The role of titanium on the microstructure and mechanical properties of additively manufactured C300 maraging steels

In this study, C300 metal powders containing two different Ti contents (0.72 and 1.17 wt%) were used to additively manufacture maraging steel samples in both horizontal and vertical directions via laser powder bed fusion (LPBF) technique. The effect of Ti addition on the microstructural and mechanical properties of the additively manufactured (AM) maraging steels was investigated using scanning, transmission electron microscopies (SEM, TEM), and electron backscatter diffraction (EBSD) along with uniaxial tensile and hardness testing procedures. Besides, X-ray diffraction (XRD) technique was employed to identify various phases formed during the LPBF process. The results showed that the horizontally printed Ti-rich samples exhibited higher retained austenite (γ) phase and superior values of hardness and tensile strength, while those ones vertically prepared showed an excellent ductility that could bring benefits in high-cycle fatigue applications. The TEM observations confirmed the presence of CoNi precipitates as well as high dislocation densities in the horizontal high Ti content samples, which are associated with higher strain hardening and tensile strength.