The microstructure of high manganese TWIP steels produced via simulated direct strip casting

Abstract

Three TWIP steels based on the composition Fe-23Mn-3Si-3.3Al with different carbon concentrations were examined. The alloys were produced by rapid solidification in an experimental apparatus designed to simulate direct strip casting conditions. Examination of the driving force for solidification for this alloy showed the preference for BCC and FCC solidification were very close for this composition, within 10% of one another. This factor combined with the high undercooling resulted in the change in the primary solidified phase. Chemical analysis of the as-cast strip showed inter-dendritic segregation of Si and Al, but negligible segregation of Mn. A simple heat treatment was sufficient to chemically homogenise all alloys and produce microstructures comprising a fully austenitic structure, consistent with thermodynamic predictions.

KEYWORDS:

• TWIP steel
• strip casting
• rapid solidification
• microstructure
• phase transformation
• driving force
• homogenization treatment
• thermodynamic predictions

Acknowledgement

We would like to acknowledge the assistance of Dr Christiane Schulz, Dr Anthony Rocissano and Mr Andre Hatem with the provision of helpful discussions, and we also note the invaluable help of Mr Dave Gray and Dr Adam Taylor with the casting experiments.

Disclosure statement

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

Additional information

Funding

The work has been carried out at Institute of Frontier Materials (IFM) Deakin University, Geelong, Australia and was funded by Universiti Tun Hussein Onn (UTHM) and Malaysia Ministry of High Education. The work was also partially financed by Deputy Vice Chancellor Research.