Mechanical properties of Ti-6Al-4V thin walls fabricated by laser powder bed fusion

Abstract

Laser powder bed fusion (PBF-LB/M) has recently garnered considerable attention for fabricating thin walls owing to its potential for producing lightweight structures. However, knowledge of the mechanical properties of thin walls with high surface-to-volume ratios remains insufficient. Specifically, no studies have been conducted for thin walls with a thickness less than 400 µm, making the size effect unclear. Therefore, the main objective of this work is to reveal the effect of thicknesses on the mechanical properties of Ti-6Al-4V samples as thin as 195 µm. To achieve this, the fabrication process was optimized to maximize the aspect ratio and properties of samples. In addition, the microstructure and surface roughness were examined to understand the size effect. The results demonstrated that the ultimate tensile strength of the thin-wall samples was similar to that of bulk Ti-6Al-4V samples fabricated via PBF-LB/M, regardless of the thickness. By contrast, the elongation of the thin-wall samples decreased with thickness, indicating a significant size effect. This size effect on elongation can be attributed to the strong influence of surface and internal defects.