Analysis of coupled mechanical and thermal behaviors in hot rolling of large rings of titanium alloy using 3D dynamic explicit FEM

Hot rolling of a large ring of titanium alloy (LRT) is a highly nonlinear incremental forming process with coupled mechanical and thermal behaviors (MTBs) which significantly affect microstructure and properties of the ring. In the study, a 3D coupled thermo-mechanical FE model of the process is developed and validated. Reasonable ranges of key process parameters are determined for successful simulation. Investigation and comparison are performed regarding the MTBs of LRTs with different blank sizes and the dependence of the MTBs on key process parameters using dynamic explicit FE simulation. The results obtained show that: (1) at the stable forming stage, along the radial direction of an LRT, the largest equivalent plastic strain (PEEQ) is found on the inside or outside surface, depending on the distribution ratio of feed amount. The smallest PEEQ appears in the middle layer. The highest temperature occurs in the interior of the inside or outside layer, depending on the mechanical behavior. The lowest temperature is found on the inside or outside surface, or on the end plane of the middle layer. (2) For LRTs with different blank sizes, effects of key process parameters on their MTBs are similar under different forming conditions, i.e., under the stable forming condition, a smaller n1, a larger v, or a higher T0 contributes to more uniform strain and temperature distributions.