Steel pipe or tube for pressure vessels, method of producing steel pipe or tube for pressure vessels, and composite pressure vessel liner

Patent metadata

Field	Value
Publication number	US-11168375-B2
Application number	US-201716333339-A
Country	US
Kind code	B2
Filing date	Aug 8, 2017
Priority date	Sep 21, 2016
Publication date	Nov 9, 2021
Grant date	Nov 9, 2021

Abstract

A steel pipe or tube for pressure vessels having excellent quench crack resistance is provided. The steel pipe or tube for pressure vessels comprises: a specific chemical composition; and a metallic microstructure in which an average grain size of prior austenite grains is 500 μm or less, and an area fraction of microstructures other than ferrite is 50% or more.

First claim

The invention claimed is:

1. A steel pipe or tube for pressure vessels, comprising:
a chemical composition consisting of, in mass %,
C: 0.30% to 0.60%,
Si: 0.01% to 2.0%,
Mn: 0.5% to 5.0%,
P: 0.0001% to 0.020%,
S: 0.0001% to 0.010%,
N: 0.0001% to 0.010%,
Al: 0.01% to 0.06%, and
optionally
one or more selected from Mo: 0.005% to 2.0%, and Cr: 0.005% to 3.0%, and
one or more selected from Ni: 0.005% to 5.0%, and V: 0.05% to 0.35%,
with the balance being Fe and inevitable impurities; and

a metallic microstructure in which an average grain size of prior austenite grains is 50 μm or more and 500 μm or less, and an area fraction of microstructures other than ferrite is 50% or more, and
a wall thickness of the steel pipe or tube for pressure vessels is 30 mm or more.

2. The steel pipe or tube for pressure vessels according to claim 1 , wherein the chemical composition satisfies a relationship of the following Expression (1):
[Mn]+1.30×[Cr]+2.67×[Mo]+0.30×[Ni]≥2.15  (1)

where brackets in the Expression (1) indicate a content, in mass %, of an element in the brackets, and indicate 0 in the case where the element is not contained.

3. The steel pipe or tube for pressure vessels according to claim 2 , wherein the chemical composition satisfies a relationship of the following Expression (2):
[Mn]+1.30×[Cr]+2.67×[Mo]+0.30×[Ni]≥2.90  (2)

where brackets in the Expression (2) indicate a content, in mass %, of an element in the brackets, and indicate 0 in the case where the element is not contained.

4. A method of producing the steel pipe or tube for pressure vessels of claim 1 , comprising:
heating a billet having the chemical composition according to claim 1 , to a temperature of 1350° C. or less;
rolling and pipe-or-tube-expanding the heated billet under a condition that a pipe or tube expansion finish temperature is 820° C. or more, to obtain a steel pipe or tube whose final wall thickness is 8.5% or more and less than 25.0% of a diameter of the billet; and
cooling the steel pipe or tube obtained in the rolling and pipe-or-tube-expanding, under a condition that an average cooling rate from 800° C. to 300° C. is 1° C./s or more.

5. A method of producing the steel pipe or tube for pressure vessels of claim 2 , comprising:
heating a billet having the chemical composition according to claim 2 , to a temperature of 1350° C. or less;
rolling and pipe-or-tube-expanding the heated billet under a condition that a pipe or tube expansion finish temperature is 820° C. or more, to obtain a steel pipe or tube whose final wall thickness is 8.5% or more and less than 25.0% of a diameter of the billet; and
cooling the steel pipe or tube obtained in the rolling and pipe-or-tube-expanding, under a condition that an average cooling rate from 800° C. to 300° C. is 0.5° C./s or more.

6. A method of producing the steel pipe or tube for pressure vessels of claim 3 , comprising:
heating a billet having the chemical composition according to claim 3 , to a temperature of 1350° C. or less;
rolling and pipe-or-tube-expanding the heated billet under a condition that a pipe or tube expansion finish temperature is 820° C. or more, to obtain a steel pipe or tube whose final wall thickness is 8.5% or more and less than 25.0% of a diameter of the billet; and
cooling the steel pipe or tube obtained in the rolling and pipe-or-tube-expanding, under a condition that an average cooling rate from 800° C. to 300° C. is 0.2° C./s or more.

7. A composite pressure vessel liner, comprising
the steel pipe or tube for pressure vessels according to claim 1 .

Assignees

• Jfe Steel Corp

Inventors

• Okano Hiroshi
• Takagi Shusaku

Classifications

• C21D8/10 Primary

  during manufacturing of tubular bodies · CPC title

• Y02E60/32

  Hydrogen storage · CPC title

• F17C2203/0648

  Alloys or compositions of metals · CPC title

• F17C2203/0604

  Liners · CPC title

• F17C2223/036

  Very high pressure (>80 bar) · CPC title