Dynamic recrystallisation in aluminium alloyed hypereutectoid steels under hot working conditions

Abstract

Hot deformation behaviour of hypereutectoid steels (0.83-0.92%C) alloyed with 0-2%Al is investigated. Compression tests were carried out in the temperature range 1000-1100 degrees C at 0.1-10 s(-1) strain rates. The stress-strain curves are analysed using work hardening rate flow stress plots to determine the critical and peak stress and the corresponding strains associated with dynamic recrystallisation. The addition of Al increases the strain hardening rate and lowers the peak strain. There is an optimum content beyond which peak strain increases with Al addition. Phase diagram calculations show that the multiphase microstructure present during deformation is responsible for the non-linear effect of Al. The steady state stress is modelled using the sine hyperbolic constitutive equation, and the activation energy for deformation is determined.