effective alternative for producing high-performance titanium components via additive manufacturing.