Effects of initial microstructure on the earring of aluminium alloys cartridge case

Defects obtained during impact extrusion of EN AW-5754 aluminium alloy during cartridge case production were investigated. In cartridge cases produced from the one metallurgical heat pronounced tendency to earing after impact extrusion observed/appeared. On the other hand the earing in cartridge cases from the other heat was not observed. Presence of earing is due to local difference in materials flow during extrusion. This behaviour is atriduted to dfference in second phase particle distribution in used preforms (slugs).