Computational simulation and Atomic scale investigation of two-step bainitic phase transformation kinetics in high carbon steel 100Cr6

摘要

In the present work,two-step heat treatment is stressed and an overall kinetics model is implemented to describe bainite transformation in high carbon steel DIN 100Cr6.In the kinetics model,the classical theory for nucleation is adopted and a simplified formulation of Trivedi equation for bainitic ferrite growth is applied,assuming para equilibrium at γ/αB interface.Bainite transformation kinetics hereby is described as a function of isothermal holding time and temperature.The calculated and experimental results show good agreements.Moreover,in order to better understand the nature of bainite transformation,atomic investigations are performed using Local field Electrode Atom Probe (LEAP).The atomic analysis results experimentally indicate that the nano cementite in lower bainite structure precipitates under para equilibrium condition.Substitutional elements,i.e.Cr,Si,Mn,distribute homogeneously in bainitic ferrite matrix and nano cementite.