FE modeling of a complete warm-bending process for optimal design of heating stages for the forming of large-diameter thin-walled Ti-6Al-4V tubes

Warm rotary draw bending (WRDB) of large-diameter thin-walled (LDTW) Ti-6Al-4V tube is a multi-nonlinear thermo-mechanical coupled process. Due to the high-cost, energy-wasting and long-term, the traditional physical experiments based on "trial and error" are no longer suitable for the WRBD process. Considering the non-uniform local heating and multi-tool constraints, a thermal-mechanical coupled 3D FE model of complete WRDB process for LDTW Ti-6Al-4V tube is established on ABAQUS as heating-bending-unloading three-stage. The FE models could predict the overall temperature distribution, describe thermo-mechanical bending deformation considering a modified Johnson-Cook model, and simulate the heating-bending-springback-cooling process. On that basis, the temperature distributions on both tube and dies under various heating schemes are compared, and the optimal heating scheme is determined on the basis of forming quality and efficiency. Combined with the experiments of WRDB, the optimal heating scheme and the established FE models are verified. In conclusion, the FE simulation provides a replacement of physical experiment and a convenient method of deformation prediction for WRDB of LDTW Ti-6Al-4V tube.