COLD ROLLED STEEL SHEET FOR CONTINUOUS TYPE SELF-BRAZING AND MANUFACTURING METHOD THEREFOR
A continuous self-brazing cold rolled steel sheet according to an embodiment of the present disclosure includes 0.02 wt % to 0.08 wt % of C, 0.03 wt % to 0.10 wt % of Mn, 0.10 wt % or less of Si (excluding 0 wt %), 0.005 wt % to 0.05 wt % of Al, 0.015 wt % or less of P (excluding 0 wt %), 0.01 wt % or less of S (excluding 0 wt %), 0.005 wt % or less of N (excluding 0 wt %), 0.0003 wt % to 0.0036 wt % of B, a remainder Fe, and other inevitable impurities, and satisfying Equations (1) and (2), in which an average crystal grain size is 8 μm to 16 μm. 0.15≤([B]/10.81)/([Al]/26.98) [Equation 1] 0.8≤([B]/10.81)/([N]/14.01)≤1.6 [Equation 2] (In Equations (1) and (2), [B], [Al] and [N] denote percent by weights of B, Al, and N.)
1 . A continuous self-brazing cold rolled steel sheet comprising 0.02 wt % to 0.08 wt % of C, 0.03 wt % to 0.10 wt % of Mn, 0.10 wt % or less of Si (excluding 0 wt %), 0.005 wt % to 0.05 wt % of Al, 0.015 wt % or less of P (excluding 0 wt %), 0.01 wt % or less of S (excluding 0 wt %), 0.005 wt % or less of N (excluding 0 wt %), 0.0003 wt % to 0.0036 wt % of B, a remainder Fe, and other inevitable impurities, and satisfying Equations (1) and (2),
wherein an average crystal grain size is 8 μm to 16 μm.
0.15≤([B]/10.81)/([Al]/26.98) [Equation 1]
0.8≤([B]/10.81)/([N]/14.01)≤1.6 [Equation 2]
(In Equations (1) and (2), [B], [Al] and [N] denote percent by weights of B, Al and N).
2 . The continuous self-brazing cold rolled steel sheet of claim 1 , wherein a weight ratio of AlN precipitates and BN precipitates satisfies Equation (3),
{[BN]/(10.81+14.01)}/{[AlN]/(26.98+14.01)}≥1 [Equation 3]
(In Equation (3), [BN] and [AlN] denote percent by weights of the BN precipitates and the AlN precipitates).
3 . The continuous self-brazing cold rolled steel sheet of claim 1 , wherein a weight ratio of N, the AlN precipitates, and the BN precipitates, existing in steel in a solid solution state, satisfies Equation (4).
([N]/14.01)/{[AlN]/(26.98+14.01)+[BN]/(26.98+14.01)}≤0.1 [Equation 4]
(In Equation (4), [N], [BN] and [AlN] denote a solid solution amount (wt %) of N, and percent by weights of the BN precipitates and the AlN precipitates).
4 . A method of manufacturing a continuous self-brazing cold rolled steel sheet, the method comprising:
Heating, at 1200° C. or more, a slab including 0.02 wt % to 0.08 wt % of C, 0.03 wt % to 0.10 wt % of Mn, 0.10 wt % or less of Si (excluding 0 wt %), 0.005 wt % to 0.05 wt % of Al, 0.015 wt % or less of P (excluding 0 wt %), 0.01 wt % or less of S (excluding 0 wt %), 0.005 wt % or less of N (excluding 0 wt %), 0.0003 wt % to 0.0036 wt % of B, a remainder Fe, and other inevitable impurities, and satisfying Equations (1) and (2);
manufacturing a hot rolled steel sheet by hot rolling the heated slab;
winding the hot rolled steel sheet;
manufacturing a cold rolled steel sheet by cold rolling the wound hot rolled steel sheet; and
annealing the cold rolled steel sheet at 600° C. to 850° C.
0.15≤([B]/10.81)/([Al]/26.98) [Equation 1]
0.8≤([B]/10.81)/([N]/14.01)≤1.6 [Equation 2]
(In Equations (1) and (2), [B], [Al] and [N] denote percent by weights of B, Al and N.)
5 . The method of claim 4 , wherein in the heating of the slab, the slab is heated at 1230° C. to 1350° C.
6 . The method of claim 4 , wherein in the manufacturing of the hot rolled steel sheet, a finish rolling temperature ranges from 875° C. to 1050° C.
7 . The method of claim 4 , wherein in the winding of the hot rolled steel sheet, a winding temperature ranges from 600° C. to 750° C.
8 . The method of claim 4 , wherein in the manufacturing of the cold rolled steel sheet, cold rolling is performed at a reduction rate of 50% to 95%.
9 . The method of claim 4 , wherein in the annealing, continuous annealing is performed for 20 seconds to 600 seconds at 600° C. to 850° C.
10 . The method of claim 4 , wherein in the annealing, batch annealing is performed for 5 hours to 72 hours at 600° C. to 800° C.
11 . The method of claim 4 , wherein in the manufactured cold rolled steel sheet, a weight ratio of AlN precipitates and BN precipitates satisfies Equation (3),
{[BN]/(10.81+14.01)}/{[AlN]/(26.98+14.01)}≥1 [Equation 3]
(In Equation (3), [BN] and [AlN] denote percent by weights of BN precipitates and AlN precipitates.)
12 . The method of claim 4 , wherein a weight ratio of N, the AlN precipitates, and the BN precipitates, existing in the manufactured cold rolled steel sheet in a solid solution state, satisfies Equation (4).
([N]/14.01)/{[AlN]/(26.98+14.01)+[BN]/(26.98+14.01)}≤0.1 [Equation 4]
(In Equation (4), [N], [BN] and [AlN] denote a solid solution amount (wt %) of N, and percent by weights of the BN precipitates and the AlN precipitates)
13 . A copper plated steel sheet comprising a base steel sheet formed by the cold rolled steel sheet of claim 1 and a copper plated layer coated on a surface of the base steel sheet.
14 . The copper plated steel sheet of claim 13 , wherein a depth, by which the plated layer is penetrated into the cold rolled steel sheet, is 2.5 μm or less.