An improved constitutive model for high-temperature flow behaviour of the Fe–Mn–Al duplex steel

ABSTRACT

The high-temperature flow curves of the Fe–Mn–Al duplex steel showed an uncommon yield-like behaviour and an abnormal dynamic recrystallisation behaviour that occurred at low temperatures rather than high temperatures. The interaction of strain partitioning and unsynchronised softening behaviour in δ-ferrite and austenite caused this peculiar flow behaviour. By discussing the stress exponent and apparent activation energy, respectively, at low and high temperatures, a modified hyperbolic sine function was developed to predict the characteristic stresses. By simplifying the material constant θ and compensating the microstructural evolution in the exponential saturation work-hardening law, an improved constitutive model was developed to predict the transient stress. The comparison between the experimental and calculated values confirmed a high prediction accuracy of this improved model.

KEYWORDS:

• Constitutive model
• flow stress
• Fe–Mn–Al steel
• duplex steel
• lightweight
• dynamic recrystallisation

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Lixiong Xu http://orcid.org/0000-0001-9440-6914

Additional information

Funding

The authors gratefully acknowledge the financial support of the National Natural Science Foundation of China [grant number 51474031].