a study of stablized nanoscale austenite in a low-alloy medium-carbon steel

The objective of this research was to investigate the microstructure of stabilized retained austenite from the q&p heat treatment the primary goal of this heat treatment was to produce a microstructure consists of stabilized retained austenite and martensite. for this purpose, a low-alloy steel with 0.4wt. % carbon was treated by quench and partitioning (q&p) process. the q&p was conducted at different quenching temperatures to obtain a considerable amount of retained austenite, while partitioning temperature and time were kept constant. using xrd profiles, volume percent, carbon concentration, and lattice parameters of retained austenite and martensite were calculated. at quenching temperature of 160°c, 12vol.% of austenite was stabilized at the room temperature, which was the highest amount achieved. the microstructural observations carried out on selected samples, revealed that retained austenite has a nanoscale particle size, about 200nm. detection of retained austenite in the sem micrographs became possible by utilizing se2 signals via the difference in phases contrast. two types of morphology, film-like and blocky type, were identified by means of tem and tkd; a schematic model was proposed in order to explain these morphologies.