Welding of Zinc Ethyl Silicate Shop Primer Overlayed Plates Using Rutile Flux Cored Wire: The Coating Thickness Influence on the Process Stability and Weld Metal Properties

Abstract In certain sectors, such as shipbuilding and offshore, corrosion causes considerable costs by material loss and rework, making material protection by shop primer necessary to create a protective barrier. FCAW is widely used in these situations but its attributes are compromised when carried out over the protective layer. The comprehension of shop primer influence during welding and its relationship with the obtained results are not completely understood. This work aimed to verify the influence of ethyl zinc silicate shop primer thickness layers applied to steel plates during welding and on the weld metal and slag characteristics produced by class E71T1-C1A2-CS2 wire. The current and voltage monitoring was carried out during welding, the weld bead dimensions and microstructure were evaluated, and the slag generated was analyzed. Primer layer thickness increased weld bead width and penetration. The electrical parameters did not indicate changes in the arc. Dilution changes resulting from increased penetration did not impact the microstructure of the weld metal. Measurements of the bead contact angle and analysis of the slag together with the analysis of electrical signals indicated, by elimination, that the thickness of the shop primer layer was responsible for the change in the fluidity of the liquid metal.