Material formability at upsetting by cylindrical and flat dies

Abstract

Upsetting processes belong to the class of elemental bulk metal forming operations. Many multi-stage cold or hot bulk metal forming processes include upsetting as one of the operations. In most of upsetting processes, billets of simple cylindrical or prismatic shape are deformed between flat or profiled dies. Upsetting processes can also be used to determine the limit strain as well as the forming limit diagram (FLD). The present paper investigates material formability in cold upsetting of billets with different geometries by using cylindrical and flat dies. Experimental results are integrated into the forming limit diagram of steel C45E. The latter is first obtained using results from several conventional tests such as cylinder upsetting between flat dies, torsion test, collar test, and Rastegaev upsetting test. Stress components are found by means of the deformation theory of plasticity. Using new experimental results the influence of history of deformation on material formability is analysed as well. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.