Cold tube PILGER mill process is one of the efficient seamless tube production methods. This method has many advantages, such as good surface quality and ability to produce long tubs. Developing micro-cracks in final tube is one of the serious challenges in this process. Numerous researches has been done to predict micro-cracks location and decrease cracks' number and length. Using finite element modeling in conjunction with damage mechanics is an important approach for this goal. In this work the main purpose is prediction of the micro-cracks location and investigating effects of process parameters on distribution of them by damage mechanic and finite element simulation. For this purpose three different damage models including Lemaitre model, modified Lemaitre model and cumulative damage model was used to predict initiation and growth of damage in this process. At first equations and finite element implementation of these three models were presented. Then VUMAT subroutines were provided for each of models and these codes were used by commercial finite element software ABAQUS. To validate provided codes they were used to simulate notched specimen tensile test, cold upsetting of a conical billet and tension-compression of a 3d notched bar and then results was compared with experimental observations. After this step, the cold PILGER mill was modeled in ABAQUS by use of VUMAT codes. Then some simulations has been done to investigate the effect of process parameters such as: friction coefficients between tools and tube, angle of tube rotation and tube feed rate on damage distribution. In simulations, two work hardening laws including isotropic and kinematic hardening were used. The results showed that Lemaitre model and cumulative damage model are not suitable for this process. It is also seen that increase in friction, increase in angle of tube rotation and decrease of tube feed rate cause increase of tubes damage. Key words: Cold pilgering process, Finite element modeling, Lemaitre model, Modified Lemaitre model, Cumulative damage model
