Laser powder bed fusion (PBF-LB/M) is an additive manufacturing (AM) technique that allows rapid production of near net-shaped components with complex geometries such as lattice structures with energy-absorption functionality for lightweight applications due to its high resolution (small laser spot size) and process flexibility (powder-bed approach).

As a member of second generation advanced high-strength steels (AHSS), high-manganese steels (HMnS) have been reported as suitable alloys for production of lattice structures with high energy-absorption capacity by PBF-LB/M. It was revealed that lattice structures (f2ccz unit cell) made of HMnS had higher weight-specific energy-absorption capacity in comparison to well-established AM materials of the same geometry (e.g. Ti6Al4V and AISI 316L), owing to the transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP) effects. However, strain localisation at z-strut (vertical strut) nodes of the f2ccz structures resulted in formation of brittle ε-martensite phase in an X30Mn22 lattice structure at the early deformation stages and consequently led to failure of these structures. Digital image correlation (DIC) analysis performed on a X30Mn22 lattice under compression shows the disintegration of the struts at early deformation stages, which ultimately caused the collective failure of the lattice, started from the high-strain regions where the rather brittle martensite phase was formed.

In order to avoid strain localisation, f2ccz geometry was modified. In line with the scope of this contribution, the vertical z-struts of the f2cczz structure were replaced by curved ones to achieve more homogeneous load distribution along directions orthogonal to the applied load and thereby preventing strain localisation at the nodes (intersection of cross-struts and z-struts). The mechanical behaviour of the modified f2ccz structures of X30Mn22 with different relative densities indicates that the proposed structures are more stable during plastic deformation and the energy-absorption capacity could be further increased.