Effect of nickel aluminide on the bainite transformation in a Fe-0.45C–13Ni–3Al–4Co steel, and associated properties

Abstract

It is known that precipitates that are present in austenite can influence its subsequent transformation behaviour. This investigation deals specifically with the role of nickel aluminide precipitates on the rate of the bainite reaction, in recent alloys intended for applications at about 400∘C. It is demonstrated that the aluminides lead to an increase in the nucleation kinetics of the bainite. Furthermore, their presence increases the total quantity of bainite that forms, thus helping to reduce the scale of the austenite retained in the final microstructure. There is therefore, an increase in the fracture and impact toughnesses without sacrificing the strength. Diffraction experiments show that the retained austenite is optimally stable during the tensile test of the alloy containing NiAl.