Evolution of microstructure and mechanical properties of medium Mn steels during double annealing

Artem Arlazarov (1, 2) , Mohamed Gouné (1, 3) , Olivier Bouaziz (1, 4) , Alain Hazotte (2) , Gérard Petitgand (1) , Patrick Barges (1)

1 ArcelorMittal Maizières Research SA
2 LEM3 - Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux
3 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
4 CDM - Centre des Matériaux

A double annealing process was applied to cold rolled medium Mn steel. The evolution of both microstructure and mechanical properties during the second annealing were analysed. Austenite reverted transformation (ART) was observed during intercritical annealing. It was shown that a complex ultra-fine microstructure composed of three phases (retained austenite/martensite/ferrite) was formed and two types of morphologies were detected (lath-like and polygonal). Furthermore, a high volume fraction of retained austenite (22%), which was stabilized at room temperature, was the origin of a TRIP effect. A good balance between strength and ductility can be achieved by optimizing the heat treatment. The various results are discussed and some mechanisms are proposed to explain the observations.

Mots clés: Medium Mn steel; Retained austenite; Martensite recrystallization; Phase transformation; Transformation induced plasticity (TRIP)

Domaines: Matériaux

Artem Arlazarov, Mohamed Gouné, Olivier Bouaziz, Alain Hazotte, Gérard Petitgand, et al.. Evolution of microstructure and mechanical properties of medium Mn steels during double annealing. Materials Science and Engineering: A, 2012, 542, pp.31-39. ⟨10.1016/j.msea.2012.02.024⟩. ⟨hal-00683481⟩