Material for cold rolled stainless steel sheets, method for manufacturing the same, and cold rolled steel sheet

Patent metadata

Field	Value
Publication number	US-10801084-B2
Application number	US-201515737045-A
Country	US
Kind code	B2
Filing date	Jul 2, 2015
Priority date	Jul 2, 2015
Publication date	Oct 13, 2020
Grant date	Oct 13, 2020

Abstract

Provided are a material for cold rolled stainless steel sheets having sufficient corrosion resistance, excellent surface quality, excellent formability, and excellent ridging resistance; a method for manufacturing the same; and a cold rolled steel sheet. A material for cold rolled stainless steel sheets according to the present invention contains C: 0.005% to 0.025%, Si: 0.02% to 0.50%, Mn: 0.55% to 1.0%, P: 0.040% or less, S: 0.01% or less, Cr: 15.5% to 18.0%, Ni: 0.01% to 1.0%, Al: 0.001% to 0.10%, and N: 0.005% to 0.025% on a mass basis, the remainder being Fe and inevitable impurities, and has a metallographic structure containing 5% to 20% of a martensite phase in terms of volume fraction, the remainder being a ferrite phase.

First claim

The invention claimed is:

1. A material for cold rolled stainless steel sheets, comprising C: 0.005% to 0.025%, Si: 0.02% to 0.50%, Mn: 0.55% to 1.0%, P: 0.040% or less, 5: 0.01% or less, Cr: 15.5% to 18.0%, Ni: 0.01% to 0.30%, Al: 0.001% to 0.07%, and N: 0.005% to 0.025% on a mass basis, the remainder being Fe and inevitable impurities,
the material having a metallographic structure containing 5% to 20% of a martensite phase in terms of volume fraction, the remainder being a ferrite phase,
wherein the proportion of selectively dissolved ferrite phase grain boundaries among ferrite phase grain boundaries exposed on a surface of a steel sheet formed by the material for the cold rolled stainless steel sheets is 20% or less of the total length of grain boundaries.

2. The material for the cold rolled stainless steel sheets according to claim 1 , further containing one or more selected from Cu: 0.1% to 1.0%, Mo: 0.1% to 0.5%, and Co: 0.01% to 0.5% on a mass basis.

3. The material for the cold rolled stainless steel sheets according to claim 1 , further containing one or more selected from V: 0.01% to 0.10%, Ti: 0.001% to 0.05%, Nb: 0.001% to 0.05%, Ca: 0.0002% to 0.0020%, Mg: 0.0002% to 0.0050%, 6: 0.0002% to 0.0050%, and REM: 0.01% to 0.10% on a mass basis.

4. The m material for the cold roiled stainless steel sheets according to claim 2 , further containing one or more selected from V: 0.01% to 0.10%, Ti: 0.001% to 0.05%, Nb: 0.001% to 0.05%, Ca: 0.0002% to 0.0020%, Mg: 0.0002% to 0.0050%, 8: 0.0002% to 0.0050% and REM: 0.01% to 0.10% on a mass basis.

5. A cold rolled ferritic stainless steel sheet obtained by cold-rolling and annealing the material for the cold rolled stainless steel sheets according to claim 1 .

6. A cold rolled ferritic stainless steel sheet obtained by cold-rolling and annealing the material for the cold rolled stainless steel sheets according to claim 2 .

7. A cold rolled ferritic stainless steel sheet obtained by cold-rolling and annealing the material for the cold rolled stainless steel sheets according to claim 3 .

8. A cold rolled ferritic stainless steel sheet obtained by cold-rolling and annealing the material for the cold rolled stainless steel sheets according to claim 4 .

9. A method for manufacturing the material for the cold rolled stainless steel sheets according to claim 1 , comprising hot rolling a steel slab to form a hot rolled sheet, annealing the hot rolled sheet in such a manner that the hot rolled sheet is held in a temperature range from 920° C. to 1,100° C. for 5 seconds to 15 minutes, cooling the hot rolled sheet in a temperature range from 1,100° C. to 500° C. at a cooling rate of 10° C./sec or more, and pickling the hot rolled sheet.

10. A method for manufacturing the material for the cold rolled stainless steel sheets according to claim 2 , comprising hot rolling a steel slab to form a hot rolled sheet, annealing the hot rolled sheet in such a manner that the hot rolled sheet is held in a temperature range from 920° C. to 1,100° C. for 5 seconds to 15 minutes, cooling the hot rolled sheet in a temperature range from 1,100° C. to 500° C. at a cooling rate of 10° C./sec or more, and pickling the hot rolled sheet.

11. A method for manufacturing the material for the cold rolled stainless steel sheets according to claim 3 , comprising hot rolling a steel slab to form a hot rolled sheet, annealing the hot rolled sheet in such a manner that the hot rolled sheet is held in a temperature range from 920° C. to 1,100° C. for 5 seconds to 15 minutes, cooling the hot rolled sheet in a temperature range from 1,100° C. to 500° C. at a cooling rate of 10° C./sec or more, and pickling the hot rolled sheet.

12. A method for manufacturing the material for the cold rolled stainless steel sheets according to claim 4 , comprising hot rolling a steel slab to form a hot rolled sheet, annealing the hot rolled sheet in such a manner that the hot rolled sheet is held in a temperature range from 920° C. to 1,100° C. for 5 seconds to 15 minutes, cooling the hot rolled sheet in a temperature range from 1,100° C. to 500° C. at a cooling rate of 10° C./sec or more, and pickling the hot rolled sheet.

Assignees

• Jfe Steel Corp

Inventors

• Mizutani Akito
• Yoshino Masataka
• Fujisawa Mitsuyuki
• Kami Chikara

Classifications

• Y02P10/20

  Recycling · CPC title

• C21D8/0226

  Hot rolling · CPC title

• C21D8/0236

  Cold rolling · CPC title

• C22C38/40 Primary

  with nickel · CPC title

• C22C38/005

  containing rare earths, i.e. Sc, Y, Lanthanides · CPC title