Laser additive manufacturing for infrastructure repair: A case study of a deteriorated steel bridge beam

As our transportation infrastructure ages, its deterioration is becoming a growing concern. Rapid and effective methods for repair can reduce the need for time- and cost-intensive replacement of structures such as roadway bridges. In this work, laser-based additive manufacturing (AM) was developed for the repair of damaged beams in steel bridges. A corroded structural beam of low-carbon A36 steel was selected for this case study and 316L stainless steel was used for repair due to its excellent mechanical properties and corrosion resistance. Simulated repair experiments were performed on specimens extracted from the beam, and prepared with various groove shapes (Rectangular, Trapezoidal, and U-shaped). More in-depth parametric and microstructural studies were carried out with a series of U-shaped specimens repaired with the linear laser input energy varied from 19.5 to 30.0 J mm–1. The tensile properties of the repaired specimens and interface structures were also investigated in detail. It was found that the repaired specimens had a slightly higher tensile strength despite a reduction in tensile elongation compared to the A36 steel base metal. The influence of interfacial microstructure and heterogeneity on the mechanical properties of the repaired specimens was discussed. Our work suggests the promising potential to employ AM for structural repair and provides fundamental insights into processing-structure-property relationships in laser AM-repaired materials.