Nickel-containing steel for low temperature service and low-temperature tank

Patent metadata

Field	Value
Publication number	US-11208703-B2
Application number	US-201716464647-A
Country	US
Kind code	B2
Filing date	Nov 30, 2017
Priority date	Dec 1, 2016
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

A nickel-containing steel for low temperature service having a determined chemical composition of a Ni content of from 5.0 to 8.0%, in which the volume fraction of retained austenite in a region of 1.5 mm from a surface in the thickness direction is from 3.0 to 20.0% by volume, and the ratio of the hardness in a region of 1.0 mm from a surface in the thickness direction to the hardness in a region of ¼ of the thickness from a surface in the thickness direction is 1.1 or less, and a low-temperature tank using the nickel-containing steel for low temperature service.

First claim

The invention claimed is:

1. A nickel-containing, steel for low temperature service, the steel comprising, in percentage by mass:
from 0.01 to 0.15% of C,
from 0.01 to 2.00% of Si,
from 0.20 to 2.00% of Mn,
0.010% or less of P,
0.0100% or less of S,
from 5.0 to 8.0% of Ni,
from 0.005 to 2.000% of Al
from 0.0010 to 0.0100% of N,
from 0 to 1.00% of Cu,
from 0 to 0.80% of Sn,
from 0 to 0.80% of Sb,
from 0 to 2.00% of Cr,
from 0 to 1.00% of Mo,
from 0 to 1.00% of W,
from 0 to 1.00% of V,
from 0 to 0.100% of Nb,
from 0 to 0.100% of Ti,
from 0 to 0.0200% of Ca,
from 0 to 0.0500% of B,
from 0 to 0.0100% of Mg,
from 0 to 0.0200% of REM, and
a balance being Fe and impurities,
wherein a volume fraction of retained austenite in a region 1.5 mm from a surface of the steel in a thickness direction, is from 3.0 to 20.0% by volume, and
wherein a ratio of a hardness in a region 1.0 mm from the surface in the thickness direction to a hardness in a region ¼ of the thickness from the surface in the thickness direction, is 1.1 or less.

2. The nickel-containing steel for low temperature service according to claim 1 ,
wherein a content of Si is from 0.01 to 0.60% by mass.

3. The nickel-containing steel for low temperature service according to claim 1 , wherein a content of Al is from 0.005 to 0.100% by mass.

4. The nickel-containing steel for low temperature service according to claim 1 , having a yield strength of from 590 to 800 MPa, a tensile strength of from 690 to 830 MPa, and a Charpy impact absorbed energy at −196° C., of 150 J or more.

5. The nickel-containing steel for low temperature service according to claim 1 , having a thickness of from 6 to 50 mm.

6. A low-temperature tank comprising the nickel-containing steel for low temperature service according to claim 1 .

7. The low-temperature tank according to claim 6 , wherein a content of Si is from 0.01 to 0.60% by mass.

8. The low-temperature tank according to claim 6 , wherein a content of Al is from 0.005 to 0.100% by mass.

9. The low-temperature tank according to claim 6 , the nickel-containing steel for low temperature service having a yield strength of from 590 to 800 MPa, a tensile strength of from 690 to 830 MPa, and a Charpy impact absorbed energy at −196° C., of 150 J or more.

10. The low-temperature tank according to claim 6 , the nickel-containing steel for low temperature service having a thickness of from 6 to 50 mm.

Assignees

• Nippon Steel Corp

Inventors

• Kashima Kazuyuki
• Kagaya Takayuki

Classifications

• C21D8/02

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

• C21D2211/001

  Austenite · CPC title

• C21D6/004

  containing Cr and Ni · CPC title

• C21D8/00

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• C22C38/60

  containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur · CPC title