Failure form and cause of hot forging combination-die kick-out for bearing ring blank

The kick-out (KO) of hot forging combination-die with high temperature and high frequency of impacting was the consumable key part,it directly bore the impact load by the hammer head,constrained the plastic flow of hot blank within the die cavity and kicked out the as-formed bearing blank. In the forming process, the surface material of the kick-out underwent large compressive strain-recovery, cyclic thermal fatigue of high temperature heating-water cooling, annealing softening of high temperature heating, skinning of surface high temperature oxidation, and plastic flow of billet on the surface,which made the kick-out fail at an early stage. The analysis of failure behavior and formation mechanism of kick-out could provide theoretical support for prolonging the service life of hot forging die.