Laser directed energy deposition and welding of a high-strength low-alloy steel for hybrid manufacturing in civil construction

Additive manufacturing (AM) is emerging as a transformative technology in metal components production industries, mainly due to its design flexibility and reduced material wastage. Among various AM techniques, Laser Beam based Directed Energy Deposition (DED-LB) enables the fabrication and repair of large metallic components with excellent metallurgical bonding and geometric precision. However, despite its increasing use in aerospace, automobile, and marine industries, the application of DED-LB in civil construction, especially for structural high-strength low-alloy (HSLA) steels remains largely unexplored. This study represents a systematic investigation on process feasibility, productivity and mechanical integrity of DED-LB fabricated HSLA. Furthermore, for a sustainable process, powder recyclability and its influence on deposition quality as well as mechanical performance was also analyzed. To further establish DED-LB as a suitable technique for hybrid manufacturing of large-scale construction components, hybrid manufacturing i.e. DED-LB as well as weldability of deposited HSLA steel by utilizing same deposition head was also investigated. The optimal process parameters combination produced fully dense, high-quality samples with a productivity of 410 g/h and a powder catchment efficiency of 76%. The deposited HSLA steel also exhibited robust tensile performance i.e., approx. 550 MPa yield strength, 790 MPa ultimate tensile strength, and 12% elongation, comparable to conventionally processed construction grade steels. Recycled powder though resulted in dense deposition but a substantial reduction in strength was observed. Good weldability with full penetration at low spot size and higher speed was also observed.