COMPUTER-CONTROLLED MEASUREMENT AND ANALYTICAL MODELING OF FLOW STRESSES DURING HOT DEFORMATION OF THE COPPER ALLOY CUZN42MN2

The increasing utilisation of FE-programs for the description and opti mization of hot forming processes (forging, extrusion etc.) has create d considerable demand for precise materials data of formability at hig h temperatures. The quality of the FE-simulations is highly dependent on the quality and reliability of boundary conditions data. Especially , data on now stresses versus strain, strain-rate and temperature are required. One of the applicable experimental methods is the upset test of cylindrical samples. In this work, a new high precision instrument called ''deformation dilatometer'' with a wide range of experimental parameter variations was used. The instrument is monitored and control led by a versatile computer software, which can create different tempe rature-time conditions under vacuum or inert gas atmosphere. Deformati on is accomplished under computer controlled, constant strain-rate. Th e reproduceability of the resulting flow stress curves is high, even a t small flow stresses. Experimental results of a copper alloy (CuZn42M n2) at different deformation temperatures and strain-rates were fitted to an analytical model describing the strain-rate-temperature depende nce of the flow stress. Finally, the analytical model will be used for the implementation of flow stress values in the newest version of the special purpose FE-program PressForm for the optimization of extrusio n manufacturing.