Electric resistance welded steel pipe or steel tube having excellent HIC resistance and low-temperature toughness in electric resistance welded part, and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-9873164-B2
Application number	US-201314430771-A
Country	US
Kind code	B2
Filing date	Sep 20, 2013
Priority date	Sep 24, 2012
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

Electric resistance welded steel pipes or steel tubes with a tensile property TS of not less than 434 MPa which have electric resistance welded parts exhibiting both excellent HIC resistance and excellent low-temperature toughness, and methods for manufacturing such steel pipes or steel tubes.

First claim

The invention claimed is:

1. An electric resistance welded steel pipe or steel tube including an electric resistance welded part, the steel pipe or steel tube having a chemical composition comprising:
C: 0.03 to 0.59%, by mass %;
Si: 0.10 to 0.50%, by mass %;
Mn: 0.40 to 2.10%, by mass %;
Al: 0.01 to 0.35%, by mass %;
Ca: 0.0001 to 0.0040%, by mass %; and
remaining Fe and unavoidable impurities as a balance, the Si content and the Mn content being such that Mn/Si (mass ratio) is in the range of 6.0 to 9.0,
wherein the steel pipe or steel tube has a tensile strength TS of not less than 434 MPa, and
in the electric resistance welded part the total amount of silicon, manganese, aluminum, calcium and chromium present in inclusions having an equivalent circle diameter of 8 μm or more is not more than 16 ppm in terms of mass % relative to the total mass of a 2 mm wide portion of the electric resistance welded part including base iron.

2. The electric resistance welded steel pipe or steel tube according to claim 1 , wherein the chemical composition further comprises Cr: 0.01 to 1.09%, by mass %.

3. The electric resistance welded steel pipe or steel tube according to claim 1 , wherein the chemical composition further comprises at least one of Cu: 0.01 to 0.35%, by mass %, Mo: 0.01 to 0.25%, by mass %, Ni: 0.01 to 0.20%, by mass %, and B: 0.0001 to 0.0030%, by mass %.

4. The electric resistance welded steel pipe or steel tube according to claim 1 , wherein the chemical composition further comprises at least one of Nb: 0.001 to 0.060%, by mass %, V: 0.001 to 0.060%, by mass %, and Ti: 0.001 to 0.080%, by mass %.

Assignees

• Jfe Steel Corp

Inventors

• Toyoda Shunsuke
• Goto Sota
• Okabe Takatoshi
• Yonemoto Atsushi

Classifications

• C22C38/28

  with titanium or zirconium · CPC title

• C21D6/002

  containing Cr (C21D6/004 takes precedence) · CPC title

• C22C38/16

  containing copper · CPC title

• C21D6/004

  containing Cr and Ni · CPC title

• C21D1/613

  Gases; Liquefied or solidified normally gaseous material · CPC title