High-strength austenitic stainless steel having excellent hydrogen embrittlement resistance characteristics and method for producing same

Patent metadata

Field	Value
Publication number	US-10501819-B2
Application number	US-201615553514-A
Country	US
Kind code	B2
Filing date	Feb 19, 2016
Priority date	Mar 6, 2015
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

This high-strength austenitic stainless steel having excellent hydrogen embrittlement resistance characteristics includes, by mass %, C: 0.2% or less, Si: 0.3% to 1.5%, Mn: 7.0% to 11.0%, P: 0.06% or less, S: 0.008% or less, Ni: 5.0% to 10.0%, Cr: 14.0% to 20.0%, Cu: 1.0% to 5.0%, N: 0.01% to 0.4%, and 0: 0.015% or less, with the balance being Fe and unavoidable impurities, wherein an average size of Cr-based carbonitrides is 100 nm or less, and an amount of the Cr-based carbonitrides is 0.001% to 0.5% in terms of % by mass.

First claim

The invention claimed is:

1. A high-strength austenitic stainless steel comprising, in terms of % by mass:
C: 0.2% or less;
Si: 0.3% to 1.5%;
Mn: 7.0% to 11.0%;
P: 0.06% or less;
S: 0.008% or less;
Ni: 5.0% to 10.0%;
Cr: 14.0% to 20.0%;
Cu: 1.0% to 5.0%;
N: 0.01% to 0.4%; and
O: 0.015% or less,
with the balance being Fe and unavoidable impurities,
wherein an average size of Cr-based carbonitrides is 100 nm or less, and an amount of the Cr-based carbonitrides is 0.001% to 0.5% in terms of % by mass.

2. The high-strength austenitic stainless steel according to claim 1 , further comprising, in terms of % by mass, one or more selected from Mo: 0.5% or less, Al: 0.3% or less, Mg: 0.01% or less, Ca: 0.01% or less, REM: 0.10% or less, B: 0.005% or less, Ti: 0.5% or less, Nb: 0.5% or less, and V: 0.5% or less.

3. The high-strength austenitic stainless steel according to claim 1 , which is used in a high pressure hydrogen gas and liquid hydrogen environment.

4. A method for producing a high-strength austenitic stainless steel, the method comprising:
a step of hot-working a semi-finished product having a component composition according to claim 1 ;
a step of performing a final heat treatment at a temperature of 1000° C. to 1150° C.; and
a step of performing cooling after the final heat treatment,
wherein, in the cooling step, an average cooling rate is controlled to be less than 2.0° C/s until the temperature reaches 750° C.;
thereby producing the high-strength austenitic stainless steel of claim 1 .

5. The high-strength austenitic stainless steel according to claim 2 , which is used in a high pressure hydrogen gas and liquid hydrogen environment.

6. A method for producing a high-strength austenitic stainless steel, the method comprising:
a step of hot-working a semi-finished product having a component composition according to claim 2 ;
a step of performing a final heat treatment at a temperature of 1000° C. to 1150° C.; and
a step of performing cooling after the final heat treatment,
wherein, in the cooling step, an average cooling rate is controlled to be less than 2.0° C/s until the temperature reaches 750° C.;
thereby producing the high-strength austenitic stainless steel of claim 2 .

Assignees

• Nippon Steel & Sumikin Sst

Inventors

• Matsumoto Kazuhisa
• Hatano Masaharu
• Ohmiya Shinichi

Classifications

• C21D8/02

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

• C21D6/005

  containing Mn · CPC title

• C22C38/50

  with titanium or zirconium · CPC title

• C21D6/004

  containing Cr and Ni · CPC title