Optimization of the horizontal overlap step of AWS A5.9 ER385 (904L) weld overlay deposited by MIG-VP

The application of coating by electric arc processes is widely used in the oil and gas, offshore, and large-scale metallurgical fields for the recovery of components and surface protection against corrosive and abrasive atmospheric environments. Cost and process efficiency are important indicators in large-scale industrial applications, along with ensuring quality in coating deposition. Mechanical and metallurgical properties, as well as morphological characteristics, depend not only on welding parameters but also on correct overlap between them. Studies aimed at investigating input variables to achieve optimized horizontal overlap between layers are increasingly common in the literature, as the search for an efficient process with better cost-effectiveness, less material waste, and that meets minimum regulatory quality requirements is extremely important. Therefore, this study aims to quantitatively investigate the minimum percentage value of bead width for horizontal overlap of coatings deposited via electric arc. To this end, a Box-Behnken design of experiment and optimization via the "desirability" method for a single bead was conducted, followed by a study of the ideal degree of overlap for theoretical overlaps of 5%, 15%, 25%, and 35% of the optimized bead width. The results showed that it is possible to achieve an overlap of approximately 23% of the optimized bead width at the minimum levels of welding speed and weaving amplitude, with maximum weaving frequency within the design experiment limits, leading to lower discard area values, with a total average dilution of the overlapped layers of 7.2%. The average experimental error regarding the total width of the overlapped beads, for theoretical and experimentally obtained overlap values, was approximately 3%.