Material for cold-rolled stainless steel sheet

Patent metadata

Field	Value
Publication number	US-10633730-B2
Application number	US-201515508665-A
Country	US
Kind code	B2
Filing date	Jul 2, 2015
Priority date	Sep 5, 2014
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

Provided is a material for a cold-rolled stainless steel sheet having a chemical composition containing, by mass %, C: 0.01% to 0.05%, Si: 0.02% to 0.75%, Mn: 0.1% to 1.0%, P: 0.04% or less, S: 0.01% or less, Cr: 16.0% to 18.0%, Al: 0.001% to 0.10%, N: 0.01% to 0.06% and the balance being Fe and inevitable impurities. The material has a metallographic structure including a martensite phase having an area ratio of 5% to 50% and the balance being a ferrite phase. A ferrite phase in portions extending from surface layers of front and back surfaces of a steel sheet has an average grain diameter of 20 μm or more and 50 μm or less, and a ferrite phase in a central portion of the sheet includes an unrecrystallized ferrite phase.

First claim

The invention claimed is:

1. A material for a cold-rolled stainless steel sheet, the material having a chemical composition containing, by mass %, C: 0.005% to 0.05%, Si: 0.02% to 0.75%, Mn: 0.1% to 1.0%, P: 0.04% or less, S: 0.01% or less, Cr: 16.0% to 18.0%, Al: 0.001% to 0.07%, N: 0.005% to 0.06%, and the balance being Fe and inevitable impurities, a metallographic structure including a martensite phase having an area ratio of 5% to 50% and the balance being a ferrite phase, and a waviness height is 2.5 μm or less,
wherein a ferrite phase in portions extending from surface layers of front and back surfaces of a steel sheet to, in a thickness direction of the sheet, positions at t/3 (t: thickness of the sheet), has an average grain diameter of 20 μm or more and 50 μm or less, and
a ferrite phase in a central portion in the thickness direction of the sheet, the central portion being a portion of the sheet other than the portions extending from, in the thickness direction of the sheet, the surface layers to the positions at t/3 (t: thickness of the sheet), includes a ferrite phase satisfying an aspect ratio of more than 3.0.

2. The material for a cold-rolled stainless steel sheet according to claim 1 , the chemical composition further containing, by mass %, one, two, or more selected from among Cu: 0.1% to 1.0%, Ni: 0.1% to 1.0%, Mo: 0.1% to 0.5%, and Co: 0.01% to 0.3%.

3. The material of a cold-rolled stainless steel sheet according to claim 2 , the material further comprising one, two, or more elements selected from, by mass, V: 0.01% to 0.25%, Ti: 0.001% to 0.015%, Nb: 0.001% to 0.030%, Mg: 0.0002% to 0.0050%, B: 0.0002% to 0.0050%, and REM: 0.01% to 0.10%.

4. The material for a cold-rolled stainless steel sheet according to claim 1 , the chemical composition further containing, by mass %, one, two, or more selected from among V: 0.01% to 0.25%, Ti: 0.001% to 0.015%, Nb: 0.001% to 0.030%, Mg: 0.0002% to 0.0050%, B: 0.0002% to 0.0050%, and REM: 0.01% to 0.10%.

Assignees

• Jfe Steel Corp

Inventors

• Ta Ayako
• Matsubara Yukihiro
• Kimura Yukio
• Yoshino Masataka
• Nakazono Keisuke
• Kaiho Sumio
• Murata Saiichi
• Kitagawa Nobukazu

Classifications

• C22C38/001

  containing N · CPC title

• C22C38/18 Primary

  containing chromium · CPC title

• C22C38/002

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

• C22C38/00

  Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00) · CPC title

• C22C38/26

  with niobium or tantalum · CPC title