Apparatus line for manufacturing seamless steel pipe and tube and method of manufacturing duplex seamless stainless steel pipe

Patent metadata

Field	Value
Publication number	US-10544476-B2
Application number	US-201515529842-A
Country	US
Kind code	B2
Filing date	Oct 7, 2015
Priority date	Nov 27, 2014
Publication date	Jan 28, 2020
Grant date	Jan 28, 2020

Abstract

An apparatus line for manufacturing seamless steel pipes and tubes includes: a heating apparatus for heating a steel raw material; a piercing apparatus for piercing the heated steel raw material thus forming a hollow material; and a rolling apparatus for applying working to the hollow material to form a seamless steel pipe having a predetermined shape. A cooling apparatus is arranged on an exit side of the rolling apparatus. A heated steel raw material is worked by the rolling apparatus after being pierced by the piercing apparatus, and thereafter, using a surface temperature of a hollow piece before being cooled by the cooling apparatus as a cooling start temperature, the hollow piece is cooled to a cooling stop temperature differing by 50° C. or more from the cooling start temperature and being equal to or above 600° C. at an average cooling speed of 1.0° C./s or more in terms of an outer surface temperature.

First claim

The invention claimed is:

1. A method of manufacturing duplex seamless stainless steel pipes and tubes using an apparatus line for manufacturing seamless steel pipes and tubes, wherein
a steel raw material is heated by a heating apparatus,
the hollow material is formed by piercing the steel raw material by a piercing apparatus,
the hollow material is formed into a hollow piece by applying hot working by a rolling apparatus,
the hollow piece is cooled by the cooling apparatus, and
the steel raw material has the composition which contains, by mass %,
0.050% or less C, 2.00% or less Si,
5.00% or less Mn, 0.05% or less P,
0.03% or less S, 16.0 to 35.0% Cr,
3.0 to 12.0% Ni, 5.0% or less Mo,
0.1% or less Al, 0.5% or less N, and
Fe and unavoidable impurities as a balance, wherein
the steel raw material is heated to a temperature of (δ A −300° C.) to (δ A +100° C.) by the heating apparatus,
hot working is applied to the rolling apparatus, and
using a surface temperature of the hollow piece before being cooled by the cooling apparatus as a cooling start temperature, the cooling apparatus cools the hollow piece to a cooling stop temperature having a temperature difference of at least 50° C. or more from the cooling start temperature and being equal to or above 600° C. at an average cooling speed of 1.0° C./s or more in terms of an outer surface temperature.

2. The method of manufacturing duplex seamless stainless steel pipes and tubes according to claim 1 , wherein
the hollow piece after cooling is made to pass through a heat-retention apparatus having a heating function.

3. The method of manufacturing duplex seamless stainless steel pipes and tubes according to claim 2 , wherein
cooling is performed in the heat-retention apparatus at an average cooling speed of 1.0° C./s or less at a position on an outer surface of the hollow piece.

4. The method of manufacturing duplex seamless stainless steel pipes and tubes according to claim 2 , wherein
heating is performed in the heat-retention apparatus at an average heating speed of 1.0° C./s or more at a position on an outer surface of the hollow piece.

5. The method of manufacturing duplex seamless stainless steel pipes and tubes in claim 1 , wherein
the steel raw material further contains, in addition to the composition, by mass %, one, two or more kinds of elements selected from a group consisting of
3.0% or less Nb, 0.1% or less Ti,
3.0% or less V, 0.5% or less Zr,
3.5% or less W, 3.5% or less Cu,
0.05% or less REM, 0.01% or less B, and
0.1% or less Ca.

6. The method of manufacturing duplex seamless stainless steel pipes and tubes according to claim 3 , wherein
the average heating speed at the position on the outer surface of the hollow piece by the heat-retention apparatus is set to 1.0° C./s or more.

7. The method of manufacturing a duplex seamless stainless steel pipes and tubes in claim 2 , wherein
the steel raw material further contains, in addition to the composition, by mass %, one, two or more kinds of elements selected from a group consisting of
3.0% or less Nb, 0.1% or less Ti,
3.0% or less V, 0.5% or less Zr,
3.5% or less W, 3.5% or less Cu,
0.05% or less REM, 0.01% or less B, and
0.1% or less Ca.

8. The method of manufacturing a duplex seamless stainless steel pipes and tubes in claim 3 , wherein
the steel raw material further contains, in addition to the composition, by mass %, one, two or more kinds of elements selected from a group consisting of
3.0% or less Nb, 0.1% or less Ti,
3.0% or less V, 0.5% or less Zr,
3.5% or less W, 3.5% or less Cu,
0.05% or less REM, 0.01% or less B, and
0.1% or less Ca.

9. The method of manufacturing a duplex seamless stainless steel pipes and tubes in claim 4 , wherein
the steel raw material further contains, in addition to the composition, by mass %, one, two or more kinds of elements selected from a group consisting of
3.0% or less Nb, 0.1% or less Ti,
3.0% or less V, 0.5% or less Zr,
3.5% or less W, 3.5% or less Cu,
0.05% or less REM, 0.01% or less B, and
0.1% or less Ca.

10. The method of manufacturing a duplex seamless stainless steel pipes and tubes in claim 6 , wherein
the steel raw material further contains, in addition to the composition, by mass %, one, two or more kinds of elements selected from a group consisting of
3.0% or less Nb, 0.1% or less Ti,
3.0% or less V, 0.5% or less Zr,
3.5% or less W, 3.5% or less Cu,
0.05% or less REM, 0.01% or less B, and
0.1% or less Ca.

Assignees

• Jfe Steel Corp

Inventors

• Sasaki Shunsuke
• Katsumura Tatsuro
• Ushida Hiroki
• Kato Yasushi

Classifications

• B21B45/02

  for lubricating, cooling, or cleaning {(in particular in combination with forging or pressing devices B21B15/005, control of flatness or profile using lubricating or cooling B21B37/44)} · CPC title

• C22C38/58

  with more than 1.5% by weight of manganese · CPC title

• C22C38/00

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

• C21D9/08

  for tubular bodies or pipes · CPC title

• C21D8/10

  during manufacturing of tubular bodies · CPC title