Damage evolution during cross wedge rolling of steel DIN 38MnSiVS5

The study of variables which influence the formation of central cavities is a constant theme in recent works about Cross Wedge Rolling (CWR). Damage modelling typically used for analysis of cold forming processes, can also be useful for the study of critical conditions in hot forming processes. Varying geometric and process parameters, damage distribution provided important information about the conditions which favor the formation of defects in parts during manufacturing. Using the Hansel-Spittel's rheological law equation, it was studied the behavior of the microalloyed steel DIN 38MnSiVS5 simulated with the finite element method (FE). Tests were carried out in an equipment available at the Metal Forming Laboratory (MFL) to validate the adopted numerical models. In those tests and simulations the stretching angle was kept constant, and three variables were evaluated: forming angle, relative reduction and speed. For this microalloyed steel the high sulfur content associated with a high working temperature determined the formation of large central cavities in the rolled parts which could be also predicted in the simulations. (C) 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM11