Elasto-plastic bending behavior of Ti–6Al–4V alloy under coupling conditions of elevated temperature and combined tension-bending

Overload failure under coupling conditions of elevated temperature and combined tension-bending (CTB) is one of the typical failure modes of aero-engine low-pressure compressor blade materials, which is commonly occurring in fighter engines performing low-altitude high-speed penetration missions. In this study, the elasto-plastic deformation behavior and fracture mechanism of Ti–6Al–4V titanium alloy under coupling conditions of elevated temperature and CTB were investigated by experiments and finite element analysis (FEA). CTB tests were conducted on Ti–6Al–4V alloy in the pre-tension ratio range of 0.60–0.90 and in the temperature range of 298 K–573 K. The results show that the maximum bending load, effective bending modulus, and total energy dissipated for the Ti–6Al–4V alloy at room temperature increase with the increase of the pre-tension ratio. The maximum bending load and the energy dissipated are significantly higher at elevated temperatures compared to that of room temperature, due to the elevated temperature induced deformation mode change from bending-dominated to tensile-dominated. The FEA results are in good agreement with the experimental results. SEM fractography indicated that the Ti–6Al–4V alloy fracture at elevated temperature showed only equiaxed dimples, which exhibited a tensile fracture mode. This study is valuable for the in-depth understanding of the deformation behavior and fracture mechanism of blade materials under elevated temperature and complex loads.