Martensitic stainless steel material

Patent metadata

Field	Value
Publication number	US-2025146112-A1
Application number	US-202318837961-A
Country	US
Kind code	A1
Filing date	May 12, 2023
Priority date	May 25, 2022
Publication date	May 8, 2025
Grant date	—

Abstract

A martensitic stainless steel material having high strength, and having excellent corrosion resistance in a corrosive environment in which SOx or NOx is mixed is provided. The martensitic stainless steel material according to the present disclosure satisfies a chemical composition described herein, and satisfies Formula (1). The yield strength is 862 MPa or more. In the martensitic stainless steel material, a number ratio of Mg oxides having an equivalent circular diameter of 2.0 μm or more with respect to Ca oxides having an equivalent circular diameter of 2.0 μm or more, Ca sulfides having an equivalent circular diameter of 2.0 μm or more, and the Mg oxides having an equivalent circular diameter of 2.0 μm or more is 45.0% or more.

0.001
≤

Ca
+
Mg

≤
0.005

(
1
)

Where, a content of a corresponding element in percent by mass is substituted for each symbol of an element in Formula (1).

First claim

1 . A martensitic stainless steel material consisting of, in mass %,
C: 0.030% or less, Si: 1.00% or less, Mn: 1.00% or less, P: 0.030% or less, S: 0.0050% or less, Cr: 11.00 to 14.00%, Ni: 4.00 to 7.50%, Mo: 1.50 to 4.50%, Co: 0.01 to 0.50%, Ti: 0.05 to 0.30%, V: 0.01 to 1.00%, Ca: 0.0005 to 0.0050%, Mg: 0.0005 to 0.0050%, Al: 0.001 to 0.100%, N: 0.0500% or less, O: 0.0500% or less, Cu: 0 to 3.50%, Nb: 0 to 0.50%, Zr: 0 to 0.050%, W: 0 to 2.00%, B: 0 to 0.0050%, rare earth metal: 0 to 0.0050%, and the balance: Fe and impurities, wherein: within ranges of contents of elements of the martensitic stainless steel material, contents of the elements satisfy Formula (1); a yield strength is 862 MPa or more; and in the martensitic stainless steel material, a number ratio of Mg oxides having an equivalent circular diameter of 2.0 μm or more with respect to Ca oxides having an equivalent circular diameter of 2.0 μm or more, Ca sulfides having an equivalent circular diameter of 2.0 μm or more, and the Mg oxides having an equivalent circular diameter of 2.0 μm or more is 45.0% or more;

0.001
≤

Ca
+
Mg

≤
0.005

(
1
)

where, a content of a corresponding element in percent by mass is substituted for each symbol of an element in Formula (1).

2 . The martensitic stainless steel material according to claim 1 , containing one or more elements selected from a group consisting of:
Cu: 0.01 to 3.50%, Nb: 0.01 to 0.50%, Zr: 0.001 to 0.050%, W: 0.01 to 2.00%, B: 0.0001 to 0.0050%, and rare earth metal: 0.0001 to 0.0050%.

3 . The martensitic stainless steel material according to claim 1 , wherein:
within ranges of contents of elements of the martensitic stainless steel material, contents of the elements satisfy Formula (2); and in the martensitic stainless steel material, a total number density of the Ca oxides having an equivalent circular diameter of 2.0 μm or more, the Ca sulfides having an equivalent circular diameter of 2.0 μm or more, and the Mg oxides having an equivalent circular diameter of 2.0 μm or more is 1000/cm 2 or more;

Ca
/
S

≥
0.8

(
2
)

where, a content of a corresponding element in percent by mass is substituted for each symbol of an element in Formula (2).

4 . The martensitic stainless steel material according to claim 2 , wherein:
within ranges of contents of elements of the martensitic stainless steel material, contents of the elements satisfy Formula (2); and in the martensitic stainless steel material, a total number density of the Ca oxides having an equivalent circular diameter of 2.0 μm or more, the Ca sulfides having an equivalent circular diameter of 2.0 μm or more, and the Mg oxides having an equivalent circular diameter of 2.0 μm or more is 1000/cm 2 or more;

Ca
/
S

≥
0.8

(
2
)

where, a content of a corresponding element in percent by mass is substituted for each symbol of an element in Formula (2).

Assignees

• Nippon Steel Corp

Inventors

• Kanki Kyohei
• Matsuo Daisuke
• Arai Yuji

Classifications

• C21C7/0685

  of stainless steel · CPC title

• C21C7/10

  Handling in a vacuum · CPC title

• C21C5/005

  Manufacture of stainless steel · CPC title

• C22C38/52

  with cobalt · CPC title

• C22C38/50

  with titanium or zirconium · CPC title