Die service life is one of the important factors in influencing the forging cost.The die stress distribution is simulated by using elasto-plastic finite element model.Based on the local stress and strain method

the die stress distribution is calculated from three process factors

which are the addendum transition arc of tooth die

the forming velocity and initial die temperatures

the influence lawof these process factors is analyzed.From the simulation results

tooth die stress concentration positions are located in the tooth tip and tooth toe of tooth die

and it is the main failure mode.As to the addendumof tooth tip

the die service life is directproportional to the three process factors

to the dedendum of the tip and toe

the die service life is reverse proportional to the mentioned process factors.The method of prediction die service life concerned in this research provides technical reference in mass production.