Effect of pro-eutectoid ferrite on subsequent bainite transformation kinetics simulation

Abstract

The kinetics of multiphase transformation is more complicated than single phase transformation due to the effects of prior phase transformation on the subsequent transformations. The authors have previously proposed a new method to estimate the parameters related to the isothermal kinetics of single phase transformation. This current paper investigates the application of the authors’ method to the bainite transformation process of multiphase steel G18CrMo2-6. The mathematical relationship between Pro-eutectoid ferrite (Pro-EF) fractions and the kinetics related parameters of the subsequent bainite transformation during heat treatment processes in the G18CrMo2-6 multiphase steel has been investigated. The results show the significant effect of Pro-EF fractions on the start and finish temperatures and the isothermal phase transformation parameters ‘ b’ of subsequent bainite transformation.

Investigating microstructural properties of ferrite/bainite dual-phase steel through simple process control

“…In recent years, it has been found that by incorporating the intercritical heat treatment procedure, which involves the holding at the twophase (α + γ ), the pre-formed ferrite accelerates the process of bainite transformation. Besides, the interfaces between the prior austenite and ferrite provide extra nucleation sites for the bainitic transformation [6,7]. The influence of the microstructure on the properties of the dual-phase steel cannot be ignored.…”