Ferritic stainless steel sheet and method of producing same

Patent metadata

Field	Value
Publication number	US-11377702-B2
Application number	US-201917256002-A
Country	US
Kind code	B2
Filing date	Apr 22, 2019
Priority date	Jul 18, 2018
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

A ferritic stainless steel sheet comprises: a predetermined chemical composition, wherein a difference between a maximum value and a minimum value of Vickers hardness in a thickness direction is HV 50 or less.

First claim

The invention claimed is:

1. A ferritic stainless steel sheet, comprising
a chemical composition containing, in mass %,
C: 0.001% to 0.030%,
Si: 0.10% to 1.00%,
Mn: 0.10% to 1.00%,
P: 0.050% or less,
S: 0.010% or less,
Cr: 10.0% to 24.0%,
Ni: 0.01% to 1.00%,
Al: 0.010% to 0.100%,
N: 0.001% to 0.030%, and
Ti: 0.15% to 0.40%,
with a balance of Fe and inevitable impurities,
wherein a thickness of the ferritic stainless steel sheet is 5.0 mm or more, and a difference between a maximum value and a minimum value of Vickers hardness in a direction of the thickness is HV 50 or less.

2. The ferritic stainless steel sheet according to claim 1 , wherein the chemical composition further contains, in mass %, one or more selected from
Cu: 0.01% to 1.00%,
Mo: 0.01% to 1.50%, and
Co: 0.01% to 0.50%.

3. The ferritic stainless steel sheet according to claim 1 , wherein the chemical composition further contains, in mass %, one or more selected from
Nb: 0.01% to 0.50%,
V: 0.01% to 0.50%, and
Zr: 0.01% to 0.50%.

4. The ferritic stainless steel sheet according to claim 1 , wherein the chemical composition further contains, in mass %, one or more selected from
B: 0.0003% to 0.0050%,
Ca: 0.0003% to 0.0050%,
Mg: 0.0005% to 0.0050%,
REM: 0.001% to 0.050%,
Sn: 0.01% to 0.50%, and
Sb: 0.01% to 0.50%.

5. A method of producing the ferritic stainless steel sheet according to claim 1 , the method comprising:
subjecting a steel material having the chemical composition according to claim 1 to hot rolling including a plurality of rolling passes, to obtain a hot-rolled steel sheet; and
thereafter subjecting the hot-rolled steel sheet to hot-rolled sheet annealing to obtain a hot-rolled and annealed steel sheet,
wherein in the hot rolling:
in a temperature range of 950° C. to 1200° C., a rolling pass with a rolling reduction of 15% to 50% which satisfies the following Formula (1) in relation to a rolling reduction in an immediately preceding rolling pass is successively performed three or more times,
1.05≤ r ( n )/ r ( n− 1)≤1.50  (1)

where r(n) is the rolling reduction in the rolling pass that is an nth rolling pass, r(n−1) is the rolling reduction in the immediately preceding rolling pass that is an (n−1)th rolling pass, and n is an ordinal number of the rolling pass, and n is an integer that is 2 or more and is less than or equal to a total number of rolling passes;
thereafter, in a temperature range of 900° C. or more, a time interval between rolling passes of 20 sec to 100 sec is secured at least once; and
a hot rolling finish temperature is 800° C. to 900° C., and
wherein in the hot-rolled sheet annealing:
an annealing temperature is 700° C. to 1100° C.

6. The ferritic stainless steel sheet according to claim 2 , wherein the chemical composition further contains, in mass %, one or more selected from
Nb: 0.01% to 0.50%,
V: 0.01% to 0.50%, and
Zr: 0.01% to 0.50%.

7. The ferritic stainless steel sheet according to claim 2 , wherein the chemical composition further contains, in mass %, one or more selected from
B: 0.0003% to 0.0050%,
Ca: 0.0003% to 0.0050%,
Mg: 0.0005% to 0.0050%,
REM: 0.001% to 0.050%,
Sn: 0.01% to 0.50%, and
Sb: 0.01% to 0.50%.

8. The ferritic stainless steel sheet according to claim 3 , wherein the chemical composition further contains, in mass %, one or more selected from
B: 0.0003% to 0.0050%,
Ca: 0.0003% to 0.0050%,
Mg: 0.0005% to 0.0050%,
REM: 0.001% to 0.050%,
Sn: 0.01% to 0.50%, and
Sb: 0.01% to 0.50%.

