Scgwab S. Technology of argon-arc welding and restoration surfacing of titanium alloy VT22 using flux-cored wire and controlling magnetic field.

The thesis is devoted to the improvement of the filler flux-cored titanium wire for welding of the titanium alloy VT22, as well as the development of the technology of argon-arc welding and restoration surfacing of this alloy. It is shown in the work, that is necessary to use granules of the VT22 alloy as a metallic component in the core of a filler flux-cored titanium wire. With the use of this wire (PPT-22) for welding the alloy VT22, the weld metal of welded joints belongs to the transition class of titanium alloys, which includes the alloy VT22. It was established experimentally that the use of fluorides of rare-earth elements in a flux-cored wire leads to the refinement of β-grains in the weld, which in turn increases the impact toughness of welded joints by 30%. The regularities of the effect of the parameters of the external controlling magnetic field on the structure and shape of welds of the titanium alloy VT22 and the beads deposited on this alloy were determined. To improve the mechanical properties of welded joints of the alloy VT22, the heat treatment mode was established. As a result of annealing, the strength of the base metal, heat-affected zone and weld metal are on the same level. The use of the flux-cored wire PPT-22 as an additive in argon-arc surfacing provides a possibility of restoring worn-out surfaces of parts of the titanium alloy VT22 for the aircraft purpose with a high level of service characteristics. Based on the results of the carried out investigations, the filler flux-cored wire for welding of the titanium alloy VT22 was improved, and the technologies of argon-arc welding and restoration surfacing of this alloy were developed.