Grain growth behaviour on reheating Al–Nb-containing steel in the homogenised condition

ABSTRACT

Grain size development during reheating is important to the mechanical properties of steels, and non-uniform grain growth including abnormal and bimodal grain growth are undesirable for steel manufacturing. In this paper, reheating treatments for Al–Nb-containing steel (0.057 wt-% Al and 0.019 wt-% Nb) were selected based on Thermo-Calc predictions for the dissolution temperatures of precipitates in the steel for a fully homogenised condition. Abnormal grain growth occurred in the homogenised Al–Nb sample during reheating, associated with random dissolution of the grain boundary-pinning AlN precipitates, while bimodal grain growth was not observed. So material in a homogenised condition would not be expected to provide a fully uniform grain structure during reheating treatment.

KEYWORDS:

• HSLA steel
• homogenisation
• reheating treatment
• abnormal grain growth
• bimodal grain growth

Acknowledgements

The authors would like to thank TATA Steel Europe for the provision of material and the School of Metallurgy and Materials at the University of Birmingham for providing the facilities required for the research.

Disclosure statement

No potential conflict of interest was reported by the authors.