Dynamic Impact of High-Speed Cooling Gas Jet on Heat-Affected Zone

In the introduction the object of research is pointed – semiautomatic arc welding with a melting electrode of components from the low-carbonic steels in protective gas (GSMAW). Subject of study is determination of changing the welded joints mechanic characteristics depending on ways of managing of modes of steel components welding process, and determination of ways of controlling arc welding process of the steel components. Relevance of the research consists in study and practical application of active methods of control and managing arc welding process of low-carbonic steel components with consequent reduction of the heat effect at welded joints. The scientific novelty consists in the development of a method that allows the use of protective gases to control the cooling zone of the heat effect of the weld (namely, overheating and recrystallization areas), which differs from the known methods described in the patents of the Russian Federation and the United States by the fact that the cooling inert gas acts during the achievement in the zone of heat effect of peak temperatures after the formation of the weld and is directed from the welding against the movement of the welding torch, in order to influence the process of structural transformation of the base metal, occurrence of mechanical deformations, and visible zone of heat effect. The main part of the article presents the results of dynamic impact of cooling gas on the process of arc welding of steel components. The installation designed to create the dynamic impact of cooling gas on the welded joints is described. Pictures from infrared camera are presented, with which the location of dynamic impact was defined. Process of cooling was done with using jets with different size. The analysis of results shows the significant reduction of visible size of the heat-affected zone on the welded joints. Mechanic deformations are also minimized because of cooling the heat-affected zone. The consequence of cooling is decreasing the module of the inner tension value, also minimizing the relative offset, that improves the basing of components in the welded constructions. In conclusion, it is considered that the use of protective gas outside the welding zone, and in the heat-affected zone for cooling the base metal and controlling the process of phase transformations, reduces the visible heat-affected zone of welded components and their visible deformation