High toughness high carbon cold rolled steel sheet having excellent formability, and method for manufacturing same

Abstract

One embodiment of the present invention provides: a high toughness high carbon cold rolled steel sheet having excellent formability comprising, by weight %, C: 0.80% to 1.25%, Mn: 0.2% to 0.6%, Si: 0.01% to 0.4%, P: 0.005% to 0.02%, S: 0.01% or less, Al: 0.01% to 0.1%, Cr: 0.01% to 1.0%, Sn: 0.05% to 0.5%, the remainder being Fe and other unavoidable impurities, in which a microstructure includes, by area %, retained austenite: 1% to 10%, martensite: 1% to 10%, ferrite: 5% or less (including 0%), the remainder being bainite, and has an average grain size of 3 μm to 20 μm, and an internal oxide layer formed directly below the surface has a thickness of 10 μm or less; and a method for manufacturing same.

Dependencies are inferred from the claim text.