9. The ferritic stainless steel sheet according to claim 6 , wherein the chemical composition further contains, in mass %, one or more selected from
B: 0.0003% to 0.0050%,
Ca: 0.0003% to 0.0050%,
Mg: 0.0005% to 0.0050%,
REM: 0.001% to 0.050%,
Sn: 0.01% to 0.50%, and
Sb: 0.01% to 0.50%.

10. A method of producing the ferritic stainless steel sheet according to claim 2 , the method comprising:
subjecting a steel material having the chemical composition according to claim 2 to hot rolling including a plurality of rolling passes, to obtain a hot-rolled steel sheet; and
thereafter subjecting the hot-rolled steel sheet to hot-rolled sheet annealing to obtain a hot-rolled and annealed steel sheet,
wherein in the hot rolling:
in a temperature range of 950° C. to 1200° C., a rolling pass with a rolling reduction of 15% to 50% which satisfies the following Formula (1) in relation to a rolling reduction in an immediately preceding rolling pass is successively performed three or more times,
1.05≤ r ( n )/ r ( n− 1)≤1.50  (1)

where r(n) is the rolling reduction in the rolling pass that is an nth rolling pass, r(n−1) is the rolling reduction in the immediately preceding rolling pass that is an (n−1)th rolling pass, and n is an ordinal number of the rolling pass, and n is an integer that is 2 or more and is less than or equal to a total number of rolling passes;
thereafter, in a temperature range of 900° C. or more, a time interval between rolling passes of 20 sec to 100 sec is secured at least once; and
a hot rolling finish temperature is 800° C. to 900° C., and
wherein in the hot-rolled sheet annealing:
an annealing temperature is 700° C. to 1100° C.

11. A method of producing the ferritic stainless steel sheet according to claim 3 , the method comprising:
subjecting a steel material having the chemical composition according to claim 3 to hot rolling including a plurality of rolling passes, to obtain a hot-rolled steel sheet; and
thereafter subjecting the hot-rolled steel sheet to hot-rolled sheet annealing to obtain a hot-rolled and annealed steel sheet,
wherein in the hot rolling:
in a temperature range of 950° C. to 1200° C., a rolling pass with a rolling reduction of 15% to 50% which satisfies the following Formula (1) in relation to a rolling reduction in an immediately preceding rolling pass is successively performed three or more times,
1.05≤ r ( n )/ r ( n− 1)≤1.50  (1)

where r(n) is the rolling reduction in the rolling pass that is an nth rolling pass, r(n−1) is the rolling reduction in the immediately preceding rolling pass that is an (n−1)th rolling pass, and n is an ordinal number of the rolling pass, and n is an integer that is 2 or more and is less than or equal to a total number of rolling passes;
thereafter, in a temperature range of 900° C. or more, a time interval between rolling passes of 20 sec to 100 sec is secured at least once; and
a hot rolling finish temperature is 800° C. to 900° C., and
wherein in the hot-rolled sheet annealing:
an annealing temperature is 700° C. to 1100° C.

12. A method of producing the ferritic stainless steel sheet according to claim 4 , the method comprising:
subjecting a steel material having the chemical composition according to claim 4 to hot rolling including a plurality of rolling passes, to obtain a hot-rolled steel sheet; and
thereafter subjecting the hot-rolled steel sheet to hot-rolled sheet annealing to obtain a hot-rolled and annealed steel sheet,
wherein in the hot rolling:
in a temperature range of 950° C. to 1200° C., a rolling pass with a rolling reduction of 15% to 50% which satisfies the following Formula (1) in relation to a rolling reduction in an immediately preceding rolling pass is successively performed three or more times,
1.05≤ r ( n )/ r ( n− 1)≤1.50  (1)

where r(n) is the rolling reduction in the rolling pass that is an nth rolling pass, r(n−1) is the rolling reduction in the immediately preceding rolling pass that is an (n−1)th rolling pass, and n is an ordinal number of the rolling pass, and n is an integer that is 2 or more and is less than or equal to a total n

Assignees

• Jfe Steel Corp

Inventors

• Kawabe Hidetaka
• Fujisawa Mitsuyuki
• Shimizu Hiroshi
• Uchino Tomohiko

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C21D6/004

  containing Cr and Ni · CPC title

• C22C38/001 Primary

  containing N · CPC title

• C21D6/005

  containing Mn · CPC title

• C22C38/60

  containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur · CPC title