Electric resistance welded clad steel pipe or tube and method of producing same

Patent metadata

Field	Value
Publication number	US-11079045-B2
Application number	US-201716331235-A
Country	US
Kind code	B2
Filing date	Aug 31, 2017
Priority date	Sep 12, 2016
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

Provided is an electric resistance welded clad steel pipe or tube in which a region where solidification microstructure is formed, i.e. a region in a weld particularly having significant influence on properties, is reduced without impairing its function as a clad pipe or tube. An electric resistance welded clad steel pipe or tube comprises: a first layer made of carbon steel or low-alloy steel as base metal; and a second layer placed on one surface of the first layer, and made of stainless steel or a nickel-containing alloy as cladding metal, wherein the base metal is not exposed at a cladding metal-side surface of the electric resistance welded clad steel pipe or tube in a weld, and no solidification microstructure is contained in each of circular sections of 0.1 mm in radius respectively centered at specific three positions in a plane perpendicular to a pipe or tube longitudinal direction.

First claim

The invention claimed is:

1. An electric resistance welded clad steel pipe or tube, comprising:
a first layer made of carbon steel or low-alloy steel as base metal; and
a second layer placed on one surface of the first layer, and made of stainless steel or a nickel-containing alloy as cladding metal,
wherein the base metal is not exposed at a cladding metal-side surface of the electric resistance welded clad steel pipe or tube in a weld, and
no solidification microstructure is contained in each of circular sections of 0.1 mm in radius respectively centered at the following positions (i) to (iii) in a plane perpendicular to a pipe or tube longitudinal direction:
(i) a position that is 1 mm in depth from an outer surface of the electric resistance welded clad steel pipe or tube in the weld and is 0.3 mm in a transverse direction of weld metal from a center of a width of the weld metal in a pipe or tube circumferential direction;
(ii) a position that is a center of the electric resistance welded clad steel pipe or tube in a thickness direction in the weld and is 0.3 mm in the transverse direction of the weld metal from the center of the width of the weld metal in the pipe or tube circumferential direction; and
(iii) a position that is 1 mm in depth from an inner surface of the electric resistance welded clad steel pipe or tube in the weld and is 0.3 mm in the transverse direction of the weld metal from the center of the width of the weld metal in the pipe or tube circumferential direction.

2. The electric resistance welded clad steel pipe or tube according to claim 1 , composed of the first layer and the second layer.

3. The electric resistance welded clad steel pipe or tube according to claim 2 , wherein one of the following (A) and (B) is satisfied:
(A) the first layer is located on an outer side of the electric resistance welded clad steel pipe or tube, and metallic microstructure at the positions (i) and (ii) is metallic microstructure in which a total area ratio of ferrite and bainite is 90% or more and an average grain size of ferrite and bainite is 15 μm or less; and
(B) the first layer is located on an inner side of the electric resistance welded clad steel pipe or tube, and metallic microstructure at the positions (ii) and (iii) is metallic microstructure in which a total area ratio of ferrite and bainite is 90% or more and an average grain size of ferrite and bainite is 15 μm or less.

4. The electric resistance welded clad steel pipe or tube according to claim 1 , composed of the first layer, the second layer, and a third layer placed on an other surface of the first layer and made of stainless steel or a nickel-containing alloy as cladding metal.

5. The electric resistance welded clad steel pipe or tube according to claim 4 , wherein metallic microstructure at the position (ii) is metallic microstructure in which a total area ratio of ferrite and bainite is 90% or more and an average grain size of ferrite and bainite is 15 μm or less.

6. The electric resistance welded clad steel pipe or tube according to claim 1 , wherein the cladding metal is stainless steel having a chemical composition containing, in mass %,
C: 0.15% or less,
Si: 5.0% or less,
Mn: 2.0% or less,
P: 0.1% or less,
S: 0.1% or less,
Ni: 1.0% or less,
Cr: 11.0% or more, and
N: 0.5% or less,
with the balance being Fe and inevitable impurities.

7. The electric resistance welded clad steel pipe or tube according to claim 1 , wherein the cladding metal is stainless steel or a nickel-containing alloy having a chemical composition containing, in mass %,
C: 0.15% or less,
Si: 5.0% or less,
Mn: 2.0% or less,
P: 0.1% or less,
S: 0.1% or less,
Ni: 6.0% or more,
Cr: 15.0% or more, and
N: 0.5% or less,
with the balance being Fe and inevitable impurities.

