Graduate School

Project C2: Data transfer and upscaling through massive parallelization and efficient data management


Person in charge:  Dr.-Ing Leslie T. Mushongera

Motivation and goals:
The reported kinetic theories of pearlitic transformation assume a constant lamellae spacing and growth rate, which is a reasonable assumption for a steady-state evolution. However,  there are instances for e.g., formation of divergent pearlite, where the evolution is characterized by increase in lamellae spacing and simultaneous decrease in growth. In the C2 project, we perform large-scale simulations to  identify the regimes and thermodynamic conditions that induce anomalous divergence in some pearlitic alloys. To gain deeper insights into the anomolous diffusive mechanism, the numerical simulations are conducted for range of temperatures above lower Ae1 in Fe-C-Mn steels. The objective here is to develop of unified kinetic theory that also accounts for this fascinating non-steady evolution of pearlite.
Methods Results
  1. Application of a phase-field tool coupled to CALPHAD.
  2. Thermodynamics of the alloy system are obtained from TCFE8.
  3. Incorporation of ternary diffusion interactions via MobFe2 data.
  4. Systematic tailoring of alloy compositions using ThermoCalc.
  5. Elemental chemical composition and phase analysis.
  6. Quantification of lamellae spacing and kinetics.
  1. Pearlite divergence is observed inalloys with compositions falling in the austenite-ferrite-cementite three phase field.
  2. Mn contents inherited by pearlite during growth continually increased during growth.
  3. A continuous depletion of  C in austenite triggers divergence.
  4. The slow diffusion of Mn in austenite causes  depletion of C.
  5. Divergence prominent closer to lower Ae1 temperature.