RELATIONSHIP OF ENERGY-DISSIPATION EFFICIENCY TO MICROSTRUCTURAL EVOLUTION IN HOT-WORKING OF AISI-304 STEEL

On the basis of dynamic materials, modeling maps of energy dissipation efficiency were evaluated for 304 stainless steel from synthesized st ress-strain curves over the ranges 900-1200 degrees C and 10(-3) to 10 (2) s(-1). The constitutive equations as well as the ductility and mic rostructural evaluation were determined from torsion tests; these resu lts were found to be in good agreement with the literature. High value s of dissipation efficiency are obtained in association with the occur rence of now curve peaks and flow softening resulting from dynamic rec rystallization. However, the efficiency associated with the same softe ning mechanism during steady state at high strains is fairly low. In c onsequence, it seems an inadequate parameter to define the mechanism o r to predict the ductility.