A comparison of the internal stresses in a transformation-induced plasticity-assisted steel and a twinning-induced plasticity steel

ABSTRACT

An analysis of the loading–unloading behaviour of tensile tests was performed in a transformation-induced plasticity-assisted (TRIP-assisted) steel, duplex high Mn steel (22% Mn–3% Al–3% Si) for a wide range of grain sizes, D. The Bauschinger effect observed during unloading was so strong that plastic deformation was detected before complete unloading was reached. In addition, the yield stress, ${\overline{\sigma }}_y$, or the flow stress, ${\overline{\sigma }}_{\epsilon }$, are related to the grain size according to the Hall–Petch relationship. This behaviour was compared with a twinning-induced plasticity (TWIP), steel (22% Mn–0.6% C). The high levels of internal stresses obtained in both steels can be rationalised on account of the reinforcement of the austenitic matrix by the increasing volume fraction of ϵ-martensite or deformation twins of nanometric thickness.

KEYWORDS:

• Bauschinger effect
• transformation-induced plasticity-assisted (TRIP-assisted)
• twinning-induced plasticity (TWIP)
• Hall–Petch
• mechanical twinning
• ϵ-martensite
• internal stresses
• back-stresses

Acknowledgements

We would like to thank D.J. Badiola and J. Alkorta for their scientific support in this research work. Finally, we would like to show my deep appreciation to P. Jiménez, J. de las Cuevas, M. de las Cuevas and C. M. Cardona.

Disclosure statement

No potential conflict of interest was reported by the authors.