Flow forming is a metal forming technique used to manufacture hollow cylindrical tubes with favorable mechanical properties and high surface finish quality. The current work is concerned with the effect of process parameters on ductile failure during the forming process. The process is simulated using commercial finite element solver Abaqus/Explicit, and a user defined field subroutine is developed for the implementation of damage into the finite element framework. Johnson-Cook plasticity model is used to define the constitutive behavior of 4340 steel alloy. Modified Mohr-Coulomb damage model is utilized, and it is extended to include temperature and strain rate effects. The model parameters are adopted from the literature. The effect of temperature on damage evolution is studied through three different modelling approaches. Incorporation of temperature related parameters into the constitutive framework changes both the maximum damage values and distribution of damage through the thickness. Furthermore, the effect of roller feed rate and revolution speed on damage is examined. It is concluded that the feed rate has a stronger influence on damage evolution than roller revolution speed. Increasing feed rate or revolution speed results in higher damage levels. However, under a constant ratio of feed rate to revolution speed, the damage is found to be insusceptible to increase in feed rate.