Effect of layer thickness variation on mechanical properties of WC-reinforced 316L stainless steel graded structures fabricated via laser powder bed fusion

316L stainless steel (316L SS) faces limitations in its application due to inadequate strength. While incorporating high-strength ceramic particles can significantly enhance tensile strength via second-phase strengthening, the inherent brittleness of ceramics often severely compromises elongation. Fabricating ceramic/316L SS gradient layered structures (GLS) via laser powder bed fusion (LPBF) offers a promising route to synergistically improve both strength and ductility. This study aims to elucidate the influence of alternating layer thickness, a key structural parameter, on microstructural evolution and mechanical properties. To this end, GLS specimens consisting of alternating 2 wt.% WC/316L SS composite layers and pure 316L SS layers were fabricated by LPBF, with material switching intervals of 5, 7, and 10 layers. The results demonstrate that the specimen with a 7-layer interval achieves the optimal comprehensive performance, featuring the smallest average grain size (∼16.1 μm) and a superior strength-ductility balance (ultimate tensile strength: 816.5 MPa, elongation: 49.5%). This work elucidates the systematic regulatory role of alternating layer thickness, providing a theoretical basis and practical guidance for designing high-performance gradient materials via LPBF.