Structural-phase state and mechanical properties of β titanium alloy produced by rotary swaging with subsequent aging

Abstract

The structure and phase composition of β titanium alloy Ti-15V-3Cr-3Al-3Sn-1Zr-1Mo processed by rotary swaging with subsequent aging was studied using the methods of EBSD, scanning and transmission electron microscopy, and X-ray diffraction analysis. It was found that the treatment leads to the decomposition of deformed supersaturated β solid with the precipitation of a lamellar α/α" phase with a volume fraction of up to 20 % and the thickness range from 7 to 35 nm depending on the aging temperature. The study of mechanical properties showed that rotary swaging at 800 °C and subsequent aging at a temperature of 420 °C for 10 h leads to an almost twofold increase in the ultimate strength of the alloy from 800 to 1550 MPa while maintaining satisfactory ductility (∼ 4 %). An increase in the aging temperature to 450 °C leads to a decrease in the strength characteristics of the alloy due to the coagulation of α/α"-phase precipitates and a decrease of internal stresses in the β phase. The results obtained create good prerequisites for the application of the treated alloy, including in aerospace industry.