Studies on Impact Extrusion (8th Report). On Cold Impact Extrusion of Brass

Abstract

A study on cold impact backward extrusion of 65/35 brass was carried out. The influence of various lubricants on extrusion forces, the extrusion force curves, and the corresponding physical properties of extruded shells were in detail examined. The experimental results were summarized as follows: (1) The effect of lubrication was almost similar both in static and impact extrusion. Lubrication with lanolin and zinc phosphate/wax or lanolin systems, etc. were proved suitable for the process. (2) Under these lubricating conditions, a specific force of about 200 kg/mm² was required for processing 20 mmφ shells with reduction of 53∼64%, and the limit of reduction was about 60% of these shells. (3) The impact extrusion force curves were almost analogous to the one in static extrusion. (4) The hardness distribution and the microstructure of the shells were studied. The extruding texture developed in the wall was in good agreement with the texture obtained by rolling. The residual stresses along the wall surface were determined. (5) In season cracking tests, the impact extruded shells might have too high resistance to form any crack on the wall.