Stray grains evolution and high-temperature stress rupture behavior of crystallographic lamellar microstructure in Ni-based superalloys prepared by laser powder bed fusion

• High-temperature stress rupture failure in CLM Ni-based superalloys is primarily due to intergranular fracture in <110> grain regions, with sub-grain boundary fracture occurring only under high temperature and low stress (980 °C/260 MPa). • Stray grains, formed due to unstable heat flow in the melt pool during LPBF, severely reduce stress rupture life under both tested conditions. • Despite shorter stress rupture lifetimes, deformation twins are activated within <110> grains, contributing to excellent plasticity under both test conditions. • Future optimization of CLM via LPBF should focus on eliminating high-angle grain boundaries in <110> grains to enhance high-temperature performance.