Enhanced Room Temperature Impact-Toughness in Nano Pearlite

Nano-pearlitic steels can be made in bulk by choosing the appropriate composition and heat treatment. Elements like Al and Co increase the number of nucleation sites decreasing the lamellar spacing to the nano-meter regime. A decrease in lamellar spacing in nano-pearlite leads to enhancement of strength and fracture toughness. However, the room temperature impact toughness of these steels is pretty low, and decreasing the spacing does not affect it. A study has been conducted to investigate whether a change in the composition of pearlite while retaining the lamellar spacing in the nano-meter regime can improve the impact toughness. Fully pearlitic steel with higher Mn content was produced by isothermal transformation at 550°C, having an interlamellar spacing of 57.2 ± 2.3 nm. The impact energy absorbed during the Charpy test at 25°C is obtained as 5 ± 0.3 J which is almost double of similar studies done on nano-pearlite.