A study on the extent of ironing of EDD steel at elevated temperature

An experimental investigation has been carried out to determine the effect of extent of deformation (ironing) over the cup wall at elevated temperatures. Clearance between punch and die is varied to decrease the amount of deformation over the cup wall. The thickness distribution of the drawn cups at different temperatures and clearance is studied and it is found that even at elevated temperatures there will be a certain limit unto which clearance between punch and die can be decreased. For EDD steel sheet of 2 mm thickness this temperature appears after blue brittle regime in which material exhibits unusual strength. In this region punch load requirements increases which leads to necking at the punch corner and finally fracture in the initial stages of drawing operation. Upon increasing the clearance the quality of cups are similar to that in case of deep drawing operation. © 2010 CIRP.