Novel functionally-graded material design of additive manufactured Corrax maraging stainless steel lattice

The effects of a functionally-graded material (FGM) designed with two types of unit cells, cubic and face-centered cubic with Z-axis struts (FCCZ), on the compressive performances and fracture mechanisms of powder bed fusion-laser beam (PBF-LB) Corrax maraging stainless steel lattices were investigated. FGM lattices with gradient directions parallel and vertical to the compressive loading were respectively designated as FGM-P and FGM-V lattices. The results showed that the FCCZ lattice exhibited higher compressive properties than the cubic lattice did. The fracture modes of FCCZ and cubic lattices were respectively ∼45° shear fracture and layer-by-layer fracture. The FGM-V lattice exhibited higher specific energy absorption at 50 % strain than the FCCZ and cubic lattices did by 7.6 % and 19.4 %, respectively. This phenomenon can be attributed to the effective alleviation of strain localization in the FGM-V lattice postponing the fracture. Furthermore, the specific energy absorptions of PBF-LB Corrax lattices were comparable to those of PBF-LB Ti-based alloy lattices in the literature. Thus, the PBF-LB Corrax lattice appears to be a potential low-cost material for high-performance and lightweight structural applications. This lattice design extends the flexibility of additive manufactured lattices and provides a specific guideline for further improving their mechanical performances.