Austenitic stainless steel having increased yield ratio and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-12173392-B2
Application number	US-202017772324-A
Country	US
Kind code	B2
Filing date	Jul 8, 2020
Priority date	Oct 29, 2019
Publication date	Dec 24, 2024
Grant date	Dec 24, 2024

Abstract

Disclosed is an austenitic stainless steel having an increased yield ratio. The disclosed austenitic stainless steel is characterized by comprising, in percent by weight (wt %), 0.1% or less (exclusive of 0) of C, 0.2% or less (exclusive of 0) of N, 1.5 to 2.5% of Si, 6.0 to 10.0% of Mn, 15.0 to 17.0% of Cr, 0.3% or less (exclusive of 0) of Ni, 2.0 to 3.0% of Cu, and the remainder of Fe and other inevitable impurities, and satisfying Expressions (1) and (2) below.

3.2≤5.53+1.4Ni−0.16Cr+17.1(C+N)+0.722Mn+1.4Cu−5.59Si≤7  Expression (1):

551−462(C+N)−9.2Si−8.1Mn−13.7Cr−29(Ni+Cu)≤110  Expression (2):
wherein C, N, Si, Mn, Cr, Ni, and Cu indicate the content (wt %) of respective elements.

First claim

The invention claimed is:

1. An austenitic stainless steel having an increased yield ratio comprising, in percent by weight (wt %), 0.1% or less (exclusive of 0) of C, 0.2% or less (exclusive of 0) of N, 1.5 to 2.5% of Si, 6.0 to 10.0% of Mn, 15.0 to 17.0% of Cr, 0.3% or less (exclusive of 0) of Ni, 2.0 to 3.0% of Cu, and the remainder of Fe and other inevitable impurities, and satisfying Expressions (1) and (2) below:
3.2≤5.53+1.4Ni−0.16Cr+17.1(C+N)+0.722Mn+1.4Cu−5.59Si≤7  Expression (1):

551−462(C+N)−9.2Si−8.1Mn−13.7Cr−29(Ni+Cu)≤110  Expression (2):

(wherein C, N, Si, Mn, Cr, Ni, and Cu indicate the content (wt %) of respective elements).

2. The austenitic stainless steel according to claim 1 , wherein the austenitic stainless steel satisfies Expression (3) below:
[4.4+23(C+N)+1.3Si+0.24(Cr+Ni+Cu)+0.1*Mn]+0.16*[((Cr+1.5Si+18)/(Ni+0.52Cu+30(C+N)+0.5Mn+36)+0.262)*161−161]≥17  Expression (3):

(wherein C, N, Si, Mn, Cr, Ni, and Cu indicate the content (wt %) of respective elements).

3. The austenitic stainless steel according to claim 1 , wherein a yield ratio is 0.6 or more.

4. The austenitic stainless steel according to claim 1 , wherein a yield strength is 600 MPa or more.

5. The austenitic stainless steel according to claim 1 , wherein an elongation is 35% or more.

6. A method for manufacturing an austenitic stainless steel having an increased yield ratio, the method comprising:
preparing a slab comprising, in percent by weight (wt %), 0.1% or less (exclusive of 0) of C, 0.2% or less (exclusive of 0) of N, 1.5 to 2.5% of Si, 6.0 to 10.0% of Mn, 15.0 to 17.0% of Cr, 0.3% or less (exclusive of 0) of Ni, 2.0 to 3.0% of Cu, and the remainder of Fe and other inevitable impurities, and satisfying Expressions (1) and (2) below;
hot rolling the slab;
hot annealing a hot-rolled steel sheet;
cold rolling the hot-rolled, annealed steel sheet; and
cold annealing the cold-rolled steel sheet at a temperature of 1,050° C. or higher:
3.2≤5.53+1.4Ni−0.16Cr+17.1(C+N)+0.722Mn+1.4Cu−5.59Si≤7  Expression (1):

551−462(C+N)−9.2Si−8.1Mn−13.7Cr−29(Ni+Cu)≤110  Expression (2):

(wherein C, N, Si, Mn, Cr, Ni, and Cu indicate the content (wt %) of respective elements).

7. The method according to claim 6 , wherein the slab satisfies Expression (3) below:
[4.4+23(C+N)+1.3Si+0.24(Cr+Ni+Cu)+0.1*Mn]+0.16*[((Cr+1.5Si+18)/(Ni+0.52Cu+30(C+N)+0.5Mn+36)+0.262)*161−161]≥17  Expression (3):

(wherein C, N, Si, Mn, Cr, Ni, and Cu indicate the content (wt %) of respective elements).

8. The method according to claim 6 , wherein the cold annealing is performed for 10 seconds to 10 minutes.

9. The method according to claim 6 , wherein the hot rolling is performed at a temperature of 1,100 to 1,300° C.

10. The method according to claim 6 , wherein the hot annealing is performed at a temperature of 1,000 to 1,100° C. for 10 seconds to 10 minutes.

Assignees

• Posco

Inventors

• Song Seokweon
• Kim Hak
• Park Mi-Nam

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C22C38/42

  with copper · CPC title

• C22C38/02

  containing silicon · CPC title

• C21D2211/001

  Austenite · CPC title

• C21D9/46

  for sheet metals · CPC title