Multi-phase transformation kinetics of HSLA steels during continuous cooling: experiments and cellular automaton (CA) simulation

ABSTRACT

Kinetics of multiply ferrite/bainite phase transformation of HSLA steels is investigated by experiments and cellular automaton (CA) simulation. Peak-differentiation method to elucidate the sequential ferrite and bainite phase transformation individually, which is verified by the CA simulation. Such CA modelling executed using classic JMAK theory, but also gives an insight of microstructure evolution of the multi-phase transformation routine on different cooling rate. From that, it enables classic JMAK modelling to capture the detached phase transformation with different growth models and interface-migration mechanisms. Also, we find that the final phase constitution is sensitive to the cooling rate. With increasing the cooling rate, bainite sheaves nucleated at prior austenite boundaries and ferrite/austenite interfaces are significantly facilitated, which seriously inhibits the growth of prior ferrites. The scenario can be interpreted by the CA simulation and the influence of the cooling rate on sequential multi-phase transformation can be also obtained.

KEYWORDS:

• Phase transformation
• ferrite
• bainite
• cooling rate
• cellular automaton

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financed by the National Natural Science Foundation of China (gran numbers U1660201 and 51975404), and the Project of Natural Science Foundation of Tianjin city (grant numbers 18JCQNJC03300 and 18YFZCGX00050) for grant and financial support.