Cold-rolled steel sheet having excellent thermal-resistance and moldability, and method for manufacturing same
AssigneePosco
InventorsMinho Jo, Young-Kwang Hong
Life of this patent
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Abstract
A cold-rolled steel sheet having excellent heat resistance and moldability according to an exemplary embodiment of the present invention includes 0.002 to 0.01 wt % of C, 0.1 to 1.0 wt % of Mn, less than 0.01 wt % (except for 0 wt %) of P, 0.01 wt % or less (except for 0 wt %) of N, 0.01 to 0.05 wt % of Nb, and 0.01 to 0.08% of Ti, with the balance being Fe and inevitable impurities, and has a microstructure in which the area fraction of recrystallized grains is 5 area % or less, and the dislocation density is 1×1015/m2 or less.
Claims6
A cold-rolled steel sheet having excellent heat resistance and moldability, comprising 0.002 to 0.01 wt % of C, 0.1 to 1.0 wt % of Mn, less than 0.01 wt % (except for 0 wt %) of P, 0.01 wt % or less (except for 0 wt %) of N, 0.01 to 0.05 wt % of Nb, and 0.01 to 0.08 wt % of Ti, with the balance being Fe and inevitable impurities, and
- having a microstructure in which an area fraction of recrystallized grains is 5 area % or less, and a dislocation density is 1×1015/m2 or less,
- wherein a precipitation index defined by the following Equation 1 is 10 or more:
- Precipitation index=[Min([Ti], [N])+4×Min([Nb], [C])+2×Min([Ti]−[N], [C]−[Nb])]×104 [Equation 1]
- where in Equation 1:
- [Ti], [N], [Nb], and [C] are each a value obtained by dividing a content (wt %) of each component by each atomic weight thereof, and
- Min(A, B) is the smaller value of A and B, or, when Min(A, B) is a negative value, Min(A, B) is 0.
Dependencies are inferred from the claim text.