Ferritic stainless steel sheet and method for producing same

Patent metadata

Field	Value
Publication number	US-2022017984-A1
Application number	US-201917299308-A
Country	US
Kind code	A1
Filing date	Nov 27, 2019
Priority date	Dec 11, 2018
Publication date	Jan 20, 2022
Grant date	—

Abstract

A ferritic stainless steel sheet has a predetermined chemical composition and thickness, and has an area ratio of crystal grains of 45 μm or more in grain size of 20% or less.

First claim

1 . A ferritic stainless steel sheet comprising:
a chemical composition containing, in mass %, C: 0.001% to 0.020%, Si: 0.05% to 1.00%, Mn: 0.05% to 1.50%, P: 0.04% or less, S: 0.010% or less, Al: 0.001% to 0.300%, Cr: 10.0% to 13.0%, Ni: 0.65% to 1.50%, Ti: 0.15% to 0.35%, and N: 0.001% to 0.020%, with a balance consisting of Fe and inevitable impurities; an area ratio of crystal grains of 45 μm or more in grain size of 20% or less; and a thickness of 5.0 mm or more.

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 1.00%, W: 0.01% to 0.20%, and Co: 0.01% to 0.20%.

3 . The ferritic stainless steel sheet according to claim 1 , wherein the chemical composition further contains, in mass %, one or more selected from
V: 0.01% to 0.20%, Nb: 0.01% to 0.10%, and Zr: 0.01% to 0.20%.

4 . The ferritic stainless steel sheet according to claim 1 , wherein the chemical composition further contains, in mass %, one or more selected from
B: 0.0002% to 0.0050%, REM: 0.001% to 0.100%, Mg: 0.0005% to 0.0030%, Ca: 0.0003% to 0.0050%, Sn: 0.001% to 0.500%, and Sb: 0.001% to 0.500%.

5 . A method for producing the ferritic stainless steel sheet according to claim 1 , the method comprising the following (a) and (b) and optionally comprising the following (c):
(a) heating a slab having the chemical composition according to claim 1 to a temperature range of 1050° C. or more and 1250° C. or less; (b) subjecting the slab to hot rolling at a cumulative rolling reduction in a temperature range of T 1 [° C.] to T 2 [° C.] of 50% or more and a coiling temperature of 500° C. or more, to obtain a hot-rolled steel sheet; and (c) subjecting the hot-rolled steel sheet to hot-rolled sheet annealing in a temperature range of 600° C. or more and less than 800° C., wherein T 1 and T 2 are respectively defined by the following formulas (1) and (2):
T 1 [° C.]=144Ni+66Mn+885  (1)

T 2 [° C.]=91Ni+40Mn+1083  (2)

where Ni and Mn are respectively Ni content and Mn content in mass % in the chemical composition of the slab.

6 . The ferritic stainless steel sheet according to claim 2 , wherein the chemical composition further contains, in mass %, one or more selected from
V: 0.01% to 0.20%, Nb: 0.01% to 0.10%, and Zr: 0.01% to 0.20%.

7 . The ferritic stainless steel sheet according to claim 2 , wherein the chemical composition further contains, in mass %, one or more selected from
B: 0.0002% to 0.0050%, REM: 0.001% to 0.100%, Mg: 0.0005% to 0.0030%, Ca: 0.0003% to 0.0050%, Sn: 0.001% to 0.500%, and Sb: 0.001% to 0.500%.

8 . The ferritic stainless steel sheet according to claim 3 , wherein the chemical composition further contains, in mass %, one or more selected from
B: 0.0002% to 0.0050%, REM: 0.001% to 0.100%, Mg: 0.0005% to 0.0030%, Ca: 0.0003% to 0.0050%, Sn: 0.001% to 0.500%, and Sb: 0.001% to 0.500%.

9 . The ferritic stainless steel sheet according to claim 6 , wherein the chemical composition further contains, in mass %, one or more selected from
B: 0.0002% to 0.0050%, REM: 0.001% to 0.100%, Mg: 0.0005% to 0.0030%, Ca: 0.0003% to 0.0050%, Sn: 0.001% to 0.500%, and Sb: 0.001% to 0.500%.

