SAW is a fusion welding process that utilizes an electric arc generated between a continuously fed bare filler wire electrode and the base metal, with the entire arc column and molten weld pool completely submerged beneath a layer of granular, fusible flux. When the welding power supply is activated, an arc is struck between the electrode tip and the workpiece surface; the arc’s high temperature (up to 6000℃) melts the end of the filler wire, the adjacent base metal surface, and a portion of the surrounding flux. The molten flux forms a liquid slag blanket that isolates the arc and weld pool from the ambient atmosphere, preventing oxidation and nitrogen absorption of the molten metal. As the welding carriage moves steadily, the molten filler metal mixes with the molten base metal to form the weld pool; simultaneously, the liquid slag floats to the surface of the weld pool, further protecting the weld metal during solidification. After cooling, the solidified slag layer is easily removed, revealing a smooth, uniform weld seam.

 

    - Granular Flux: Serves four core functions: atmospheric shielding (blocks O₂ and N₂), arc stabilization (ionizes easily to maintain arc continuity), deoxidation and desulfurization (contains active components like SiO₂ and MnO to react with impurities in the molten metal), and shaping the weld bead (the viscous slag constrains the molten metal flow to form a regular weld profile).

    - Filler Wire: Matched to the base metal grade (e.g., H08MnA for carbon steel, H10Mn2 for low-alloy steel) to ensure weld mechanical properties; continuous wire feeding enables uninterrupted welding and high deposition efficiency.

    - Power Supply and Welding Carriage: DC or AC power supplies are available—DC is preferred for stable arc and deep penetration, while AC reduces magnetic blow in large-scale welding. The automated welding carriage controls travel speed (typically 10–60 cm/min) and wire feed rate with high precision, ensuring consistent weld penetration and bead width.

 

    SAW achieves a deposition rate of 10–40 kg/h, 5–10 times higher than shielded metal arc welding (SMAW), thanks to continuous wire feeding and high allowable welding current (up to 2000 A for multi-wire SAW). Multi-wire SAW (tandem or twin-wire systems) further boosts deposition rates by 30–50% compared to single-wire systems, making it ideal for thick-plate welding and mass production.

 

    The slag and flux shielding eliminates arc spatter and reduces weld metal contamination, resulting in welds with low porosity, minimal inclusions, and uniform mechanical properties. The slow cooling rate of the weld pool, facilitated by the slag blanket, reduces the risk of cold cracking and improves weld toughness. Automated process control minimizes human error, ensuring consistent weld penetration and bead geometry across long weld seams (e.g., 10+ meter seams for ship hulls).

 

    The submerged arc eliminates intense arc radiation, ultraviolet rays, and visible light glare, protecting operators from eye and skin damage. The flux layer also captures most welding fumes, reducing airborne particulate matter and improving workshop air quality compared to open-arc welding processes.

 

    The high deposition rate reduces welding time and labor costs; the low spatter rate minimizes material waste (filler metal utilization rate exceeds 95%, compared to 60–70% for SMAW). The minimal post-weld cleaning requirement (only slag removal is needed) further lowers overall production costs.

 

    SAW is the primary welding method for ship hull plates (thickness 10–80 mm), deck structures, and offshore platform jackets. Its ability to weld thick plates in a single pass (or fewer passes) and form high-strength welds meets the strict structural integrity requirements of marine equipment.

 

    Used for welding cylindrical shells, head plates, and nozzles of carbon steel and low-alloy steel pressure vessels (operating pressure ≥1.6 MPa) and boilers. The low impurity content and high toughness of SAW welds ensure compliance with standards such as ASME Section VIII and GB 150.

 

    Applied in the construction of steel bridges, factory building frames, crane beams, and transmission towers. SAW excels in welding long, straight butt welds and fillet welds for H-beams and box-section columns, delivering high efficiency and structural reliability.

 

    Ideal for welding large-diameter (≥500 mm) oil and gas transmission pipelines and large-volume storage tanks (capacity ≥10,000 m³). The high welding speed and consistent quality ensure tight, leak-proof welds that withstand harsh operating conditions.

 

    Used for welding the underframe, side beams, and bogie frames of railway locomotives and freight cars, where high weld strength and fatigue resistance are critical for safe operation under heavy loads.