Effect of feeding length on deforming behavior of Ti-3Al-2.5 V tubular components prepared by tube gas forming at elevated temperature

In order to investigate the deforming behavior of the tubular components with a large expansion ratio fabricated by tube gas forming technique, the Ti-3Al-2.5 V tubular components with 50 % expansion ratio were studied under the forming conditions of internal pressure and axial feeding at 800 °C. Through thickness measurements, EBSD and tensile tests, the effects of axial feeding on deforming behaviors, such as thickness distribution, microstructure, and mechanical properties of Ti-3Al-2.5 V tubular components, were investigated in details. The results showed that the average thinning ratio of the bulging area could be reduced significantly and the thickness distribution of the workpiece was more uniform with increasing of the feeding. Feeding length influenced the microstructure and strength of components. When the axial feeding ratio (actual feeding length/theoretical feeding length) was 56 %, the component had even higher tensile strength than the original tube because of the grain refinement. If the axial feeding was excessive large, the grain size became adversely coarser, which in turn reduced the tensile strength. These investigations illustrated that tube gas forming under high pressure had potential for fabricating complicated shaped titanium alloy tubular components by reasonably designing and controlling the deforming process.