Effect of initial microstructure on mechanical properties in warm caliber rolling of high carbon steel

► The effect of initial microstructure on change of micro-hardness, tension, and Charpy tests were investigated by warm caliber rolling (WCR). ► Smaller ferrite grain and dispersed cementite particles with smaller interspacing increased the strength and toughness. ► In WCR, elongation hardly decreased compared to the conventional hot rolling. ► Depending on the microstructure change, WCR guaranteed higher impact energy and the mode of fracture varied as well.