Patent ID: 8440030

Claim:
A fine spheroidized steel sheet having an excellent heat treatment characteristic, comprising: 0.5 to 1.0 wt % of C, 0.1 to 1.2 wt % of Mn, 0 to 0.4 wt % of Si, 0.01 to 0.1 wt % of Al, 0 to 0.01 wt % of S, and Fe and an inevitably added impurity as residuals, wherein the fine spheroidized steel sheet has a fine pearlite structure in which a lamellar interval of cementite at room temperature after a hot rolling and cold rolling is 1.0 μm or less, and a volume fraction of the fine pearlite is 80% or more, and wherein in the fine spheroidized steel sheet, an average diameter of a spheroidized carbide after spheroidizing annealing is 0.3 μm or less, and a spheroidized ratio is 90% more.