IMPACT OF TIG WELDING ON THE STRUCTURE AND MECHANICAL PROPERTIES OF JOINTS OF PSEUDO-β-TITANIUM ALLOY

摘要

Structural pseudo-β-titanium alloys attract a lot of interest in fabrication of complex constructions for critical purposes. This alloy class includes alloys with the structure represented by one β-phase after hardening or normalizing from the β-region. The alloy weldability is an important factor at application of pseudo-β-titanium alloys in aircraft and rocket engineering. By their mechanical characteristics, the welded joints of modern pseudo-β titanium alloys should match the level of base metal mechanical properties. In this work, the impact of argon arc welding, as well as further heat treatment on the phase composition, structure and mechanical properties of welded joints of pseudo-β-titanium alloy was studied. It was established that as a result of the impact of thermal cycle of welding predominantly β-phase in the quantity of 77% is recorded in the weld metal of joints of pseudo-β alloy VT19. Application of VT1-00sv filler wire enhances the quantity of dispersed α-phase particles and reduces the quantity of β-phase in the weld metal to 60%, respectively. Annealing results in formation of a uniform, homogeneous finely-dispersed two-phase (α+β)-structure with tensile strength values of welded joints on the level of σ_t = 1010 MPa, that exceed the respective base metal values by 12%.