The author considers gas-dynamic influence upon microhardness and weld configuration of single-pass welds from steel 30HGSA when welding with consumable electrode under double-jet shielding. The relations to the chosen controlled welding parameters (Q, L, I) are developed and the controlling influence of the gas-dynamic affect of dynamic shield gas jet over formation of welds from alloy-treated steel 30HGSA is determined.

The paper considers the ways of weld geometry controlling when consumable electrode welding under single-jet and double-jet gas shielding. The authors provide comparative results of experimental studies on the effects of shielding gas supply upon the weld geometry in weld joints produced from construction carbon steel 45. It has been established that gas-dynamic effect of the shielding gas has a significant impact upon shaping and weld geometry when consumable electrode welding under double-jet gas shielding.

Chemical composition of weld metal and properties of a joint weld are dominated by the processes occurring in the drop of molten electrode metal and in metal of the weld pool. Under certain conditions in consumable electrode welding with jet gas shielding the drop of electrode metal is influenced significantly both by main forces and the force of gas-dynamic impact of the shielding gas jet. The results of research have revealed that changing rate of shielding gas flow on the nozzle section influences the processes taking place in the welding area. There are changes in the transfer frequency of electrode metal drops and chemical composition of weld metal.

The effect of side limiters (shaping blocks) on the formation of the structure and hardness of AISI 308LSi stainless steel workpieces obtained by multilayer build-up welding in an argon environment has been studied. The studies were carried out on specimens deposited using graphite limiters, copper limiters and without limiters. As a result of numerical simulation, it was found that the lowest temperatures of the specimen metal are observed when using copper limiters, and the highest when using graphite limiters (different thermal conductivity of materials) in comparison with the temperatures of the specimen obtained without limiters. With the use of graphite limiters, most of the specimen’s metal is in the temperature range of austenite formation (45%) and a more uniform growth of structural elements is observed, without sharp transitions between the deposited layers, in contrast to the other two types of specimens. The high value of the thermal conductivity of copper leads to an increase in the difference in the size of the dendrites between the central and peripheral side parts of the deposited specimen. The highest values of hardness are observed in the specimen obtained using graphite blocks, due to the more active diffusion of δ-ferrite into austenite by an average of 12%, compared with the other investigated specimens, despite the overall increase in size dendrites. The technology of electric arc multilayer build-up welding with the use of shaping graphite blocks makes it possible to produce a workpiece with a uniform structure and properties. The above makes it a promising direction in electric arc additive manufacturing.

The paper reports findings of the study on influence of changing active shielding gas flows on consumable electrode welding and manganese content in the weld metal. A procedure to predict manganese content in the weld metal according to the velocity of a shielding gas flow, manganese content in electrode wire and base metal is proposed. A regression dependence of manganese content in the weld metal on the velocity of active shielding gas flow from the nozzle is determined.