Abstract <p>Submerged Arc Additive Manufacturing (SAAM) despite being less explored, is a promising technique for the efficient and cost-effective fabrication of bulk structures with high deposition rates, enhanced surface finish, and the capacity to work with large structural components. However, thermal accumulation between the subsequent layers strongly affects the microstructural and mechanical performance. In this study, the effect of inter-layer time delay on microstructural evolution and mechanical performance of SAAM-fabricated EL8 low-carbon steel is investigated. A clear transition from columnar to nearly equiaxed grains was observed by increasing the interlayer delay time. The evolution occurs due to variations in heat distributions across the sample and solidification conditions. An increased interlayer delay reduces the thermal accumulation, thereby modifying the effective cooling conditions and promoting a refined grain structure. An intermediate inter-layer time delay resulted in a more refined grain structure, improved surface finish, and increased mechanical properties, whereas excessive inter-layer delay time caused over-cooling, porosity, and inclusions, which reduced the mechanical properties. This study reveals that low carbon steel (EL8) holds promising features for large-scale additive manufacturing with homogeneous mechanical properties.</p> Graphical abstract <p>figa</p>