Improving mechanical properties of maraging steel by optimizing laser power in hybrid laser-arc directed energy deposition

Owing to its exceptional mechanical properties, Co-free maraging steel is extensively used in the aeronautic, shipbuilding, and military fields. Introducing a laser as a preheating source in the Arc-based Directed Energy Deposition (DED-Arc) for the self-developed, low-cost, Co-free maraging steel welding wire, utilizing the synergistic effect between the laser and the arc, to explore its potential in optimizing material properties. Among these factors, the selection and optimization of laser power are particularly crucial for enhancing material properties. This study aims to enhance the mechanical properties of maraging steel by optimizing laser power using hybrid laser-arc directed energy deposition (HLADED) technology, combined with a deposition strategy that incorporates forced interlayer cooling. The macro-morphology, microstructure, and mechanical properties of thin-walled structures fabricated under different laser powers were systematically analyzed. Results indicate that laser oscillation facilitates grain refinement, with grain size initially decreasing and then increasing as laser power increases from 0 to 1000 W. Both ultimate tensile strength (UTS) and microhardness exhibit an initial increase followed by a decrease. Notably, at a laser power of 750 W, better surface quality and microstructural refinement were achieved, resulting in an average grain size of 13.53 μm, UTS of 1293.2 MPa, and microhardness of 413.5 HV. However, excessively high laser power (1000 W) leads to grain coarsening and increased austenite content, thereby reducing the material's strength and hardness. This study provides a novel strategy and theoretical guidance for the additive manufacturing of maraging steel.