Technological Features of Selection of Parameter Values of Arc Welding Mode in Shielding Gas Mixture Ar + CO2

 Gas-shielded arc welding today occupies a leading position among the methods for producing permanent joints in industrial conditions. The emergence of new materials with complex alloying and hardening systems makes carbon dioxide, traditionally used as a protective medium, inefficient for use. One of the effective ways to solve these problems is to change the composition of the protective gas atmosphere, which allows you to significantly change the physical and metallurgical processes of melting the electrode wire and the forming the weld. At the same time, the transition to the use of protective gas mixtures based on argon is usually carried out without understanding the essence of the technology and possible problems associated with the specifics of penetration of the base metal, which can cause a number of serious problems. The present paper describes important regularities between technological characteristics of  arc welding  in a shielding gas mixture Ar + CO2 and welding mode parameters under conditions of deviation of their values from the most effective ones in order to ensure the stability of the processes of electrode metal transfer and the formation of the deposited weld metal bead. On the basis of experimental data, the most probable causes of the appearance of a dangerous and difficult-to-detect defect in the formation of a welded seam in the form of non-fusion between individual beads of the deposited metal and along the fusion line with the base metal of the welded parts have been established. The defect is common and can cause unpredictable failure of the welded joint without visible plastic deformation. Empirical dependences for determining values of the main parameters of the welding mode are proposed as well. Important regularities have been established that make it possible to increase the efficiency of arc welding technology in the environment of protective gas mixtures in the conditions of domestic production.