<p>This study explores the gas metal arc welding (GMAW) process to manufacture bimetallic 316L and low-carbon steel (LCS). The microstructure and mechanical properties of as-printed 316L, LCS, and the bimetal were analyzed. The primary objective was to develop a material that enhances mechanical properties while preserving corrosion resistance, making it suitable for deployment in harsh marine environments. It can be used in ocean engineering components such as offshore platform supports, ship propulsion shafts, and seawater pipelines. Multi-scale characterization techniques, including optical microscopy (OM), scanning electron microscopy (SEM), electron back-scattering diffraction (EBSD), and x-ray diffraction (XRD), revealed clear gradient transition characteristics at the bimetallic interface. The thickness of the elemental diffusion zone was approximately 30 μm, with no cracks and only minimal porosity defects observed at the interface. Microstructural analysis indicated that the 316L side primarily consisted of coarse columnar austenite grains, whereas the carbon steel side exhibited acicular ferrite and Widmanstätten structures. Near the interface, a small amount of martensite phase formed due to Cr and Ni diffusion. XRD analysis confirmed that the interface region was predominantly composed of an α-ferrite (BCC) matrix and residual austenite (FCC), with no intermetallic compounds or brittle phases detected. Tensile test results demonstrated that the developed bimetallic material achieves a tensile strength of 803.8 MPa and elongation of 40.4%, outperforming conventional WAAM materials (502.3–560.3 MPa, 21.4–33.5%) and CMT-produced materials (478.1 MPa, 11.3%). Hardness tests showed the bimetallic structure has good strength. By adjusting processing parameters and implementing an interlayer cooling approach, the stress concentration at interfaces due to mismatched thermal expansion coefficients of dissimilar materials was significantly reduced.</p>