The Study Of Technological Properties Of The Titanium Alloy Ti-6a1-4v. Part 2

This second part of the article describes the results of studies on technological properties (formability and solid state weldability) of sheet titanium alloy VT6 (Ti-6Al-4V) with improved superplastic properties at low temperatures. When studying the formability of the sheet blanks, the radius of curvature R and average thickness S in the spherical part of the formed samples were determined. The ratio R/S was calculated and represented as a function of the forming time. The presented dependences show that the values of the optimum angle of a conical matrix depend on the forming temperature. The alloy under study had a sufficient formability at temperatures of T = 750 and 800 degrees C corresponding to the temperature range of the low-temperature superplasticity effect. Studies of solid state weldability of sheet blanks made it possible to establish that with an increase in the welding temperature from T = 650 to 800 degrees C, the average grain size increased from 1 to 8 mu m, while the relative pore length in the zone of the solid-phase joint decreased from 0.21 at T = 650 degrees C to 0.04 at T = 800 degrees C. The mechanical shear tests of the welded specimens showed that the shear strength of the welded joints varied from 91.4 to 96.9% of the parent material strength depending on the welding temperature. The study of technological properties revealed that the titanium alloy VT6 could be successfully used in superplastic forming and diffusion welding (SPF/DB) technologies under conditions of low-temperature superplasticity at the temperatures of T = 700 - 800 degrees C. The effective fabrication of a hollow blade model of a threelayer corrugated structure supports this idea.