Damage Evolution During Thread Rolling of TC16 Titanium Alloy Using Coupled Johnson-Cook Constitutive and Damage Models.

In this work, a coupled Johnson-Cook (J-C) constitutive and damage modeling framework was established to investigate damage evolution during thread-rolling of TC16 titanium alloy. The J-C constitutive parameters were calibrated through tensile tests under different strain rates and temperatures, while the stress-triaxiality-dependent damage parameters were identified using specimens with different stress states. A finite element model of two-die radial thread rolling for MJ6 × 1 threads was developed using ABAQUS/Explicit. The mechanical response of the model was evaluated by comparing the numerically predicted and experimentally measured fracture displacements, with a maximum relative deviation of 7.63% in fracture displacement. The calibrated framework was subsequently applied to analyze stress distribution, plastic deformation localization, and damage evolution during the thread rolling process. The results indicate that damage accumulation is mainly concentrated at the thread root and the transition region between the thread flank and root. The damage of the thread can be attributed to the combined effects of high equivalent plastic strain, stress concentration, and an unfavorable stress state. The predicted damage localization agrees well with the experimentally observed fracture region under the investigated rolling condition. These findings demonstrate the applicability and limitations of the coupled Johnson-Cook constitutive damage framework for analyzing defect evolution in complex forming processes.