This study systematically investigated the microstructural evolution

mechanical property mismatch

and their effects on fatigue performance in laser-remelted nickel-based superalloys through multiscale experimental characterization and finite element simulations. By combining nanoindentation tests

fatigue experiments

and an improved indentation inverse analysis algorithm

the spatial distribution of mechanical parameters in the remelting zone (RZ)

remelting-affected zone (RAZ)

and base material (BM) was quantified. The results demonstrate that the RZ

characterized by coarse columnar grains and Laves phase formation due to non-equilibrium solidification

exhibits significantly reduced strength compared to the BM. However

dendritic-cellular substructures within the RZ mitigate macroscopic performance anisotropy through grain boundary pinning effects. Although the RAZ shows elevated geometrically necessary dislocation (GND) density and twin boundary proliferation

residual tensile stresses lead to underestimated nominal hardness measurements. Fatigue analysis reveals a stress shielding effect in the heterogeneous material system: cyclic softening and mean stress relaxation in the RZ under high-stress conditions substantially reduce crack driving forces

shifting fatigue failure initiation to the BM. This work establishes a cross-scale theoretical framework for optimizing the performance of laser-repaired components.