Ferrite-based stainless steel sheet having low specific gravity and production method therefor

Patent metadata

Field	Value
Publication number	US-11242578-B2
Application number	US-201816498220-A
Country	US
Kind code	B2
Filing date	Mar 27, 2018
Priority date	Mar 30, 2017
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

This ferritic stainless steel sheet contains, by mass %: C: 0.001% to 0.020%; Si: 0.01% to 4.00%; Mn: 0.01% to 3.00%; P: 0.010% to 0.040%; S: 0.0001% to 0.0100%; Cr: 10.0% to 15.0%; N: 0.001% to 0.020%; Al: 0.50% to 10.0%; and either one or both of Ti: 0.05% to 0.40% and Nb: 0.05% to 0.40%, with the balance being Fe and unavoidable impurities, in which Cr/(Si+Al) is 10.0 or less, and a specific gravity is 7.6 g/cm 3 or less.

First claim

The invention claimed is:

1. A ferritic stainless steel sheet having a low specific gravity comprising, by mass %:
C: 0.001% to 0.020%;
Si: 0.01% to 4.00%;
Mn: 0.01% to 3.00%;
P: 0.010% to 0.040%;
S: 0.0001% to 0.0100%;
Cr: 10.0% to 15.0%;
N: 0.001% to 0.020%;
Al: 0.50% to 10.0%; and
either one or both of Ti: 0.05% to 0.40% and Nb: 0.05% to 0.40%,
with the balance being Fe and unavoidable impurities,
wherein Cr/(Si+Al) is 10.0 or less, and a specific gravity is 7.6 g/cm 3 or less,
a precipitation amount of AlN is 0.010% or less by mass %, and
a sum of a maximum value of an Al concentration and a maximum value of a Si concentration in a region from a steel sheet surface to a depth of 5 nm is 15 at % or more.

2. The ferritic stainless steel sheet having a low specific gravity according to claim 1 , further comprising one or more of, by mass %:
Cu: 0.01% to 3.00%;
Ni: 0.01% to 2.00%;
Mo: 0.01% to 3.00%;
V: 0.01% to 0.50%;
B: 0.0002% to 0.0050%;
Ca: 0.0005% to 0.0100%;
W: 0.1% to 3.0%;
Zr: 0.01% to 0.10%;
Ta: 0.01% to 0.10%;
Hf: 0.01% to 0.10%;
Sn: 0.005% to 0.50%;
Co: 0.03% to 0.30%;
Mg: 0.0002% to 0.010%;
Sb: 0.005% to 0.50%;
REM: 0.002% to 0.20%; and
Ga: 0.0002% to 0.30%.

3. A method for producing the ferritic stainless steel sheet having a low specific gravity according to claim 1 , the method comprising:
a step of annealing a cold-rolled sheet; and
a pickling step that is performed after the step of annealing the cold-rolled sheet,
wherein in the step of annealing the cold-rolled sheet, an annealing temperature is set to be 900° C. or higher, and a cooling rate from 900° C. to 600° C. is set to be 100° C./sec or more, and
in the pickling step, first, the cold-rolled sheet is immersed in a molten alkali salt at a temperature of 440° C. or lower for 5 seconds to 30 seconds, and thereafter, the cold-rolled sheet is cooled to room temperature at a cooling rate of 50° C./sec or less, and next, the cold-rolled sheet is immersed in a nitric hydrofluoric acid solution in which an amount of hydrofluoric acid is 10 to 30 g/l and an amount of nitric acid is 20 to 60 g/l at a temperature of 30° C. to 60° C. for 10 seconds to 60 seconds thereby producing the ferritic stainless steel sheet according to claim 1 .

Assignees

• Nippon Steel Stainless Steel Corp

Inventors

• Hamada Junichi
• Abe Masatoshi
• HAYASHI Atsutaka

Classifications

• C21D8/02

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

• C22C38/50

  with titanium or zirconium · CPC title

• C21D6/005

  containing Mn · CPC title

• C21D6/002

  containing Cr (C21D6/004 takes precedence) · CPC title

• C23G1/08

  Iron or steel · CPC title