STEEL SHEET FOR HOT STAMPING AND METHOD FOR PRODUCING STEEL SHEET FOR HOT STAMPING, AND HOT STAMP FORMED BODY

1 . A steel sheet for hot stamping, comprising a composition containing:

in mass %,

C: 0.100% to 0.600%;

Si: 0.50% to 3.00%;

Mn: 1.20% to 4.00%;

Ti: 0.005% to 0.100%;

B: 0.0005% to 0.0100%;

P: 0.100% or less;

S: 0.0001% to 0.0100%;

Al: 0.005% to 1.000%;

N: 0.0100% or less;

Ni: 0% to 2.00%;

Cu: 0% to 2.00%;

Cr: 0% to 2.00%;

Mo: 0% to 2.00%;

Nb: 0% to 0.100%;

V: 0% to 0.100%;

W: 0% to 0.100%, and

a total of one kind or two or more kinds selected from a group consisting of REM, Ca, Ce and Mg: 0% to 0.0300%,

with a balance being Fe and impurities,

wherein surface roughness of the steel sheet satisfies Rz>2.5 μm, and coating oil in an amount of 50 mg/m 2 to 1500 mg/m 2 is applied onto a surface.

2 . The steel sheet for hot stamping according to claim 1 ,

wherein an amount of S contained in the coating oil which is applied onto the steel sheet is 5% or less in mass %.

3 . The steel sheet for hot stamping according to claim 1 ,

wherein the composition of the steel sheet contains, in mass %,

one kind or two or more kinds selected from a group consisting of

Ni: 0.01% to 2.00%,

Cu: 0.01% to 2.00%,

Cr: 0.01% to 2.00%,

Mo: 0.01% to 2.00%,

Nb: 0.005% to 0.100%,

V: 0.005% to 0.100%, and

W: 0.005% to 0.100%.

4 . The steel sheet for hot stamping according to claim 1 ,

wherein the composition of the steel sheet contains, in mass %,

a total of 0.0003% to 0.0300% of one kind or two or more kinds selected from the group consisting of REM, Ca, Ce and Mg.

5 . A method for producing a steel sheet for hot stamping, comprising:

a step of casting a slab containing,

in mass %,

C: 0.100% to 0.600%;

Si: 0.50% to 3.00%;

Mn: 1.20% to 4.00%;

Ti: 0.005% to 0.100%;

B: 0.0005% to 0.0100%;

P: 0.100% or less;

S: 0.0001% to 0.0100%;

Al: 0.005% to 1.000%;

N: 0.0100% or less;

Ni: 0% to 2.00%;

Cu: 0% to 2.00%;

Cr: 0% to 2.00%;

Mo: 0% to 2.00%;

Nb: 0% to 0.100%;

V: 0% to 0.100%;

W: 0% to 0.100%, and

a total of one kind or two or more kinds selected from a group consisting of REM, Ca, Ce and Mg: 0% to 0.0300%,

with a balance being Fe and impurities, and hot rolling the slab directly or by allowing the slab to cool and heating the slab to obtain a hot-rolled steel sheet;

a step of pickling the hot-rolled steel sheet for 30 seconds or more in an aqueous solution having a temperature of 80° C. to lower than 100° C. and including an inhibitor with a concentration of an acid being 3 mass % to 20 mass %; and

a step of applying a rust inhibiting oil to the steel sheet after carrying out the pickling,

wherein a rust inhibiting oil remaining amount on a steel sheet surface is limited to 50 mg/m 2 to 1500 mg/m 2 .

6 . The method for producing a steel sheet for hot stamping according to claim 5 ,

wherein the rust inhibiting oil is applied to the hot-rolled steel sheet which has been pickled.

7 . The method for producing a steel sheet for hot stamping according to claim 5 , further comprising:

a step of cold rolling the hot-rolled steel sheet which has been pickled to obtain a cold-rolled steel sheet,

wherein the rust inhibiting oil is applied to the cold-rolled steel sheet.

8 . The method for producing a steel sheet for hot stamping according to claim 5 , further comprising:

a step of cold rolling the hot-rolled steel sheet which has been pickled, and further performing thermal treatment in a continuous annealing facility or a box type annealing furnace to obtain a cold-rolled steel sheet,

wherein the rust inhibiting oil is applied to the cold-rolled steel sheet.

9 . The method for producing a steel sheet for hot stamping according to claim 5 ,

wherein an amount of S in the rust inhibiting oil that is applied to the steel sheet is 5% or less in mass %.

10 . The method for producing a steel sheet for hot stamping according to claim 5 ,

wherein a composition of the slab contains, in mass %,

one kind or two or more kinds selected from a group consisting of

Ni: 0.01% to 2.00%,

Cu: 0.01% to 2.00%,

Cr: 0.01% to 2.00%,

Mo: 0.01% to 2.00%,

Nb: 0.005% to 0.100%,

V: 0.005% to 0.100%, and

W: 0.005% to 0.100%.

11 . The method for producing a steel sheet for hot stamping according to claim 5 ,

wherein a composition of the slab contains, in mass %,

a:total of 0.0003% to 0.0300% of one kind or two or more kinds selected from the group consisting of REM, Ca, Ce and Mg.

12 . A hot stamp formed body, comprising a composition containing:

in mass %,

C: 0.100% to 0.600%;

Si: 0.50% to 3.00%;

Mn: 1.20% to 4.00%;

Ti: 0.005% to 0.100%;

B: 0.0005% to 0.0100%;

P: 0.100% or less;

S: 0.0001% to 0.0100%;

Al: 0.005% to 1.000%;

N: 0.0100% or less;

Ni: 0% to 2.00%;

Cu: 0% to 2.00%;

Cr: 0% to 2.00%;

Mo: 0% to 2.00%;

Nb: 0% to 0.100%;

V: 0% to 0.100%;

W: 0% to 0.100%, and

a total of one kind or two or more kinds selected from a group consisting of REM, Ca, Ce and Mg: 0% to 0.0300%,

with a balance being Fe and impurities,

wherein three or more irregularities in a range of 0.2 μm to 8.0 μm in depth are present per 100 μm in an interface between scale and a base iron, and tensile strength is 1180 MPa or more.

13 . The hot stamp fonned body according to claim 12 ,

wherein an Si oxide, FeO, Fe 3 O 4 and Fe 2 O 3 are included in a surface of the hot stamp formed body, and a thickness of the scale is 10 μm or less.

14 . The hot stamp formed body according to claim 12 ,

wherein the composition of the hot stamp formed body contains, in mass %,

one kind or two or more kinds selected from a group consisting of

Ni: 0.01% to 2.00%,

Cu: 0.01% to 2.00%,

Cr: 0.01% to 2.00%,

Mo: 0.01% to 2.00%,

Nb: 0.005% to 0.100%,

V: 0.005% to 0.100%, and

W: 0.005% to 0.100%.

15 . The hot stamp formed body according to claim 12 ,

wherein the composition of the hot stamp formed body contains, in mass %,

a total of 0.0003% to 0.0300% of one kind or two or more kinds selected from the group consisting of REM, Ca, Ce and Mg.