Ferritic stainless steel sheet and method for manufacturing the same

1. A ferritic stainless steel sheet having a chemical composition consisting of, by mass %:

C: 0.005 to 0.030%,

Si: 0.05 to 1.00%,

Mn: 0.05 to 1.00%,

P: 0.040% or less,

S: 0.030% or less,

Al: 0.031 to 0.150%,

Cr: 10.8 to 14.4%,

Ni: 1.20 to 2.50%,

N: 0.005 to 0.060%,

optionally at least one element selected from the group consisting of Co, Cu, Mo, W, V, Zr, Nb, B, Mg, Ca, Y, REM, and Sb, and

a balance being Fe and incidental impurities,

wherein:

the steel sheet has an elongation after fracture of 28% or more, and

a surface of the steel sheet has a ridging height of 3.0 μm or less when a tensile strain of 23% is applied in a rolling direction to the steel sheet.

2. The ferritic stainless steel sheet according to claim 1 , wherein the chemical composition includes, by mass %, at least one selected from the group consisting of:

Co: 0.01 to 0.50%,

Cu: 0.01 to 0.80%,

Mo: 0.01 to 0.30%, and

W: 0.01 to 0.50%.

3. The ferritic stainless steel sheet according to claim 2 , wherein the chemical composition includes, by mass %, at least one selected from the group consisting of:

V: 0.01 to 0.10%,

Zr: 0.01 to 0.10%, and

Nb: 0.01 to 0.30%,

wherein a value of formula (1) below is 0.0 or less:

54×(V+Zr+Nb)−5×Mn−19×Ni+1.0  formula (1)

where, in formula (1) above, respective element symbols represent contents (mass %) of respective elements, or 0 when corresponding elements are not present.

4. The ferritic stainless steel sheet according to claim 3 , wherein the chemical composition includes, by mass %, at least one selected from the group consisting of:

B: 0.0003 to 0.0030%,

Mg: 0.0005 to 0.0100%,

Ca: 0.0003 to 0.0030%,

Y: 0.01 to 0.20%, and

REM (rare earth metal): 0.001 to 0.100%.

5. The ferritic stainless steel sheet according to claim 4 , wherein the chemical composition includes, by mass %, Sb: 0.001 to 0.500%.

6. A method for manufacturing the ferritic stainless steel sheet according to claim 5 , the method comprising:

hot-rolling a steel slab having the chemical composition so as to form a hot-rolled sheet;

performing hot-rolled sheet annealing that includes holding the hot-rolled sheet at a temperature in a range of 900° C. or more and 1100° C. or less for 5 seconds to 15 minutes so as to form a hot-rolled and annealed sheet;

cold-rolling the hot-rolled and annealed sheet so as to form a cold-rolled sheet; and

performing cold-rolled sheet annealing that includes holding the cold-rolled sheet at a temperature in a range of 780° C. or more and 830° C. or less for 5 seconds to 5 minutes; thereby producing the ferritic stainless steel sheet of claim 5 .

7. The ferritic stainless steel sheet according to claim 3 , wherein the chemical composition includes, by mass %, Sb: 0.001 to 0.500%.

8. The ferritic stainless steel sheet according to claim 2 , wherein the chemical composition includes, by mass %, at least one selected from the group consisting of:

B: 0.0003 to 0.0030%,

Mg: 0.0005 to 0.0100%,

Ca: 0.0003 to 0.0030%,

Y: 0.01 to 0.20%, and

REM (rare earth metal): 0.001 to 0.100%.

9. The ferritic stainless steel sheet according to claim 8 , wherein the chemical composition includes, by mass %, Sb: 0.001 to 0.500%.

10. The ferritic stainless steel sheet according to claim 1 , wherein the chemical composition includes, by mass %, at least one selected from the group consisting of:

V: 0.01 to 0.10%,

Zr: 0.01 to 0.10%, and

Nb: 0.01 to 0.30%,

wherein a value of formula (1) below is 0.0 or less:

54×(V+Zr+Nb)−5×Mn−19×Ni+1.0  formula (1)

where, in formula (1) above, respective element symbols represent contents (mass %) of respective elements, or 0 when corresponding elements are not present.

11. The ferritic stainless steel sheet according to claim 10 , wherein the chemical composition includes, by mass %, at least one selected from the group consisting of:

B: 0.0003 to 0.0030%,

Mg: 0.0005 to 0.0100%,

Ca: 0.0003 to 0.0030%,

Y: 0.01 to 0.20%, and

REM (rare earth metal): 0.001 to 0.100%.

12. The ferritic stainless steel sheet according to claim 11 , wherein the chemical composition includes, by mass %, Sb: 0.001 to 0.500%.

13. The ferritic stainless steel sheet according to claim 10 , wherein the chemical composition includes, by mass %, Sb: 0.001 to 0.500%.

14. The ferritic stainless steel sheet according to claim 1 , wherein the chemical composition includes, by mass %, at least one selected from the group consisting of:

B: 0.0003 to 0.0030%,

Mg: 0.0005 to 0.0100%,

Ca: 0.0003 to 0.0030%,

Y: 0.01 to 0.20%, and

REM (rare earth metal): 0.001 to 0.100%.

15. The ferritic stainless steel sheet according to claim 14 , wherein the chemical composition includes, by mass %, Sb: 0.001 to 0.500%.

16. The ferritic stainless steel sheet according to claim 1 , wherein the chemical composition includes, by mass %, Sb: 0.001 to 0.500%.

17. A method for manufacturing the ferritic stainless steel sheet according to claim 1 , the method comprising:

hot-rolling a steel slab having the chemical composition so as to form a hot-rolled sheet;

performing hot-rolled sheet annealing that includes holding the hot-rolled sheet at a temperature in a range of 900° C. or more and 1100° C. or less for 5 seconds to 15 minutes so as to form a hot-rolled and annealed sheet;

cold-rolling the hot-rolled and annealed sheet so as to form a cold-rolled sheet; and

performing cold-rolled sheet annealing that includes holding the cold-rolled sheet at a temperature in a range of 780° C. or more and 830° C. or less for 5 seconds to 5 minutes; thereby producing the ferritic stainless steel sheet of claim 1 .

18. The ferritic stainless steel sheet according to claim 2 , wherein the chemical composition includes, by mass %, Sb: 0.001 to 0.500%.