The influence of aging temperature and aging time on the mechanical and tribological properties of selective laser melted maraging 18Ni-300 steel

Selective laser melting (SLM) is an additive manufacturing and 3D printing technology which offers flexibility in geometric design and rapid production of complex structures. Maraging steels have high strength and good ductility, and therefore have been widely used in aerospace and tooling sectors for many years. This work aims to study the influence of aging temperature and aging time on the microstructure, mechanical property (hardness, strength and ductility) and tribological property of SLM maraging 18Ni-300 steel. The results reveal that the aging conditions had a significant impact on the strength and wear-resistance of the SLM maraging steel. The optimal aging conditions for the SLM maraging steel produced in this work were 490 °C for 3 h under which strength and wear-resistance were maximised. Lower or higher aging temperature led to under-aging or over-aging phenomena, reducing the strength and wear-resistance performance. Shorter or longer aging time also resulted in the decrease of strength and wear-resistance performance of the SLM maraging steel as compared with the optimal conditions. The variation of the mechanical and tribological properties is primarily due to changes in phase compositions and microstructures of the SLM maraging steels.