Damage growth prediction in seamless tube manufacturing by cold three-roller tube rolling process

Cold tube rolling process is one of the current seamless tube manufacturing methods. One of the serious problems of this process is micro-cracks in final product. Numerical modeling is a method to predict and reduce these micro-cracks. In the current paper damage in cold three-roller pilger process is simulated by finite element method. In these simulations to predict damage evolution three different damage models, including Lemaitre model, modified Lemaitre model and cumulative damage model are used. In conjunction with these models isotropic and combined hardening rules is also considered. Forming benchmarks are simulated to validate provided codes for the mentioned models. Then the process is simulated and good agreement is observed between current results and previous numerical and experimental results. The results show that three models correctly predict damage distribution but predicted damage by Lemaitre model is more than modified Lemaitre model due to ignoring crack closure in compressive loads. It is also concluded that using combined hardening rule predict damage growth less than using isotropic hardening. all of the models suggest that crack initiation take place in the outer surface of the tube.