Effect of thermal history control on mechanical properties of laser powder bed fusion maraging steel

The mechanical properties of maraging steel produced by laser powder bed fusion (LPBF) are influenced by the fractions of martensite and austenite phases. In this study, a Fe-20.8Ni-6.2Ti-1.7Al novel maraging steel (NMS), which is sensitive to thermal history, is used to explore the effect of thermal history during the LPBF process on the microstructure and corresponding properties of the NMS. The microstructural evolution, mechanical properties and tribological behaviors of NMS were investigated. As increasing the preheating temperature, the content of retained austenite in NMS was reduced. Compared with the LPBF-processed NMS at room temperature, the NMS-200 showed a better strength-ductility combination, achieving a tensile strength of 1405 MPa and a ductility of 12.9 %. The improved mechanical properties can be primarily attributed to grain boundary strengthening, dislocation strengthening and precipitate strengthening. Furthermore, NMS-200 showed a lower wear rate (1.41 x 10-5 mm3/Nm) than that of the NMS sample. This approach highlights the potential for controlling microstructure and enhancing the mechanical properties of materials via the tuning of thermal history during the LPBF process.