Microstructure and mechanical properties of low-carbon Q & P steel pretreated with intercritical annealing

The success of obtaining both high strength and high formability in low-carbon quenched and partitioned( Q & P) steels depends on their microstructural constituents. In this regard,the effect of annealing temperature on the volume fraction and distribution of carbon in retained austenite in a low-carbon Q & P steel was studied. The microstructures of Q & P steels subjected to different annealing temperatures were studied in detail by electron microscopy,electron microprobe,and X-ray diffraction techniques. The results suggest that intercritical annealing is beneficial in increasing the volume fraction of retained austenite,which is a consequence of the distribution of alloying elements during intercritical annealing. Moreover,the mechanical properties of intercritically annealed Q & P steel,especially its ductility,are significantly enhanced.