Hybrid manufacturing process combining laser powder-bed fusion and forging for fabricating Ti–5Al–5V–5Mo–3Cr–1Zr alloy with exceptional and isotropic mechanical properties

Abstract

The metal additive manufacturing (AM) technology offers a unique advantage for production of complex and unconventional parts. However, the thermal history during the AM process often leads to anisotropy in the mechanical properties and inherent porosity of the deposits, which limits their performance compared to traditional forgings. To overcome these limitations, laser powder bed fusion (LPBF) technology was employed to produce single-step die-forging preforms. This innovative approach used coarse powder with a wide distribution of particle sizes to create a variety of molten pool structures, preventing the growth of columnar β grains in AM Ti–5Al–5V–5Mo–3Cr–1Zr (Ti-55531) alloys. The subsequent die-forging process eliminated inherent defects and regulated grains to be near-equiaxed, significantly improving the mechanical properties and reducing anisotropy. With proper post-heat treatment, the strength-ductility trade-off of the Ti-55531 alloy was adjusted to meet standards. This unconventional process route produced parts with isotropic and excellent mechanical properties, overcoming the defects and anisotropic properties of AM parts. This supplement to the traditional manufacturing process of high-performance titanium alloy parts holds great promise for future applications.