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5.5 mm high-strength welding wire steel ER55-D2-Ti rods during drawing caused by excessively high tensile strength， a systematic synergistic optimization of residual element control， steel cleanliness improvement， and controlled rolling and controlled cooling processes was conducted under full scrap electric arc furnace conditions. By establishing a precise scrap charging model and optimizing refining and RH vacuum degassing processes， the contents of Sn， As， and Sb were controlle withind 0.035%， 0.004 0%， and 0.002 0%， respectively. Meanwhile， the oxygen content in molten steel was decreased to below 15 ppm， and the type A inclusion level was controlled below 0.5. In addition，by adjusting the on-line cooling i

ntensity，the laying temperature was narrowed to 800 ℃–815 ℃， and the cooling rate was reduced， thereby prolonging the ferrite phase transformation process. After the synergistic process optimization， the microstructure of the welding wire steel transformed into a dual-phase structure consisting of ferrite and granular bainite， with the ferrite volume fraction increasing from approximately 10% to about 40% and a pronounced grain refinement. The average tensile strength of the wire rod decreased by 115 MPa， while the strength variation within the same coil was reduced from 93 MPa to below 50 MPa. Consequently， the drawing performance of welding wire steel rods was improved ，wire breakage during drawing was significantly alleviated， and the welding spatter rate decreased from 4.78% to 1.33%. The results demonstrate that the coordinated regulation of chemical composition， steel cleanliness， and thermo-mechanical processing effectively enables the synergistic optimization of microstructure and mechanical properties of high-strength welding wire steel， providing an efficient technical pathway for stable production and quality improvement under full scrap electric arc furnace conditions.