Synergistic Optimization of Composition and Processing for Flux‐Cored 316L Welding Wire with Enhanced Cryogenic Performance

Reliable cryogenic performance of welded joints is critical for the safety of liquefied natural gas storage and transport systems, yet conventional 316L flux‐cored wires often exhibit limited toughness due to ferrite embrittlement and oxide inclusions. In this study, the composition and processing parameters of flux‐cored 316L welding wire are synergistically optimized to enhance microstructural stability and cryogenic toughness. The primary ferrite solidification mode, stacking fault energy, and Md 3 0 parameters are calculated to guide alloy design, and welds produced under different heat inputs (12–20 kJ cm −1 ) are systematically evaluated at ambient and −196 °C. The optimized addition of deoxidizing and austenite‐stabilizing elements effectively reduce ferrite content and refine oxide inclusions, resulting in a homogeneous microstructure. Increasing heat input improves molten pool fluidity and inclusion flotation, yielding a 45.3 J average impact energy at −196 °C—≈45% higher than that of commercial wires. Microanalysis reveals complex MnSiCrO oxides, while cryogenic tensile testing confirms transformation‐induced plasticity behavior involving γ → ε → α′ martensitic transformation, which substantially enhances low‐temperature strength and ductility.