Stainless steel and production method therefor

Patent metadata

Field	Value
Publication number	US-10626486-B2
Application number	US-201515533499-A
Country	US
Kind code	B2
Filing date	Jul 2, 2015
Priority date	Dec 11, 2014
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

Stainless steel that has excellent formability and ridging resistance and can be produced with high productivity is provided. The stainless steel comprises: a chemical composition containing, in mass %, C: 0.005% to 0.050%, Si: 0.01% to 1.00%, Mn: 0.01% to 1.0%, P: 0.040% or less, S: 0.010% 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 0.06%, with a balance being Fe and incidental impurities; and a microstructure containing a martensite phase of 1% to 10% in volume fraction with respect to a whole volume of the microstructure.

First claim

The invention claimed is:

1. A stainless steel comprising:
a chemical composition consisting of, in mass %,
C: 0.005% to 0.050%,
Si: 0.01% to 1.00%,
Mn: 0.01% to 1.0%,
P: 0.040% or less,
S: 0.010% or less,
Cr: 15.5% to 18.0%,
Ni: 0.01% to 1.0%,
Al: 0.001% to 0.10%,
N: 0.005% to 0.06%, and
optionally
one or more selected from Cu: 0.1% to 1.0%, Mo: 0.1% to 0.5%, and Co: 0.01% to 0.5%, and
one or more selected from V: 0.01% to 0.25%, Ti: 0.001% to 0.022%, Nb: 0.001% to 0.05%, Ca: 0.0002% to 0.0020%, Mg: 0.0002% to 0.0050%, B: 0.0002% to 0.0050%, and REM: 0.01% to 0.10%,
with a balance being Fe and incidental impurities; and
a microstructure containing a martensite phase of 1% to 10% in volume fraction with respect to a whole volume of the microstructure,
wherein mean elongation after fracture is 25% or more, in-plane anisotropy of elongation after fracture |ΔEl| is 3% or less, mean Lankford value is 0.70 or more, in-plane anisotropy of Lankford value |Δr| is 0.30 or less, and ridging height is 2.5 μm or less.

2. A method for producing the stainless steel according to claim 1 , the method comprising:
hot rolling a steel slab having the chemical composition according to claim 1 into a hot rolled sheet;
performing hot-rolled sheet annealing of holding the hot rolled sheet in a temperature range of 900° C. or more and 1050° C. or less for 5 seconds to 15 minutes, to form a hot-rolled and annealed sheet;
cold rolling the hot-rolled and annealed sheet into a cold rolled sheet; and
performing cold-rolled sheet annealing of holding the cold rolled sheet in a temperature range of 850° C. or more and 950° C. or less for 5 seconds to 5 minutes.

Assignees

• Jfe Steel Corp

Inventors

• Mizutani Akito
• Yoshino Masataka
• Fujisawa Mitsuyuki
• Ta Ayako

Classifications

• C21D2211/008

  Martensite · CPC title

• C22C38/00

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

• C22C38/04

  containing manganese · CPC title

• C21D9/46

  for sheet metals · CPC title

• C21D8/0226

  Hot rolling · CPC title