Simultaneous improvement of strength and ductility in an ultra-high strength pearlitic steel achieved by high density nano-carbides

Nanolamellar pearlitic steel with simultaneous improvement of strength and ductility was achieved by low temperature annealing at 300 degrees C in a high-carbon (0.92 wt.%) pearlitic steel. The sample annealed for 120 min (300 degrees C-120 min) exhibits a yield strength of 2.15 f 0.03 GPa, much higher than that of the cold-drawn counterpart (1.88 GPa). The uniform elongation is 6.0 f 0.7 %, comparable to that of the patented one (the rod before cold drawing). High density dislocations, dispersed nano-carbides embedded in ferrite lamellae, together with basically continuous cementite lamellae ought to be the ovreall ultra-high strength contributions. Furthermore, the excellent combination of strength and ductility were briefly discussed in terms of the microstructure.