Micromechanical modelling of constitutive behavior of austempered ductile iron (ADI) at high strain rate

In this work, the uniaxial stress-strain response of austenitic ductile iron at high strain rate has been investigated. Traction tests were performed at low (0.001/s) and high rates (740/s and 1200/s) at RT and low temperature. Results showed that the strain rate has a considerable effect on work hardening and ductility. The work hardening seems to be the result of the competition of ferrite and retained austenite behavior under varying combinations of temperature and strain rate. The strain rate was found to increase the material failure strain. Numerical simulations performed with unit cell model indicated that this effect could due to strain localization along inter-spheroids ligaments supported by thermal softening.