Unveiling the cellular microstructure-property relations in maraging steel via laser powder bed fusion

Additive manufacturing enables rapid fabrication of complex components through layer-by-layer formation. At present, there is a paucity of addressing the effects on cellular microstructures and mechanical properties during the process of laser powder bed fusion (LPBF). Therefore, this study systematically investigated the influence of cellular microstructure and mechanical properties response of maraging steel by LPBF. Increasing the laser scanning speed does not lead to a noticeable change in the phase fraction, but it reduces the average size of the cellular structure from 0.6 μm to 0.35 μm. The scanning speed is 400 mm/s and 1000 mm/s are both have adverse effects on performance, resulting in inadequate fusion and keyhole defects, respectively. The optimal scanning speed for fabricating samples is determined to be 800 mm/s, which exhibits the highest room temperature tensile strength and elongation. The ultimate tensile strength measures at 1088.3±2.0 MPa, with an elongation of 16.76±0.2%. The mechanism of the evolution of surface morphology, defects, and energy input were clarified, the relationship between cellular structure size and mechanical property was also established.