Assessment of deposition strategy and overlap in laser-directed energy deposition of H13 tool steel

Laser-directed energy deposition (L-DED) is a highly versatile additive manufacturing technology that supports both the fabrication of near-net-shape components and the repair of critical parts, thereby extending service life, enhancing material utilization, and reducing overall production costs. These advantages are particularly significant in die and mold applications, which demand materials capable of withstanding severe thermal and mechanical loads. In this context, AISI H13 hot-work tool steel is among the most widely adopted materials due to its superior hardness, wear resistance, and thermal stability, making it an ideal candidate for L-DED technology. The present study aims to comprehensively investigate the influence of deposition strategy, overlap distance, and two sets of laser power, powder-feed rate, and scanning speed on the quality of L-DED H13 single-layer depositions. A systematic evaluation of surface waviness, microhardness, microstructure, and defects was carried out. The findings indicate that an overlap of 60% results in the least waviness, while the implementation of a unidirectional scanning approach enhances surface uniformity by approximately 25% compared to a bidirectional strategy. Microhardness values up to 720 HV were achieved, exceeding those of conventionally manufactured H13. The findings highlight process windows that enable defect-free depositions without substrate preheating, providing practical guidelines for optimizing L-DED of H13 tool steel components.