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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 finite element model was developed to determine the temperature distribution in the preheating phase of the friction surfacing (FS) process. In the present study consumable rod was used as a tool. As a model of the heat source, a model applicable to the traditional friction stir welding (FSW) was used. The developed model has been validated by a full-scale experiment. Temperature fields were obtained for different modes of the FS process, where the variable parameters were the axial force and the speed of rotation of the consumable rod. The difference between calculated and experimental data is less than 10%. Influence of the axial force magnitude on the consumable rod and the rod rotation speed on the temperature field generated by friction and plastic deformation of the consumable rod was established.