Normalling heat treatable steel sheet having godd low impact toughness and method for the same

摘要

A normalized heat-treated steel sheet having excellent low-temperature impact toughness and a manufacturing method manufacturing method are provided. The normalized heat-treated steel sheet of the present invention, by weight, C: 0.04 to 0.1%, Si: 0.05 to 0.5%, Mn: 1.0 to 2.0%, Sol.Al: 0.015 to 0.04%, Nb: 0.003 to 0.03%, Ti: 0.005~0.02%, Cu: 0~0.35%, Ni: 0.05~0.8%, N: 0.002~0.008%, P: 0.01% or less (excluding 0%), S: 0.003% or less, balance Fe and inevitable It has a steel microstructure composed of 70 to 90 area% of polygonal ferrite and 10 to 30 area% of spheroidized pearlite, which contains impurities and has a grain size of 20 μm or less.