STEEL SHEET FOR HOT PRESS FORMED MEMBER HAVING EXCELLENT PAINTING ADHESION AND POST-PAINTING CORROSION RESISTANCE, AND METHOD FOR MANUFACTURING SAME
Provided is a steel sheet for a hot press formed member having excellent painting adhesion and post-painting corrosion resistance, and a method for manufacturing the same. A steel sheet for hot press forming according to one aspect of the present invention comprises a base steel sheet and a plated layer formed on a surface of the base steel sheet, wherein the ratio of an area occupied by pores to the entire area of a surface layer portion may be 10% or more in a cross section of the surface layer portion observed when the plated layer is cut in a thickness direction thereof.
1 . A steel sheet for a hot press formed member having excellent painting adhesion and post-painting corrosion resistance, comprising:
a base steel sheet; and
a plated layer formed on a surface of the base steel sheet,
wherein a ratio of an area occupied by pores to an entire area of a surface layer portion is 10% or more in a cross-section of the surface layer portion observed when the plated layer is cut in a thickness direction thereof, and
wherein the composition of the base steel sheet further comprises, by wt %, one or more among a sum of one or more selected from a group consisting of Cr, Mo, and W: 0.01 to 4.0%, a sum of one or more selected from a group consisting of Ti, Nb, Zr, and V: 0.001 to 0.4%, Cu+Ni: 0.005 to 2.0%, Sb+Sn: 0.001 to 1.0%, and B: 0.0001 to 0.01%.
2 . The steel sheet for the hot press formed member having excellent painting adhesion and post-painting corrosion resistance of claim 1 , wherein a ratio of an area occupied by pores to an entire area of a surface layer portion is 15% or more in a cross-section of the surface layer portion observed when the plated layer is cut in a thickness direction thereof.
3 . The steel sheet for the hot press formed member having excellent painting adhesion and post-painting corrosion resistance of claim 1 , wherein the plated layer is an aluminum alloy plated layer.
4 . The steel sheet for the hot press formed member having excellent painting adhesion and post-painting corrosion resistance of claim 3 , wherein the aluminum alloy plated layer has an average content of Fe of 30 wt % or more.
5 . The steel sheet for the hot press formed member having excellent painting adhesion and post-painting corrosion resistance of claim 3 , wherein the aluminum alloy plated layer has an average content of Fe of 40 wt % or more.
6 . The steel sheet for the hot press formed member having excellent painting adhesion and post-painting corrosion resistance of claim 1 , wherein the base steel sheet has a composition including, by wt %, carbon (C): 0.04 to 0.5%, silicon (Si): 0.01 to 2%, manganese (Mn): 0.01 to 10%, aluminum (Al): 0.001 to 1.0%, phosphorus (P): 0.05% or less, sulfur (S): 0.02% or less, nitrogen (N): 0.02% or less, and a balance of iron (Fe) and inevitable impurities.
7 . A manufacturing method of a steel sheet for a hot press formed member having excellent painting adhesion and post-painting corrosion resistance, comprising operations of:
aluminum plating a surface of a base steel sheet and coiling to obtain an aluminum plated steel sheet;
annealing the aluminum plated steel sheet to obtain an aluminum alloy plated steel sheet; and
cooling the aluminum alloy plated steel sheet,
wherein an amount of the aluminum plating is 30 to 200 g/m 2 based on one side of the steel sheet,
coiling tension is 0.5 to 5 kg/mm 2 during coiling,
the annealing is performed for 30 minutes to 50 hours in a heating temperature range of 550 to 750° C. in a batch annealing furnace,
when heating is performed from room temperature to the heating temperature during the annealing, an average temperature increase rate is 20 to 100° C./h, and a temperature increase rate in a section from the heating temperature −50° C. to the heating temperature is 1 to 15° C./h, and
a difference between an atmosphere temperature and a temperature of the steel sheet in the batch annealing furnace is 5 to 80° C.
8 . The manufacturing method of the steel sheet for the hot press formed member having excellent painting adhesion and post-painting corrosion resistance of claim 7 , wherein the base steel sheet has a composition including, by wt %, carbon (C): 0.04 to 0.5%, silicon (Si): 0.01 to 2%, manganese (Mn): 0.01 to 10%, aluminum (Al): 0.001 to 1.0%, phosphorus (P): 0.05% or less, sulfur (S): 0.02% or less, nitrogen (N): 0.02% or less, and a balance of iron (Fe) and inevitable impurities.
9 . The manufacturing method of the steel sheet for the hot press formed member having excellent painting adhesion and post-painting corrosion resistance of claim 8 , wherein the composition of the base steel sheet further comprises, by wt %, one or more among a sum of one or more selected from a group consisting of Cr, Mo, and W: 0.01 to 4.0%, a sum of one or more selected from a group consisting of Ti, Nb, Zr, and V: 0.001 to 0.4%, Cu+Ni: 0.005 to 2.0%, Sb+Sn: 0.001 to 1.0%, and B: 0.0001 to 0.01%.