The installation and renovation works of steel structures are often performed using gas metal arc welding. Thereby, the welded elements of these structures are frequently protected by a variety of primers and coatings, especially in shipbuilding. Complex nonequilibrium physical and chemical processes occurring under the influence of high temperatures and electric arc discharge, as well as the presence of the products that affect the welding parameters, have a significant impact on the joints’ quality. Experimental studies on the coatings’ breakdown products influence on the gas metal arc welding parameters were performed with epoxy, alkyd, polyacrylate, polyvinyl butyral primers, epoxy zinc filled, vinyl chloride, vinyl isobutyl, and organosilicate coatings. The peculiarity of welding current waveform parameters was studied using oscillograms processing. It was found that the main coatings breakdown products that influence the current waveform are oxygen and carbon monoxide.

A technology of metal modification with carbon nanotubes (CNTs) is developed using electric arc surfacing. It involves the use of extruded metal rods containing CNTs as a deposited material. This technology is used to modify an AMg5 alloy. A comparison of the macro- and microstructures of the metal modified by the developed technology by adding CNTs and the corresponding unmodified metal does not reveal a significant difference. However, CNTs are detected in the modified metal using scanning electron microscopy, and microhardness analysis shows that the addition of CNTs increases the microhardness of the upper layers of the deposited metal.

The construction assembly and the repair of steel constructions painted with protective coatings are often carried out using arc welding. During the welding process, the coating in the weld zone is degrading. The protective coatings breakdown products are involved in the pore and non-metallic inclusion formation in the weld, the composition and distribution study of which makes it possible to analyze the reactions occurring during the welding. In this study, welding beads were deposited on the coated sheet surface by MAG welding. The distribution of inclusions (the average diameter and the relative content) along with the porosity in different bead zones were investigated by optical and scanning electron microscopy and digital image processing, and the chemical composition of inclusions was determined using energy-dispersive X-ray spectroscopy. The amount of diffusible hydrogen in the deposited metal was estimated with the vacuum method. In this work, four organosilicate coatings grades, differing in their purpose and heat resistance, were used, and their effect on the weld was studied.