8. The electric resistance welded clad steel pipe or tube according to claim 6 , wherein the chemical composition of the cladding metal further contains, in mass %, at least one of the following (a), (b), and (c):
(a) one or more selected from the group consisting of
Mo: 20.0% or less,
Cu: 5.0% or less,
Al: 2.0% or less,
Co: 3.0% or less,
W: 5.0% or less, and
Ta: 5.0% or less,

(b) one or more selected from the group consisting of
Ti: 2.0% or less,
Nb: 5.0% or less,
V: 2.0% or less, and
Zr: 2.0% or less, and

(c) one or more selected from the group consisting of
B: 0.0050% or less,
Ca: 0.0050% or less,
Mg: 0.0030% or less, and
REM: 0.10% or less.

9. The electric resistance welded clad steel pipe or tube according to claim 7 , wherein the chemical composition of the cladding metal further contains, in mass %, at least one of the following (a), (b), and (c):
(a) one or more selected from the group consisting of
Mo: 20.0% or less,
Cu: 5.0% or less,
Al: 2.0% or less,
Co: 3.0% or less,
W: 5.0% or less, and
Ta: 5.0% or less,

(b) one or more selected from the group consisting of
Ti: 2.0% or less,
Nb: 5.0% or less,
V: 2.0% or less, and
Zr: 2.0% or less, and

(c) one or more selected from the group consisting of
B: 0.0050% or less,
Ca: 0.0050% or less,
Mg: 0.0030% or less, and
REM: 0.10% or less.

10. The electric resistance welded clad steel pipe or tube according to claim 1 , wherein the base metal is carbon steel or low-alloy steel having a chemical composition containing, in mass %,
C: 0.02% to 0.20%,
Si: 0.01% to 1.0%,
Mn: 0.1% to 2.0%,
P: 0.05% or less,
S: 0.01% or less, and
Al: 0.1% or less,
with the balance being Fe and inevitable impurities.

11. The electric resistance welded clad steel pipe or tube according to claim 10 , wherein the chemical composition of the base metal further contains, in mass %, one or more selected from the group consisting of
Ti: 0.1% or less,
Nb: 0.2% or less,
Cu: 0.5% or less,
Ni: 0.5% or less,
Cr: 0.5% or less,
Mo: 0.5% or less,
V: 0.1% or less, and
Ca: 0.0005% to 0.0050%.

12. A method of producing an electric resistance welded clad steel pipe or tube, the method comprising:
preparing a clad steel strip including a first layer made of carbon steel or low-alloy steel as base metal and a second layer placed on one surface of the first layer and made of stainless steel or a nickel-containing alloy as cladding metal;
subjecting both transverse ends of the clad steel strip to groove machining, to form a groove;
forming the clad steel strip into a pipe or tube shape, to obtain an open pipe or tube that is a cylindrical strip before welding; and
electric resistance welding a pair of butted parts of the open pipe or tube facing each other, to obtain an electric resistance welded clad steel pipe or tube,
wherein in the groove machining, the transverse ends of the clad steel strip are indented from a second layer side,
the groove satisfies the following conditions:
a clad interface between the second layer and the first layer turns from the second layer side toward a thickness center of the clad steel strip;
a bevel angle θ 1 on the second layer side is 10° or more and 50° or less;
a groove depth d 1 is 10% or more and 45% or less of a thickness t of the clad steel strip; and
a projection clad ratio R1 defined by the following Expression (1) is 25% or more and 50% or less,
R 1=( t c1 *+d 1)/ t× 100(%)  (1)

where R1 is the projection clad ratio, t c1 * is a thickness of the second layer at a root surface in mm, d 1 is the groove depth on the second layer side in mm, and t is the thickness of the clad steel strip in mm,
the electric resistance welding is performed by, while subjecting the pair of butted parts to gas shielding, butt pressing the pair of butted parts with an amount of upse

Assignees

• Jfe Steel Corp

Inventors

• Ide Shinsuke
• Matsumoto Akihide
• Matsumoto Atsushi
• Okabe Takatoshi

Classifications

• B32B15/011 Primary

  all layers being formed of iron alloys or steels · CPC title

• C22C38/02

  containing silicon · CPC title

• C21D9/08

  for tubular bodies or pipes · CPC title

• C22C38/00

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

• C22C19/056

  with the maximum Cr content being at least 10% but less than 20% · CPC title