Effect of Remelting Process on Surface Quality and Tensile Behaviour of a Maraging Steel Manufactured by Selective Laser Melting

Selective laser melting (SLM) of 18Ni-300 maraging steel is of substantial interest due to its wide application as a mould material in automotive sectors. Selective laser remelting (SLRM) is often employed during SLM, which offers the potential to improve quality of the metallic parts fabricated by SLM. This study investigated the effect of the remelting process on the surface quality and tensile strength of 18Ni-300 maraging steel manufactured by SLM. The experimental results demonstrated that the remelting process was found to contribute to a smoother surface morphology on the top surface and no obvious observed difference in the side surface morphology. The SLM-built and SLRM-built samples exhibited the Ra roughness values of 3.11 ± 0.31 μm and 3.44 ± 0.48 μm, respectively, which showed no significant difference. The Ra values on the side surface increased from 7.76 ± 0.25 μm to 11.57 ± 3.44 μm after remelting. This was because more powder particles were exposed to molten pools during remelting. In addition, the yield strength increased from 890 ± 27 MPa to 938 ± 36 MPa after the remelting process, whereas the ultimate tensile strength remained at the same level. The SLM-built and SLRM-built samples achieved the ultimate tensile strength values of 1068 ± 12 MPa and 1070 ± 19 MPa, respectively. Moreover, both processing conditions showed a ductile fracture mode. These significant findings indicate the possibility of combining SLM and selective laser remelting to produce better performing 18Ni-300 maraging steel components.