Study of the decomposition behavior of retained austenite and the partitioning of alloying elements during tempering in CMnSiAl TRIP steels

[Display omitted] •The volume fraction of retained austenite showed strong dependence on the tempering temperature of galvanized TRIP steels.•Cementite was precipitated from retained autenite at tempering temperatures above 400°C.•Si showed stronger tendency toward partitioning of Si compared to Mn and Al. Tempering approach is designed for better understanding the effects of heat treatment induced by production process when manufacturing on the transformation-induced plasticity steels containing 1.0wt.% Al. Specific attention is placed on the roles of tempering temperature and the holding time on the decomposition of retained austenite and the redistribution of alloying elements. Using transmission electron microscopy, we found the retained austenite was decomposed into ε-carbide and ferrite in the steels tempered at 300°C for 9h. An increase in the temperature of 400°C and the holding time over 3h accelerate the nucleation kinetics of cementite formation, leading to the deteriorated thermal stability of austenite. In addition, atom probe tomography studies confirmed the partitioning tendency of alloying elements across the ferrite/cementite interfaces as well as the compositional spikes of Mn at the interfaces during tempering over 400°C for 9h.