Steel sheet, coated steel sheet, press-formed product, processed member, method for manufacturing press-formed product, and method for manufacturing processed member

1 . A steel sheet comprising a single-layered outer coating disposed on a surface, the single-layered outer coating including an organic resin and an inorganic material, the steel sheet having a tensile strength of 1180 MPa or greater, wherein

in the single-layered outer coating, a concentration of the inorganic material in a region of the single-layered outer coating, which is a region extending to 20% of a thickness of the single-layered outer coating from a steel-sheet-side, is higher than a concentration of the inorganic material in another region of the single-layered outer coating, which is a region extending to 20% of the thickness from an outer-surface-side.

2 . The steel sheet according to claim 1 , wherein the thickness of the single-layered outer coating is 0.4 μm or greater.

3 . The steel sheet according to claim 1 , wherein the steel sheet satisfies one or both of conditions (A) and (B), described below:

(A) the steel sheet is sheared, and a surface of the steel sheet in a sheared end portion has a slide mark having a length of 0.5 mm or less, and

(B) the steel sheet is bent, and N1 satisfies equation (1), where N1 is the number of cracks formed in a sheared end face,

(

N

⁢

1

/

R

⁢

1

)

×

T

⁢

1

≤

1

.

0

(

1

)

where N1 is the number of cracks formed in the sheared end face of a bent portion, R1 is a bend radius (mm) of the bent portion in which the number of cracks is evaluated, and T1 is a pre-processing thickness (mm) of the steel sheet.

4 . A coated steel sheet comprising a single-layered outer coating disposed on a surface of a coated layer, the single-layered outer coating including an organic resin and an inorganic material, the coated steel sheet including a substrate steel sheet having a tensile strength of 1180 MPa or greater, wherein

in the single-layered outer coating, a concentration of the inorganic material in a region of the single-layered outer coating, which is a region extending to 20% of a thickness of the single-layered outer coating from a steel-sheet-side, is higher than a concentration of the inorganic material in another region of the single-layered outer coating, which is a region extending to 20% of the thickness from an outer-surface-side.

5 . The coated steel sheet according to claim 4 , wherein the thickness of the single-layered outer coating is 0.4 μm or greater.

6 . The coated steel sheet according to claim 4 , wherein the coated steel sheet satisfies one or both of conditions (C) and (D), described below:

(C) the coated steel sheet is sheared, and a surface of the coated steel sheet in a sheared end portion has a slide mark having a length of 0.5 mm or less, and

(D) the coated steel sheet is bent, and N2 satisfies equation (2), where N2 is the number of cracks formed in a sheared end face,

(

N

⁢

2

/

R

⁢

2

)

×

T

⁢

2

≤

1

.

0

(

2

)

where N2 is the number of cracks formed in the sheared end face of a bent portion, R2 is a bend radius (mm) of the bent portion in which the number of cracks is evaluated, and T2 is a pre-processing thickness (mm) of the coated steel sheet.

7 . A press-formed product resulting from press-forming of the steel sheet according to claim 1 .

8 . A press-formed product resulting from press-forming of the steel sheet according to claim 3 .

9 . A press-formed product resulting from press-forming of the coated steel sheet according to claim 4 .

10 . A press-formed product resulting from press-forming of the coated steel sheet according to claim 6 .

11 . A method for manufacturing a press-formed product, the method comprising the step of press-forming the steel sheet according to claim 1 .

12 . A method for manufacturing a press-formed product, the method comprising the step of press-forming the coated steel sheet according to claim 4 .

13 . A method for manufacturing a processed member, the method comprising the steps of shearing and/or bending the steel sheet according to claim 1 .

14 . A method for manufacturing a processed member, the method comprising the steps of shearing and/or bending the coated steel sheet according to claim 4 .

15 . A processed member comprising the steel sheet according to claim 1 , wherein the steel sheet satisfies one or both of (A) and (B), described below:

(A) a surface of the steel sheet in a sheared end portion has a slide mark having a length of 0.5 mm or less, and

(B) N1 satisfies equation (1), where N1 is the number of cracks formed in a sheared end face,

(

N

⁢

1

/

R

⁢

1

)

×

T

⁢

1

≤

1

.

0

(

1

)

where N1 is the number of cracks formed in the sheared end face of a bent portion, R1 is a bend radius (mm) of the bent portion in which the number of cracks is evaluated, and T1 is a pre-processing thickness (mm) of the steel sheet.

16 . A processed member comprising the coated steel sheet according to claim 4 , wherein the coated steel sheet satisfies one or both of (C) and (D), described below:

(C) a surface of the coated steel sheet in a sheared end portion has a slide mark having a length of 0.5 mm or less, and

(D) N2 satisfies equation (2), where N2 is the number of cracks formed in a sheared end face,

(

N

⁢

2

/

R

⁢

2

)

×

T

⁢

2

≤

1

.

0

(

2

)

where N2 is the number of cracks formed in the sheared end face of a bent portion, R2 is a bend radius (mm) of the bent portion in which the number of cracks is evaluated, and T2 is a pre-processing thickness (mm) of the coated steel sheet.