This study investigates the influence of substrate preheating on microstructure and wear resistance of LPBF‑fabricated H13 steel, focusing on surface degradation mechanisms. Raising preheating from 200 °C to 500 °C reduced retained austenite and promoted bainite formation, which increased hardness and wear resistance. Under low loads, tribo‑oxide layers provided protection; under high loads, strain hardening in the deformation layer dominated. The 500 °C preheated sample showed superior yield strength (1451 MPa) and oxidation resistance due to carbide precipitation. Post‑aging treatments further altered wear behavior: tempering at 550 °C for 4 h dissolved cellular structures, causing oxidative and delamination wear, while tempering at 500 °C for 8 h retained cellular structures, hindering crack propagation and reducing delamination, resulting in oxidative and abrasive wear. These findings establish clear processing–structure–property relationships, offering a basis for optimizing heat treatments to improve the surface durability of LPBF H13 steel for mold applications.

additive manufacturing