Process parameter development for the production of thin walls made of maraging steel X3NiCoMoTi18-9-5 processed by Laser Metal Deposition

This study investigates the fabrication of thin walls made of maraging steel M300 (X3NiCoMoTi18-9-5) using Laser Metal Deposition (LMD), a powder-based additive manufacturing (AM) process. LMD enables the production of high-density components with complex geometries. For tool steels such as maraging steel, which is distinguished by its exceptional mechanical strength, the optimization of process parameters is essential to attaining the desired material properties while minimizing defect formation. The inherent high strength of M300 in the as-welded state, when combined with its capability to achieve a tensile strength of approximately 2,000 MPa through artificial ageing, facilitates the fabrication of components with reduced wall thicknesses [1]. Additionally, the tool steel’s low distortion properties further enhance its applicability in precision manufacturing. The aforementioned properties render this type of steel especially well-suited for lightweight construction applications. One example of the application of these materials is the aviation sector, where reducing the weight of components can save fuel and therefore CO 2 emissions [2]. This study aims to identify process parameters for producing uniform-thickness thin walls over their entire height according to the geometry designed. These parameters subsequently form the basis for thin-walled structures such as honeycomb structures on existing components (e.g. stiffening ribs). A preliminary process window for thin wall production was systematically delineated in a parameter study using the single bead deposition method. However, various issues were encountered during the investigation. For instance, it was found that the construction of the wall at a high scanning speed of 1,000 mm/min led to defects that could not be avoided even by adjusting several parameters like laser power, layer height and material supply. Furthermore, an excess of laser power resulted in an unstable weld pool. Defects such as lack of fusion occur in the lower welding layers, but these can be largely eliminated by adjusting the laser power depending on the construction height and by adjusting the scanning speed.