Microstructure and orientation - dependent fatigue performance of direct metal laser sintered maraging steel

The microstructure of maraging steel produced by direct metal laser sintering (DMLS) is influenced by various factors, including parameters of the DMLS process and post-treating methods. This study investigates the effect of build orientation on the microstructure and fatigue behaviour of M300 maraging steel manufactured using DMLS. Microstructural characterization was conducted using light microscopy (LM) and scanning electron microscopy (SEM). The study also involved analysing fracture surfaces using SEM and performing fatigue tests on additively manufactured samples. The research reveals that the presence of inclusions in the specimens has resulted from trapped powder on the edge of the melted pool or from trapped metal oxides. These defects, especially when located near the surface of the specimens, often represent a weak spot and the source of initial cracks.