Abstract
In industrial practice of bulk forging, e.g. extrusion, abrupt changes in strain rate during material’s deformation occur. For accurate prediction of the material flow during a forging process and characterisation of the plastic deformation, the experimental investigation of the effect on the transient change in strain rate (CSR) on plastic material flow behaviour is necessary. The present paper deals with an investigation of this effect on the flow stress of an AD 31 aluminium alloy, ordered to the Al-Mg-Si aluminium alloys system, during its deformation within the temperature range of 300 – 510oC. During continuous uniaxial compression loading of a cylindrical specimen, the strain rate was abruptly increased or decreased from its initial value at engineering strain of ~35 %. The results of the experimental investigations were used to determine the isothermal flow stress-strain curves of the AD 31 alloy. On the basis of these curves, the strain rate sensitivity index m as a function of true strain as well as temperature was determined.