摘要：

Maraging steels are a class of low-carbon ultra-high-strength martensitic steels. Due to their excellent weldability, these steels have been widely applied for laser-based additive manufacturing (AM). MAR-60HRC is a newly developed maraging grade for AM with a nominal chemical composition of 13.0Ni-15.0Co-10.0Mo-0.2Ti, Fe bal. (wt%), capable of achieving hardness levels of~740 HV. Alternatively, 18Ni300 is a commercialized maraging steel with an excellent combination of strength and toughness at the peak aged hardness (i.e.,~590 HV). This work aims to investigate the properties and microstructure of MAR-60HRC fabricated by Laser Directed Energy Deposition (L-DED). Further, the manufacturability of bimetallic parts comprising a tough 18Ni300 core and a hard MAR-60HRC on the surface was evaluated. After proper aging, the multi-layered material showed a surface hardness of~720 HV1 and apparent fracture toughness of 71MPa m1/2, higher than that of MAR-60HRC (i.e., 60MPa m1/2), and lower than 18Ni300 (i.e., 90MPa m1/2). The excellent combination of surface hardness and fracture toughness was discussed, considering the crack arrest at the interface and the flawless interface between the two steels.

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