Electron beam powder bed fusion of Ti-6Al-2Sn-4Zr-2Mo lattice structures: morphometrical and mechanical characterisations

Abstract

Metallic light and complex structures, such as lattice, made by Ti-6Al-2Sn-4Zr-2Mo (Ti6242) have potential applications in many different industries, especially in light and high-temperature-resistant aerospace and aeronautical components. An advantage of the electron beam powder bed fusion (PBF-EB) process over conventional and other additive manufacturing processes is the ability to fabricate lattice structures easily. However, the control of the effect of the manufacturing process for fabricating such small features is central to define the structure’s mechanical properties. This work investigates the effects of PBF-EB parameters on the geometrical quality of Ti6242 lattice structures. The selected cell consists of 12 rhombic areas connected by 24 struts joined in 12 vertices. The structures were produced in two cell sizes and two strut diameters under nine different process sets. X-ray computed tomography and scanning electron microscopy analyses were used to characterise the morphometrical parameters of each as-built cell and the interlayer integrity of the struts. Evolution under compressive loads was used to determine the mechanical properties of the lattice structures and the failure mechanism underlying the influence of process parameters on the mechanical properties. The as-built Ti6242 lattices were well-formed without voids and cracks. The outcomes revealed a significant effect of the considered lattice structure and process setup on the morphometric parameters. Even minor variations of the main processing parameters considerably impacted the mechanical properties of the structure.