10 . A method for producing the ferritic stainless steel sheet according to claim 2 , the method comprising the following (a) and (b) and optionally comprising the following (c):
(a) heating a slab having the chemical composition according to claim 2 to a temperature range of 1050° C. or more and 1250° C. or less; (b) subjecting the slab to hot rolling at a cumulative rolling reduction in a temperature range of T 1 [° C.] to T 2 [° C.] of 50% or more and a coiling temperature of 500° C. or more, to obtain a hot-rolled steel sheet; and (c) subjecting the hot-rolled steel sheet to hot-rolled sheet annealing in a temperature range of 600° C. or more and less than 800° C., wherein T 1 and T 2 are respectively defined by the following formulas (1) and (2):
T 1 [° C.]=144Ni+66Mn+885  (1)

T 2 [° C.]=91Ni+40Mn+1083  (2)

where Ni and Mn are respectively Ni content and Mn content in mass % in the chemical composition of the slab.

11 . A method for producing the ferritic stainless steel sheet according to claim 3 , the method comprising the following (a) and (b) and optionally comprising the following (c):
(a) heating a slab having the chemical composition according to claim 3 to a temperature range of 1050° C. or more and 1250° C. or less; (b) subjecting the slab to hot rolling at a cumulative rolling reduction in a temperature range of T 1 [° C.] to T 2 [° C.] of 50% or more and a coiling temperature of 500° C. or more, to obtain a hot-rolled steel sheet; and (c) subjecting the hot-rolled steel sheet to hot-rolled sheet annealing in a temperature range of 600° C. or more and less than 800° C., wherein T 1 and T 2 are respectively defined by the following formulas (1) and (2):
T 1 [° C.]=144Ni+66Mn+885  (1)

T 2 [° C.]=91Ni+40Mn+1083  (2)

where Ni and Mn are respectively Ni content and Mn content in mass % in the chemical composition of the slab.

12 . A method for producing the ferritic stainless steel sheet according to claim 4 , the method comprising the following (a) and (b) and optionally comprising the following (c):
(a) heating a slab having the chemical composition according to claim 4 to a temperature range of 1050° C. or more and 1250° C. or less; (b) subjecting the slab to hot rolling at a cumulative rolling reduction in a temperature range of T 1 [° C.] to T 2 [° C.] of 50% or more and a coiling temperature of 500° C. or more, to obtain a hot-rolled steel sheet; and (c) subjecting the hot-rolled steel sheet to hot-rolled sheet annealing in a temperature range of 600° C. or more and less than 800° C., wherein T 1 and T 2 are respectively defined by the following formulas (1) and (2):
T 1 [° C.]=144Ni+66Mn+885  (1)

T 2 [° C.]=91Ni+40Mn+1083  (2)

where Ni and Mn are respectively Ni content and Mn content in mass % in the chemical composition of the slab.

13 . A method for producing the ferritic stainless steel sheet according to claim 6 , the method comprising the following (a) and (b) and optionally comprising the following (c):
(a) heating a slab having the chemical composition according to claim 6 to a temperature range of 1050° C. or more and 1250° C. or less; (b) subjecting the slab to hot rolling at a cumulative rolling reduction in a temperature range of T 1 [° C.] to T 2 [° C.] of 50% or more and a coiling temperature of 500° C. or more, to obtain a hot-rolled steel sheet; and (c) subjecting the hot-rolled steel sheet to hot-rolled sheet annealing in a temperature range of 600° C. or more and less than 800° C., wherein T 1 and T 2 are respectively defined by the following formulas (1) and (2):
T 1 [° C.]=144Ni+66Mn+885  (1)

T 2 [° C.]=91Ni+40Mn+1083  (2)

where Ni and Mn are respectively Ni content and Mn content in mass % in the chemical composition of the slab.

14 . A method for producing the ferritic stainless steel sheet according to claim 7 , the method comprising the following (a) and (b) and optionally comprising the following (c):
(a) heating a slab having the chemical composition according to claim 7 to a temperature range of 1050° C. or more and 1250° C. or less; (b) subjecting the slab to hot rolling at a cumulative rolling reduction in a temperature range of T 1 [° C.] to T 2 [° C.] o

Assignees

• Jfe Steel Corp

Inventors

• Inoue Keishi
• Kawabe Hidetaka
• Yoshino Masataka
• Fujisawa Mitsuyuki

Classifications

• C21D8/02

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

• C22C38/60

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

• C22C38/54

  with boron · CPC title

• C22C38/52

  with cobalt · CPC title

• C22C38/04

  containing manganese · CPC title