Characterization of Stainless Steel 316L and Ti-6Al-4V parts printed using Wire Arc Additively Manufactured (WAAM)

Author

de Azúa Ruiz-Falcó, Cristina

Abstract

Wire Arc Additive Manufacturing (WAAM) is a technique with great potential to produce structures complex metal and large format without the need for special tools, reducing prices and manufacturing times and maximizing the performance of materials. The WAAM process entails high and successive thermal variations due to the repeated application of layers, which implies high heating and cooling rates in the newly deposited layers and reheating of the previously deposited layers. This affects the resulting microstructure, phase balance and mechanical properties. In this research, the mechanical and microstructural behaviour of SS316L and Ti-6Al-4V parts manufactured by WAAM is studied. The anisotropic behaviour of WAAM parts: in various locations (lower, central and upper layers) and orientations (transversal and longitudinal directions) have been investigated for SS316L. Furthermore, the influence of the printing intersections on Ti-6Al-4V have been investigated.
SS316L results showed an anisotropy in mechanical properties has been observed. This behaviour is related to different cooling rates along the part. The decrease on cooling rate while layers are added generate an increase on grain size. Grain refinement have a significant influence on mechanical properties. A decrease in hardness and E, UTS, YS and elongation is observed as the material is deposited. The stress-strain curves show higher values of tensile stress in the specimens in the lower part (567 ± 6 GPa), while in the upper part the values are around 482 ± 4 GPa.
Ti-6Al-4V results showed an increase in grain size in printing intersections due to slow CR. This affected mechanical properties obtaining lower values of hardness, UTS, YS and higher ductility. Values of hardness on intersections around 330 HV compared to straight values of 365 HV, and an increase in ductility in intersections samples due to higher content of beta phase is obtained.

Director

Abad Roldán, Manuel
Gómez Gras, Giovanni 

Degree

IQS SE - Master’s Degree in Materials Science and Engineering

Date

2022-06-08