Rolled ferritic stainless steel sheet, method for producing the same, and flange part

Patent metadata

Field	Value
Publication number	US-10648053-B2
Application number	US-201515128891-A
Country	US
Kind code	B2
Filing date	Mar 26, 2015
Priority date	Mar 26, 2014
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

The present invention provides a rolled ferritic stainless steel material excellent in corrosion resistance and toughness, in particular suitable as a material for a flange and a method for producing the same and flange part. The rolled ferritic stainless steel material contains, by mass %, C: 0.001 to 0.08%, Si: 0.01 to 1.0%, Mn: 0.01 to 1.0%, P: 0.01 to 0.05%, S: 0.0002 to 0.01%, Cr: 10.0 to 25.0%, and N: 0.001 to 0.05%, has a balance of Fe and unavoidable impurities, has a thickness of 5 mm or more, and has an area ratio of crystal grains with a <011> direction within 15° from the rolling direction of 20% or more in a cross-section parallel to the rolling direction at any location between the left and right ends of the steel sheet.

First claim

The invention claimed is:

1. A method of production of a hot rolled steel sheet or a hot rolled steel strip comprised of ferritic stainless steel, comprising performing a hot rolling process making a hot rolling finishing temperature 805° C. to 880° C. and a coiling process at a coiling temperature of 300 to 470° C. or less,
wherein the hot rolled steel sheet or the hot rolled steel strip comprises ferritic stainless steel material containing, by mass %, C: 0.001 to 0.08%, Si: 0.01 to 1.0%, Mn: 0.01 to 1.0%, P: 0.01 to 0.05%, S: 0.0002 to 0.01%, Cr: 10.0 to 25.0%, and N: 0.001 to 0.05%, having a balance of Fe and unavoidable impurities, having a thickness of 5 mm or more, and having an area ratio of crystal grains with a <011> direction within 15° from the rolling direction of 20% or more in a cross-section parallel to the rolling direction at any location between the left and right ends of the steel sheet,
wherein the hot rolled steel sheet or hot rolled steel strip each have a Charpy impact value measured at 0° C. based on JISZ2242 of 11 J/cm 2 or more.

2. The method of production of the hot rolled steel sheet or the hot rolled steel strip comprised of ferritic stainless steel according to claim 1 , wherein in a cross-section parallel to the rolling direction at any location between the left and right ends of the steel sheet, a sum of the lengths of low-angle grain boundaries with a crystal misorientation of less than 15° is 10% or more with respect to a sum of lengths of the crystal grain boundaries.

3. The method of production of the hot rolled steel sheet or the hot rolled steel strip comprised of ferritic stainless steel according to claim 1 , wherein the hot rolled steel sheet or the hot rolled steel strip comprised of ferritic stainless steel further contains, by mass %, one or more of Ti: 0.01 to 0.4%, Nb: 0.01 to 0.6%, B: 0.0002 to 0.0030%, Al: 0.005 to 0.3%, Ni: 0.1 to 1%, Mo: 0.1 to 2.0%, Cu: 0.1 to 3.0%, V: 0.05 to 1.0%, Mg: 0.0002 to 0.0030%, Sn: 0.01 to 0.3%, Sb: 0.01 to 0.3%, Zr: 0.01 to 0.1%, Ta: 0.01 to 0.1%, Hf: 0.01 to 0.1%, W: 0.01 to 2.0%, Co: 0.01 to 0.2%, Ca: 0.0001 to 0.0030%, REM: 0.001 to 0.05%, and Ga: 0.0002 to 0.1%, and having an Mn content of 0.01 to 0.5%.

4. The method of production of the hot rolled steel sheet or the hot rolled steel strip comprised of ferritic stainless steel according to claim 1 , wherein the hot rolled steel sheet or hot rolled steel strip comprised of ferritic stainless steel is used as a flange part.

5. The method of production of the hot rolled steel sheet or the hot rolled steel strip comprised of ferritic stainless steel according to claim 1 , wherein in the hot rolled steel sheet or a hot rolled steel strip comprised of ferritic stainless steel material the Cr content is in a range from 10.0 to 18.0% by mass %.

6. The method of production of the hot rolled steel sheet or the hot rolled steel strip comprised of ferritic stainless steel according to claim 5 , wherein in a cross-section parallel to the rolling direction at any location between the left and right ends of the steel sheet, a sum of the lengths of low-angle grain boundaries with a crystal misorientation of less than 15° is 10% or more with respect to a sum of lengths of the crystal grain boundaries.

7. The method of production of the hot rolled steel sheet or the hot rolled steel strip comprised of ferritic stainless steel according to claim 5 or 6 , wherein the hot rolled steel sheet or hot rolled steel strip comprised of ferritic stainless steel material further contains, by mass %, one or more of Ti: 0.01 to 0.4%, Nb: 0.01 to 0.6%, B: 0.0002 to 0.0030%, Al: 0.005 to 0.3%, Ni: 0.1 to 1%, Mo: 0.1 to 2.0%, Cu: 0.1 to 3.0%, V: 0.05 to 1.0%, Mg: 0.0002 to 0.0030%, Sn: 0.01 to 0.3%, Sb: 0.01 to 0.3%, Zr: 0.01 to 0.1%, Ta: 0.01 to 0.1%, Hf: 0.01 to 0.1%, W: 0.01 to 2.0%, Co: 0.01 to 0.2%, Ca: 0.0001 to 0.0030%, REM: 0.001 to 0.05%, and Ga: 0.0002 to 0.1%, and having an Mn content of 0.01 to 0.5%.

Assignees

• Nippon Steel & Sumikin Sst

Inventors

• Hamada Junichi
• Ito Koji

Classifications

• C22C38/50

  with titanium or zirconium · CPC title

• C22C38/54

  with boron · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title

• C21D8/0263

  following hot rolling · CPC title

• C22C38/06

  containing aluminium · CPC title