The determining role of intercritical annealing condition on retained austenite and mechanical properties of a low carbon steel: Experimental and theoretical analysis

The impact of intercritical annealing (IA) temperature and time on retained austenite and mechanical properties are elucidated in a low carbon steel containing 2.85 wt% Mn. Experimental studies indicated that the multi-phase microstructure consisted of intercritical ferrite, martensite/bainite, retained austenite and fine dispersion of precipitations. The volume fraction of retained austenite attained a maximum value of 14% on IA at 680 degrees C for 30 min. The partition behavior of alloying elements during intercritical annealing was studied by scanning transmission electron microscopy (STEM) and analyzed kinetically by DICTRA simulation. Appropriate fraction of retained austenite obtained at 680 degrees C for 30 min was attributed to the extent of partitioning of carbon and manganese into the reverted austenite that contributed to best balance of mechanical properties.